An underlay element and a method of arranging an underlay element

Abstract

The present disclosure relates to an underlay element (1) configured to be arranged between a flooring (10) and a sub-floor (20), including a foamed base layer (2) configured to be arranged on the sub-floor (20), a deformation resistant layer (3) attached to the foamed base layer (2), the deformation resistant layer (3) being more rigid than the foamed base layer (2). The disclosure further relates to a flooring covering including an underlay element (1).

Description

[0001] AN UNDERLAY ELEMENT AND A METHOD OF ARRANGING

[0002] AN UNDERLAY ELEMENT

[0003] Technical field

[0004] The present disclosure relates to an underlay element for flooring. More specifically, the disclosure relates to an underlay element configured to be provided between a flooring and a sub-floor. The present disclosure also relates to a floor covering including such an underlay element, and to a method to arrange a floor covering including such an underlay element.

[0005] Technical background

[0006] An underlay, such as a foam, may be arranged between a floor covering and a sub-floor. The underlay may compensate for any unevenness of the subfloor and may, for example, reduce the risk of damaging components of the floor covering, such as floor panels. Moreover, the underlay may improve the characteristics of the floor covering, such as its comfort and / or sound properties, e.g., the reflective walking sound and / or impact sound. In some configurations, the underlay may function as a moisture barrier.

[0007] Currently commercially available underlays for flooring are focused to be cost effective and easily produced, yet still have the abilities of absorb unevenness's and still provide sound reduction. Common materials used are IXPE, EVA, XPS or more high-end PET and XPO type of underlays. All types of underlays compress over time which may result in that the support of the underlay ceases to be sufficient.

[0008] Some types of floor panels arranged on an underlay are more prone to becoming deformed or even damaged when subject to load or stress, especially during an extended period of time. Such load or stress can be simulated in a Castor chair test where high local forces may occur. In particular, mechanical locking systems provided to join adjacent floor panels may become negatively affected. This type of problems may particularly arise for thin floor panels and / or for floor panels having low elastic moduli. Examples include, e.g., plastic flooring, such as LVT (Luxury Vinyl Tile) and SPC (Stone Plastic Composite), and thin laminate flooring. The displacement, due to compression of the underlay, of certain portions of the floor panels during load or stress may result in failure of the mechanical locking system. As a result of the displacement, the joints of adjacent floor panels, and sometimes the core of the floor panel, fail and break. The floor panels suffer what is called fatigue stress and is over-exerted and thus fail in the mechanical locking system, such as breakage of the locking strip. Failure of the mechanical locking system causes in most cases delamination and / or height differences between adjacent floor panels.

[0009] EP2615222A2 discloses an underlay for a laminate or parquet floor comprising a heavy layer and a spring layer. WO2022139664A1 discloses an underlay element comprising restrictions members configured to provide a certain dampening effect of the compression of the underlay element.

[0010] In view of the above discussion, it is clear that there is a need for improved an underlay, which solve at least some of the problems stated above, preferably while preserving at least some of the advantages described above.

[0011] Summary

[0012] It is an object of at least embodiments of the present disclosure to provide an improved underlay element for a flooring.

[0013] According to a first aspect of the present disclosure, an underlay element configured to be arranged between a flooring and a sub-floor is provided. The underlay element comprises a foamed base layer configured to be arranged on the sub-floor, a deformation resistant layer attached to the foamed base layer, the deformation resistant layer being more rigid than the foamed base layer.

[0014] The deformation resistant layer may have a tensile force at maximum load exceeding 100 N as measured in accordance with ISO527-l:2012 and ISO527-2 / - 3:2018.

[0015] ISO527-l:2012 and ISO527-3:2018 is the relevant standard for sheets < 1 mm thick, and ISO527-l:2012 and ISO527-2:2018 is the relevant standard for sheets > 1 mm thick. Therefore, reference is made to ISO527-l:2012 and ISO527-2 / -3:2018 in the present disclosure, wherein ISO527-l:2012 and ISO527-3:2018 is applicable for a deformation resistant layer being < 1 mm thick, and ISO527-l:2012 and ISO527- 2:2018 is applicable for a deformation resistant layer being > 1 mm thick.

[0016] In one example, the deformation resistant layer has a tensile force at maximum load exceeding 150 N as measured in accordance with ISO527-l:2012 and ISO527-2 / -3:2018, such as exceeding 165 N as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018. The deformation resistant layer may have a tensile force at maximum load of 150-400 N as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018.

[0017] In an example wherein the deformation resistant layer has a tensile force at maximum load exceeding 100 N, the deformation resistant layer can be rigid and / or strong enough to distribute a load, static and dynamic, applied in a direction perpendicular to the planar extension of the underlay element, such as distribute a load over an area of the underlay element. For example, the deformation resistant layer may be rigid and / or strong enough to distribute the load without any substantial compression of the underlay element, such as distribute the load over an area of the underlay element. Thereby, compression of the foamed base layer may at least be reduced, such that strength of a mechanical locking system of the flooring arranged on the underlay element can be improved, and / or maintained over time.

[0018] The deformation resistant layer may have a strain at maximum load being less than 0.5 mm / mm as measured in accordance with ISO527-l:2012 and ISO527-2 / - 3:2018, such as less than 0.25 mm / mm as measured in accordance with ISO527- 1:2012 and ISO527-2 / -3:2018.

[0019] In an example wherein the deformation resistant layer may have a strain at maximum load being less than 0.5 mm / mm, the deformation layer may resist deformation, and may thereby improve strength of a mechanical locking system of the flooring arranged on the underlay element.

[0020] The deformation resistant layer may have a stress at maximum load exceeding 15 MPa, such as exceeding 20 MPa, as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018.

[0021] The underlay element may be configured to be arranged below a flooring comprising floor panels being assembled to each other by a mechanical locking device, or mechanical locking system.

[0022] The floor panels may be assembled in a floating assembly, such as in a glue- free installation.

[0023] The underlay element may be configured to support floor panels being loosely arranged on the underlay element.

[0024] The underlay element may be configured to extend, such as continuously extend, below a mechanical locking device, or mechanical locking system, of adjacent floor panels.

[0025] The underlay element may be configured to cooperate with a mechanical locking device, or mechanical locking system, of floor panels.

[0026] The foamed base layer may be compressible.

[0027] The deformation resistant layer may be less compressible than the foamed base layer.

[0028] A density of the foamed base layer may be less than a density of the deformation resistant layer. The foamed base layer may have a compressive strength about 50-900 kPa (at 0.5 mm) as measured in accordance with EN16354:2018, such as 50-500 kPa (at 0.5 mm) as measured in accordance with EN16354:2018, such as 50-250 kPa (at 0.5 mm) as measured in accordance with EN16354:2018.

[0029] The deformation resistant layer may be un-foamed.

[0030] The deformation resistant layer may be fibre-reinforced.

[0031] The deformation resistant layer may be reinforced by organic and / or inorganic fibres. The fibres may be chosen from the group of natural fibres, glass fibres, polymer fibres, mineral-based fibres, carbon fibres, and a combination thereof.

[0032] The deformation resistant layer may comprise a glass fibre reinforcement wherein the glass fibres may have a stiffness of 52-95 GPa as measured according to ASTM C1557-20.

[0033] The deformation resistant layer may comprise a glass fibre reinforcement having a weight of 10-180 g / m2.

[0034] The underlay element may further comprise a plurality of restrictions members at least partly embedded in the foamed base layer, the restrictions members being configured to restrict compression of the underlay element by being less compressible than the foamed base layer.

[0035] A density of the deformation resistant layer may be 250-3000 kg / m3, preferably 500-3000 kg / m3, more preferably 800-1500 kg / m3. A density of the deformation resistant layer may exceed 500 g / m3.

[0036] A density of the foamed base layer may be 20-700 kg / m3, preferably 20-300 kg / m3. The density of the foamed base layer may be less than 500 kg / m3, such as less than 300 kg / m3-

[0037] The density of the deformation resistant layer may be at least two times the density of the foamed layer.

[0038] A thickness of the foamed base layer may exceed a thickness of the deformation resistant layer.

[0039] A thickness of the foamed base layer may be 0.4 - 3.5 mm, such as 0.6 - 1.8 mm.

[0040] A thickness of the deformation resistant layer may be 0.05-2 mm, such as 0.25- 0.75 mm. The thickness of the deformation resistant layer may exceed 0.2 mm.

[0041] A thickness of the deformation resistant layer may be less than 30 % of a thickness of the foamed base layer.

[0042] The deformation resistant layer may have a tensile modulus exceeding 100 MPa as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018. ISO527-l:2012 and ISO527-3:2018 is the relevant standard for sheets < 1 mm thick, and ISO527-l:2012 and ISO527-2:2018 is the relevant standard for sheets > 1 mm thick. Therefore, reference is made to ISO527-l:2012 and ISO527-2 / -3:2018 in the present disclosure, wherein ISO527-l:2012 and ISO527-3:2018 is applicable for a deformation resistant layer being < 1 mm thick, and ISO527-l:2012 and ISO527- 2:2018 is applicable for a deformation resistant layer being > 1 mm thick.

[0043] The deformation resistant layer may form a vapour barrier.

[0044] The underlay element may consist of the deformation resistant layer and the foamed base layer, optionally with an adhesive attaching the deformation resistant layer to the foamed based layer.

[0045] The deformation resistant layer may be provided with an adhesive configured to attach the deformation resistant layer to the foamed base layer.

[0046] The foamed base layer may comprise a thermoplastic polymer.

[0047] The foamed base layer may comprise one or more cross-linked expanded polymers.

[0048] The deformation resistant layer may comprise a thermoplastic material.

[0049] The underlay element may have a planar extension exceeding a planar extension of a floor panel intended to be arranged on the underlay element.

[0050] According to a second aspect of the present disclosure, a floor covering, comprising an underlay element and at least two floor panels configured to be arranged on the underlay element, is provided. The underlay element comprises a foamed base layer configured to be arranged on a sub-floor and a deformation resistant layer attached to the foamed base layer, wherein the deformation resistant layer is more rigid than the foamed base layer and said at least two floor panels are configured to be arranged on the deformation resistant layer, wherein said at least two floor panels are configured to be joined to each other by a mechanical locking system comprising a locking strip provided at a first edge of a first floor panel, configured to cooperate with a locking groove provided at an adjacent edge of a second floor panel, wherein the locking strip protrudes from the first edge in a first direction and extends along the first edge in a second direction, wherein the underlay element is configured to extend beyond an extension of the locking strip at least in the first direction towards the adjacent edge of the second floor panel.

[0051] The underlay element may be configured to extend below the locking strip along at least a portion of the extension of the locking strip in the second direction.

[0052] The underlay element may be configured to extend below the locking strip along the entire extension of the locking strip in the second direction. A planar extension of the underlay element may exceed a planar extension of at least one of the floor panels.

[0053] The at least two floor panels may be configured to be loosely arranged on the underlay element.

[0054] The underlay element in the second aspect of the disclosure may be the underlay element disclosed above with reference to the first aspect.

[0055] According to a third aspect of the present disclosure, a method to arrange a floor covering comprising an underlay element and at least two floor panels is provided. The method comprises: arranging an underlay element on a sub-floor, the underlay element comprising a foamed base layer configured to be arranged on the sub-floor and a deformation resistant layer attached to the foamed base layer, the deformation resistant layer being more rigid than the foamed base layer, joining a first edge of a first floor panel to an adjacent edge of a second floor panel by a mechanical locking system comprising a locking strip protruding from the first edge in a first direction and extending along the first edge of the first floor panel in a second direction, the locking strip being configured to cooperate with a locking groove provided at the adjacent edge of the second floor panel, arranging the joined floor panels on the underlay element such that the underlay element extends beyond an extension of the locking strip at least in the first direction towards the adjacent edge of the second floor panel.

[0056] The underlay element may be configured to extend below the locking strip along at least a portion of the extension of the locking strip in the second direction.

[0057] The underlay element may be configured to extend below the locking strip along the entire extension of the locking strip in the second direction.

[0058] A planar extension of the underlay element may exceed a planar extension of at least one of said at least two floor panel.

[0059] The at least two floor panels may be configured to be loosely arranged on the underlay element.

[0060] The underlay element in the third aspect of the disclosure may be the underlay element disclosed above with reference to the first aspect.

