JP7291285B1 - Underfloor material and floor structure - Google Patents

Abstract

An underfloor material excellent in waterproofness and workability and a floor structure including the same are provided. SOLUTION: At least the upper layer of the underfloor material 20 is composed of a medium density fiberboard that contains a water repellent agent so that the contact angle of water with respect to the surface is greater than 90 degrees. [Selection drawing] Fig. 4B

Description

The present invention relates to an underfloor material and a floor structure.

Conventionally, during the construction of a building such as a house, the underfloor material sometimes gets wet when it rains or snows. was likely to occur.

Therefore, after installing the underfloor material, a waterproof sheet is laid on the underfloor material to cure it, or a water-repellent paint is sprayed on the surface of the underfloor material to make it water-repellent. This prevents the underfloor material from getting wet (for example, see Patent Document 1 below).

Japanese Patent No. 5592033

However, even if a waterproof sheet is laid on the underfloor material and cured, rainwater and snowmelt water enter between the waterproof sheet and the underfloor material through gaps in the waterproof sheet formed around vertical members such as pillars. something happened. The presence of the waterproof sheet makes it difficult for moisture that has entered between the waterproof sheet and the underfloor material to evaporate, resulting in the problem that the underfloor material absorbs the water.

In addition, when the surface of the underfloor material is sprayed with a water-repellent paint to make it water-repellent, additional spraying work is required when applying the underfloor material, which is a problem in that it takes time and effort to apply the underfloor material. there were.

The present invention has been made in view of the above points, and an object of the present invention is to provide an underfloor material excellent in waterproofness and workability, and a floor structure including the same.

In order to achieve the above object, in the present invention, at least the upper layer of the underfloor material is composed of a medium density fiberboard with low water absorption, and the medium density fiberboard contains a water repellent agent, It was designed so that the contact angle of water with respect to the surface is greater than 90 degrees.

Specifically, the first invention is an underfloor material to be applied below a floor finishing material, wherein at least the upper layer contains a water repellent agent so that the contact angle of water with respect to the surface is greater than 90 degrees. It is characterized by being constructed of medium density fiberboard that is configured to be large.

In the first invention, at least the upper layer of the underfloor material is made of medium density fiberboard (MDF: Medium Density Fiberboard) having low water absorption. A medium-density fiberboard is a wooden board formed by hot-pressing wood fibers together with an adhesive, and has a low water absorption rate. Therefore, even if rainwater or snowmelt water enters between the waterproof sheet and the underfloor material during construction of a building such as a house (before construction of the floor finishing material), it is not absorbed into the underfloor material. In addition, according to such an underfloor material, the adhesive-coated wood fibers adhere to the nails driven into the nail holes so as to separate the wood fibers. It becomes difficult for rainwater and snowmelt water to infiltrate. By using such an underfloor material that is excellent in waterproofness and water resistance to nail holes, even if rainwater or snowmelt water enters between the waterproof sheet and the underfloor material before the construction of the floor finishing material, the underfloor material The material does not absorb water and deform (expansion in thickness, warping, twisting), and mold growth can be suppressed.

In the first invention, the medium-density fiberboard constituting at least the upper layer of the underfloor material contains a water-repellent agent, so that the contact angle of water with respect to the surface becomes greater than 90 degrees (has water repellency). It is configured as follows. Therefore, even if rainwater or snowmelt water enters the gap between the waterproof sheet and the subfloor material through the gaps in the waterproof sheet formed around the vertical members such as columns before the floor finishing material is applied, rainwater and The snowmelt water becomes water droplets with a contact angle of more than 90 degrees on the upper surface of the underfloor material, and does not spread on the upper surface of the underfloor material and stays in the voids in the form of water droplets. The water droplets remaining in the gaps act as plugs, making it difficult for rainwater and snowmelt water to enter the gaps any further. That is, since at least the upper layer of the underfloor material is a water-repellent layer having water repellency, it is possible to prevent rainwater and snowmelt water from entering between the waterproof sheet and the underfloor material one after another. Also, even if water droplets reach the seams of the underfloor material, the water droplets with a contact angle of more than 90 degrees with the upper surface of the underfloor material act as plugs, preventing rainwater and snowmelt water from entering the seams. That is, since at least the upper layer of the underfloor material is a water-repellent layer having water repellency, it is possible to prevent rainwater and melted snow water from entering through the joints of the underfloor material.

