Mineral wool insulation

Abstract

An insulated flat roof system of a building comprises in sequence, a support structure, a layer of insulation and an overlying weatherproof membrane which seals the roofing system against ingress of water. The layer of insulation comprises: - a lower insulation layer comprising a plurality of adjacent lamellas, and - an upper insulation layer comprising a plurality of adjacent pressure distribution boards, each pressure distribution board overlying and being supported by the lower insulation layer

Description

Mineral wool insulation

[0001] This invention relates to an insulated flat roof system of a building and to mineral wool lamellas and mineral wool boards for an insulated flat roof system of a building.

[0002] A common type of insulated flat roof system of a building comprises, in sequence, a support structure, a layer of insulation and an overlying weatherproof membrane which seals the roofing system against ingress of water. This is sometime referred to as a “warm roof” as the insulation is arranged above the structural deck which is thus kept warm. The weatherproof membrane may be retained by mechanical fixing, by adhesion or by overlying ballast. As used herein, the term “flat roof” means a roof system which is substantially horizontal, that is to say with an inclination of between +5% and -5%; indeed, flat roof systems are generally arranged with an inclination of about 2% to facilitate water run-off.

[0003] Mineral wool flat roof panels can provide an advantageous combination of thermal performance, mechanical resistance (including compression strength and point load resistance), longevity, good resistance to fire and flames and ease of installation. One aim of the present invention is to provide an insulated flat roof system and mineral wool insulation for a flat roof system which further improves sustainability by reducing the amount of raw materials required for a desired performance of the flat roof. It has surprisingly been found that this aim can be achieved by using the combination of features defined in the present claims.

[0004] In accordance with one of its aspects, the present invention provides a flat roof system as defined in claim 1. Additional aspects of the invention are defined in other independent claims. The dependent claims define preferred and / or alternative embodiments.

[0005] The support structure may comprise a timber deck, a metal deck or a concrete deck. A vapour control layer, for example a polymer sheet, polyethylene sheet, reinforced polyethylene sheet, bitumen layer or bitumen bonded felt, may be provided between the support structure and the mineral wool insulation layer.

[0006] The roof system may be a warm roof, for example, a warm roof with a built-up felt or asphalt roof covering, a warm roof with a single ply membrane or an inverted / protected membrane / green roof.

[0007] The insulated flat roof system may be installed during construction of a new building. Alternatively, it may be used for renovation of an existing building. In the latter case, any existing insulated flat roof system may be removed prior to installation of the new flat roof system, or the new insulated flat roof system may be installed on top of the or part of the existing flat roof system.

[0008] As will be understood by those familiar with mineral wool insulation, a mineral wool lamella is a strip of mineral wool insulation which is cut from a mineral wool blanket and is used in an orientation that is rotated by 90° about its longitudinal axis with respect to its orientation prior to being cut from the mineral wool blanket; thus, top and bottom major (generally horizonal) surfaces of the mineral wool blanket as manufactured become (generally vertical) side surface of the lamella. The use of lamellas allows the strips of a mineral wool blanket manufactured with its mineral wool fibres orientated primarily horizontally to be used with its mineral wool fibres orientated primarily vertically; vertical orientation of the fibres is useful for providing compression strength. Thus it is preferred that, when used in the insulated flat roof system, the majority of the mineral fibres of each lamella have an orientation which is substantially vertical, notably at least 75% of the mineral fibres of each lamella have an orientation that is within ±30° with respect to the vertical, preferably at least 75% of the mineralP1792-WO R00F2DHC 11 March 2026fibres of each lamella having an orientation that is within ±15° with respect to the vertical. Preferably, each lamella is provided with a visual indication to denote the orientation in which it is to be used in the insulated flat roof system.

[0009] On the other hand, it is preferred that when used in the insulated flat roof system, the majority of the mineral fibres of each overlying pressure distribution board have an orientation which is substantially horizonal, notably at least 75% of the mineral fibres of each overlying pressure distribution board have an orientation that is within ±30° with respect to the horizontal, preferably at least 75% of the mineral fibres of each overlying pressure distribution board having an orientation that is within ±15° with respect to the horizontal. This facilities provision of a desired point load resistance.

[0010] In one preferred arrangement the mineral fibres of the lamellas are lightly crimped, notably with a crimp factor which is > 1.0 and <1.3. The crimp factor provides an indication of the degree of crimping and thus of fibre re-orientation during manufacture of the mineral wool blanket; it may be assessing a determining a reduction in line speed which causes longitudinal compression of the mineral wool blanket. A crimp factor of 1.3 indicates such a reduction in line speed by a factor of 1.3. Such light crimping may be used to adjust the thermal conductivity, density and compression strength of the lamellas. In an alternative preferred arrangement, the mineral fibres of the lamellas are not crimped.

