Floor structure of wooden building

Abstract

To provide the floor structure of a building, in which the floor beam of an upper floor is exposed to the ceiling of a lower floor and in which electric wiring can be conducted easily to a newly installed partition wall when the change of the room arrangement of an upper-floor room is required.SOLUTION: The floor structure includes a floor material layer 2 including a plurality of beams 1, a floor base material layer 21 laid in contact with upper surfaces of the plurality of beams 1, and a floor finishing material layer 22 laid in contact with an upper surface of the floor base material layer 21, wherein the floor material layer 2 has a columnar space 203 vertically penetrating the floor base material layer 21 at a position including a portion directly above the beam 1, an upper portion of the columnar space 203 is covered with the floor finishing material layer 22, and a columnar space communication hole 221 is formed in the floor finishing material layer 22 at a position above the columnar space 211. A lid body 222 for covering the columnar space communication hole 221 is detachably fixed to the floor finishing material layer 22.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a floor structure of a wooden building with a lower floor as a living space. [Background technology]

[0002] In small wooden houses, an open-plan living style has been proposed, with open ceilings and fewer partitions (Non-Patent Document 1). Based on this living method, it is preferable for residential buildings to have low eaves heights and small interior space volumes, in terms of energy efficiency, etc. Lowering the floor height is an effective way to reduce eaves height (however, this is limited to buildings with two or more floors), and reducing the floor height also makes it possible to reduce the number of staircase steps, which is also preferable in terms of efficiently using floor space in small wooden houses.

[0003] In this approach to space utilization, a known method is to expose the beams on the ceiling of the lower floor to improve the interior view and ensure ceiling height while suppressing the floor height. When using this method, the beams divide the attic space, so electrical wiring routes for lights and other fixtures installed on the ceiling must be secured separately by drilling wiring holes in the beams or by using a double floor structure (Patent Document 1). However, structurally, there are restrictions on the locations where wiring holes can be drilled in the beams, and using a double floor structure has the problem of complicated construction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-213856 [Non-patent literature]

[0005] [Non-Patent Document 1] Wonder Device | BESS Log House (https: / / www.bess.jp / products / wonderdevice / ) Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention was invented in consideration of the above-mentioned conventional problems, and aims to provide a floor structure that is easy to construct in a wooden building with a so-called "exposed beam" appearance, in which the floor beams of the upper floors are exposed on the ceiling of the lower floor, and that allows the ceiling height of the lower floors to be set high while keeping the floor height low, while ensuring electrical wiring paths within the floor structure. [Means for solving the problem]

[0007] In order to solve the above problems, the floor structure of a building according to an embodiment of the present invention comprises: a plurality of beams that are installed in parallel at predetermined intervals and have flush upper surfaces; a floor underlayment layer laid in contact with the upper surfaces of the plurality of beams; a floor finishing material layer laid in contact with the upper surface of the underfloor material layer; In the flooring layer, a columnar space penetrating the first flooring layer from top to bottom is formed at a position including directly above at least one of the beams, and is covered with the second flooring layer; a length of a cross section of the columnar space perpendicular to the longitudinal direction of the beams is greater than a width of the beams, and both horizontal ends of the cross section of the columnar space perpendicular to the longitudinal direction of the beams extend from both side surfaces of the beams in a plan view; The floor finishing material layer is characterized in that a columnar space communication hole is formed at a position that includes at least a portion of the upper part of the columnar space, and a lid that covers the columnar space communication hole is removably fixed at a position where the height of its upper surface is flush with the upper surface of the floor finishing material layer. [Effects of the Invention]

