Waterproof sheet fixture

Abstract

To provide a waterproof sheet fixture that makes it easy to securely fix a waterproof sheet while increases strength.SOLUTION: A waterproof sheet 2 is fixed on a front surface of a tabular waterproof sheet fixture 3. The waterproof sheet fixture has a groove-live center groove-like part 32 surrounding a center point C3. A center part 31 surrounded by the center groove-like part 32 is polygonal. The number of interior angles of the center part 31 is 4 or more and 8 or less in a plan view.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tarpaulin fastener. [Background technology]

[0002] The waterproof sheet fixing device described in Patent Document 1 comprises an insertion hole through which a fastener for fixing the waterproof sheet fixing device to a base is inserted, a raised portion that is raised from the insertion hole toward the outer periphery, a groove portion that is formed further toward the outer periphery from the raised portion and surrounds the insertion hole in a circular shape, and a fixing plate that is positioned outer periphery of the groove portion and to which the waterproof sheet is fixed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-187338 A Summary of the Invention [Problem to be solved by the invention]

[0004] The waterproof sheet fastener described in Patent Document 1 has a groove that surrounds the insertion hole in a circular shape. This allows the waterproof sheet fastener to have a higher moment of area than if it were made of a flat plate, and makes it possible to increase the strength even with a thin plate.

[0005] In addition, the waterproof sheet is fixed to the fixing plate located on the outer periphery of the groove. When a strong wind blows the waterproof sheet upward, a large force is applied to the connection between the outer edge of the waterproof sheet fixing device and the waterproof sheet. Therefore, if the waterproof sheet is not firmly fixed to the fixing plate located on the outer periphery of the groove, the waterproof sheet will be peeled off from the waterproof sheet fixing device by the wind, etc.

[0006] An object of the present invention is to provide a waterproof sheet fastener which has high strength and can easily and securely fasten a waterproof sheet. [Means for solving the problem]

[0007] As a means for solving the above-mentioned problems, a plate-shaped waterproof sheet fixing device is provided to fix a waterproof sheet to its front surface, the device having a central groove-like portion that is groove-shaped surrounding a central point, the central portion surrounded by the central groove-like portion being polygonal in shape, and the number of interior angles of the central portion being 4 or more and 8 or less when viewed in a plane.

[0008] Through ingenuity, the inventors have discovered that the waterproof sheet fastener of the present invention has a high moment of area and high strength when the central section surrounded by the central groove section has a polygonal shape with the number of interior angles being 4 to 8 in plan view. With this configuration, the central groove section makes the moment of area higher than that of a waterproof sheet fastener that does not have a central groove section, thereby increasing its strength.

[0009] Furthermore, when the maximum distance from the central point to the outer end of the central groove is the same, a configuration in which the central groove surrounds the central portion in a polygonal shape has a larger surface area of ​​the portion located outside the central groove compared to a configuration in which the central groove surrounds the central portion in a circular shape. With this configuration, the surface area of ​​the portion located outside the central groove is larger, so that even if a force is applied that blows the waterproof sheet upward, the waterproof sheet is firmly fixed to the waterproof sheet fastener and is less likely to peel off from the waterproof sheet fastener.

[0010] In the present invention, it is preferable that the central portion has a pentagonal shape with five interior angles in a plan view.

[0011] Through ingenuity, the inventors discovered that the waterproof sheet fastener of the present invention has a pentagonal central section surrounded by a central groove, which increases the moment of inertia and hence strength. With this configuration, the central groove further increases the moment of inertia and therefore strength.

[0012] In the present invention, it is preferable that the waterproof sheet further comprises a central through hole located at the central point and through which a fixing member for fixing the waterproof sheet to a waterproof base is inserted.

[0013] According to this configuration, the central groove portion increases the moment of inertia, thereby increasing strength. Also, the surface area of ​​the portion located outside the central groove portion is increased, so that even if a force is applied to blow the waterproof sheet upward, the waterproof sheet is firmly fixed to the waterproof sheet fixing device, and the waterproof sheet is less likely to peel off from the waterproof sheet fixing device.

[0014] In the present invention, it is preferable that the waterproof sheet further includes an outer portion located outside the central groove-shaped portion when viewed in a plane, and that the outer portion has a groove-shaped outer groove-shaped portion spaced apart from the central groove-shaped portion, and an outer through hole through which a fixing member for fixing the waterproof sheet to an existing waterproof sheet fixing device is inserted.