[0061] According to fourth aspect of the present disclosure, an underlay element configured to be arranged between a sub-floor and a flooring comprising one or more floor panels is provided. The underlay element comprises a foamed base layer configured to be arranged on the sub-floor, a deformation resistant layer attached to the foamed base layer, the deformation resistant layer being more rigid than the foamed base layer, wherein the underlay element is configured to extend below a locking strip protruding from an edge of a floor panel in a first direction and extending along the edge in a second direction, the locking strip being configured to cooperate with a locking groove provided at an edge of an adjacent floor panel for joining two adjacent floor panels, and wherein the underlay element is configured to extend beyond an extension of the locking strip in the first direction towards the edge of the adjacent floor panel.

[0062] The underlay element may be configured to extend below the locking strip along at least a portion of the extension of the locking strip in the second direction.

[0063] The underlay element may be configured to extend below the locking strip along the extension of the locking strip in the second direction.

[0064] A planar extension of the underlay element may exceed a planar extension of at least one of the floor panels.

[0065] The one or more floor panels may be configured to be loosely arranged on the underlay element.

[0066] The underlay element in the fourth aspect of the disclosure may be the underlay element disclosed above with reference to the first aspect.

[0067] Brief description of the drawings

[0068] FIG. 1 discloses joined floor panels arranged on a conventional underlay element.

[0069] FIG. 2A-B discloses an example of an underlay element, wherein FIG. 2A shows a perspective view and FIG. 2B shows a side view.

[0070] FIG. 3 discloses an example of an underlay element provided in form of a roll.

[0071] FIG. 4A discloses a first example of joined floor panels arranged on an underlay.

[0072] FIG. 4B discloses a second example of joined floor panels arranged on an underlay.

[0073] FIG. 4C discloses a third example of joined floor panels arranged on an underlay.

[0074] FIG. 5 discloses an underlay element including restriction members.

[0075] FIG. 6 discloses an example of a floor covering comprising underlay elements and floor panels in a top view.

[0076] FIG. 7 discloses an example of a floor covering comprising underlay elements and floor panels in a top view.

[0077] FIG. 8 discloses an arrangement of layers for a reference example used in tests. FIG. 9 discloses an arrangement of layers for examples of the present disclosure used in tests.

[0078] Detailed description

[0079] FIG. 1 discloses floor panels 101, 102 arranged on a conventional underlay element 100 comprising a compressible material, which is pre-attached to the floor panels 101, 102. The underlay element 100 is arranged on a sub-floor 103. The floor panels 101, 102 are joined to each other by a mechanical locking system 104, comprising among other a locking strip 105 and an integrated tongue 106 formed in a core 110 of the floor panel 102 arranged in a tongue groove 107. As visible in the FIG. 1, a load P applied on one of the floor panels 102 results in that the underlay element 100 becomes compressed below the locking strip 105. The load P may be a dynamic load, such as a castor chair, moving furniture, pallet trolley, etc., and the load will over time create a permanent compression of the underlay element 100. The rigid floor panel 102 will thereby flex up and down. The integrated tongue 106 has been displaced from the tongue groove 107 and does no longer lock the floor panels 101, 102 in a vertical direction. The cyclic flexing of the floor panel 102 results in fatigue stress, breaking the joint, and / or break, such as breaking the locking strip 105.

[0080] The floor panels 101, 102 may also be subjected to a static load P, such as a piece of furniture, which creates a permanent pressure zone that may cause the underlay element 100 to compress as shown in FIG. 1. The compression of the underlay element 100 may result in that the locking joints of the floor panels 101, 102 separate.

[0081] FIGS. 2A-B shows an underlay element 1 according to the present disclosure. The underlay element 1 is suitable for thin floorings, such a flooring having a thickness of less than 10 mm, such that less than 7 mm. The underlay element 1 may be configured for thin laminate floorings, e.g., having a thickness being less than 10 mm, such that less than 7 mm. The underlay element 1 may be configured for laminate floorings having a thickness of 3-7 mm. The underlay element 1 may be configured for thin plastic floorings, e.g. having a thickness being less than 10 mm, such that less than 7 mm. The underlay element 1 may be configured for plastic floorings having a thickness of 3-7 mm. The plastic flooring may be formed by Luxury Vinyl Tiles (LVT tiles), Stone Plastic (Polymer) Composite panels (SPC panels), or Expanded Polymer Core panels (EPC panels), also known as Water Proof Core panels (WPC panels). The underlay element 1 may be configured for other plastic floorings, such as PU floorings, PP floorings, PET floorings, or PE floorings. The underlay element 1 comprises a foamed base layer 2 and a deformation resistant layer 3. The deformation resistant layer 3 is arranged on the foamed base layer 2. The deformation resistant layer 3 has a first surface and a second surface. A flooring is intended to be arranged on the first surface of the deformation resistant layer 3. When positioned in a room, the first surface of the deformation resistant layer 3 forms an upper surface. The foamed base layer 2 has a first surface and a second surface. The second surface of the foamed base layer 2 is configured to be arranged on a sub-floor. When positioned in a room, the second surface of the foamed base layer 2 forms a lower surface, facing the sub-floor. The deformation resistant layer 3 is configured to be arranged on the first surface of the foamed base layer 2, such that the second surface of the deformation resistant layer 3 is facing the first surface of the foamed base layer 2.

[0082] The first surface of the deformation resistant layer 3 may be planar, or substantially planar. The first surface of the deformation resistant layer 3 may be free from recesses and / or channels. The deformation resistant layer 3 may be free from recesses and / or channels.

[0083] The first surface of the deformation resistant layer 3 may have an extension in one plane only.

[0084] The deformation resistant layer 3 may be a film.

[0085] The deformation resistant layer 3 is attached to the foamed base layer 2, for example, by an adhesive, and / or being pressed by applying heat and pressure to the foamed base layer 2.

[0086] The deformation resistant layer 3 may be attached to the foamed base layer 2 as a film. In one example, the deformation resistant layer 3 may not be a coating applied on the foamed base layer 2, but applied as a film.

[0087] In one example, the underlay element 1 consists of the deformation resistant layer 3 and the foamed base layer 2, optionally with an adhesive attaching the deformation resistant layer 3 to the foamed base layer 2.

[0088] The underlay element 1 may have a rectangular shape, as shown in FIG. 2A. The underlay element 1 may have a planar extension, extending in a length direction and in width direction.

[0089] The deformation resistant layer 3 may be a continuously extending on the foamed base layer 2. The deformation resistant layer 3 may substantially cover a planar extension of the foamed base layer 2.

[0090] FIG. 2B shows a side view of a part of the underlay element 1. The side view corresponds to a cross-sectional view of the underlay element 1 as well. The underlay element 1 may be provided in form of a roll, as shown in FIG. 3. The underlay element 1 may be rolled such that the deformation resistant layer 3 forms an outer surface of the roll. The underlay element 1 may be unrolled on the sub-floor and cut into a suitable length to fit the shape of the room.

[0091] The deformation resistant layer 3 is more rigid than the foamed base layer 2. The deformation resistant layer 3 is less compressible than the foamed base layer 2. The deformation resistant layer 3 is configured to restrict compression of the underlay element 1, in a direction perpendicular to the planar extension of the underlay element 1, when a load is applied to a flooring applied on the underlay element 1, which will be discussed below with reference to FIGS. 4A-4C. The foamed base layer 2 is compressible, such that the foamed base layer 2 may adapt to any irregularities of the sub-floor, and / or reduce sound.

[0092] The deformation resistant layer 3 may have a tensile force at maximum load exceeding, or equal, 100 N as measured in accordance with ISO527-l:2012 and ISO527-2 / -3:2018. By having a tensile force at maximum load exceeding 100 N, the deformation resistant 3 is rigid and / or strong enough to distribute a load, static and dynamic, applied in a direction perpendicular to the planar extension of the underlay element 1, i.e., in the thickness direction of the underlay element 1. The deformation resistant 3 is rigid and / or strong enough to distribute the load over an area of the underlay element 1. For example, the deformation resistant layer 3 may be rigid and / or strong enough to distribute the load without any substantial compression of the underlay element 1 by distributing the load over an area of the underlay element 1.

[0093] In one example, the deformation resistant layer has a tensile force at maximum load exceeding, or equal, 150 N, for example, exceeding, or equal, 165 N, as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018. In one example, the deformation resistant layer has a tensile force at maximum load exceeding, or equal, 169 N as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018. The deformation resistant layer may have a tensile force at maximum load of 150-400 N as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018.

[0094] The deformation resistant layer 3 may have a strain at maximum load being less than, or equal, 0.5 mm / mm, such as less than, or equal, 0.25 mm / mm, as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018. In one example, the deformation resistant layer 3 may have a strain at maximum load being less than, or equal, 0.17 mm / mm, as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018. The deformation resistant layer 3 may have a strain at maximum load of 0.02-0.25 mm / mm, as measured in accordance with ISO527- 1:2012 and ISO527-2 / -3:2018.

[0095] In an example wherein the deformation resistant layer 3 has a strain at maximum load being less than 0.5 mm / mm, the deformation layer 3 may resist deformation, and may thereby improve strength of a mechanical locking system of the flooring arranged on the underlay element.

[0096] The deformation resistant layer 3 may have a stress at maximum load exceeding, or equal, 15 MPa, such as exceeding, or equal, 20 MPa, as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018. In one example, the deformation resistant layer 3 may have a stress at maximum load exceeding of 15- 50 MPa, as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018.

[0097] 150527-1:2012 and ISO527-3:2018 is the relevant standard for sheets < 1 mm thick, and 150527-1:2012 and 150527-2:2018 is the relevant standard for sheets > 1 mm thick. Therefore, reference is made to 150527-1:2012 and ISO527-2 / -3:2018 in the present disclosure, wherein 150527-1:2012 and ISO527-3:2018 is applicable for a deformation resistant layer being < 1 mm thick, and 150527-1:2012 and ISO527- 2:2018 is applicable for a deformation resistant layer being > 1 mm thick.

[0098] A thickness of the deformation resistant layer 3 may be less than a thickness of the foamed base layer 2. In one example, the thickness of the deformation resistant layer 3 is less than 30 % of a thickness of the foamed base layer 2.

[0099] In examples, the thickness of the foamed base layer 2 may be 0.4 - 3 mm, such as 0.6 - 1.8 mm. The thickness of the foamed base layer 2 exceed 0.4 mm.

[0100] The thickness of the deformation resistant layer may be 0.05-2 mm, such as 0.25-0.75 mm. The thickness of the deformation resistant layer 3 may exceed 0.2 mm. The thickness of the deformation resistant layer 3 may be 0.2-1 mm, such as 0.2-0.75 mm.

[0101] A total thickness of the underlay element 1 may be 0.45 to 3 mm, such as 0.65 to 2.55 mm.

[0102] Thickness is measured in direction perpendicular to the planar extension of the underlay element 1, such as in the z direction as indicated in FIGS. 2A-2B.

[0103] A density of the foamed base layer 2 may be less than a density of the deformation resistant layer 3. For example, the density of the deformation resistant layer 3 may be at least two times the density of the foamed layer 2. The density of the deformation resistant layer 3 may be 250-3000 kg / m3, preferably 500-3000 kg / m3, more preferably 800-1500 kg / m3. The density of the deformation resistant layer 3 may exceed 500 g / m3. A density of the foamed base layer 2 may be 20-700 kg / m3, preferably 20-300 kg / m3. The density of the foamed base layer 2 may be less than 500 kg / m3, such as less than 300 kg / m3-

[0104] The foamed base layer 2 is foamed, for example, by a blowing agent. The foamed base layer may have a compressive strength about 50-900 kPa (at 0.5 mm) as measured in accordance with EN16354:2018, such as 50-500 kPa (at 0.5 mm) as measured in accordance with EN16354:2018, such as 50-250 kPa (at 0.5 mm) as measured in accordance with EN16354:2018. Thereby, sound insulating properties may be obtained, and the foamed base layer 2 may adapt to irregularities of the sub-floor.

[0105] The deformation resistant layer 3 may be un-foamed. The deformation resistant layer 3 may however comprise hollow particles, such as hollow glass particles. The deformation resistant layer 3 may comprise cork particles, or similar, to improve sound damping properties.

[0106] The deformation resistant layer 3 may be fibre reinforced. The fibres reinforcing the deformation resistant layer 3 may be organic and / or inorganic fibres. The fibres may be natural fibres, glass fibres, carbon fibres, polymer fibres, mineralbased fibres, or a combination thereof. Examples of polymer fibres are nylon, aramid. Examples of natural fibres are wood, such as cellulose, sisal, hemp, coconut, cotton, kenaf, flaw, jute, abaca, banana leaf fibres, bamboo, wheat straw. In an example wherein the fibres are glass fibres, the glass fibres may be of E-type and / or of S-type.