In addition, in the first invention, only by using the underfloor material composed of a medium density fiberboard having water repellency at least in the upper layer, a water-repellent paint is sprayed after construction of the underfloor material, as in the conventional method. Underfloor material with excellent waterproof properties that prevents rainwater and melted snow water from entering between the waterproof sheet and the underfloor material without special processing work before construction of the floor finishing material, and does not absorb water even if it does infiltrate. can be easily constructed.

As described above, according to the first invention, it is possible to provide an underfloor material excellent in waterproofness and workability.

In a second aspect of the invention, in the first aspect, an intermediate layer portion and a lower layer portion are laminated in order from top to bottom below the upper layer portion, and the lower layer portion contains a water-repellent agent, thereby The intermediate layer is made of a medium-density fiberboard having a water contact angle of greater than 90 degrees, and the intermediate layer portion is made of a honeycomb panel having a plurality of holes extending in the thickness direction formed in a honeycomb shape. It is characterized by

By the way, the medium-density fiberboard has low water absorption and excellent waterproofness, but is heavy in weight. Therefore, when a thick underfloor material is used, if the entire underfloor material is made of medium-density fiberboard, the weight of the underfloor material becomes heavy and the workability is poor.

Therefore, in the second invention, the underfloor material has a three-layer structure, and the upper layer and the lower layer are made of medium density fiberboard having water repellency with excellent waterproofness and nail hole water stopping properties, while the middle layer is made of medium density fiberboard. aims to reduce the weight of the underfloor material by constructing it with a relatively lightweight and highly rigid honeycomb panel in which a plurality of holes are formed. By configuring in this way, even if rainwater or snowmelt water enters between the waterproof sheet and the underfloor material before the construction of the floor finishing material, the underfloor material with excellent waterproofness that does not absorb water is impaired in workability. can be provided without

According to a third invention, in the second invention, the upper layer portion and the lower layer portion are thinner than the intermediate layer portion.

In the third invention, the underfloor material is formed such that the intermediate layer portion made of a honeycomb panel that is lighter than the medium density fiberboard is thicker than the upper and lower layer portions made of the medium density fiberboard. is configured to With such a configuration, it is possible to further reduce the weight of the underfloor material.

A fourth invention is a floor structure comprising an underfloor material and a floor finishing material applied on the underfloor material, wherein the underfloor material is any one of the first to third inventions. It is characterized by being an underfloor material according to.

In the fourth invention, the underfloor material having excellent waterproofness is used in the floor structure including the underfloor material and the floor finishing material. Therefore, even if rainwater or snowmelt water enters between the waterproof sheet and the subfloor material before the floor finishing material is applied, the subfloor material absorbs water and deforms (thickness expansion, warping, twisting). It is also possible to suppress the occurrence of mold. In addition, it is possible to easily construct an underfloor material excellent in waterproofness without performing special processing work such as spraying a water-repellent paint after constructing the underfloor material, unlike the conventional floor structure.

As described above, according to the present invention, at least the upper layer of the underfloor material is composed of a medium density fiberboard with low water absorption, and the medium density fiberboard further contains a water repellent agent, so that it is resistant to the surface. By configuring the underfloor material so that the contact angle of water is greater than 90 degrees, it is possible to provide an underfloor material excellent in waterproofness and workability, and a floor structure including the same.

FIG. 1 is a perspective view showing a partially cutaway floor structure according to Embodiment 1. FIG. 2 is a cross-sectional view showing a floor structure according to Embodiment 1. FIG. FIG. 3 is a perspective view showing a part of the underfloor material cut away. FIG. 4A is a cross-sectional view showing a state before construction of a floor finishing material of a conventional floor structure. 4B is a cross-sectional view showing a state before construction of the floor finishing material of the floor structure according to Embodiment 1. FIG. FIG. 5 is a schematic diagram showing the state of the water permeability test. FIG. 6 shows the test results of the water permeability test.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. The following embodiments are essentially merely preferred examples, and are not intended to limit the scope of the invention, its applications, or its uses.

<<Embodiment 1 of the Invention>>
As shown in FIGS. 1 and 2, the floor structure 1 is constructed by laying a plurality of plate-like floor finishing materials 10 on a plurality of plate-like underfloor materials 20, . be. In the first embodiment, the floor structure 1 is applied to a floor assembly by a joist-less construction method in which the subfloor material 20 is fixed to the joists or floor beams without providing joists.

－Composition of the floor structure－
As shown in FIGS. 1 and 2 , the floor structure 1 includes a floor finishing material 10 and an underfloor material 20 . A plurality of underfloor members 20, . of floor coverings 10, . . . , 10 are laid. In addition, in the floor structure 1 shown in FIG. 1, a plurality of connecting members 3 are provided perpendicularly to each of the two large pulls 2, 2 so as to connect each of the two adjacent large pulls 2,2.