[0011] As used herein:i) “compression strength” means compression strength as measured in accordance with EN 826;ii) “point load resistance” means point load resistance as measured in accordance with EN12430;iii) “thermal conductivity”, “lambda” and “A” mean thermal conductivity measured at 10 °C in accordance with EN 12667;iv) “A group” means the declared value of thermal conductivity according to EN 12667 (i.e. the thermal conductivity rounded up to the next milliwatt).The coordinates x-y are used herein to indicate a horizontal plane of the insulated flat roof system with the coordinate z indicating the vertical direction with respect to the insulated flat roof system.

[0012] Each lamella is preferably a unitary lamella, that is to say that prior to incorporation in the insulated flat roof system it is not attached to any of the other lamellas or to the pressure distribution board.

[0013] The average density of the lamellas is > 90 kg / m3and < 120 kg / m3, preferably > 95 kg / m3and < 115 kg / m3, more preferably > 100 kg / m3and < 110 kg / m3. As used herein, the term “average density” of the lamella is equivalent to the total mass of the lamella divided by its total volume.

[0014] One preferred type of lamella is a progressively varying density lamella, that is to say a lamella in which density varies progressively across its width in the x direction (the width of the lamella being smaller than its length in the y direction) without any step change in density. The preferred type of progressive varying density lamella is a centre light progressively varying density lamella, that is to say a lamella having its lowest density at a central portion of the lamella across its width in the x direction with the density increasing progressively in the x direction towards each of the side surfaces of the lamella. Each lamella preferably has - a first side layer running along a length of the lamella and extending from a first side surface of the lamella for 20 mm into the width of the lamella and having a first side layer density, - a second side layer running along a length of the lamella and extending from a second side surface of the lamella for 20 mm into the width of the lamella and having a second side layerP1792-WO R00F2DHC 11 March 2026density, and-a median layer having a width of 20 mm, the median layer being positioned equidistant between the first side layer and the second side layer and having a median layer density, and each of the first side layer density and the second side layer density is at preferably at least 10 % greater, more preferably at least 20 % greater and even more preferably at least 25% greater than the median layer density.Such varying density lamellas may be produced, for example, by arranging during manufacture of the mineral wool blanket for a combination of :- a bottom horizontal layer of mineral wool of the mineral wool blanket to be compressed, for example by suction on a collecting belt of mineral fibres;- the height of the mineral wool blanket to be reduced by compression as it travels along the manufacturing line using a series of horizontal roller arranged at progressively decreasing heights; and- atop horizontal layer of mineral wool of the mineral wool blanket to be compressed, for during passage through a curing oven.

[0015] Another alternative preferred type of lamella is a dual density lamella cut from a dual density mineral wool blanket, that is to say a mineral wool blanket comprising a high density surface layer of mineral wool (notably having i) a thickness which is > 5mm and / or < 40 mm and / or ii) a density which is > 130 kg / m3and / or < 250 Kg / m3) and a lower density underlying layer of mineral wool. In a dual density mineral wool blanket there is a step change in density between at least two adjacent layers of the mineral wool in the sense that when considering adjacent 10mm thick planar layers of mineral wool parallel to the major surfaces, there is a step change in average density between at least two such immediately adjacent layers which is > 10 % of the density of the layer having the higher density. For example, in a dual density mineral wool blanket having a 15mm thick surface layer having a density of 220 kg / m3and an underlying 285mm thick layer of mineral wool having a density of 140 kg / m3, there is a step change in density of 80 kg / m3(i.e. 36% of the density of the higher density) in respect of i) a notional layer of mineral wool which forms a planar layer parallel to the major surfaces and which is positioned to fill the depth between 15mm and 5mm below the major surface of the high density layer and ii ) a notional layer of mineral wool which forms a planar layer parallel to the major surfaces and which is positioned to fill the depth between 25mm and 15mm below the major surface of the high density layer. When used in an insulated flat roof system of a building, the dual density lamella has its high-density layer arranged in a substantially vertical plane i.e. in the z direction.