[0107] The fibres may be orientated in at least in one direction, preferably at least two directions. For example, the fibres may be substantially orientated in a plane parallel to the planar extension of the underlay element 1. In one example, the fibres may be orientated in a plane parallel to the planar extension of the underlay element and in a direction substantially perpendicular to the plane.

[0108] The fibres may be provided as individual fibres in the deformation resistant layer 3, or may be provided as entangled fibres in the deformation resistant layer 3. The fibres may be provided in form of a woven structure of fibres. The woven structure may be plain, twill, atlas and / or leno.

[0109] In alternatives, the fibres may be provided in form of a non-woven. In a nonwoven, the fibres may have a length of 5-175 mm, for example, 10-100 mm. In other example the fibres may have a length of 15-75 mm.

[0110] The fibres may be positioned within of the deformation resistant layer 3. The fibres may be positioned in a lower portion of the deformation resistant layer 3, in an upper portion of deformation resistant layer 3, and / or in a centre portion of deformation resistant layer 3. The fibres may be embedded in the deformation resistant layer 3.

[0111] The fibre reinforcement in form of a glass fibre reinforcement may have a weight of 5-250 g / m2, for example, 10-180 g / m2such as 15-100 g / m2.

[0112] The glass fibres may have a stiffness of 52-95 GPa as measured according to ASTM C1557-20, such as 65-92 GPa, for example, 70-90 GPa as measured according to ASTM C1557-20.

[0113] The fibres may be glass fibres having a tensile strength in a range of 1800-4900 MPa as measured according to ASTM C1557-20, such as 2000-4900 MPa, for example, 2000-3800 MPa as measured according to ASTM C1557-20.

[0114] Further, the deformation resistant layer 3 may have a tensile modulus exceeding, or equal, 100 MPa, such as exceeding, or equal, 200 MPa, as measured in accordance with ISO527-l:2012 and ISO527-2 / -3:2018. The deformation resistant layer 3 may have a tensile modulus exceeding of 100-750 MPa, as measured in accordance with ISO527-l:2012 and ISO527-2 / -3:2018.

[0115] ISO527-l:2012 and ISO527-3:2018 is the relevant standard for sheets < 1 mm thick, and ISO527-l:2012 and ISO527-2:2018 is the relevant standard for sheets > 1 mm thick. Therefore, reference is made to ISO527-l:2012 and ISO527-2 / -3:2018 in the present disclosure, wherein 150527-1:2012 and ISO527-3:2018 is applicable for a deformation resistant layer being < 1 mm thick, and 150527-1:2012 and ISO527- 2:2018 is applicable for a deformation resistant layer being > 1 mm thick.

[0116] The deformation resistant layer 3 may comprise a thermoplastic material. The thermoplastic material may be polyethylene (PE), ethylene vinyl acetate (EVA), polyethylene terephthalate (PET), polypropylene (PP), polyolefin (PO), polystyrene (PS), thermoplastic polyurethane (TPU), or a combination thereof. The material of the deformation resistant layer 3 may also comprise thermoset polymers, for example, thermosetting polyurethane. The deformation resistant layer 3 may further comprise fillers, such as organic or inorganic fillers. One example of fillers are mineral fillers, such as calcium carbonate.

[0117] In one example, the deformation resistant layer comprises, or is formed of, duct tape applied on the foamed base layer 2.

[0118] The deformation resistant layer 3 may form a vapour barrier. The vapour barrier may be an integrated part of the deformation resistant layer 3.

[0119] The foamed base layer 2 may comprise one or more thermoplastic polymers.

[0120] The polymers may be polyethylene (PE), ethylene vinyl acetate (EVA), polyethylene terephthalate (PET), polypropylene (PP), polyolefin (PO), polystyrene (PS), such as extruded PP (XPP), polystyrene (PS), such as extruded PS (XPS), thermoplastic polyurethane (TPU), or a combination thereof.

[0121] The foamed base layer 2 may comprise one or more cross-linked expanded polymers. Such polymers are thermoplastic before the cross-linking process.

[0122] The polymers may be polyethylene (PE), preferably irradiation cross-linked PE (IXPE), ethylene vinyl acetate (EVA), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), preferably extruded PP (XPP) or cross-linked PP (IXPP), polystyrene (PS), preferably extruded PS (XPS) or expanded PS (EPS), or polyolefin (PO), preferably cross-linked PO (XPO), thermoplastic polyurethane (TPU), or a combination thereof.

[0123] The foamed base layer 2 may comprise polyurethane (PU).

[0124] In one example, the material of the foamed base layer 2 may comprise thermoset polymers as thermosetting polyurethane. The foamed base layer 2 may further comprise fillers, such as organic or inorganic fillers. One example of fillers are mineral fillers, such as calcium carbonate.

[0125] The cross-linked thermoplastic material may have a degree of cross-linking between 40% and 80%.

[0126] The material of the foamed base layer 2 may comprise a cellular foam. For example, a cell or pore size may range from 10 to 1300 microns. The cellular foam may be a closed-cell foam which may provide a more rigid foamed base layer 2 and which may provide an improved thermal insulation and / or moisture barrier. An open-cell foam, however, is equally conceivable, which may provide a more lightweight foamed base layer 2 and may provide improved sound dampening. Also, the amount of material needed in the foamed base layer may be reduced.

[0127] The foamed base layer 2 may comprise at least one filler. The filler may comprise an organic filler and / or an inorganic filler. Any of these fillers may increase the flexural strength and / or rigidity of the underlay element. The organic filler may also provide a light-weight material that may reduce a weight of the underlay element 1. For example, the organic filler may comprise cork particles and / or woodbased particles, such as wood fibres or wood flour. A top cut, such as a particle size D98, of the wood-based particles may be 1000 p.m. Alternatively, a particle size may be less than 1000 p.m, preferably according to ASTM Ell-17. For example, the particle size may be 0-250 p.m, e.g., 40% of which may be greater than 75 p.m. A bulk density of the wood-based particles may be 100-250 kg / m3. The cork particles may have a modulus of compression of 8-20 MPa and / or a bulk density of 55-320 kg / m3, such as 55-240 kg / m3. The foamed base layer 2 may comprise cork particles to a degree of up to 70 wt%. For example, the inorganic filler may comprise a mineral- based material, such as calcium carbonate (CaCCh), barium sulphate, wollastonite, talc, sand material, clay material, such as bentonite, or glass fibres.

[0128] The filler may have a size, preferably an average size, not exceeding 0.15 mm, such as not exceeding 0.10 mm, preferably in two or three perpendicular dimensions. An organic filler may have preferred size smaller than 0.25 mm, preferably in two or three perpendicular dimensions. In some embodiments herein, a particle size of the inorganic and / or organic filler in the first and / or second material may be determined according to ASTM Ell-17.

[0129] FIGS. 4A-4C show the underlay element 1 when a flooring 10 is arranged on the underlay element 1, thereby forming a floor covering. A lower surface of the flooring 10 is arranged on an upper surface of the deformation resistant layer 3. A lower surface of the foamed base layer 2 is arranged on a sub-floor 20. An upper surface of the flooring 10 may have a planar extension in a plane substantially parallel to the planar extension of the underlay element 1.

[0130] The deformation resistant layer 3 may have a planar extension substantially parallel to a planar extension of a lower surface of the flooring 10.

[0131] In FIGS. 4A-4C, the flooring 10 comprises at least a first floor panel 11 and a second floor panel 12, which are shown in part in FIGS. 4A-4C. In the following, the term panel is used for all shapes of panels and tiles.

[0132] In FIGS. 4A-4C, the first floor panel 11 and the second floor panel 12 are joined to each other along a first edge 15 by a mechanical locking system, which also may be referred to as a mechanical locking device. If the panels have an oblong shape, the first edge 15 may be a long side edge, or a short side edge. The mechanical locking system comprises at least a locking strip 13 configured to cooperate with a locking groove 16 for locking the first floor panel 11 to the second floor panel 12 in a horizontal direction. In the example shown in FIGS. 4A-4C, the first floor panel 11 comprises the locking strip 13 and the second floor panel 12 comprises the locking groove 16.

[0133] The locking strip 13 and the locking groove 16 each comprises a locking surface 17a, 17b configured to restrict movements in the horizontal direction. The locking surface 17a of the locking strip 13 is configured to cooperate with the locking surface 17b of the locking groove 16 to lock adjacent panels 11, 12 in the horizontal direction. The locking strip 13 protrudes from the first edge 15 in a first direction (depicted as x in FIGS. 4A-4C), perpendicular, or substantially perpendicular, to a second direction. The locking strip 13 extends along the first edge 15 in the second direction (depicted as y in FIGS. 4A-4C), parallel, or substantially parallel, to the first edge 15. The mechanical locking system may further comprise a locking tongue 14 configured to cooperate with a tongue groove 19 for locking in a vertical direction.

[0134] In the example shown in FIG. 4A, the locking tongue 14 is provided on the first floor panel 11 and the tongue groove 19 is provided on the second floor panel 12. In the example shown in FIG. 4A, the locking tongue 14 is provided as a separate part, for example, as an injection moulded tongue, inserted in a displacement groove 18. The locking tongue 14 is displaceable in the displacement groove 18. In the locked position, as in FIG. 4A, the locking tongue 14 cooperating with the tongue groove 19, prevents movements between the first floor panel 11 and the second floor panel 12 in the vertical direction.

[0135] In the example shown in FIG. 4B, the locking tongue 14' is formed as an integrated part of one of the floor panels 11, 12. In FIG. 4B, the locking tongue 14' is formed as an integrated part of the second floor panel 12. The locking tongue 14' may be an integrated part of the core of one of the floor panels 11, 12. The integrated locking tongue 14 'is configured to cooperate with a tongue groove 19' on the other of the floor panels 11, 12, and in FIG. 4B the tongue groove 19' in the first floor panel 11. The tongue groove 19' and the locking tongue 14' have cooperating locking surfaces, configured to prevent prevents movements between the first floor panel 11 and the second floor panel 12 in the vertical direction.

[0136] In the example shown in FIG. 4C, the second panel 12 is provided with a locking tongue 14'' configured to with the tongue groove 19'' extending into the core of the first floor panel 11. The horizontal extension of the locking tongue 14'' into the tongue groove 19'' prevents movements between the first floor panel 11 and the second floor panel 12 in the vertical direction.

[0137] The mechanical locking system shown in FIG. 4C may be a mechanical locking system configured to join adjacent panels along a long side edge. Such as a mechanical locking system may be referred to as a first mechanical locking system, or a first mechanical locking device. The mechanical locking system shown in FIGS. 4A and 4C may be a mechanical locking system configured to join adjacent panels along a short side edge. Such as a mechanical locking system may be referred to as a second mechanical locking system, or a second mechanical locking device.

[0138] In FIGS. 4A-4C, the underlay element 11, including the foamed base layer 2 and the deformation resistant layer 3, extends beyond the extension of the locking strip 13 in the first direction (depicted as x in FIGS. 4A-4C). The deformation resistant layer 3 may distribute any load applied on the flooring, and / or at least partially restrict compression of the underlay element 1 by the load, such as distributing the load over an area of the underlay element 1. Thereby, the load is distributed on a larger surface of the underlay element 1 such that the locking strip 13 remains at least substantially unaffected by the load applied. In FIGS. 4A-4C, a load P, which may be static or dynamic, is applied on the first floor panel 11, adjacent the first edge. The load P is applied in a direction substantially perpendicular to the planar extension of the flooring 10, i.e., in the thickness direction of the underlay element 1 (depicted as z in FIGS. 4A-4C). The deformation resistant layer 3 distributes the load, such as in the horizontal direction and over an area of the underlay element 1, in order to avoid substantial compression of the underlay element 3, which otherwise would result in bending of the locking strip 13. Bending or the locking strip 13 may result in breakage of the joint between the panels, and / or breakage of the locking strip 13 itself, as discussed above with reference to FIG. 1 and known underlay elements.

[0139] The deformation resistant layer 3 having a tensile force at maximum load exceeding 100 N as measured in accordance with ISO527-l:2012 and ISO527-2 / - 3:2018. Thereby, the deformation resistant layer 3 distributes a load applied to the flooring 10 in a manner that the mechanical locking system of the panels of the flooring 10 are subjected to less deformation, and thereby, less damage. The load may be distributed over an area of the underlay element 1.