In addition, when the floor structure 1 is provided on the first floor of a building (is part of the first floor floor assembly), the reference numeral 2 in FIGS. is laid on a plurality of drawers 2, . . . , 2. On the other hand, when the floor structure 1 is provided on the second floor of a building (is a part of the second floor framing), the reference numeral 2 indicates floor beams, and the plurality of subfloor members 20, . 2, . . . , laid on top of 2.

The floor finishing material 10 may have any structure. For example, it is possible to use a material in which a decorative sheet, a veneer, or the like is adhered to the upper surface of a wooden base material with an adhesive.

<Detailed structure of underfloor material>
As shown in FIG. 3 , the underfloor material 20 includes an upper layer portion 21 , an intermediate layer portion 22 and a lower layer portion 23 . The upper layer portion 21, the intermediate layer portion 22, and the lower layer portion 23 are laminated in this order from top to bottom. In addition, in the first embodiment, since it is applied to the floor assembly by the joist-less construction method, the underfloor material 20 is thicker (20 mm or more in thickness) than when it is applied to the floor assembly by the joist construction method in which joists are provided. formed.

The upper layer portion 21 and the lower layer portion 23 are made of a medium density fiberboard (MDF) having a density (g/cm ³ ) of 0.6 or more and less than 0.85. In this embodiment, medium-density fiberboards having a density of 0.7 g/cm ³ and a thickness of 2 to 9 mm are used as the upper layer 21 and the lower layer 23 . From the viewpoint of suppressing warpage, it is preferable that the upper layer portion 21 and the lower layer portion 23 have the same thickness, but the upper layer portion 21 and the lower layer portion 23 may have different thicknesses.

The medium-density fiberboards forming the upper layer portion 21 and the lower layer portion 23 contain an adhesive with excellent water resistance. In Embodiment 1, the upper layer portion 21 and the lower layer portion 23 are composed of a medium-density fiberboard containing a urea-melamine cocondensation resin-based adhesive. The adhesive used for the medium-density fiberboard is not limited to the urea/melamine cocondensation resin adhesive, and may contain diphenylmethane diisocyanate, phenol resin, or the like.

The intermediate layer portion 22 is composed of a honeycomb panel in which a plurality of holes 22a extending in the thickness direction are formed in a honeycomb shape. The honeycomb panel that constitutes the intermediate layer portion 22 is formed by laminating paper made water-resistant by applying a water-resistant agent with a water-resistant adhesive. The method of imparting water resistance to paper is not limited to applying a water resistance agent, and instead of the water resistance agent, a resin may be applied, or a water resistance agent or resin may be impregnated.

In Embodiment 1, a honeycomb panel in which a surface material is not attached to the outer peripheral portion and the outermost peripheral holes 22 a are exposed is used as the intermediate layer portion 22 . If the paper constituting the intermediate layer portion 22 (honeycomb panel) does not have water resistance or has low water resistance, a water resistant agent or resin is applied or applied to the outer peripheral portion of the intermediate layer portion 22 (honeycomb panel). Impregnation is preferred.

The honeycomb panel forming the intermediate layer portion 22 may have a surface material adhered to the outer peripheral portion thereof, as shown in FIG. The surface material attached to the outer peripheral portion of the intermediate layer portion 22 is preferably made of a material having water resistance, or is made to have water resistance by applying or impregnating a water-resistant agent or resin. .

In Embodiment 1, a honeycomb panel made of paper is used as the intermediate layer portion 22, but the material of the honeycomb panel constituting the intermediate layer portion 22 has a density equal to that of the upper layer portion 22. 21 and the lower layer portion 23, preferably half or less of the density of the upper layer portion 21 and the lower layer portion 23, more preferably 1/10 or less of the density of the upper layer portion 21 and the lower layer portion 23. It can be anything as long as it is. In this embodiment, a honeycomb panel having a density of 0.05 g/cm ³ and a thickness of 10 to 20 mm is used as the intermediate layer portion 22 .

The underfloor material 20 is a sandwich panel in which an intermediate layer 22 made of a honeycomb panel is sandwiched between an upper layer 21 and a lower layer 23 made of medium-density fiberboard, and the layers are bonded together with a water-resistant adhesive. be. In this way, the underfloor material 20 has a three-layer structure, and the intermediate layer 22 is composed of a honeycomb panel that has a significantly lower density than medium-density fiberboards and is lightweight, so that the weight of the underfloor material 20 can be reduced. can.