[0008] The floor structure of a wooden building of the present invention is constructed as described above, and uses the columnar spaces provided in the underfloor material layer as electrical wiring paths at the intersections with the beams. This floor structure eliminates the need for a double-floor structure to ensure electrical wiring paths, even when using the so-called "beam exposure" technique, which exposes the beams to the interior space of the lower floor. This reduces construction costs. Furthermore, since it is not necessary to drill wiring holes in the beams to ensure electrical wiring paths, there is no need to consider the location of the wiring holes in the beams. In this way, a floor structure for a wooden building can be provided that allows the ceilings of the lower floors to be set high and the floor height to be reduced, making it cost-effective and easy to construct. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a vertical cross-sectional view of a floor structure according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional perspective view of the floor structure of FIG. 1. [Figure 3] 1 shows a plan of the floor structure of the first and second embodiments of the present invention (a plan is a view showing the arrangement of columns, beams, etc. from above). [Figure 4] FIG. 3 is a floor plan showing the layout of the underfloor plywood 211. [Figure 5] Figure 4 shows the layout plan showing the electrical wiring route. [Figure 6] FIG. 6 is a vertical cross-sectional view of a floor structure according to a second embodiment of the present invention, taken along line AA in FIG. 5. [Figure 7] FIG. 7 is a cross-sectional perspective view of the floor structure of FIG. 6. [Figure 8] 8b is a vertical cross-sectional view of a floor structure according to a third embodiment of the present invention, and FIG. 8b is an enlarged view of the beam 1 and the peripheral portion of the columnar space 203 in FIG. 8a. [Figure 9] This shows the procedure for installing a new partition wall on the floor structure shown in Figure 8 and installing electrical wiring inside the newly installed partition wall. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a floor structure of a wooden building according to one embodiment of the present invention will be described with reference to the drawings. (First embodiment)

[0011] FIG. 1 is a vertical cross-sectional view of a floor structure according to a first embodiment of the present invention, and more specifically, a cross-sectional view taken from a direction perpendicular to the long side of a floor underlayment plywood 211. FIG. 2 is a cross-sectional perspective view of the floor structure of FIG. 1. As shown in FIGS. 1 and 2, the floor structure of a wooden building according to the first embodiment comprises a beam 1, a flooring layer 2 constructed horizontally on the upper surface of the beam 1, a ceiling space 3 in contact with the underside of the flooring layer 2, and a ceiling material layer 4 constructed horizontally below the flooring layer 2 across the ceiling space 3. The underside of the ceiling material layer 4 is formed at a height higher than the underside of the beam 1, and the upper surface of the flooring layer 2 appears in the upper floor room F2 as the floor surface of the upper floor room F2. A portion of the side surface and the underside of the beam 1 and the underside of the ceiling material layer 4 appear in the lower floor room F1 as the ceiling of the lower floor room F1.

[0012] The beams 1 of the wooden building in this embodiment have a vertically long rectangular cross section as shown in Fig. 1, and the height of the cross section varies depending on the distance between the columns across which the beam 1 is spanned. Note that the cross section of the beam 1 is not necessarily limited to a rectangle as long as the upper surface is horizontal, and for example, the underside may have the grain of a log exposed.

[0013] FIG. 3 is a floor plan of a floor structure according to a first embodiment of the present invention (this also applies to the second embodiment described later). The beams 1 of the wooden building in this embodiment are arranged in parallel with multiple beams spaced apart at intervals equal to the modules, and in parallel with multiple beams spaced apart perpendicularly at intervals equal to an integral multiple of the modules. A module is a basic dimension that serves as a design standard in architecture (in Japanese wooden houses, one module is generally defined as 3 shaku (approximately 910 mm), and this is also followed in this embodiment). As an example, the beams in FIG. 3 are arranged such that beams 101 to 105 are arranged parallel to the left and right of the figure, while beams 1A, 1B, and 1C, which are perpendicular to these, are arranged parallel to the depth of the figure. Beams 101 and 1C form girths that contact the exterior wall. Beams 101 to 105 are arranged from front to back at intervals equal to the modules, and beams 1A, 1B, and 1C, which are perpendicular to these, are arranged at intervals twice the modules. Beams 101, 104, and 105 are spanned between beams 1A and 1C, and the rectangular area surrounded by beams 101, 1C, 104, and 1B is an open space, with beam 1B spanned between beams 101 and 104, and beams 102 and 103 spanned between beams 1A and 1B.

[0014] As shown in Fig. 1, the flooring layer 2 of the wooden building of this example is composed of an underfloor material layer 21 (an example of a first flooring layer) laid horizontally in contact with the upper surface of the beam 1, and a floor finishing material layer 22 (an example of a second flooring layer) laid horizontally in contact with the upper surface of the underfloor material layer 21. Underfloor plywood 211 is used for the underfloor material layer 21, and solid wood flooring is used for the floor finishing material layer 22, and as shown in Fig. 2, they are laid horizontally without any gaps to form the floor of the upper floor room F2.