[0140] For example, the fibre reinforcement of the wear resistant layer may improve load distribution in a direction parallel to the plane of the deformation resistant layer 3, i.e., in a horizontal direction.

[0141] ISO527-l:2012 and ISO527-3:2018 is the relevant standard for sheets < 1 mm thick, and ISO527-l:2012 and ISO527-2:2018 is the relevant standard for sheets > 1 mm thick. Therefore, reference is made to ISO527-l:2012 and ISO527-2 / -3:2018 in the present disclosure, wherein ISO527-l:2012 and ISO527-3:2018 is applicable for a deformation resistant layer being < 1 mm thick, and ISO527-l:2012 and ISO527- 2:2018 is applicable for a deformation resistant layer being > 1 mm thick.

[0142] The underlay element 11 may extend at least partially along the extension of the locking strip in the second direction, substantially parallel to the first edge 15 (depicted as y in FIGS. 4A-4C).

[0143] The first floor panel 11 may be arranged on the underlay element 1. The second floor panel 12 is positioned adjacent the first floor panel 11, in order to be joined to the first floor panel 11 along a joint edge. The joint edge may be a short side joint edge or a long side joint edge, if the panels have an oblong shape. In the example shown in FIGS. 4A-4B, a short side joint edge is shown. The first floor panel 11 and the second floor panel 12 are joined to each other by the mechanical locking system. The locking strip 13 may be provided at the first edge 15 of the first floor panel 11, and the locking strip 13 is configured to cooperate with the locking groove 16 provided at the adjacent edge of the second floor panel 12. The first edge of the first floor panel 11 and the adjacent edge of the second floor panel 12 forms the joint edge. The locking strip 13 protrudes from the first edge of the first floor panel 11 in the first direction. The first direction may be substantially perpendicular to the first edge. The first direction may be substantially perpendicular to the joint edge. The locking strip 13 extends along the first edge of the first floor panel 11 in a second direction. The second direction may be substantially parallel to the first edge 15. The locking strip 13 may extend along the first edge 15 in a direction substantially parallel to the first edge. The locking strip 13 may extend along the first edge in a direction substantially parallel to the joint edge. The second direction may be substantially perpendicular to the first direction.

[0144] As shown in FIGS. 4A-4C, the underlay element 4 extends beyond an extension of the locking strip in the first direction (depicted as x in FIGS. 4A-4C), i.e., in a direction substantially perpendicular to the first edge 15, towards the adjacent edge of the second floor panel 12. The underlay element 4 may extend beyond at least a portion of an extension of the locking strip in the second direction (depicted as y in FIGS. 4A-4C), i.e., in a direction substantially parallel to the first edge 15.

[0145] The first and the second floor panels 11, 12 may be loosely arranged on the underlay element 1. Thereby, the first and the second floor panels 11, 12 are not attached to the underlay element 1.

[0146] As visible in FIGS. 6 and 7, the underlay element 1 may have a planar extension exceeding the first and / or the second floor panel 11, 12. The underlay element 1 may have an extension exceeding the first and / or the second floor panel 11, 12 in a length direction, and / or in a width direction.

[0147] An area of the underlay element 1 may exceed an area of the first and / or the second floor panel 11, 12.

[0148] FIG. 5 shows an example of the underlay element 1 described above with reference to FIGS. 2-4 being provided with a plurality of restriction members 30. The first and second floor panels 11, 12 shown in FIG. 5 corresponds to the first and second floor panels 11, 12 described above with reference to FIGS. 4A-4C.

[0149] The restrictions members 30 are arranged in the foamed base layer 2. The restrictions members 30 may be at least partly embedded in the foamed base layer 2. The restrictions members 30 may be formed of a material different from the material of the foamed base layer 2.

[0150] The restrictions member 30 are configured to at least partially restrict compression of the underlay element 1, for example, in a thickness direction of the underlay element 1. The restriction members 30 may each have size exceeding 0.25 mm in at least one direction, such as in the thickness direction of the underlay element 1. The restriction members 30 may be essentially uniformly distributed throughout the foamed base layer 2.

[0151] The restriction members 30 may have a horizontal extension in the foamed base layer 2 as well as a vertical extension, corresponding the extension in the thickness direction of the foamed base layer 2.

[0152] The restriction members 30 are configured to be less compressible than the foamed base layer 2. The restriction members are described in WO2022139664A1, which hereby is incorporated by reference in its entirety.

[0153] FIGS. 6-7 shows a flooring covering as seen from above, comprising a flooring 10 and underlay elements la, lb, ac. The flooring 10 comprises a plurality of first floor panels 11a, 11, 11c and a plurality of second floor panels 12a, 12b, 12c. Each of the first floor panels 11a, lib, 11c may correspond to the first floor panel 11 described above with reference to FIGS. 4A-4C and 5. Each of the second floor panels 12a, 12b, 12c may correspond to the second floor panel 12 described above with reference to FIGS. 4 and 5. Each of the underlay elements la, lb, lc corresponds to the underlay element 1 described above with reference to FIGS. 2A- 2B, 3, 4, and 5.

[0154] In FIG. 6, the flooring 10 is arranged on a first underlay element la, a second underlay element lb, and a third underlay element lc. The underlay elements la, lb, lc are arranged substantially parallel to each other. The underlay elements la, lb, lc are arranged adjacent each other, preferably in contact with each other, or arranged with a gap, preferably being less than 35 mm, such as less than 15 mm, between each other. Each of the underlay elements la, lb, lc corresponds to the underlay element 1 described above with reference to FIGS. 2A-2B, 3, 4, and 5. The underlay elements la, lb, lc each has an oblong shape, extending in a length direction and in a width direction. The first and second floor panels 11a, 11, 11c, 12a, 12b, 12c each have an oblong shape, extending in a length direction and in a width direction. In the example shown in FIG. 6, the first and second floor panels 11a, 11, 11c, 12a, 12b, 12c are arranged on the underlay elements la, lb, lc such that the length direction of the floor panels 11a, 11, 11c, 12a, 12b, 12c is substantially perpendicular to the length direction of the underlay elements la, lb, lc.

[0155] A first 11a of the plurality of the first floor panels 11a, lib, 11c is arranged on the underlay elements la, lb. The length direction of the first floor panel 11a is substantially perpendicular to the length direction of the underlay elements la, lb, lc.

[0156] The first 11a of the first floor panels 11a, lib, 11c is joined to a second lib of the first floor panels 11a, lib, 11c by a mechanical locking system along a short side edge of respective panels to form a short side joint edge 32. The first 11a and second lib of the first floor panels 11a, lib, 11c are arranged on the underlay elements la, lb, lc, such that the short side joint edge 32 is arranged within the extension of one of the underlay elements la, lb, lc. In the example in FIG. 6, the short side joint edge 32 is arranged within the extension of the second underlay element lb. In the example in FIG. 6, an entirety of the short side joint edge 32 is arranged within the extension of the second underlay element lb.

[0157] The mechanical locking system of the short side joint edge 32 may comprise a locking strip protruding from one of the short side edges of the first 11a or the second lib of the first floor panels 11a, lib, 11c. The underlay element lb arranged below the short side joint edge 32 extends beyond an extension of the locking strip at least in a first direction substantially perpendicular to the short side edge. In the example shown in FIG. 6, the underlay elements lb arranged below the short side joint edge 32 extends beyond the extension of the locking strip at least in a second direction substantially parallel to the short side edge as well. In FIG. 6, the underlay elements la, lb, lc arranged below all short side joint edges 32 extend beyond an extension of the locking strip at least in a first direction substantially perpendicular to the short side edge, and beyond the extension of the locking strip at least in a second direction substantially parallel to the short side edges as well.

[0158] Thereafter, a first 12 of the second floor panels 12a, 12b, 12c is joined to the first 11a of the first floor panels 11a, lib, 11c by a mechanical locking system along a long side edge of respective panels to form a long side joint edge 31.

[0159] The mechanical locking system of the long side joint edge 31 may comprise a locking strip protruding from one of the long side edges of one of the first floor panels 11a, lib, 11c, or one of the second floor panels 12a, 12b, 12c. The underlay element la, lb, lc arranged below the long side joint edge 31 extends beyond an extension of the locking strip at least in a first direction substantially perpendicular to the long side edge. The underlay elements la, lb, lc arranged below the long side joint edge 31 extends beyond at least a portion of the extension of the locking strip at least in a second direction substantially parallel to the long side joint edge 31. In FIG. 6, the underlay elements la, lb, lc arranged below the long side joint edge 31 extends beyond a majority of the extension of the locking strip at least in a direction substantially parallel to the long side joint edge 31. It is only at a distance between any of the underlay elements la, lb, lc the extension of the underlay element la, lb, lc is abrupted. In relation to the length of the long side joint edge 31, the distance between adjacent underlay element la, lb, lc does not affect the performance of the mechanical locking system, even if a load is applied in the vicinity of the distance. The underlay elements la, lb, lc distribute the load, such as distribute the load over an area of the underlay elements la, lb, lc, and at least prevents the mechanical locking system from damages, as described with reference to FIGS. 4A-4C.

[0160] In FIG. 7, the flooring 10 is arranged on a first underlay element la, a second underlay element lb, and a third underlay element lc. The underlay elements la, lb, lc are arranged substantially parallel to each other. The underlay elements la, lb, lc are arranged adjacent each other, preferably in contact with each other, or arranged with a gap, preferably being less than 35 mm, such as less than 15 mm, between each other. Each of the underlay elements la, lb, lc corresponds to the underlay element 1 described above with reference to FIGS. 2A-2C, 3, 4 and 5. The underlay elements la, lb, lc each has an oblong shape, extending in a length direction and in a width direction. The first and second floor panels 11a, 11, 11c, 12a, 12b, 12c each have an oblong shape, extending in a length direction and in a width direction. In the example shown in FIG. 7, the first and second floor panels are arranged on the underlay elements la, lb, lc such that the length direction of the floor panels is substantially parallel to the length direction of the underlay elements la, lb, lc.

[0161] A first 11a of the plurality of the first floor panels 11a, lib, 11c is arranged on the underlay element la. The length direction of the first floor panel 11a is substantially parallel to the length direction of the underlay elements la, lb.

[0162] The first 11a of the first floor panels 11a, lib, 11c is joined to a second lib of the first floor panels 11a, lib, 11c by a mechanical locking system along a short side edge of respective panels to form a short side joint edge 32. The first 11a and second lib of the first floor panels 11a, lib, 11c are arranged on the underlay element la such the short side joint edge 32 is arranged within the extension of underlay element la. The short side joint edge 32 between the first 11a and second lib of the first floor panels 11a, lib, 11c is arranged within the extension of the second underlay element lb. An entirety of the short side joint edge 32 between the first 11a and second lib of the first floor panels 11a, lib, 11c is arranged within the extension of the second underlay element lb. Thereafter, a first 12 of the second floor panels 12a, 12b, 12c is joined to the first 11a of the first floor panels 11a, lib, 11c by a mechanical locking system along a long side edge of respective panels to form a long side joint edge 31.

[0163] The mechanical locking system of the long side joint edge 31 may comprise a locking strip protruding from one of the long side edges of one of the first floor panels 11a, lib, 11c or one of the second floor panels 12a, 12b, 12c. The underlay element la arranged below the long side joint edge 31 extends beyond an extension of the locking strip at least in a first direction substantially perpendicular to the long side edge. In FIG. 7, the underlay elements la, lb, lc arranged below the long side joint edge 31 extends beyond an extension of the locking strip at least in a second direction substantially parallel to the long side edge as well. In FIG. 7, the long side joint edge 31 is arranged within the extension of the underlay element la. In the example in FIG. 7, an entirety of the long side joint edge 31 is arranged within the extension of the underlay element la.