[0016] The width of each lamella (in the x direction) is > 160 mm and preferably < 340 mm. One particularly preferred width is 300mm, another particularly preferred width is 240 mm. These widths facilitate arrangement of respectively 4 and 5 lamellas on a pallet having a width of 1.2 m. Preferably, each lamella has a length (in the y direction) which is > 1900 mm and < 2450 mm one particularly preferred length being 2000 mm and another particularly preferred length being 2400mm; this facilitates handling of the lamellas and assembly of the insulated flat roof system. Alternatively, each lamella may a length (in the y direction) which is > 950 mm and < 1250 mm, for example 1000 mm or 1200 mm. The height of each lamella (in the z direction) is preferably > 150 mm and < 550 mm, more preferably > 200 mm and < 500 mm.

[0017] The thermal conductivity of each lamella is < 45 mW / m.K, preferably < 44 mW / m.K, more preferably < 43 mW / m.K; this provides suitable thermal performance. Each lamella is preferably in A group 43; alternatively, each lamella may be in A group 44 or A group 42.

[0018] Each lamella has a compression strength which is > 65 kPa and < 90 kPa, preferably a compression strength which is > 70 kPa and < 85 kPa.P1792-WO R00F2DHC 11 March 2026

[0019] Each overlying pressure distribution boards has an average density which is > 160 kg / m3and < 260 kg / m3, preferably > 180 kg / m3and < 220 kg / m3.

[0020] Each pressure distribution board has a thickness (in the z direction) which is > 10 mm, and preferably < 50 mm. More preferably, the thickness of each pressure distribution board is > 20 mm and preferably < 40 mm.

[0021] The lamellas and the pressure distribution boards comprise an organic mineral wool binder which serves to hold the mineral wool fibres together, notably an organic, thermoset binder. The mineral wool binder may make up > 2 wt%, > 2.5 wt% or > 3 wt% and / or < 7 wt% or < 6 wt% or < 5 wt% of the lamellas and the pressure distribution boards. The binder content may be determined by LOI (loss on ignition). The mineral wool binder may be a phenol formaldehyde based binder, particularly extended with urea. Alternatively, the mineral wool binder and the lamellas and / or pressure distribution boards may be formaldehyde free. In the latter case, each lamella and / or pressure distribution board (comprising the mineral wool binder) preferably comprises less than 5 ppm or less than detectable limits of free formaldehyde and / or consist of materials which together comprise less than these amounts of free formaldehyde and / or releases levels of formaldehyde in standardised tests adapted to simulate ordinary use which allows it to be classified as having no or undetectable levels of formaldehyde release. Preferably, such products release less than 10pg / m3, more preferably less than 5 pg / m3of formaldehyde during the period of 24-48 hours from the start of testing in accordance with ISO 16000. The mineral wool binder may be a sugar-based binder, that is to say a binder which is the reaction product(s) of a binder solution whose solid content comprises at least 50 wt% sugar(s). The mineral wool binder may be the reaction product(s) of a binder solution whose solid content comprises at least 70 wt% reducing sugar(s), preferably in combination with a source of nitrogen to form a Maillard reaction product, notably in combination with preferably at least 10 wt% of i) amine(s) and / or ii) ammonium salt(s) of carboxylic acid(s).

[0022] The layer of insulation preferably has a fire classification of Euroclass A2 (or alternatively A1) as determined under EN 13501-1.

[0023] The weatherproof membrane may be a single ply membrane. It may be selected from a bitumen membrane, a fully bonded built-up bitumen membrane, mastic asphalt, a polymer membrane, a PVC membrane; an EPDM (ethylene propylene diene terpolymer) membrane; a membrane applied in liquid form. The adhesive may be a “hot melt” adhesive, for example a bitumen or bitumen-based adhesive. The hot melt adhesive may be applied in liquid form, for example poured on to or spread over the mineral wool insulation panel prior to application of the membrane. Alternatively, the adhesive may be contained within the membrane and released by heating the membrane, for example by torching a bituminous membrane. The adhesive may be a cold adhesive; it may be a polymer adhesive. The adhesive may be a polyurethane adhesive, a polyacrylic adhesive, a rubber adhesive or a rubber contact adhesive.

[0024] In addition to adhesion between the weatherproof membrane and the mineral wool insulation panel, the roofing system may comprise anchors, notably mechanical fixations, to secure the weatherproof membrane, for example to secure the weatherproof membrane to the mineral wool insulation panel and / or to the support structure. In preferred embodiments, no such anchors are used, the adhesion between the weatherproof membrane and the mineral wool insulation panel providing sufficient peel strength. In other embodiments, between one and four such anchors are used per mineral wool insulation panel; common know comparable roof systems require a greater number of anchors.P1792-WO R00F2DHC 11 March 2026

[0025] An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings of which:Fig 1 is a schematic side view of an insulated flat roof system of a building;Fig 2 is a top view of part of a layer of insulation;Fig 3 is a side view of part of the layer of insulation;Fig 4 is a bottom view of part of the layer of insulation;Fig 5 is an end view of part of the layer of insulation;Fig 6 is a side view of one preferred form of lamella, andFig 7 is a side view of another preferred form of lamella..