[0015] Figure 4 is a floor plan showing the layout of the underfloor plywood 211 in Figure 3. The underfloor plywood 211 used in the underfloor material layer 21 of the wooden building of this embodiment has a short side length that is approximately equal to the module spacing, and a ratio of long side to short side length of 2:1, as shown in Figure 4, and some are square, cut so that the long side length is the same as the short side length, and are laid out in a staggered pattern so that the vertices of the outer periphery of four adjacent underfloor plywoods 211 do not coincide. The underfloor plywood 211 is arranged in this manner on the top surface of the beam 1, so that in the example shown in Figure 4, the line connecting the midpoints of both long sides of the underfloor plywood 211 coincides with the center line of the beam 102 in the underfloor plywood 211a1, with the center line of the beam 103 in the underfloor plywood 211b2, with the center line of the beam 104 in the underfloor plywood 211c1, and with the center line of the beam 105 in the underfloor plywood 211d2 and the underfloor plywood 211d4.

[0016] The long sides of the underfloor plywood 211 used in the first embodiment are tongued as shown in Fig. 2, and the underfloor plywood 211 whose long sides are adjacent to each other are bonded to the tongues of the long sides using an adhesive. At the locations where the long sides of the underfloor plywood 211 adjacent to each other and the center line of the beam 1 coincide in plan view, nails are driven into the underfloor plywood 211 at specified intervals, ensuring a specified edge distance from each long side, and the underfloor plywood 211 is fixed to the beam 1 directly below.

[0017] The joint surfaces of the short sides are arranged so as to coincide with the center line of the beam 1 in a plan view, and are nailed at predetermined intervals with a predetermined end distance from each short side, and are fixed to the top surface of the beam 1 directly below. The underfloor plywood 211 is arranged so that the line connecting the center lines of both long sides also coincides with the center line of the beam 1 in a plan view, and is nailed at predetermined intervals in a river-shaped pattern on the line connecting the center lines of both long sides and on a line with a predetermined edge distance from both short sides, and is fixed to the beam 1 directly below. The underfloor plywood 211 laid on the top surface of the beam 1 forms the underfloor material layer 21 in this way, and is fixed to the beam 1 directly below it.

[0018] As shown in FIG. 1 , among the beams 1 of this embodiment, beams 101 to 105 are arranged at equal intervals as the modules. The side surfaces of the beams 1 are fixed with rafters 311 at a predetermined distance below the underside of the floor subfloor material layer 21. As shown in FIG. 2 , the rafters 311 are made of lightweight steel frame with a small U-shaped cross section in the illustrated embodiment, but elongated members made of materials other than lightweight steel, such as wood, may also be used. Thus, for example, in FIG. 1 , multiple rafters 312 are installed between the rafter 311 attached to the right side of beam 102 and the rafter 311 attached to the left side of beam 103, which faces the right side of beam 102. The multiple rafters 312 are installed at approximately equal intervals as shown in FIG. 2 . In the illustrated embodiment, the rafters 312 are made of lightweight steel frame with a square-shaped cross section, but elongated members made of materials other than lightweight steel, such as wood, may also be used. The ceiling underlayment material constituting the ceiling material layer 4 is laid with its upper surface in contact with the lower surface of the above-mentioned roof joist material 312, as shown in FIGS.

[0019] As shown in Fig. 2, the ceiling material layer 4 of this embodiment is constructed by laying gypsum board flush with the underside of the rough joist 312 as a ceiling underlayment material, with no gaps, and the entire underside being painted with water-based paint or covered with wallpaper or vinyl cloth (not shown). As shown in Fig. 1, the outer periphery of the ceiling material layer 4 abuts against the side of the beam 1, and the height of the underside of the ceiling material layer 4 is higher than the height of the underside of the beam 1, so the interior of the lower floor living room F1 creates a "beam-exposed" landscape with part of the side and underside of the beam 1 exposed.

[0020] In this embodiment, the height of the underside of the ceiling material layer 4 is higher than the underside of the beam 1, as shown in Figure 1, so the attic space 3 between the upper surface of the ceiling material layer 4 and the underside of the floor base plywood 211 is divided into 3a, 3b, 3c, and 3d by beams 102, 103, and 104, as shown in Figure 3, as an example, and each forms a separate space.