[0164] The first 11a, lib, 11c and second floor panels 12a, 12b, 12c are further positioned on the underlay elements la, lb, lc and joined along short and long side edges. In the example in FIG. 7, some of the short side joint edges overbridges the distance between adjacent underlay elements la, lb. In the short joint edge 32 positioned over the distance between adjacent underlay elements la, lb, the underlay elements la, lb protrudes beyond the locking element of one of the floor panels 11a, lib in a direction substantially perpendicular to the short joint edge 32. The underlay elements la, lb extends at least below a portion of the locking element of one of the floor panels 11a, lib in a direction substantially parallel to the short joint edge 32. The underlay elements la, lb arranged below the short side joint edge 32 extends beyond a majority of the extension of the locking strip at least in a direction substantially parallel to the short side joint edge 32. It is only at a distance between any of the underlay elements la, lb any of the underlay elements la, lb the extension of the underlay element la, lb is abrupted. In relation to the length of the short side joint edge 32, the distance between adjacent underlay elements la, lb does not affect the performance of the mechanical locking system, even if a load is applied in the vicinity of the distance. The underlay elements la, lb distribute the load, such as distribute over an area, and at least prevents the mechanical locking system from damages, as described with reference to FIGS. 4A- 4C.

[0165] The first and / or the second floor panels 11a, lib, 11c, 12a, 12b, 12c may be positioned on the underlay elements la, lb, lc such that it is avoided that a short side joint edge and / or a long side joint edge is arranged in the vicinity of a gap between adjacent underlay elements la, lb, lc. For example, the first and / or the second floor panels 11a, lib, 11c, 12a, 12b, 12c may be positioned on the underlay elements la, lb, lc such that it is avoided that a short side edge is arranged in the vicinity of a gap between adjacent underlay elements la, lb, lc. The first and / or the second floor panels 11a, lib, 11c, 12a, 12b, 12c may be positioned on the underlay elements la, lb, lc such that the short side joint edge 32 is positioned within an extension of one of the underlay elements la, lb, lc. An entirety of the short side joint edge 32 may be positioned within the extension of the second underlay element lb.

[0166] Further, the first and / or the second floor panels 11a, lib, 11c, 12a, 12b, 12c may be positioned on the underlay elements la, lb, lc such that the length direction of the floor panels is substantially perpendicular to the length direction of the underlay elements la, lb, lc.

[0167] The width of the underlay elements la, lb, lc may be provided with a width, or may be cut to a width, being a non-integer of the length and / or the width of the floor panels 11a, lib, 11c, 12a, 12b, 12c. In an example wherein the floor panels are positioned on the underlay elements la, lb, lc with a length direction of the floor panels 11a, lib, 11c, 12a, 12b, 12c substantially perpendicular to a length direction of the underlay elements la, lb, lc, the width of the underlay elements la, lb, lc may be a non-integer of the length of the floor panels 11a, lib, 11c, 12a, 12b, 12c, as shown in FIG. 6. In an example wherein the floor panels are positioned on the underlay elements la, lb, lc with a length direction of the floor panels substantially parallel to a length direction of the underlay elements la, lb, lc, the width of the underlay elements la, lb, lc may be a non-integer of the width of the floor panels, as shown in FIG. 7.

[0168] The length of the underlay elements la, lb, lc may exceed the length of the floor panels 11a, lib, 11c, 12a, 12b, 12c, such as being at least twice the length of the floor panels 11a, lib, 11c, 12a, 12b, 12c. As an alternative or complement, the width of the underlay elements la, lb, lc may exceed the width of the floor panels 11a, lib, 11c, 12a, 12b, 12c, such as being at least twice the length of the floor panels 11a, lib, 11c, 12a, 12b, 12c.

[0169] The mechanical locking system for joining short side edges 32 described with reference to FIGS. 6 and 7 may be of the type described above with reference to FIGS. 4A and 4B. The mechanical locking system for joining long side edges 31 described with reference to FIGS. 6 and 7 may be of the type described above with reference to FIG. 4C. In the examples above, the underlay element may have a planar extension exceeding a planar extension of a floor panel intended to be arranged on the underlay element.

[0170] If the floor panels have a square shape, the edge referred to a long side edge above may be a first edge, and the edge referred to a short side edge above may be a second edge.

[0171] The floor panels described above may be of any type, such as wood-based or polymer based. The floor panels may be parquet floor panels or laminate floor panels. The floor panels may be so-called Luxury Vinyl Tiles (LVT tiles), Stone Plastic (Polymer) Composite panels (SPC panels), or Expanded Polymer Core panels (EPC panels), also known as Water Proof Core panels (WPC panels). The floor panels may have a thickness of 2-12 mm. In one example, the floor panels have a thickness of 2.0-8.0 mm, such as 4.0-6.0 mm.

[0172] The underlay element 1 may be used in conjunction with thermoplastic-based floor panels or thin laminate floor panels.

[0173] By deformation resistant layer 3 is meant a layer at least partially resisting, or at least reducing, deformation of the layer in a direction perpendicular to the planar extension of the underlay element 1. The term deformation resistant layer 3 is not limited to a layer resisting all types of deformation, and / or all loads.

[0174] The underlay element of any of the examples may optionally further comprise a thin foil or a film, for example, comprising PE or being metallized, attached, such as laminated, to the foamed base layer 2 or the deformation resistant layer 3. Such a foil or a film of, e.g., 0.01-0.05 mm or 0.20 mm in thickness may provide an additional moisture barrier and / or a vapour barrier to the underlay element. In examples, such a foil or film providing as an additional moisture barrier and / or a vapour barrier be an integrated part of the deformation resistant layer 3.

[0175] It is contemplated that there are numerous modifications of the embodiments described herein, which are still within the scope of the disclosure as defined by the appended claims. For example, it is contemplated that more than one wear resistant foil may be arranged on a core for forming a building panel.

[0176] Examples

[0177] Castor chair test

[0178] The castor chair test (CC test) according to "ISO4918 and EN 425" but the specification is governed by "EN 16511 - Loose-laid panels - Semi-rigid multilayer modular floor covering (MMF) panels with wear resistant top layer" was performed according to below.

[0179] The foamed base layer was cut to fit under the plank test area, attached to each other with tape and the whole test subject is inserted in the machine and test started. According to ISO4918 the test can be conducted up to 25,000 cycles.

[0180] The foamed base layer used below was Rungyang IXPE 1520 having a compressive strength at 0.5 mm of 59 kPa, a density of 75 kg / m3and a thickness of 2 mm.

[0181] The floor panel in the test was a SPC floor panel produced by Tengchen having a thickness of 5.5 mm.

[0182] The following duct tapes were used:

[0183] - TESA 4662: 48 mm width, 0.23 mm thick, tensile force 177 N, stress at maximum load 15 MPa, tensile module 217 MPa, strain at maximum load 0.17 mm / mm.

[0184] - Nashua 357: 48 mm width 0.33 mm thick, tensile force 391 N, stress at maximum load 24.7 MPa.- Duck advance: 48 mm width, 0.23 mm thick, tensile force 169 N, stress at maximum load 15.5 MPa.

[0185] Tensile force, stress at maximum stress at maximum load, tensile module, and strain at maximum load measured in accordance with 150527-1:2012 and ISO527-2 / - 3:2018.

[0186] FIGS. 8 and 9 shows the arrangement of layers. FIG. 8 shows an arrangement of the layers in all References. FIG. 9 shows an arrangement of the layers in all Examples. In all References (FIG. 8), a tape layer 300 is arranged below the foamed base layer 200 such that the Reference has the same thickness as the corresponding Example.

[0187] Reference 1

[0188] The SPC floor panel 400 was arranged on the foamed base layer 200 (Rungyang IXPE 1520). A layer 300 of duct tape TESA 4662 was applied on a lower surface of the foamed base layer 200, facing away from the SPC floor panel 400. No adhesive is present between the floor panel 400 and the foamed base layer 200. Total thickness of underlay is 2.23 mm.

[0189] Example 1

[0190] The SPC floor panel 400 was arranged on an example of the underlay element comprising the foamed base layer (Rungyang IXPE 1520) 200 and a deformation resistant layer 300 in form of duct tape TESA 4662 attached to the foamed base layer 300, wherein the deformation resistant layer 102 is arranged between the floor panel 400 and the foamed base layer 200. No adhesive is present between the floor panel 400 and the underlay element. Total thickness of the underlay element is 2.23 mm.

[0191] Reference 2

[0192] The SPC floor panel 400 was arranged on the foamed base layer 200 (Rungyang IXPE 1520). A layer 300 of duct tape Nashua 357 was applied on a lower surface of the foamed base layer 300, facing away from the SPC floor panel 400. No adhesive is present between the floor panel 400 and the foamed base layer 200. Total thickness of underlay is 2.33 mm.

[0193] Example 2

[0194] The SPC floor panel 400was arranged on an example of the underlay element comprising the foamed base layer 200 (Rungyang IXPE 1520) and a deformation resistant layer 300 in form of duct tape Nashua 357 attached to the foamed base layer 200, wherein the deformation resistant layer 300 is arranged between the floor panel 400 and the foamed base layer 200. No adhesive is present between the floor panel 400 and the underlay element. Total thickness of the underlay element is 2.33 mm.

[0195] Reference 3

[0196] The SPC floor panel 400 was arranged on the foamed base layer 200 (Rungyang IXPE 1520). A layer 300 of duct tape Duck advance was applied on a lower surface of the foamed base layer 200, facing away from the SPC floor panel 400. No adhesive is present between the floor panel 400 and the foamed base layer 200. Total thickness of underlay is 2.23 mm.

[0197] Example 3

[0198] The SPC floor panel 400 was arranged on an example of the underlay element comprising the foamed base layer 200 (Rungyang IXPE 1520) and a deformation resistant layer 300 in form of duct tape Duck advance attached to the foamed base layer 200, wherein the deformation resistant layer 300 is arranged between the floor panel 400 and the foamed base layer 200. No adhesive is present between the floor panel 400 and the underlay element 200. Total thickness of the underlay element is 2.23 mm.

[0199] Results

[0200] According to ISO 4918 and EN 425, Reference 1 failed at 15400 revolutions due to visible breakage of floor locking and delamination (see Table 1). Example 1 had not failed at 15400 revolutions. Note that Example 1 had similar damages as Reference 1 but that the same damage types occurred at later revolutions than for Reference 1. E.g. occasional snapping sound at 3000 (Reference 1) vs 5000 (Example 1), roof of tongue groove starting to bend at 7000 (Reference 1) vs 10000 (Example 1).

[0201] Reference 2 (see Table 1) experienced flexing in the floor locking at 10000 cycles and breakage at 15000 cycles. Example 2 experienced flexing in the floor locking at 15000 cycles and presumable breakage at 15000 cycles. Reference 2 failed due to delamination at 20000 cycles, Example 2 did not fail.

[0202] Reference 3 (see Table 1) experienced flexing in the floor locking at 15,000 cycles and breakage at 20000 cycles. Example 3 experienced flexing in the floor locking at 20000 cycles and presumable breakage at 20000 cycles. Reference 3 failed due to delamination at 23568 cycles. The test was continued Example 3 until it failed (delaminated at 31000 cycles).

[0203]

[0204] Residual indentation test

[0205] Tested performed according to ASTM F3261-17 "Resilient Modular Rigid Polymeric", Residual indentation ASTM F1914 (according to ASTM F1700) with the following exceptions:

[0206] - tested with either one or two replicates,

[0207] - test specimens' dimensions: 5 x 5 cm2.

[0208] The floor panel in the test was a SPC floor panel produced by Tengchen having a thickness of 4.5 mm.

[0209] The following duct tapes were used:

[0210] - TESA 4662: 48 mm width, 0.23 mm thick, tensile force 177 N, stress at maximum load 15 MPa, tensile module 217 MPa, strain at maximum load 0.17 mm / mm.

[0211] - SILVERTEJP (BILTEMA): 50 mm width 0.17 mm thick, tensile force 212 N, stress at maximum load 20 MPa, tensile module 440 MPa, strain at maximum load 0.08 mm / mm.

[0212] Tensile force, stress at maximum stress at maximum load, tensile module, and strain at maximum load measured in accordance with 150527-1:2012 and ISO527-2 / - 3:2018.

[0213] FIGS. 8 and 9 shows the arrangement of layers. FIG. 8 shows an arrangement of the layers in all References. FIG. 9 shows an arrangement of the layers in all Examples. In all References (FIG. 8), a tape layer 300 is arranged below the foamed base layer 200 such that the Reference has the same thickness as the corresponding Example.

[0214] Reference 1

[0215] The SPC floor panel 400, provided with Liteback® technology, was arranged on a foamed base layer 200 of Rungyang IXPE 1010 (compressive strength at 0.5 mm of 139 kPa, a density of 100 kg / m3, a thickness of 1 mm). A layer 300 of duct tape TESA 4662 was applied on a lower surface of the foamed base layer 200, facing away from the SPC floor panel 400. No adhesive is present between the floor panel 400 and the foamed base layer 200. Total thickness of underlay is 1.23 mm.