Specifically, in the case of the underfloor material 20 having a size of 910 mm×1820 mm and a thickness of 24 mm, a single-layer structure (medium density fiberboard only) would weigh 27.8 kg, while a medium density fiberboard of 5.5 mm thickness would weigh 27.8 kg. A three-layer structure in which the intermediate layer portion 22 made of a honeycomb panel with a thickness of 13 mm is sandwiched between the upper layer portion 21 and the lower layer portion 23 made of the same material has a weight of 15.6 kg. From this, it can be seen that weight reduction can be achieved by making the underfloor material 20 a three-layer structure instead of a single-layer structure.

A plurality of holes 22a are formed in the honeycomb panel constituting the intermediate layer portion 22, and the intermediate layer portion 22 is sandwiched between the upper layer portion 21 and the lower layer portion 23 made of medium density fiberboard. . Therefore, the upper and lower ends of the plurality of holes 22 a of the honeycomb panel forming the intermediate layer portion 22 are closed by the upper layer portion 21 and the lower layer portion 23 . Therefore, even if water enters the end of the underfloor material 20, the wall surface that defines the outermost hole 22a of the underfloor material 20 when the outer peripheral portion of the intermediate layer portion 22 is not covered with a sheet or thin plate The water only comes into contact with the inner hole 22a, and no water comes into contact with the wall surface defining the internal hole 22a.

(water repellency)
The underfloor material 20 is configured such that the contact angle of water with respect to the upper surface 20a is greater than 90 degrees. Specifically, in the first embodiment, when forming the medium density fiberboard that constitutes the upper layer 21 of the underfloor material 20, the surface of the medium density fiberboard has water repellency (at any point on the surface The upper surface 20a is configured to have water repellency by adding a necessary amount of paraffin (water repellent) so that the contact angle of water becomes larger than 90 degrees.

The upper surface 20a of the underfloor material 20 is preferably configured so that the contact angle of water is 110 degrees or more from the viewpoint of excellent water repellency, and is configured so that the contact angle of water is 120 degrees or more. is more preferable.

Further, in Embodiment 1, the lower layer portion 23 is also configured in the same manner as the upper layer portion 21 . That is, the underfloor material 20 is configured such that the contact angle of water with respect to the lower surface 20b is also greater than 90 degrees.

(water absorption rate)
The upper layer portion 21 and the lower layer portion 23 of the underfloor material 20 are configured to have a water absorption rate of 15% or less. The upper layer portion 21 and the lower layer portion 23 are preferably configured to have a water absorption rate of 13.6% or less, more preferably 13.2% or less. preferable.

Here, the water absorption rate is obtained by measuring the weight (m1) of a 50 mm square test piece that has reached a constant weight in an environment with a relative humidity of 65 ± 5%, and then placing the test piece in water at 20 ± 1 ° C. After soaking for 24 hours, the specimen was taken out and subjected to a water absorption test to measure the weight (m2). The value obtained by dividing the body weight difference (m2-m1) by the weight before water immersion (m1) and multiplying it by 100) is used.

As described above, the medium-density fiberboard containing an adhesive having excellent water resistance has a low water absorption rate because the wood fibers are coated with the adhesive, making it difficult for water to penetrate between the wood fibers. Therefore, by using an adhesive and a water-repellent agent with excellent water resistance in molding the medium-density fiberboards that constitute the upper layer 21 and the lower layer 23, and by adjusting the mixing ratio thereof, the water absorption of the upper layer 21 and the lower layer 23 can be improved. The rate can be set to the desired water absorption rate, which in this embodiment is 15% or less (preferably 13.6% or less, more preferably 13.2% or less).

In addition, the above water absorption rate test was performed on structural plywood (cedar) and structural plywood (surface layer larch, core layer cedar) with a thickness of 12 mm that were conventionally used as underfloor materials, and the water absorption rate was calculated. The rates were 82% and 61%. From this, it can be seen that the water absorption rate of the upper layer portion 21 and the lower layer portion 23 of the underfloor material 20 of Embodiment 1 is significantly lower than that of the conventional underfloor material.

(moisture permeability)
Since the upper layer portion 21 and the lower layer portion 23 of the underfloor material 20 are made of medium-density fiberboard, the resistance to moisture permeability is lower than that of plywood or the like. Further, in the first embodiment, the underfloor material 20 is not composed only of medium-density fiberboards, but an intermediate layer made of honeycomb panels is placed between the upper layer portion 21 and the lower layer portion 23 made of medium-density fiberboards. A sandwich panel sandwiching the layer part 22 is formed. In the first place, medium-density fiberboards have lower moisture permeability resistance than plywood or the like. The thickness of the medium-density fiberboard can be made thinner than in the case of a single-layer structure of only the medium-density fiberboard, and the honeycomb panel in which the plurality of holes 22a are formed is considered to have almost no resistance to moisture permeability. Therefore, the moisture permeation resistance of the underfloor material 20 can be kept low.