[0015] Through ingenuity, the inventors have discovered that the waterproof sheet fastener of the present invention has a higher moment of area and higher strength when provided with an outer groove-like portion. With this configuration, the outer groove-like portion, which is a groove-like portion spaced apart from the central groove-like portion, further increases the moment of area and increases the strength.

[0016] In the present invention, it is preferable that the pair of outer through holes are located symmetrically with respect to the central point.

[0017] With this configuration, compared to a configuration in which the two outer through holes are positioned offset to one side from the center point, the points that are fixed to the existing waterproof sheet fastener are even, and the waterproof sheet fastener is stably supported by the existing waterproof sheet fastener. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a plan view showing the waterproof sheet fastener. [Diagram 2] FIG. 2 is a cross-sectional view taken along the line II-II in FIG. [Diagram 3]10 is a flowchart showing a construction method using a waterproof sheet fastener. [Figure 4] 1 is a drawing showing a method for verifying the strength of a waterproof sheet fastener. [Diagram 5] 13 is a diagram showing a verification result. [Figure 6] 13 is a diagram showing a verification result. [Figure 7] FIG. 11 is a plan view showing another example of a waterproof sheet fastener. [Figure 8] 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 7. [Figure 9] 1 is a flowchart showing a renovation method using a tarpaulin fastener. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The waterproof sheet fastener according to the present invention will be described below with reference to the drawings. In the following description, the direction of the arrow U in the drawings will be taken as the "upper side" and the direction of the arrow D as the "lower side".

[0020] The cross-sectional line II-II shown in Fig. 1 extends in a straight line from the left side of the paper, through the center point C3, to the right side of the paper. As shown in Figs. 1 and 2, the waterproof sheet fixing device 3 is plate-shaped and is placed on the waterproof base 1. The waterproof sheet fixing device 3 is also fixed to the waterproof base 1, and the waterproof sheet 2 is fixed to the front surface. In this way, the waterproof sheet 2 is fixed to the waterproof base 1.

[0021] In this embodiment, the waterproof sheet fastener 3 has a central through-hole 34 located at the central point C3. The waterproof sheet fastener 3 is fixed to the waterproof substrate 1 by a tapping screw 14 inserted into the central through-hole 34. In other words, the waterproof sheet 2 is fixed to the waterproof substrate 1 by the waterproof sheet fastener 3. However, the waterproof sheet fastener 3 may be fixed to the waterproof substrate 1 by an anchor bolt depending on the type of the waterproof substrate 1.

[0022] The waterproof sheet 2 and the existing waterproof sheet 12 (see FIG. 7) are sheet-like members made of a resin material. Specifically, the waterproof sheet 2 is a vinyl chloride-based waterproof sheet. The resin material is not limited to this, and may be other resins, such as polyolefin-based resins, ethylene-vinyl acetate copolymers, etc., and these may also be used in combination. The waterproof sheet 2 may also be a sheet-like member made of rubber.

[0023] The waterproof foundation 1 is a waterproof structure that is waterproofed by a waterproof sheet 2. In this embodiment, the waterproof foundation 1 is the rooftop framework of a building. The waterproof foundation 1 has a plate-shaped metal roof 1a that is corrugated with repeated peaks and valleys in a vertical cross-sectional view, and a heat insulating material 1b that is laid on top of the metal roof 1a. The waterproof foundation 1 may have other forms. For example, the waterproof foundation 1 may be a framework made of wood, concrete, or a combination of metal and concrete. Furthermore, the surface portion of the waterproof foundation 1 may be a vertical surface such as a vertical wall or an inclined surface in addition to a horizontal surface.

[0024] 2, a line CH is an imaginary line that passes through the center of the waterproof sheet fixing device 3. A point C3 located on the line CH indicates the center point of the waterproof sheet fixing device 3.

[0025] 1 and 2, the waterproof sheet fastener 3 is a disk-shaped member with a diameter of about 50 to 100 mm. However, the waterproof sheet fastener 3 is not limited to this, and may have other shapes. For example, the waterproof sheet fastener 3 may be a square or polygon in a plan view.