[0026] The warm deck, roof system 10 of Fig 1 comprises (in sequence from the interior to the exterior of a building) a support structure 11 provided by a metal deck, an optional vapour control layer 12, a layer of insulation 13, and a overlying weatherproof membrane 14, in this case a single ply membrane secured to the layer of insulation 13 by an adhesive (not shown). A plurality of mechanical anchors (not shown) pass through the overlying weatherproof membrane 14 and through layer of insulation 13 into the supporting structure 11.

[0027] As shown in Fig 3, the layer of insulation 13 comprises:- a lower insulation layer 31 comprising a plurality of adjacent mineral wool lamellas 41, 42; and- an upper insulation layer 32 comprising a plurality of mineral wool pressure distribution boards 321, 322.

[0028] A first section of lamellas 41 comprises a plurality of adjacent, unitary mineral wool lamellas 411, 412, 413, 414. Similarly, a second section of lamellas 42 comprises a plurality of adjacent, unitary mineral wool lamellas 421, 422, 423, 424.

[0029] Each pressure distribution board 31,32 overlies, sits on and is supported by the lower insulation layer 31. It is preferred for the x-y position of the pressure distribution boards 31,32 to be offset from the x-y positions of the lamella sections 41 ,42 so that each edge of the pressure distribution board is offset with respect to its underlying lamella sections. Figures 2 to 4 illustrate such an offset in the x direction (but not in the y direction).

[0030] Each pressure distribution board 31,32 comprises a non-woven glass veil 33 adhered to its upper surface.

[0031] As shown in the enlarged, schematic side view of the lamella in Fig 6, each of these lamella hasa first side layer 61 running along a length of the lamella (in the y direction) and extending from a first side surface 611 of the lamella 411 for 20 mm into the width of the lamella (in the x direction) and having a first side layer density,a second side layer 62 running along a length of the lamella (in the y direction) and extending from a second side surface 621 of the lamella for 20 mm into the width of the lamella (in the x direction) and having a second side layer density, anda median layer 63 having a width of 20 mm, the median layer being positioned equidistant between the first side layer 61 and the second side layer 62 and having a median layer density.

[0032] Table 1 shows an example of components of the insulating layer 31 (using lamellas of the type described with reference to Fig 6) and the properties that these provided:Table 1: Example of components of insulating layerP1792-WO ROOF2DHC 11 March 2026

[0033] Fig 7 shows an enlarged, schematic side view of an alternative preferred form of lamella. This is a dual density type lamella which has:- a high density layer of mineral wool 71 which runs along a length of a first side 711 of the lamella (in the y direction) and extends from the first side surface 711 of the lamella 411 part way towards the centre (in the x direction), and- a lower density layer of mineral wool 72 which makes up the rest of the lamella.

[0034] Table 2 shows an alternative example of components of the insulating layer 31 (using dual density lamellas) and the properties that these provided:Table 2: Example of components of insulating layerP1792-WO ROOF2DHC 11 March 2026

[0035] Examples 1 and 2 provides comparable compression strength and point load resistance to an ordinary slab form of mineral wool flat roof board insulation having a monolithic density of about 135 kg / m3; it thus provides a lighter insulation layer which requires a reduced amount of raw material to obtain a desired performance for an insulated flat roof system of a building.P1792-WO ROOF2DHC 11 March 2026