[0216] Example 1 The SPC floor panel 400, provided with Liteback® technology, was arranged on an example of the underlay element comprising a foamed base layer 200 in form of Rungyang IXPE 1010 (compressive strength at 0.5 mm of 139 kPa, a density of 100 kg / m3, a thickness of 1 mm) and a deformation resistant layer 300 in form of duct tape TESA 4662 attached to the foamed base layer 200, wherein the deformation resistant layer 300 is arranged between the floor panel 400 and the foamed base layer 200. No adhesive is present between the floor panel 400 and the underlay element. Total thickness of the underlay element is 1.23 mm.

[0217] Reference 2

[0218] The SPC floor panel 400, provided with Liteback® technology, was arranged on a foamed base layer 200 of Soft Silence IXPE 1010 (compressive strength at 0.5 mm of 140 kPa, a density of 158 kg / m3, a thickness of 1.5 mm). A layer 300 of duct tape TESA 4662 was applied on a lower surface of the foamed base layer 200, facing away from the SPC floor panel 400. No adhesive is present between the floor panel 400 and the foamed base layer 200. Total thickness of underlay is 1.73 mm.

[0219] Example 2

[0220] The SPC floor panel 400, provided with Liteback® technology, was arranged on an example of the underlay element comprising a foamed base layer 200 in form of Soft Silence IXPE 1010 (compressive strength at 0.5 mm of 140 kPa, a density of 158 kg / m3, a thickness of 1.5 mm) and a deformation resistant layer 300 in form of duct tape TESA 4662 attached to the foamed base layer 200, wherein the deformation resistant layer 300 is arranged between the floor panel 400 and the foamed base layer 200. No adhesive is present between the floor panel 400 and the underlay element. Total thickness of the underlay element is 1.23 mm.

[0221] Reference 3

[0222] The SPC floor panel 400 (without Liteback®) was arranged on a foamed base layer 200 of Soft Silence IXPE 1010 (compressive strength at 0.5 mm of 140 kPa, a density of 158 kg / m3, a thickness of 1.5 mm). A layer 300 of duct tape SILVERTEJP (BILTEMA) was applied on a lower surface of the foamed base layer 200, facing away from the SPC floor panel 400. No adhesive is present between the floor panel 400 and the foamed base layer 200. Total thickness of the underlay element is 1.67 mm.

[0223] Example 3

[0224] The SPC floor panel 400 (without Liteback®) was arranged on an example of the underlay element comprising a foamed base layer 200 in form of Soft Silence IXPE 1010 (compressive strength at 0.5 mm of 140 kPa, a density of 158 kg / m3, a thickness of 1.5 mm) and a deformation resistant layer 300 in form of duct tape SILVERTEJP (BILTEMA) attached to the foamed base layer 200, wherein the deformation resistant layer 300 is arranged between the floor panel 400 and the foamed base layer 200. No adhesive is present between the floor panel 400 and the underlay element. Total thickness of the underlay element is 1.67 mm.

[0225] Reference 4

[0226] The SPC floor panel 400 (without Liteback®) was arranged on a foamed base layer 200 of Rungyang IXPE 1520 (compressive strength at 0.5 mm of 59 kPa, a density of 75 kg / m3, a thickness of 2 mm). A layer 300 of duct tape SILVERTEJP (BILTEMA) was applied on a lower surface of the foamed base layer 200, facing away from the SPC floor panel 400. No adhesive is present between the floor panel 400 and the foamed base layer 200. Total thickness of the underlay element is 2.17 mm.

[0227] Example 4

[0228] The SPC floor panel 400 (without Liteback®) was arranged on an example of the underlay element comprising the foamed base layer 200 Rungyang IXPE 1520 (compressive strength at 0.5 mm of 59 kPa, a density of 75 kg / m3, a thickness of 2 mm) and a deformation resistant layer 300 in form of duct tape SILVERTEJP (BILTEMA) attached to the foamed base layer 200, wherein the deformation resistant layer 300 is arranged between the floor panel 400 and the foamed base layer 200. No adhesive is present between the floor panel 400 and the underlay element. Total thickness of the underlay element is 2.17 mm.

[0229] Results

[0230] The Examples got less residual indentation than the references, both for floor panels with and without Liteback® (see Table 2), thus improving the underlay elements.

[0231] In Table 2, residual indentation for References and Examples is expressed as "Residual indentation, %" in accordance with ASTM F1914.

[0232] Lowered indentation %" is

[0233] Item list

[0234] 1. An underlay element (1) configured to be arranged between a flooring (10) and a sub-floor (20), comprising a foamed base layer (2) configured to be arranged on the sub-floor (20), a deformation resistant layer (3) attached to the foamed base layer (2), the deformation resistant layer (3) being more rigid than the foamed base layer (2), wherein the deformation resistant layer (3) has a tensile force at maximum load exceeding 50 N as measured in accordance with ISO527-2 / -3:2018, preferably exceeding 100 N as measured in accordance with ISO527-2 / -3:2018, more preferably exceeding 150 N as measured in accordance with ISO527-2 / -3:2018.

[0235] 2. The underlay element according to item 1, wherein a density of the foamed base layer (2) is less than a density of the deformation resistant layer (3).

[0236] 3. The underlay element according to item 1 or 2, wherein the foamed base layer (2) has a compressive strength about 50-900 kPa (at 0.5 mm) as measured in accordance with EN16354:2018, preferably 50-500 kPa (at 0.5 mm), more preferably 50-250 kPa (at 0.5 mm).

[0237] 4. The underlay element according to any one of the preceding items, wherein the deformation resistant layer (3) is un-foamed.

[0238] 5. The underlay element according to any one of the preceding items, wherein the deformation resistant layer (3) is fibre reinforced.

[0239] 6. The underlay element according to item 5, wherein the deformation resistant layer (3) is reinforced by glass fibres, polymer fibres, mineral-based fibres, carbon fibres and / or natural fibres.

[0240] 7. The underlay element according to item 5 or 6, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement wherein the glass fibres have a stiffness of 52-95 GPa as measured according to ASTM C1557-20.

[0241] 8. The underlay element according to any one of item 5-7, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement having a weight of 10-180 g / m2.

[0242] 9. The underlay element according to any one of the preceding items, wherein the foamed base layer (2) is compressible, and the underlay element (1) further comprises a plurality of restrictions members (30) at least partly embedded in the foamed base layer (2), said restrictions members (30) being configured to restrict compression of the underlay element (1) by being less compressible than the foamed base layer (2).

[0243] 10. The underlay element according to any one of the preceding items, wherein a density of the deformation resistant layer (3) is 250-3000 kg / m3, preferably 500-3000 kg / m3, more preferably 800-1500 kg / m3.

[0244] 11. The underlay element according to any one of the preceding items, wherein a density of the foamed base layer (2) is 20-700 kg / m3, preferably 20-300 kg / m3.

[0245] 12. The underlay element according to any one of the preceding items, wherein a thickness of the foamed base layer (2) is 0.4-3.5 mm, preferably 0.6-1.8 mm.

[0246] 13. The underlay element according to any one of the preceding items, wherein a thickness of the deformation resistant layer (3) is 0.05-2 mm, preferably 0.25-0.75 mm.

[0247] 14. The underlay element according to any one of the preceding items, wherein a thickness of the foamed base layer (2) exceeds a thickness of the deformation resistant layer (3).

[0248] 15. The underlay element according to any one of the preceding items, wherein a thickness of the deformation resistant layer (3) is less than 30 % of a thickness of the foamed base layer (2).

[0249] 16. The underlay element according to any one of the preceding items, wherein the deformation resistant layer (3) has a tensile modulus exceeding 100 MPa as measured in accordance with ISO527-2 / -3:2018.

[0250] 17. The underlay element according to any one of the preceding items, wherein the deformation resistant layer (3) has a tensile strength at maximum load exceeding 50 N as measured in accordance with ISO527-2 / -3:2018.

[0251] 18. The underlay element according to any one of the preceding items, wherein the deformation resistant layer (3) forms a vapour barrier.

[0252] 19. The underlay element according to any one of the preceding items, wherein the underlay element (1) consists of the deformation resistant layer (3) and the foamed base layer (2).

[0253] 20. The underlay element according to any one of the preceding items, wherein the deformation resistant layer (3) is provided with an adhesive configured to attach the deformation resistant layer (3) to the foamed base layer (2).

[0254] 21. The underlay element according to any one of the preceding items, wherein the foamed base layer (2) comprises cross-linked expanded polymers. 22. The underlay element according to any one of the preceding items, wherein the deformation resistant layer (3) comprises a thermoplastic material.

[0255] 23. The underlay element according to any one of the preceding items, wherein the underlay element (1) has a planar extension exceeding a planar extension of a floor panel (11, 12) intended to be arranged on the underlay element (1).

[0256] 24. A floor covering, comprising an underlay element (1) and at least two floor panels (11, 12) configured to be arranged on the underlay element (1), wherein the underlay element (1) comprises a foamed base layer (2) configured to be arranged on a sub-floor (20) and a deformation resistant layer (3) attached to the foamed base layer (2), wherein the deformation resistant layer (3) is more rigid than the foamed base layer (2), and said at least two floor panels (11, 12) are configured to be arranged on the deformation resistant layer (3), wherein said at least two floor panels (11, 12) are configured to be joined to each other by a mechanical locking system comprising a locking strip (13) provided at a first edge of a first floor panel (1), configured to cooperate with a locking groove (16) provided at an adjacent edge of a second floor panel (12), wherein the locking strip (13) protrudes from the first edge in a first direction and extends along the first edge in a second direction, wherein the underlay element (1) is configured to extend beyond an extension of the locking strip (13) at least in the first direction towards the adjacent edge of the second floor panel (12).

[0257] 25. The floor covering according to item 24, wherein the underlay element (1) is configured to extend below the locking strip (13) along at least a portion of the extension of the locking strip (13) in the second direction.

[0258] 26. The floor covering according to item 24 or 25, wherein the underlay element (1) is configured to extend below the locking strip (13) along the entire extension of the locking strip (13) in the second direction.

[0259] 27. The floor covering according to any one of items 24-26, wherein a planar extension of the underlay element (1) exceeds a planar extension of at least one of the floor panels (11, 12).

[0260] 28. The floor covering according to any one of items 24-27, wherein said at least two floor panels (11, 12) are configured to be loosely arranged on the underlay element.

[0261] 29. The floor covering according to any one of items 24-28, wherein the deformation resistant layer (3) has a tensile force at maximum load exceeding 50 N as measured in accordance with ISO527-2 / -3:2018, preferably exceeding 100 N as measured in accordance with ISO527-2 / -3:2018, more preferably exceeding 150 N as measured in accordance with ISO527-2 / -3:2018.

[0262] 30. The floor covering according to any one of items 24-29, wherein a density of the foamed base layer (2) is less than a density of the deformation resistant layer (3).

[0263] 31. The floor covering according to any one of items 24-30, wherein the foamed base layer (2) has a compressive strength about 50-900 kPa (at 0.5 mm) as measured in accordance with EN16354:2018, preferably 50-500 kPa (at 0.5 mm), more preferably 50-250 kPa (at 0.5 mm).

[0264] 32. The floor covering according to any one of items 24-31, wherein the deformation resistant layer (3) is un-foamed.

[0265] 33. The floor covering according to any one of items 24-32, wherein the deformation resistant layer (3) is fibre reinforced.

[0266] 34. The floor covering according to any one of items 24-33, wherein the deformation resistant layer (3) is reinforced by glass fibres, polymer fibres, mineralbased fibres, carbon fibres and / or natural fibres.

[0267] 35. The floor covering according to any one of items 24-34, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement wherein the glass fibres have a stiffness of 52-95 GPa as measured according to ASTM C1557-20.

[0268] 36. The floor covering according to any one of items 24-35, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement having a weight of 10-180 g / m2.

[0269] 37. The floor covering according to any one of items 24-36, wherein the foamed base layer (2) is compressible, and the underlay element (1) further comprises a plurality of restrictions members (30) at least partly embedded in the foamed base layer (2), said restrictions members (30) being configured to restrict compression of the underlay element (1) by being less compressible than the foamed base layer (2).

[0270] 38. The floor covering according to any one of items 24-37, wherein a density of the deformation resistant layer (3) is 250-3000 kg / m3, preferably 500- 3000 kg / m3, more preferably 800-1500 kg / m3.