[0021] 1, a ceiling molding 41 is attached to the periphery of the underside of the ceiling material layer 4 with its side surface in contact with the beam 1, and is installed so that the underside of the ceiling molding 41 is higher than the underside of the beam 1. In the illustrated form, the cross section of the ceiling molding 41 is rectangular, but its shape and size can be selected arbitrarily depending on the design, and the shapes of parts other than the upper surface in contact with the underside of the ceiling material layer 4 and the side surface in contact with the side surface of the beam 1 may be arbitrary. By installing the ceiling molding 41 in this position, it conceals any gap that may occur between the beam 1 and the ceiling material layer 2.

[0022] In this embodiment, a columnar space 203 is formed in the underfloor material layer 21, penetrating the layer 21 from top to bottom, as shown in Fig. 2. The columnar space 203 in the illustrated form is a rectangle with rounded corners in a plan view, penetrating the layer 21 from top to bottom, and its height is the same as the thickness of the layer 21. The columnar space 203 is located at a position where it intersects with the beam 1 in a plan view, as shown in Figs. 2 and 4. The size of the columnar space 203 is such that the width of the cross section perpendicular to the longitudinal direction of the beam 1 that intersects it is slightly larger than the width of the beam 1, as shown in Fig. 1, and both ends extend at approximately equal lengths from both side surfaces of the beam 1. 2, the length of the cross section of the columnar space 203 in the longitudinal direction of the beam 1 is narrower than the spacing between the nails 213 that are driven to fasten the underfloor plywood 211 that forms the underfloor material layer 21 to the beam 1 directly below, so the nailing intervals at the points that straddle the columnar space 203 can also be set to a predetermined interval. Since the floor finishing material layer 22 is laid without gaps on the upper surface of the underfloor material layer 21 as described above, the drilled portion of the columnar space 203 in the underfloor material layer 21 is covered by the floor finishing material layer 22.

[0023] In the underfloor plywood 211 used in the underfloor material layer 21 of this embodiment, a columnar space 203 is drilled in advance at a position away from the outer edge of the underfloor plywood 211, in a manner that intersects with a line connecting the midpoints of both long sides of the underfloor plywood 211, before the underfloor plywood 211 is fixed to the upper surface of the beam 1. In the illustrated embodiment, the columnar space 203 is formed at this position in the underfloor plywood 211, and therefore can be formed without requiring any particular reinforcement, unlike when the columnar space 203 is formed by cutting out both outer edges across the joints between adjacent underfloor plywoods 211.

[0024] Figure 5 is a floor plan showing the electrical wiring route in Figure 4. Electrical cord 5, which supplies electricity to electric lights and other devices installed on the ceiling of lower-floor living room F1, is routed in attic space 3, which is the space between the underside of underfloor material layer 21 and the upper surface of ceiling material layer 4, as shown in Figures 1 and 5. In the illustrated embodiment, this attic space 3 is divided into spaces 3a, 3b, 3c, and 3d by beams 102, 103, and 104 as shown in Figure 3. In this divided attic space 3, for example, adjacent attic spaces 3b and 3c are connected via columnar spaces 203 provided in underfloor plywood 211b2, so that electrical cord 5 routed in attic space 3b can be extended to attic space 3c via columnar space 203. (Second embodiment)

[0025] Unlike the first embodiment, the floor structure of the second embodiment of the present invention is applicable to cases where so-called four-sided nailing is required for laying the underfloor plywood 211. Figure 6 is a view of the floor structure of this embodiment seen from a direction parallel to the long side of the underfloor plywood 211, and is a cross-sectional view taken along line AA in Figure 5.

[0026] As shown in FIG. 6, the floor structure of this embodiment includes support members 212 whose upper surfaces are aligned with the upper surfaces of the beams 1 at locations where there are no beams 1 directly below the long sides of adjacent subfloor plywoods 211 whose long sides are adjacent to each other, in order to enable nailing all around the subfloor plywood 211. The subfloor plywoods 211 of this embodiment are fixed to the support members 212 by nailing one or both of their long sides at predetermined intervals. Note that although the subfloor plywood 211 in FIG. 7 has tongues on its long sides, in the floor structure of this embodiment, the subfloor plywood 211 is nailed all around to form the subfloor material layer 21. Therefore, unlike the floor structure of the first embodiment, it is not necessary to use subfloor plywood 211 with tongues on its long sides, and it is not necessary to use adhesive on the long sides of the subfloor plywood 211 to bond it to the long sides of adjacent subfloor plywood 211.