-Floor structure construction method-
The floor structure 1 is constructed as follows.

First, an underfloor material 20 is constructed above a plurality of large drawers 2, . Specifically, a plurality of underfloor members 20, . 2 and connecting member 3.

After construction of the underfloor materials 20, a plurality of floor finishing materials 10, . . . , 10 are constructed on the constructed plurality of underfloor materials 20, . Specifically, a plurality of floor finishing materials 10, . fixed to

The floor structure 1 is constructed as described above.

－Characteristics of floor structure－
<Waterproofness of underfloor material>
The underfloor material 120 shown in FIG. 4A using conventional structural plywood that has not been subjected to water-repellent finishing or the like has a high water absorption rate. Therefore, before the construction of the floor finishing material, the space S101 between the waterproof sheet 125 and the subfloor material 120, which is lifted by the vertical member from the gap formed around the vertical member such as the column of the waterproof sheet 125 for curing, When rainwater or snowmelt water enters, the underfloor material 120 gets wet (absorbs water) with the rainwater or snowmelt water.

Specifically, in the conventional underfloor material 120 whose upper surface 120a has high wettability because it is not water-repellent, the gap S101 between the waterproof sheet 125 and the underfloor material 120 from the gap in the waterproof sheet 125 The rainwater or snowmelt water that has entered into the surface layer veneer is sucked into the surface layer veneer at the point of infiltration and flows in the fiber direction of the surface layer veneer. As the rainwater and snowmelt water sucked into the surface layer veneer flow in the fiber direction, the rainwater and snowmelt water spread over the entire surface layer veneer and are successively sucked into the surface layer veneer.

In addition, in the conventional underfloor material 120, the nail holes of the nails 5 penetrating the underfloor material 120 have a low water-tightness, and rainwater and snowmelt water entering between the waterproof sheet 125 and the underfloor material 120 are prevented from reaching the underfloor material 120. The moisture penetrated into the nail holes and was absorbed into the interior of the underfloor material 120 (the layer inside from the surface layer) through the nail holes. That is, in the conventional underfloor material 120, the underfloor material 120 has high water absorption, and deformation (expansion in thickness, warping, twisting) of the underfloor material 120 and generation of mold are likely to occur.

In contrast, in Embodiment 1, at least the upper layer 21 of the underfloor material 20 is composed of a medium density fiberboard with low water absorption, and the medium density fiberboard contains a water repellent agent, so that the surface It is configured so that the contact angle of water with respect to it becomes larger than 90 degrees (has water repellency).

Therefore, as shown in FIG. 4B, rainwater enters the gap S1 between the waterproof sheet 25 and the underfloor material 20, which is lifted up by the vertical members from the gaps formed around the vertical members such as the pillars of the protective waterproof sheet 25. Even if snow or snowmelt water enters, rainwater or snowmelt water forms water droplets wd with a contact angle greater than 90 degrees on the upper surface 20a of the underfloor material 20, does not spread on the upper surface 20a of the underfloor material 20, and is in a state of water droplets wd. stays in the gap S1. In this way, the water droplets wd remaining in the gap S1 serve as plugs, making it difficult for rainwater and snowmelt water to enter the gap S1 any further.

In addition, since the water absorption rate of the upper layer 21 of the underfloor material 20 is low (15% or less), the waterproof sheet 25 and the underfloor material 20 rise from the gaps between the waterproof sheets 25 around the vertical members such as pillars due to the vertical members. Even if rainwater or snowmelt water enters the space S1 between It does not permeate inside from the upper surface 20a of 20.

Further, even if rainwater or snowmelt water that has entered between the waterproof sheet 25 and the underfloor material 20 becomes water droplets wd and reaches the seams of the underfloor material 20, the contact angle with the upper surface of the underfloor material is greater than 90 degrees. The water droplets wd serve as plugs, preventing rainwater and snowmelt water from entering the seams.

Furthermore, in the underfloor material 20 of Embodiment 1, since the upper layer 21 has high nail hole water resistance, rainwater or snowmelt water that has entered between the waterproof sheet 25 and the underfloor material 20 becomes water droplets wd, which causes the nails to become water droplets wd. Even if it reaches the nail hole of 5, it does not penetrate into the underfloor material 20 from the nail hole.