[0026] The waterproof sheet fixing device 3 comprises a groove-shaped central groove-shaped region 32 surrounding a central point C3, a central region 31 surrounded by the central groove-shaped region 32, an outer region 33 located outside the central groove-shaped region 32 in a planar view, and a central through hole 34 located at the central point C3 and through which a tapping screw 14 (corresponding to the fixing member of the present invention) for fixing the waterproof sheet 2 to the waterproof base 1 is inserted.

[0027] A layer H for fixing the waterproof sheet 2 is formed on the front surfaces of the central region 31 and the outer regions 33. The waterproof sheet 2 is fixed to the front surfaces of the central region 31 and the outer regions 33 by this layer H. Specifically, the waterproof sheet 2 is fixed to the waterproof sheet fixing device 3 by heat fusion or solvent welding, or the like.

[0028] [Central groove-like area] The central groove-shaped region 32 is a region formed in a concave shape. In other words, the central groove-shaped region 32 is a recess. The bottom of the central groove-shaped region 32 is located closer to the waterproof base 1 side than the front surface of the outer region 33. The central region 31 is surrounded by a series of recesses connecting the longitudinal ends of the central groove-shaped region 32. Specifically, the central groove-shaped region 32 surrounds the central region 31 so as to form a polygonal shape.

[0029] [Central part] 1 and 2, the central portion 31 is located around the central point C3. In other words, the central portion 31 is located around the central through-hole 34. The central portion 31 has a polygonal shape in a planar view. The number of interior angles of the central portion 31 is preferably 4 to 8 in a planar view. In this embodiment, the central portion 31 has a pentagonal shape with five interior angles in a planar view.

[0030] [Outer part] 1 and 2, the outer portion 33 is positioned around the central groove portion 32. The outer portion 33 is flat. The outer portion 33 includes an outer groove portion 33a that is spaced apart from the central groove portion 32 and has a groove shape.

[0031] [Outer groove-like part] The outer groove portion 33a is a portion formed in a concave shape. In other words, the outer groove portion 33a is a recess. The bottom of the outer groove portion 33a is located closer to the waterproof base 1 than the front surface of the outer portion 33. The longitudinal size of the outer groove portion 33a is 4.8 to 14.8 mm.

[0032] The number, arrangement, and orientation of the outer groove-like portions 33a are arbitrary. In this embodiment, the number of the outer groove-like portions 33a is multiple. The outer groove-like portions 33a are adjacent to the vertices of the polygonal central portion 31 on the radially outer side. In other words, the outer groove-like portions 33a are arranged on a straight line passing through the vertices of the polygonal central portion 31 and the central point C3. Furthermore, the multiple outer groove-like portions 33a are arranged at equal intervals in the circumferential direction. The outer groove-like portions 33a extend in a direction away from the central point C3.

[0033] As shown in FIG. 1, the linear distance L1 in the radial direction from the outer end of the central groove portion 32 to the inner end of the outer groove portion 33a is smaller than the linear distance L2 in the radial direction from the outer end of the outer groove portion 33a to the outer edge of the outer portion 33. When a strong wind blows the waterproof sheet 2 upward, a large force is applied to the connection between the outer edge of the outer portion 33 and the waterproof sheet 2. By arranging the outer groove portion 33a closer to the central point C3, the area from the outer end of the outer groove portion 33a to the outer edge of the outer portion 33 is larger in the outer portion 33 compared to a configuration in which the outer groove portion 33a is arranged closer to the outer edge of the outer portion 33, so that the waterproof sheet 2 is less likely to peel off from the outer portion 33.

[0034] Next, a construction method using the waterproof sheet fastener 3 will be described with reference to the flowchart shown in Fig. 3. Note that the order of the steps described below may be changed or multiple steps may be performed simultaneously, as long as no contradiction occurs.

[0035] The waterproof sheet fasteners 3 are placed on the waterproof substrate 1 (Step S01). Specifically, a plurality of waterproof sheet fasteners 3 are placed on the waterproof substrate 1 at equal intervals.

[0036] Next, the waterproof sheet fastener 3 is fixed to the waterproof base 1 (step S02). Specifically, as shown in Fig. 2, a tapping screw 14 is inserted into the central through hole 34 of the waterproof sheet fastener 3, and the waterproof sheet fastener 3 is fixed to the waterproof base 1 by the tapping screw 14. This is not limiting, and the waterproof sheet fastener 3 may be fixed to the waterproof base 1 by an adhesive or the like.