[0027] Of the beams 1 of this embodiment, the beams 101 to 105, which are arranged at equal intervals as the modules, have rafters 311 fixed to their side surfaces, as in the first embodiment. For example, in the form shown in Fig. 6, the rafters 311 are fixed to the front side surface of the beam 102. A plurality of rafters 312 are installed at approximately equal intervals between the rafters 311 fixed to the side surface of the beam 101 (not shown in Fig. 6) facing the front side surface of the beam 102, parallel to the receiving material 212 and avoiding the position of the receiving material 212. The ceiling underlayment material constituting the ceiling material layer 4 is laid in contact with the underside of the rafters 312, as shown in Figs. 6 and 7.

[0028] As shown in Figure 6, the outer periphery of the ceiling material layer 4 in this embodiment abuts against the side surface of the beam 1, and the upper surface of the ceiling material layer 4 does not abut against the underside of the receiving material 212, leaving a gap. Since the height of the underside of the ceiling material layer 4 in this embodiment is higher than the height of the underside of the beam 1, the interior of the lower floor living room F1 creates a "beam exposed" landscape in which part of the side surface and the underside of the beam 1 are exposed.

[0029] In this embodiment, the lower surface of the ceiling material layer 4 is located higher than the lower surface of the beam 1 as shown in Fig. 6, and a gap is secured between the upper surface and the lower surface of the support material 212. The attic space 3 between the upper surface of the ceiling material layer 4 and the lower surface of the subfloor plywood 211 is partitioned by the beam 1, but not by the support material 212, and as an example, as shown in Fig. 3, is partitioned by beams 102, 103, and 104 to form separate spaces 3a, 3b, 3c, and 3d.

[0030] In this embodiment, the floor underlayment layer 21 has a columnar space 203 that penetrates the floor underlayment layer 21 vertically, as shown in Figure 6. The columnar space 203 is located at a position where it intersects with the beams 1 arranged at equal intervals as the modules in a plan view, as shown in Figure 4. The electrical cord 5 wired in the attic space 3 can be extended to the adjacent attic space 3 via the columnar space 203, as shown in Figure 6. (Third embodiment)

[0031] The floor structure of the third embodiment of the present invention is a structure that enables electrical wiring to be installed inside the newly installed partition wall 7 when attempting to change the floor plan by installing a new partition wall 7 in the upper floor living room F2 in the floor structure having the beam 1, underfloor material layer 21, and floor finishing material layer 22 of the first embodiment. Figure 8 is a vertical cross-sectional view of the floor structure of the third embodiment of the present invention, more specifically a cross-sectional view seen from a direction perpendicular to the long side of the underfloor plywood 211, and Figure 8b is an enlarged view of the beam 1 and the peripheral portion of the columnar space 203 in Figure 8a.

[0032] 8, in the floor finishing material layer 22 of this embodiment, a columnar space-communicating hole 221 is formed so as to penetrate the floor finishing material layer 22 vertically at a position directly above the columnar space 203 of the floor finishing material layer 22, and a lid 222 having the same shape as the columnar space-communicating hole 221 in a plan view is removably fixed to the flooring material layer 2, i.e., to the underfloor material layer 21 and the floor finishing material layer 22, at a position where the height of the upper surface is flush with the upper surface of the floor finishing material layer 22, and constitutes a part of the floor finishing material layer 22. The columnar space-communicating hole 221 of this embodiment only needs to be located in a position that includes at least a part of the upper part of the columnar space 203, and may be formed so as to span the upper parts of multiple columnar spaces 203 as long as it is located at the upper part of multiple columnar spaces 203 formed on the same beam 1. In addition, in the illustrated embodiment, solid wood flooring is used for the floor finishing material layer 22, but the columnar space communication holes 221 formed therein may be formed within a single piece of solid wood flooring, or may be formed across multiple pieces of solid wood flooring.