[0271] 39. The floor covering according to any one of items 24-38, wherein a density of the foamed base layer (2) is 20-700 kg / m3, preferably 20-300 kg / m3.

[0272] 40. The floor covering according to any one of items 24-39, wherein a thickness of the foamed base layer (2) is 0.4-3.5 mm, preferably 0.6-1.8 mm. 41. The floor covering according to any one of items 24-40, wherein a thickness of the deformation resistant layer (3) is 0.05-2 mm, preferably 0.25-0.75 mm.

[0273] 42. The floor covering according to any one of items 24-41, wherein a thickness of the foamed base layer (2) exceeds a thickness of the deformation resistant layer (3).

[0274] 43. The floor covering according to any one of items 24-42, wherein a thickness of the deformation resistant layer (3) is less than 30 % of a thickness of the foamed base layer (2).

[0275] 44. The floor covering according to any one of items 24-43, wherein the deformation resistant layer (3) has a tensile modulus exceeding 100 MPa as measured in accordance with ISO527-2 / -3:2018.

[0276] 45. The floor covering according to any one of items 24-44, wherein the deformation resistant layer (3) has a tensile strength at maximum load exceeding 50 N as measured in accordance with ISO527-2 / -3:2018.

[0277] 46. The floor covering according to any one of items 24-45, wherein the deformation resistant layer (3) forms a vapour barrier.

[0278] 47. The floor covering according to any one of items 24-46, wherein the underlay element (1) consists of the deformation resistant layer (3) and the foamed base layer (2).

[0279] 48. The floor covering according to any one of items 24-47, wherein the deformation resistant layer (3) is provided with an adhesive configured to attach the deformation resistant layer (3) to the foamed base layer (2).

[0280] 49. The floor covering according to any one of items 24-48, wherein the foamed base layer (2) comprises cross-linked expanded polymers.

[0281] 50. The floor covering according to any one of items 24-49, wherein the deformation resistant layer (3) comprises a thermoplastic material.

[0282] 51. A method to arrange a floor covering comprising an underlay element (1) and at least two floor panels (11, 12), comprising arranging an underlay element (1) on a sub-floor (20) , the underlay element

[0283] (1) comprising a foamed base layer (2) configured to be arranged on the sub-floor (20) and a deformation resistant layer (3) attached to the foamed base layer

[0284] (2), the deformation resistant layer (3) being more rigid than the foamed base layer (2), joining a first edge of a first floor panel (11) to an adjacent edge of a second floor panel (12) by a mechanical locking system comprising a locking strip (13) protruding from the first edge in a first direction and extending along the first edge of the first floor panel (11) in a second direction, the locking strip (13) being configured to cooperate with a locking groove (16) provided at the adjacent edge of the second floor panel (12), arranging the joined floor panels (11, 12) on the underlay element (1) such that the underlay element (1) extends beyond an extension of the locking strip (13) at least in the first direction towards the adjacent edge of the second floor panel (12).

[0285] 52. The method according to item 51, wherein the underlay element (1) is configured to extend below the locking strip (13) along at least a portion of the extension of the locking strip (13) in the second direction.

[0286] 53. The method according to item 51 or 52, wherein the underlay element (1) is configured to extend below the locking strip (13) along the entire extension of the locking strip (13) in the second direction.

[0287] 54. The method according to any one of items 51-53, wherein a planar extension of the underlay element (1) exceeds a planar extension of at least one of said at least two floor panel (11, 12) .

[0288] 55. The method according to any one of items 51-54, wherein said at least two floor panels (11, 12) are configured to be loosely arranged on the underlay element (1).

[0289] 56. The method according to any one of items 51-55, wherein the deformation resistant layer (3) has a tensile force at maximum load exceeding 50 N as measured in accordance with ISO527-2 / -3:2018, preferably exceeding 100 N as measured in accordance with ISO527-2 / -3:2018, more preferably exceeding 150 N as measured in accordance with ISO527-2 / -3:2018.

[0290] 57. The method according to any one of items 51-56, wherein a density of the foamed base layer (2) is less than a density of the deformation resistant layer (3).

[0291] 58. The method according to any one of items 51-57, wherein the foamed base layer (2) has a compressive strength about 50-900 kPa (at 0.5 mm) as measured in accordance with EN16354:2018, preferably 50-500 kPa (at 0.5 mm), more preferably 50-250 kPa (at 0.5 mm).

[0292] 59. The method according to any one of items 51-58, wherein the deformation resistant layer (3) is un-foamed.

[0293] 60. The method according to any one of items 51-59, wherein the deformation resistant layer (3) is fibre reinforced. 61. The method according to any one of items 51-60, wherein the deformation resistant layer (3) is reinforced by glass fibres, polymer fibres, mineralbased fibres, carbon fibres and / or natural fibres.

[0294] 62. The method according to any one of items 51-61, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement wherein the glass fibres have a stiffness of 52-95 GPa as measured according to ASTM C1557-20.

[0295] 63. The method according to any one of items 51-62, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement having a weight of 10-180 g / m2.

[0296] 64. The method according to any one of items 51-63, wherein the foamed base layer (2) is compressible, and the underlay element (1) further comprises a plurality of restrictions members (30) at least partly embedded in the foamed base layer (2), said restrictions members (30) being configured to restrict compression of the underlay element (1) by being less compressible than the foamed base layer (2).

[0297] 65. The method according to any one of items 51-64, wherein a density of the deformation resistant layer (3) is 250-3000 kg / m3, preferably 500-3000 kg / m3, more preferably 800-1500 kg / m3.

[0298] 66. The method according to any one of items 51-65, wherein a density of the foamed base layer (2) is 20-700 kg / m3, preferably 20-300 kg / m3.

[0299] 67. The method according to any one of items 51-66, wherein a thickness of the foamed base layer (2) is 0.4-3.5 mm, preferably 0.6-1.8 mm.

[0300] 68. The method according to any one of items 51-67, wherein a thickness of the deformation resistant layer (3) is 0.05-2 mm, preferably 0.25-0.75 mm.

[0301] 69. The method according to any one of items 51-68, wherein a thickness of the foamed base layer (2) exceeds a thickness of the deformation resistant layer (3).

[0302] 70. The method according to any one of items 51-69, wherein a thickness of the deformation resistant layer (3) is less than 30 % of a thickness of the foamed base layer (2).

[0303] 71. The method according to any one of items 51-70, wherein the deformation resistant layer (3) has a tensile modulus exceeding 100 MPa as measured in accordance with ISO527-2 / -3:2018.

[0304] 72. The method according to any one of items 51-71, wherein the deformation resistant layer (3) has a tensile strength at maximum load exceeding 50 N as measured in accordance with ISO527-2 / -3:2018.

[0305] 73. The method according to any one of items 51-72, wherein the deformation resistant layer (3) forms a vapour barrier. 74. The method according to any one of items 51-73, wherein the underlay element (1) consists of the deformation resistant layer (3) and the foamed base layer (2).

[0306] 75. The method according to any one of items 51-74, wherein the deformation resistant layer (3) is provided with an adhesive configured to attach the deformation resistant layer (3) to the foamed base layer (2).

[0307] 76. The method according to any one of items 51-75, wherein the foamed base layer (2) comprises cross-linked expanded polymers.

[0308] 77. The method according to any one of items 51-76, wherein the deformation resistant layer (3) comprises a thermoplastic material.

[0309] 78. An underlay element (1) configured to be arranged between a subfloor (20) and a flooring (10) comprising one or more floor panels (11, 12), comprising a foamed base layer (2) configured to be arranged on the sub-floor (20). a deformation resistant layer (3) attached to the foamed base layer (2), the deformation resistant layer (3) being more rigid than the foamed base layer (2), wherein the underlay element is (1) configured to extend below a locking strip (13) protruding from an edge of a floor panel (11) in a first direction and extending along the edge in a second direction, the locking strip (13) being configured to cooperate with a locking groove (16) provided at an edge of an adjacent floor panel (12) for joining two adjacent floor panels (11, 12), and wherein the underlay element (1) is configured to extend beyond an extension of the locking strip (13) in the first direction towards the edge of the adjacent floor panel (12).

[0310] 79. The underlay element according to item 78, wherein the underlay element (1) is configured to extend below the locking strip (13) along at least a portion of the extension of the locking strip (13) in the second direction.

[0311] 80. The underlay element according to any one of items 78-79, wherein the underlay element (1) is configured to extend below the locking strip (13) along the entire extension of the locking strip (13) in the second direction.

[0312] 81. The underlay element according to any one of items 78-80, wherein a planar extension of the underlay element (1) exceeds a planar extension of at least one of the floor panels (11, 12).

[0313] 82. The underlay element according to any one of items 78-81, wherein the floor panels (11, 12) are configured to be loosely arranged on the underlay element (1). 83. The underlay element according to any one of items 78-82, wherein the deformation resistant layer (3) has a tensile force at maximum load exceeding 50 N as measured in accordance with ISO527-2 / -3:2018, preferably exceeding 100 N as measured in accordance with ISO527-2 / -3:2018, more preferably exceeding 150 N as measured in accordance with ISO527-2 / -3:2018.

[0314] 84. The underlay element according to any one of items 78-83, wherein a density of the foamed base layer (2) is less than a density of the deformation resistant layer (3).

[0315] 85. The underlay element according to any one of items 78-84, wherein the foamed base layer (2) has a compressive strength about 50-900 kPa (at 0.5 mm) as measured in accordance with EN16354:2018, preferably 50-500 kPa (at 0.5 mm), more preferably 50-250 kPa (at 0.5 mm).

[0316] 86. The underlay element according to any one of items 78-85, wherein the deformation resistant layer (3) is un-foamed.

[0317] 87. The underlay element according to any one of items 78-86, wherein the deformation resistant layer (3) is fibre reinforced.

[0318] 88. The underlay element according to any one of items 78-87, wherein the deformation resistant layer (3) is reinforced by glass fibres, polymer fibres, mineral-based fibres, carbon fibres and / or natural fibres.

[0319] 89. The underlay element according to any one of items 78-88, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement wherein the glass fibres have a stiffness of 52-95 GPa as measured according to ASTM C1557- 20.

[0320] 90. The underlay element according to any one of items 78-89, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement having a weight of 10-180 g / m2.

[0321] 91. The underlay element according to any one of items 78-90, wherein the foamed base layer (2) is compressible, and the underlay element (1) further comprises a plurality of restrictions members (30) at least partly embedded in the foamed base layer (2), said restrictions members (30) being configured to restrict compression of the underlay element (1) by being less compressible than the foamed base layer (2).

[0322] 92. The underlay element according to any one of items 78-91, wherein a density of the deformation resistant layer (3) is 250-3000 kg / m3, preferably 500- 3000 kg / m3, more preferably 800-1500 kg / m3.

[0323] 93. The underlay element according to any one of items 78-92, wherein a density of the foamed base layer (2) is 20-700 kg / m3, preferably 20-300 kg / m3. 94. The underlay element according to any one of items 78-93, wherein a thickness of the foamed base layer (2) is 0.4-3.5 mm, preferably 0.6-1.8 mm.

[0324] 95. The underlay element according to any one of items 78-94, wherein a thickness of the deformation resistant layer (3) is 0.05-2 mm, preferably 0.25-0.75 mm.

[0325] 96. The underlay element according to any one of items 78-95, wherein a thickness of the foamed base layer (2) exceeds a thickness of the deformation resistant layer (3).

[0326] 97. The underlay element according to any one of items 78-96, wherein a thickness of the deformation resistant layer (3) is less than 30 % of a thickness of the foamed base layer (2).

[0327] 98. The underlay element according to any one of items 78-97, wherein the deformation resistant layer (3) has a tensile modulus exceeding 100 MPa as measured in accordance with ISO527-2 / -3:2018.

[0328] 99. The underlay element according to any one of items 78-98, wherein the deformation resistant layer (3) has a tensile strength at maximum load exceeding 50 N as measured in accordance with ISO527-2 / -3:2018.

[0329] 100. The underlay element according to any one of items 78-99, wherein the deformation resistant layer (3) forms a vapour barrier.

[0330] 101. The underlay element according to any one of items 78-100, wherein the underlay element (1) consists of the deformation resistant layer (3) and the foamed base layer (2).

[0331] 102. The underlay element according to any one of items 78-101, wherein the deformation resistant layer (3) is provided with an adhesive configured to attach the deformation resistant layer (3) to the foamed base layer (2).