[0037] Next, the waterproof sheet 2 is laid over the waterproof base 1 and the waterproof sheet fastener 3 (step S03). The waterproof sheet 2 is also fixed to the front surface of the waterproof sheet fastener 3 (step S04). In this embodiment, the layer H made of thermoplastic synthetic resin of the waterproof sheet fastener 3 is melted by an electromagnetic induction heater to fuse the waterproof sheet 2 to the front surface of the waterproof sheet fastener 3. However, the waterproof sheet 2 may be fused to the front surface of the waterproof sheet fastener 3 by the layer H made of a solvent.

[0038] [Verification of the strength of waterproof sheet fixing devices using outer grooves] A simulation was used to investigate the relationship between the shape of the outer groove-like portion 33a and the strength of the waterproof sheet fixing device 3. The steel material of the waterproof sheet fixing device 3 was SUS430. The thickness of the steel material was set to 0.6 mm.

[0039] As shown in Figure 4, with the back surface of the outer edge of the waterproof sheet fastener 3 fixed to a fixing part located below the waterproof sheet fastener 3, a load was applied in the direction of gravity to two symmetrical points on the outer part 33 with respect to the center point C3. The displacement (second moment of area) of the waterproof sheet fastener 3 under this condition was calculated by simulation.

[0040] As shown in FIG. 5, the load applied to the waterproof sheet fastener 3 was changed to 200N, 400N, 600N, 800N, 1000N, 1200N and 1400N.

[0041] Samples were prepared in which the shape of the central portion 31 surrounded by the central groove portion 32 in a planar view was a triangle, a rectangle, a pentagon, a hexagon, a heptagon, or an octagon. In addition, for comparison with these samples, samples were prepared in which the central portion 31 in a planar view was a circle.

[0042] As shown in FIG. 5, the samples in which the central portion 31 is a square, pentagon, hexagon, heptagon, or octagon in plan view tend to have a smaller amount of displacement than the samples in which the central portion 31 is a triangle in plan view. In addition, the samples in which the central portion 31 is a square, pentagon, hexagon, heptagon, or octagon in plan view tend to have a smaller amount of displacement than the samples in which the central portion 31 is a circle in plan view. Therefore, the shape of the central portion 31 surrounded by the central groove-like portion 32 is preferably a polygonal shape having 4 to 8 sides in plan view. Among these, the samples in which the central portion 31 is a pentagon in plan view tend to have a smaller amount of displacement. Therefore, it is particularly preferable that the central groove-like portion 32 surrounds the central portion 31 in a pentagonal shape, and the central portion 31 is a pentagon in plan view.

[0043] On the other hand, it was found that the sample in which the central portion 31 was triangular in plan view had a larger amount of displacement than the other samples, especially at loads of 200 N and 400 N. Therefore, when the central portion 31 is triangular in plan view, it is not preferable because the waterproof sheet fastener 3 is easily displaced by the force of wind blowing the waterproof sheet 2 upward.

[0044] Next, as shown in FIG. 6, the displacement of a sample having a pentagonal central portion 31 in plan view and multiple outer groove portions 33a was examined. Seven types of samples AG with different orientations and arrangements of the outer groove portions 33a were prepared, as well as a sample (only pentagonal) without the outer groove portions 33a as a comparison. FIG. 6 shows the central portions 31 of these samples AG and the orientations of the outer groove portions 33a in plan view. Specifically, in FIG. 6, the central portion 31 and the central groove portion 32 are shown by a double pentagon surrounding the center of the waterproof sheet fastener 3. Also, the outer groove portions 33a are shown by multiple rectangles arranged in the circumferential direction. The longitudinal size of the outer groove portions 33a of these samples is 4.8 mm.

[0045] Regarding the orientation of the outer groove portion 33a, in samples B, C, D, and F, the outer groove portion 33a extends in a direction away from the center point C3. In samples E and G, the outer groove portion 33a extends in a direction perpendicular to the radial direction of the outer portion 33. In sample A, the outer groove portion 33a extends in a circumferentially inclined position relative to the radial direction of the outer portion 33. As a result, as shown in FIG. 6, the amount of displacement of samples A, B, D, E, F, and G, except for sample C, tends to be smaller than that of samples (only pentagonal) that do not have the outer groove portion 33a. In sample C, the outer groove portion 33a is positioned in contact with the central groove portion 32. Therefore, when the central portion 31 is pentagonal in plan view, if the outer groove portion 33a is located away from the central groove portion 32, the amount of displacement of the waterproof sheet fastener 3 is recognized to be small.