In order to prove this point, the following water permeability test was conducted.

(1) Specimen Two specimens X of the following two types were prepared.
I: medium density fiberboard (thickness 9 mm, density 0.79 g/cm ³ , moisture content 8.9%)
II: Plywood (thickness 9 mm, density 0.42 g/cm ³ , moisture content 10.6%, softwood)
In addition, the test sample X of I, like the medium-density fiberboard constituting the underfloor material 20, had a water absorption rate of 15% or less and a moisture permeability resistance of less than 2.5 m ² ·h · mmHg / g. It is configured.

(2) Test Method First, as shown in FIG. 5, a test device is assembled. Specifically, a nail 51 (N50, screw nail) is driven into the center of the specimen X from above. A nail 51 of N50 is driven into one of the specimens X of I (referred to as specimen X1), and a screw nail is driven into the other specimen (referred to as specimen X2). A nail 51 of N50 is driven into one of the specimens X of II (referred to as specimen X3), and a screw nail is driven into the other specimen (referred to as specimen X4). For each of the four types of specimens X1 to X4 thus formed, a cylinder 52 made of acrylic resin (inner diameter 34 mm, height 300 mm) is placed upright on the upper surface of the specimen X so as to cover the nail 51. After filling the gap between the cylinder 52 and the upper surface of the specimen X with a caulking agent 53 , these are placed on a beaker 54 having a larger diameter than the cylinder 52 .

Water (room temperature) is gently poured into cylinder 52 after assembly of the test fixture. Water is poured up to a height of 250 mm (approximately 227 ml) of the cylinder 52 . Then, they were left to stand for 8 days under an environment of 20° C. temperature and 65% relative humidity, and the remaining amount of water, the external appearance of the specimen X, and water leakage from the nail holes were periodically checked.

(3) Test Results The graph in FIG. 6 shows the results of the water permeability test. The amount of water permeation (ml) shown on the vertical axis of the graph in FIG. In addition, the ▪ mark indicates the water permeation amount of the test body X1, the ♦ mark the test body X2, the ● mark the test body X3, and the ▴ mark the test body X4.

As can be seen from the graph in FIG. 6, among the four types of test specimens X1 to X4, the test specimen X4 has the largest amount of water permeation. became impossible. Next, the test specimen X3 had a large amount of water permeation, and almost no water was left in the cylinder 52 on the fourth day after the start of the test, making it impossible to continue the test. From this result, specimens X3 and X4
In this case, since a large nail hole is formed when the nail 51 is driven in, water spreads (permeates) from the nail hole in the fiber direction of the specimen X, and along the nail 51, the water under the specimen X (beaker 54) can be easily passed through (the water stoppage of the nail hole is low).

On the other hand, the test specimens X1 and X2 constituting the underfloor material 20 of Embodiment 1 have significantly lower water permeability than the test specimens X3 and X4 among the four types of test specimens X1 to X4, and the test is started. Almost no water flowed out from inside the cylinder 52 even after three days had passed. In the test specimens X1 and X2, water did not drip from the nail 51 to the beaker 54 even after 8 days from the start of the test. In the specimens X1 and X2, the nails 51 were driven to separate the wood fibers, and the wood fibers coated with the adhesive adhered to the nails 51, so that almost no gaps through which water could pass were formed. It is presumed that this is due to Further, the specimen X1 is formed of an adhesive containing a first adhesive (a urea-melamine cocondensation resin-based adhesive in the first embodiment) having excellent water resistance, and has a water absorption rate of 15% or less. ing. Therefore, even if a gap is formed around the nail 51 by the nail hole, it is presumed that water will not enter because the wood fibers are coated with the first adhesive having excellent water resistance. As described above, in the specimens X1 and X2, water does not permeate from the surface (upper surface) into the interior and does not enter the nail hole, and the water permeability is significantly lower than that of the specimens X3 and X4. , it can be seen that the waterproofness is extremely high.

As described above, in the underfloor material 20 of the first embodiment, the space S1 between the waterproof sheet 25 and the underfloor material 20, which is lifted up by the vertical member from the gap of the waterproof sheet 25 around the vertical member such as the pillar, Even if rainwater or snowmelt water infiltrates, the underfloor material 20 is highly waterproof and does not easily absorb water. Therefore, the underfloor material 20 of Embodiment 1 does not deform (expand in thickness, warp, twist) or grow mold due to absorption of rainwater or snowmelt water.