[0332] 103. The underlay element according to any one of items 78-102, wherein the foamed base layer (2) comprises cross-linked expanded polymers.

[0333] 104. The underlay element according to any one of items 78-103, wherein the deformation resistant layer (3) comprises a thermoplastic material.

[0334] 105. The underlay element according to any one of items 78-104, wherein the underlay element (1) has a planar extension exceeding a planar extension of a floor panel (11, 12) intended to be arranged on the underlay element (1).

[0335] 106. The underlay element according to any one of items 78-105, wherein the deformation resistant layer (3) has a strain at maximum load being less than 0.5 mm / mm, such as less than 0.25 mm / mm, as measured in accordance with ISO527- 2 / -3:2018. 107. The underlay element according to any one of items 78-106, wherein the deformation resistant layer (3) has a stress at maximum load exceeding 15 MPa, such as exceeding 20 MPa, as measured in accordance with ISO527-2 / -3:2018.

[0336] 108. The floor covering to any one of items 24-50, wherein the deformation resistant layer (3) has a strain at maximum load being less than 0.5 mm / mm, such as less than 0.25 mm / mm as measured in accordance with ISO527- 2 / -3:2018.

[0337] 109. The floor covering to any one of items 24-50, wherein the deformation resistant layer (3) has a stress at maximum load exceeding 15 MPa such as exceeding 20 MPa as measured in accordance with ISO527-2 / -3:2018.

[0338] 110. The method to any one of items 51-77, wherein the deformation resistant layer (3) has a strain at maximum load being less than 0.5 mm / mm, such as less than 0.25 mm / mm, as measured in accordance with ISO527-2 / -3:2018.

[0339] 111. The method to any one of items 51-77, wherein the deformation resistant layer (3) has a stress at maximum load exceeding 15 MPa, such as exceeding 20 MPa, as measured in accordance with ISO527-2 / -3:2018.

[0340] 112. An underlay element (1) configured to be arranged between a flooring (10) and a sub-floor (20), comprising a foamed base layer (2) configured to be arranged on the sub-floor (20), a deformation resistant layer (3) attached to the foamed base layer (2), the deformation resistant layer (3) being more rigid than the foamed base layer (2).

[0341] 113. The underlay element according to item 112, wherein the deformation resistant layer (3) has a tensile force at maximum load exceeding 100 N as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018, such as exceeding 150 N as measured in accordance with 150527-1:2012 and ISO527-2 / - 3:2018.

[0342] 114. The underlay element according to item 112 or 113, wherein the deformation resistant layer (3) has a strain at maximum load being less than 0.5 mm / mm, such as less than 0.25 mm / mm as measured in accordance with ISO527- 1:2012 and ISO527-2 / -3:2018.

[0343] 115. The underlay element according to any one of the items 112-114, wherein the deformation resistant layer (3) has a stress at maximum load exceeding 15 MPa such as exceeding 20 MPa as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018.

[0344] 116. The underlay element according to any one of the items 112-115, wherein the foamed base layer (2) has a compressive strength about 50-900 kPa at 0.5 mm as measured in accordance with EN16354:2018. 117. The underlay element according to any one of items 112-116, wherein a density of the foamed base layer (2) is less than a density of the deformation resistant layer (3).

[0345] 118. The underlay element according to any one of the items 112-117, wherein the deformation resistant layer (3) is un-foamed.

[0346] 119. The underlay element according to any one of the items 112-118, wherein the deformation resistant layer (3) comprises a thermoplastic material and is fibre reinforced.

[0347] 120. The underlay element according to any one of the items 112-119, wherein the deformation resistant layer (3) is reinforced by glass fibres, polymer fibres, mineral-based fibres, carbon fibres and / or natural fibres.

[0348] 121. The underlay element according to any one of the items 112-120, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement wherein the glass fibres have a stiffness of 52-95 GPa as measured according to ASTM C1557-20.

[0349] 122. The underlay element according to any one of the items 112-121, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement having a weight of 10-180 g / m2.

[0350] 123. The underlay element according to any one of the items 112-122, wherein a density of the deformation resistant layer (3) is 250-3000 kg / m3.

[0351] 124. The underlay element according to any one of the items 112-123, wherein a density of the foamed base layer (2) is 20-700 kg / m3.

[0352] 125. The underlay element according to any one of the items 112-124, wherein a thickness of the foamed base layer (2) is 0.4-3.5 mm.

[0353] 126. The underlay element according to any one of the items 112-125, wherein a thickness of the deformation resistant layer (3) is 0.05-2 mm, such as 0.25-0.75 mm.

[0354] 127. The underlay element according to any one of the items 112-126, wherein a thickness of the foamed base layer (2) exceeds a thickness of the deformation resistant layer (3).

[0355] 128. The underlay element according to any one of the items 112-127, wherein a thickness of the deformation resistant layer (3) is less than 30 % of a thickness of the foamed base layer (2).

[0356] 129. The underlay element according to any one of the items 112-117, wherein the deformation resistant layer (3) has a tensile modulus exceeding 100 MPa as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018, such as exceeding 200 MPa as measured in accordance with ISO527-l:2012 and ISO527-2 / - 3:2018.

[0357] 130. The underlay element according to any one of the items 112-129, wherein the underlay element (1) consists of the deformation resistant layer (3) and the foamed base layer (2).

[0358] 131. The underlay element according to any one of items 112-129, wherein the deformation resistant layer (3) is provided with an adhesive configured to attach the deformation resistant layer (3) to the foamed base layer (2).

[0359] 132. The underlay element according to any one of the items 112-131, wherein the foamed base layer (2) comprises cross-linked expanded polymers.

[0360] 133. The underlay element according to any one of the items 112-132, wherein the deformation resistant layer (3) comprises a thermoplastic material.

[0361] 134. A method to arrange a floor covering comprising an underlay element (1) and at least two floor panels (11, 12), comprising arranging an underlay element (1) on a sub-floor (20) , the underlay element (1) comprising a foamed base layer (2) configured to be arranged on the sub-floor (20) and a deformation resistant layer (3) attached to the foamed base layer (2), the deformation resistant layer (3) being more rigid than the foamed base layer (2), joining a first edge of a first floor panel (11) to an adjacent edge of a second floor panel (12) by a mechanical locking system comprising a locking strip (13) protruding from the first edge in a first direction and extending along the first edge of the first floor panel (11) in a second direction, the locking strip (13) being configured to cooperate with a locking groove (16) provided at the adjacent edge of the second floor panel (12), arranging the joined floor panels (11, 12) on the underlay element (1) such that the underlay element (1) extends beyond an extension of the locking strip (13) at least in the first direction towards the adjacent edge of the second floor panel (12).

[0362] 135. The method according to item 134, further comprising arranging the joined floor panels (11, 12) on the underlay element (1) such that the underlay element (1) extends below the locking strip (13) along at least a portion of the extension of the locking strip (13) in the second direction.

[0363] 136. The method according to item 134 or 135, further comprising arranging the joined floor panels (11, 12) on the underlay element (1) such that the underlay element (1) extends below the locking strip (13) along the entire extension of the locking strip (13) in the second direction. 137. The method according to any one of items 134-136, wherein a planar extension of the underlay element (1) exceeds a planar extension of at least one of said at least two floor panel (11, 12) .

[0364] 138. The method according to any one of items 134-137, wherein said at least two floor panels (11, 12) are configured to be loosely arranged on the underlay element (1).

Claims

Claims1. An underlay element (1) configured to be arranged between a flooring (10) and a sub-floor (20), comprising a foamed base layer (2) configured to be arranged on the sub-floor (20), a deformation resistant layer (3) attached to the foamed base layer (2), the deformation resistant layer (3) being more rigid than the foamed base layer (2), wherein the deformation resistant layer (3) comprises a thermoplastic material and is fibre reinforced, and wherein the deformation resistant layer (3) has a tensile force at maximum load exceeding 100 N, as measured in accordance with ISO527-l:2012 and ISO527- 2 / -3:2018.

2. The underlay element according to claim 1, wherein the deformation resistant layer (3) has a strain at maximum load being less than 0.5 mm / mm, such as less than 0.25 mm / mm, as measured in accordance with 150527-1:2012 and ISO527- 2 / -3:2018.

3. The underlay element according to claim 1 or 2, wherein the deformation resistant layer (3) has a stress at maximum load exceeding 15 MPa, such as exceeding 20 MPa, as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018.

4. The underlay element according to any one of the preceding claims, wherein the foamed base layer (2) has a compressive strength about 50-900 kPa at 0.5 mm as measured in accordance with EN16354:2018.

5. The underlay element according to any one of the preceding claims, wherein a density of the foamed base layer (2) is less than a density of the deformation resistant layer (3).

6. The underlay element according to any one of the preceding claims, wherein the deformation resistant layer (3) is un-foamed.

7. The underlay element according to any one of the preceding claims, wherein the deformation resistant layer (3) is reinforced by glass fibres, polymerfibres, mineral-based fibres, carbon fibres and / or natural fibres.

8. The underlay element according to any one of the preceding claims, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement wherein the glass fibres have a stiffness of 52-95 GPa as measured according to ASTM C1557-20.

9. The underlay element according to any one of the preceding claims, wherein the deformation resistant layer (3) comprises a glass fibre reinforcement having a weight of 10-180 g / m2.

10. The underlay element according to any one of the preceding claims, wherein a density of the deformation resistant layer (3) is 250-3000 kg / m3.

11. The underlay element according to any one of the preceding claims, wherein a density of the foamed base layer (2) is 20-700 kg / m3.

12. The underlay element according to any one of the preceding claims, wherein a thickness of the foamed base layer (2) is 0.4-3.5 mm.

13. The underlay element according to any one of the preceding claims, wherein a thickness of the deformation resistant layer (3) is 0.05-2 mm, such as 0.25-0.75 mm.

14. The underlay element according to any one of the preceding claims, wherein a thickness of the foamed base layer (2) exceeds a thickness of the deformation resistant layer (3).

15. The underlay element according to any one of the preceding claims, wherein a thickness of the deformation resistant layer (3) is less than 30 % of a thickness of the foamed base layer (2).

16. The underlay element according to any one of the preceding claims, wherein the deformation resistant layer (3) has a tensile modulus exceeding 100 MPa, as measured in accordance with 150527-1:2012 and ISO527-2 / -3:2018, such as exceeding 200 MPa, as measured in accordance with 150527-1:2012 and ISO527-2 / - 3:2018.

17. The underlay element according to any one of the preceding claims, wherein the underlay element (1) consists of the deformation resistant layer (3) and the foamed base layer (2).

18. The underlay element according to any one of claims 1-16, wherein the deformation resistant layer (3) is provided with an adhesive configured to attach the deformation resistant layer (3) to the foamed base layer (2).

19. The underlay element according to any one of the preceding claims, wherein the foamed base layer (2) comprises cross-linked expanded polymers.

20. A method to arrange a floor covering comprising an underlay element (1) and at least two floor panels (11, 12), comprising arranging an underlay element (1) on a sub-floor (20) , the underlay element (1) comprising a foamed base layer (2) configured to be arranged on the sub-floor (20) and a deformation resistant layer (3) attached to the foamed base layer (2), the deformation resistant layer (3) being more rigid than the foamed base layer (2), joining a first edge of a first floor panel (11) to an adjacent edge of a second floor panel (12) by a mechanical locking system comprising a locking strip (13) protruding from the first edge in a first direction and extending along the first edge of the first floor panel (11) in a second direction, the locking strip (13) being configured to cooperate with a locking groove (16) provided at the adjacent edge of the second floor panel (12), arranging the joined floor panels (11, 12) on the underlay element (1) such that the underlay element (1) extends beyond an extension of the locking strip (13) at least in the first direction towards the adjacent edge of the second floor panel (12).

21. The method according to claim 20, further comprising arranging the joined floor panels (11, 12) on the underlay element (1) such that the underlay element (1) extends below the locking strip (13) along at least a portion of the extension of the locking strip (13) in the second direction.

22. The method according to claim 20 or 21, further comprising arranging the joined floor panels (11, 12) on the underlay element (1) such that the underlayelement (1) extends below the locking strip (13) along the entire extension of the locking strip (13) in the second direction.

23. The method according to any one of claims 20-22, wherein a planar extension of the underlay element (1) exceeds a planar extension of at least one of said at least two floor panel (11, 12) .

24. The method according to any one of claims 20-23, wherein said at least two floor panels (11, 12) are configured to be loosely arranged on the underlay element (1).

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