Claims

CLAIMS1 An insulated flat roof system of a building comprising in sequence, a support structure, a layer of insulation and an overlying weatherproof membrane which seals the roof system against ingress of water,in which the layer of insulation comprises:- a lower insulation layer comprising a plurality of adjacent lamellas, and- an upper insulation layer comprising a plurality of adjacent pressure distribution boards, each pressure distribution board overlying and being supported by the lower insulation layer,in which the lamellas are stone wool lamellas having- an average density which is > 90 kg / m3and < 120 kg / m3, preferably > 95 kg / m3and < 115 kg / m3, more preferably > 100 kg / m3and < 110 kg / m3and- a width which is > 160 mm and preferably < 340 mm,- a thermal conductivity which is < 45 mW / m.K, preferably < 44 mW / m.K, and- a compression strength which is > 65 kPa and < 90 kPa, andin which the overlying pressure distribution board comprises a stone wool insulation board having:- an average density which is > 160 kg / m3and < 260 kg / m3, and- a thickness which is > 10 mm and preferably < 50 mm.2 An insulated flat roof system of a building in accordance with claim 1, in which the majority of the mineral fibres of each lamella have an orientation which is substantially vertical, notably at least 75% of the mineral fibres of each lamella have an orientation that is within ±30° with respect to the vertical, preferably at least 75% of the mineral fibres of each lamella having an orientation that is within ±15° with respect to the vertical.3 An insulated flat roof system of a building in accordance with claim 1, in which the majority of the mineral fibres of each overlying pressure distribution board have an orientation which is substantially horizonal, notably at least 75% of the mineral fibres of each overlying pressure distribution board have an orientation that is within ±30° with respect to the horizontal, preferably at least 75% of the mineral fibres of each overlying pressure distribution board having an orientation that is within ±15° with respect to the horizontal.4 An insulated flat roof system of a building in accordance with any preceding claim, in which each lamella has:a first side layer running along a length of the lamella and extending from a first side surface of the lamella for 20 mm into the width of the lamella and having a first side layer density,a second side layer running along a length of the lamella and extending from a second side surface of the lamella for 20 mm into the width of the lamella and having a second side layer density, anda median layer having a width of 20 mm, the median layer being positioned equidistant between the first side layer and the second side layer and having a median layer density,P1792-WO ROOF2DHC 11 March 2026and in which each of the first side layer density and the second side layer density is at least 10% greater than the median layer density,preferably in which each of the first side layer density and the second side layer density is at least 20% greater than the median layer density, andmore preferably in which each of the first side layer density and the second side layer density is at least 25% greater than the median layer density.5 An insulated flat roof system of a building in accordance with any of claims 1 to 3, in which each lamella is a dual density lamella comprising:- a high density layer of mineral wool which runs along a length of a first side of the lamella and extends from the first side surface of the lamella part way towards the centre of the lamella (in the x direction), and- a lower density layer of mineral wool which makes up the rest of the lamella.6 An insulated flat roof system of a building in accordance with of claim 5,in which the high density layer of mineral wool :- has an average density which is > 130 kg / m3and preferably < 240 kg / m3, more preferably > 135 kg / m3and < 220 kg / m3- has a width (in the x direction) which is > 15 mm and preferably < 60 mm, more preferably > 20mm and < 40 mmand in which the lower density layer of mineral wool:- has an average density which is > 70 kg / m3and < 100 kg / m3, preferably > 80 kg / m3and < 100 kg / m37 An insulated flat roof system of a building in accordance with any preceding claim, in which each lamella is in A group 43.8 An insulated flat roof system of a building in accordance with any preceding claim, in which each lamella has a compression strength which is > 70 kPa and < 85 kPa. 9 An insulated flat roof system of a building in accordance with any preceding claim, in which each overlying pressure distribution board has an average density which is > 180 kg / m3and < 220 kg / m3.10 An insulated flat roof system of a building in accordance with any preceding claim, in which each overlying pressure distribution board has a thickness which is > 20 mm and < 40 mm.11 An insulated flat roof system of a building in accordance with any preceding claim, in which each overlying pressure distribution board comprises an overlying mineral fibre fleece, preferably in which the overlying a mineral fibre fleece is a non-woven glass fibre fleece comprising a filler.12 An insulated flat roof system of a building in accordance with any preceding claim, in which the overlying pressure distribution board has a point load resistance which is > 950 N (EN 12430), preferably > 1000 N (EN 12430).13 An insulated flat roof system of a building in accordance with any preceding claim, in which each lamella board comprises a thermoset organic binder in a quantity which isP1792-WO ROOF2DHC 11 March 2026> 2 wt% and < 7 wt%, preferably > 3 wt% and < 5 wt% kg / m3, notably a sugar-based binder.14 An insulated flat roof system of a building in accordance with any preceding claim, in which each overlying pressure distribution board comprises a thermoset organic binder in a quantity which is > 2 wt% and < 7 wt%, preferably > 3 wt% and < 5 wt% kg / m3, notably a sugar-based binder.15 An insulated flat roof system of a building in accordance with any preceding claim, in which the layer of insulation has a fire classification of at least A2 as determined under EN 13501-1.16 An insulated flat roof system of a building in accordance with any preceding claim, in which the layer of insulation covers a surface area of the roof which is at least 50 m2, preferably at least 100 m2, more preferably at least 200 m2.17 A mineral wool lamella configured for use as the lamella of an insulated flat roof system of a building in accordance with any preceding claim.P1792-WO ROOF2DHC 11 March 2026

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