Further, in Embodiment 1, at least the upper layer portion 21 of the underfloor material 20 is made of a medium-density fiberboard that is excellent in waterproofness and nail-hole watertightness and has water repellency. Therefore, it is not necessary to perform special work such as water-repellent finishing after construction of the underfloor material in order to suppress the deformation of the underfloor material and the generation of mold, as in the conventional art.

-Effect of Embodiment 1-
In Embodiment 1, at least the upper layer portion 21 of the underfloor material 20 is made of a medium density fiberboard (MDF: Medium Density Fiberboard) having low water absorption. A medium-density fiberboard is a wooden board formed by hot-pressing wood fibers together with an adhesive, and has a low water absorption rate. Therefore, even if rainwater or snowmelt water enters between the waterproof sheet 25 and the underfloor material 20 during construction of a building such as a house (before construction of the floor finishing material 10), it is not sucked into the underfloor material 20.例文帳に追加Further, according to the underfloor material 20 as described above, the adhesive-coated wood fibers adhere to the nails 5 that are driven in such a manner as to separate the wood fibers, even at the locations where the nails 5 are driven. It becomes difficult for rainwater and snowmelt water to enter the nail hole. By using the underfloor material 20 having such excellent waterproofness and water resistance against nail holes, even if rainwater or snowmelt water enters between the waterproof sheet 25 and the underfloor material 20 before the construction of the floor finishing material 10, Also, the underfloor material 20 does not absorb water and is deformed (thickness expansion, warping, twisting), and the generation of mold can be suppressed.

In addition, in the first embodiment, the medium-density fiberboard that constitutes at least the upper layer 21 of the underfloor material 20 contains a water repellent agent, so that the contact angle of water with respect to the surface becomes greater than 90 degrees (water repellency is improved). have). Therefore, before the floor finishing material 10 is applied, rainwater and snowmelt water enter the gap S1 between the waterproof sheet 25 and the subfloor material 20 through gaps in the waterproof sheet 25 formed around vertical members such as columns. Even so, rainwater and snowmelt water form water droplets wd having a contact angle larger than 90 degrees on the upper surface 20a of the underfloor material 20, do not spread on the upper surface 20a of the underfloor material 20, and remain in the void S1 in the state of water droplets wd. . The water droplets wd remaining in the gap S1 act as plugs, making it difficult for rainwater and snowmelt water to enter the gap S1 any further. That is, at least the upper layer 21 of the underfloor material 20 becomes a water-repellent layer having water repellency, thereby suppressing the intrusion of rainwater and melted snow water between the waterproof sheet 25 and the underfloor material 20 one after another. can be done. Even when the water droplets wd reach the joint of the underfloor material 20, the water droplet wd having a contact angle of more than 90 degrees with the upper surface of the underfloor material plays the role of a plug, preventing rainwater and snowmelt water from entering the joint. In other words, since at least the upper layer 21 of the underfloor material 20 becomes a water-repellent layer having water repellency, it is possible to suppress the penetration of rainwater and melted snow water through the joints of the underfloor material 20 .

Further, in Embodiment 1, only by using the underfloor material 20 in which at least the upper layer portion 21 is made of a medium density fiber board having water repellency, water-repellent paint is applied after construction of the underfloor material 20 as in the conventional art. Rainwater or snowmelt water does not easily enter between the waterproof sheet 25 and the underfloor material 20 before construction of the floor finishing material 10 without performing a special processing work such as spraying, and even if it does enter, it does not absorb water. It is possible to easily construct the underfloor material 20 excellent in

As described above, according to the first embodiment, it is possible to provide the underfloor material 20 excellent in waterproofness and workability.

By the way, the medium-density fiberboard has low water absorption and excellent waterproofness, but is heavy in weight. Therefore, when using a relatively thick (20 mm or more in thickness) underfloor material 20 such as the joist-less construction method shown in the first embodiment, if the entire underfloor material 20 is composed of medium-density fiberboard, the weight becomes heavy, Lack of workability.

Therefore, in the first embodiment, the underfloor material 20 has a three-layer structure, and the upper layer 21 and the lower layer 23 are made of a medium-density fiberboard having excellent water repellency and excellent water resistance against nail holes. The intermediate layer portion 22 is made of a honeycomb panel having a plurality of holes 22a and having relatively light weight and high rigidity, thereby reducing the weight of the underfloor material 20. As shown in FIG. With this structure, even if rainwater or snowmelt water enters between the waterproof sheet 25 and the underfloor material 20 before construction of the floor finishing material 10, the underfloor material 20 is excellent in waterproofness and does not absorb water. It can be provided without impairing workability.