[0033] Figure 9 shows steps A to D for installing a new partition wall on the floor structure of this embodiment and installing electrical wiring inside the newly installed partition wall. For convenience, Fig. 9 omits the rafters 311, rafter material 312, and ceiling trim 41, and shows the electrical wiring 5 with a thick solid line. The portion of the electrical wiring 5 that is hidden by the floor material layer 2 is shown with a dashed line, and the internal structure of the newly installed partition wall 7 is omitted.

[0034] Figure 9[A] shows the state before the floor finishing material layer 22 is laid in this embodiment, and in this figure, the parts of the beam 1 that are hidden by the floor material layer 2 and the ceiling material layer 4 are shown by dashed lines. Figure 9[B] shows the state after the floor finishing material layer 22 has been laid in this embodiment, and in this state, the lid 222 covers the entire columnar space-communicating hole 221 formed in the floor finishing material layer 22, and the upper surface of the floor finishing material layer 22 and the upper surface of the lid 222 are formed flush with each other, and the floor finishing material layer 22 is composed of the columnar space-communicating hole 221 and the lid 222.

[0035] FIG. 9[C] shows the state in which the cover 222 is separated from the columnar space-communicating hole 221 in the floor finishing material layer 22 to install electrical wiring inside the newly constructed partition wall when changing the layout of the upper floor room F2 and constructing a new partition wall using the floor structure of this embodiment. In this state, the electrical wiring 5 is exposed to the upper floor room F2, so the electrical wiring 5 can be extracted, branched, and routed inside the newly constructed partition wall. If it is anticipated that branching the electrical wiring will cause the current capacity of the existing electrical wires to be exceeded during new construction, a spare electrical wiring can be installed inside the floor structure of this embodiment, running alongside the electrical wiring 5 from the distribution board to the columnar space 203 so that it can be extracted onto the floor of the upper floor room F2 during new construction. This prevents the current from exceeding the allowable capacity due to branching.

[0036] 9[D] shows the state in which the floor plan of upper room F2 is changed using the floor structure of this embodiment, a partition wall 7 is newly installed, and a branch electrical cord 52 is wired inside the partition wall 7. In this way, by using the floor structure of this embodiment, the partition wall 7 can be installed on the smooth floor of upper room F2 in the state of procedure B, and the existing electrical wiring 5 can be branched to easily wire the branch electrical cord 51 inside the partition wall 7.

[0037] The floor structure of this embodiment can also be applied to the floor structure having the beams 1, underfloor material layer 21, and floor finishing material layer 22 of the second embodiment. [Industrial Applicability]

[0038] The floor structure of the wooden building of the present invention can be suitably used in small wooden houses with low floor heights of two or more stories, when it is desired to simultaneously realize a sophisticated interior design that creates an "exposed beam" landscape and an open lifestyle. [Explanation of symbols]

[0039] 1 beam 2. Flooring layer 203 Columnar space 21 Subfloor layer 211 Flooring plywood 212 Received material 213 Nail 22 Floor covering layer 221 Columnar space communication hole 222 Lid 3 Attic space 311 Noenkake 312 Rough timber 32 Wiring storage layer 4 Ceiling material layer 41 Ceiling molding 5 Electrical cords 51 Installation location of lighting fixtures, etc. 52 Branched Electrical Cord 6 pillars 7 Partition Wall 71 Partition wall surface material 72 Partition wall interior space F1 lower floor living room F2 Upper floor room

Claims

1. A plurality of beams installed in parallel at predetermined intervals; a first flooring layer laid in contact with the upper surfaces of the beams; a second flooring layer laid in contact with an upper surface of the first flooring layer; In the flooring layer, a columnar space penetrating the first flooring layer from top to bottom is formed at a position including directly above at least one of the beams, and the upper part is covered with the second flooring layer; A floor structure of a wooden building, characterized in that a columnar space communication hole is formed in the second floor material layer at a position including at least a portion of the upper part of the columnar space, and a lid covering the columnar space communication hole is removably fixed to the second floor material layer.

2. The floor structure of a wooden building described in claim 1, characterized in that the lid body is removably fixed to the second flooring layer at a position where the height of its upper surface is flush with the upper surface of the second flooring layer.

3. A wooden building comprising the floor structure according to claim 1 or 2.

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