Further, in the first embodiment, the underfloor material 20 is not composed only of medium-density fiberboards, but an intermediate layer made of honeycomb panels is placed between the upper layer portion 21 and the lower layer portion 23 made of medium-density fiberboards. A sandwich panel sandwiching the layer part 22 is formed. In the first place, medium-density fiberboards have lower moisture permeability resistance than plywood or the like. The thickness of the medium-density fiberboard can be made thinner than in the case of a single-layer structure of only the medium-density fiberboard, and the honeycomb panel in which the plurality of holes 22a are formed is considered to have almost no resistance to moisture permeability. Therefore, even if the underfloor material 20 is relatively thick with a thickness of 20 mm or more, the moisture permeability resistance can be kept low. As a result, even if the underfloor material 20 is damp due to rain or snowfall before the construction of the floor finishing material 10, the moisture can be easily discharged from the rear surface of the underfloor material 20.例文帳に追加In addition, even if water is spilled on the floor after construction of the floor finishing material 10 and the water enters the interior through the joints of the floor finishing material 10, the moisture can be easily discharged from the rear surface of the underfloor material 20. - 特許庁

Further, in the first embodiment, the underfloor material 20 has an intermediate layer portion 22 made of a honeycomb panel that is lighter than medium density fiberboards, and the upper layer portion 21 and the lower layer portion 23 made of medium density fiberboards. It is configured to be thickly formed. According to such a configuration, the weight of the underfloor material 20 can be further reduced.

In addition, in the first embodiment, the underfloor material 20 having excellent waterproofness is used for the floor structure 1 . Therefore, even if rainwater or snowmelt water enters between the waterproof sheet 25 and the underfloor material 20 before the construction of the floor finishing material 10, the underfloor material 20 absorbs water and deforms (thickness expansion, warping, twisting). In addition, the occurrence of mold can be suppressed. In addition, the underfloor material 20 with excellent waterproofness can be easily constructed without performing a special processing work such as spraying a water-repellent paint after construction of the underfloor material 20, unlike the conventional floor structure. .

<<Other embodiments>>
In the first embodiment described above, the floor structure 1 applied to the floor assembly by the joist-less construction method in which the subfloor material 20 is fixed to the joists or floor beams without providing joists has been described. Of course, the base material 20 and the floor structure 1 can also be applied to a floor assembly by a joist construction method in which joists are provided on floor beams.

Further, when the underfloor material 20 and the floor structure 1 according to the present invention are applied to the floor assembly by the joist construction method, the underfloor material 20 may be formed to have a thickness of about 12 mm. It is not necessary to have a three-layer structure, and the upper layer portion 21 in the first embodiment may be entirely made of the medium-density fiberboard. In other words, the underfloor material 20 is not limited to the three-layer structure described in the first embodiment, and has a medium density (g/cm ³ ) of 0.6 or more and less than 0.85 with paraffin (water repellent) added. It may be composed only of a fiberboard (single layer). Even in such a case, the same effects as in the first embodiment can be obtained.

Further, application of the underfloor material 20 and the floor structure 1 according to the present invention is not limited to the floor assembly of a wooden building. The underfloor material 20 and the floor structure 1 according to the present invention can also be applied to the flooring of buildings such as reinforced concrete, steel-framed, and steel-reinforced concrete buildings.

Further, in Embodiment 1, an example in which the intermediate layer portion 22 is configured by a honeycomb panel in which holes 22a having a hexagonal cross section are formed has been described, but the honeycomb panel is a panel in which a plurality of holes 22a are arranged in a honeycomb shape. The cross-sectional shape of the hole 22a is not limited to a hexagonal shape.

The present invention is useful for subfloor materials and floor construction.

1 floor structure
10 Floor finishing materials
20 Underfloor material
20a upper surface (surface)
21 upper management
22 Intermediate layer
23 lower part

Claims (3)

A subfloor material to be constructed below the floor finishing material,
The upper layer portion, the intermediate layer portion, and the lower layer portion are laminated in order from top to bottom,
The upper layer portion and the lower layer portion are made of a medium density fiberboard that contains a water repellent agent so that the contact angle of water with respect to the surface is greater than 90 degrees ,
The intermediate layer portion is composed of a honeycomb panel in which a plurality of holes extending in the thickness direction are formed in a honeycomb shape.
An underfloor material characterized by: In the underfloor material according to claim 1 ,
The underfloor material, wherein the upper layer portion and the lower layer portion are thinner than the intermediate layer portion. A floor structure comprising an underfloor material and a floor finishing material applied over the underfloor material,
A floor structure, wherein the underfloor material is the underfloor material according to claim 1 or 2 .

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