[0046] Also, it was found that the displacement amount tended to be small for samples B, D, E, F, and G. Therefore, it is preferable that the outer groove portion 33a extends in a direction away from the center point C3 or in a direction perpendicular to the radial direction of the outer portion 33. Among them, it was found that the displacement amount was particularly small for samples B and D. Therefore, it is particularly preferable that the outer groove portion 33a extends in a direction away from the center point C3.

[0047] From the above results, it was found that when the central portion 31 is pentagonal in plan view, the outer groove-like portions 33a spaced apart from the central groove-like portion 32 affect the strength of the waterproof sheet fastener 3.

[0048] [Another embodiment] The present invention is not limited to the above-described embodiment. For example, the following other embodiments may be used. In the following other embodiments, the same components as those in the above-described embodiment are denoted by the same numbers and symbols as those in the above-described embodiment.

[0049] [1] As shown in Figures 7 and 8, the waterproof sheet fixture 3 may be overlapped on an existing waterproof sheet fixture 13 that fixes an existing waterproof sheet 12 to a waterproof base 1. The waterproof sheet fixture 3 may also be fixed to an existing waterproof sheet fixture 13. This makes it possible to lay the waterproof sheet 2 on top of the existing waterproof sheet 12 without removing the existing waterproof sheet 12 from the waterproof base 1 when renovating an existing waterproof structure.

[0050] Here, the "existing waterproof sheet" refers to a waterproof sheet that has already been laid when renovating a waterproof structure, and on whose front surface the waterproof sheet 2 is laid. The "existing waterproof sheet fastener" refers to a plate-shaped waterproof sheet fastener on whose front surface the existing waterproof sheet 12 is fixed.

[0051] The cross-sectional line VIII-VIII shown in FIG. 7 extends linearly from the upper side of the paper to the center point C3, bends clockwise at the center point C3, and extends linearly from the center point C3 toward the lower left side of the paper.

[0052] In this embodiment, the existing waterproof sheet fastener 13 has a central through-hole 13a located at the center point. The existing waterproof sheet fastener 13 is fixed to the waterproof substrate 1 by a tapping screw 14 inserted into the central through-hole 13a. In other words, the existing waterproof sheet 12 is fixed to the waterproof substrate 1 by the existing waterproof sheet fastener 13. However, the existing waterproof sheet fastener 13 may be fixed to the waterproof substrate 1 by an anchor bolt depending on the type of the waterproof substrate 1.

[0053] In this embodiment, the waterproof sheet fastener 3 has an outer through hole 33b instead of the central through hole 34. Specifically, the outer portion 33 has the outer through hole 33b through which a rivet 11 (corresponding to the fixing member of the present invention) for fixing the waterproof sheet 2 to an existing waterproof sheet fastener 13 is inserted.

[0054] [Outer through hole] 7 and 8, the pair of outer through-holes 33b are located symmetrically with respect to the center point C3. As a result, compared to a configuration in which the pair of outer through-holes 33b are located on only one side of the center point C3, the points fixed to the existing waterproof sheet fastener 13 are uniform, so the waterproof sheet fastener 3 is stably supported by the existing waterproof sheet fastener 13.

[0055] The outer portion 33 is positioned so as to overlap with the outer portion 13c of the existing waterproof sheet fastener 13. In other words, the outer through-hole 33b is arranged so as to overlap with the outer portion 13c of the existing waterproof sheet fastener 13. This makes it easier for the rivet 11 inserted into the outer through-hole 33b to be fixed to the outer portion 13c of the existing flat waterproof sheet fastener 13.

[0056] Next, a method for renovating a waterproof structure using the waterproof sheet fastener 3 will be described with reference to the flowchart in Fig. 9. Note that the order of the steps described below may be changed or multiple steps may be performed simultaneously, as long as no contradiction occurs.

[0057] The waterproof sheet fastener 3 is placed at a position where it overlaps with the existing waterproof sheet fastener 13 (step S11). Specifically, as shown in Fig. 8, the waterproof sheet fastener 3 is placed at a position where the center point of the existing waterproof sheet fastener 13 and the center point C3 of the waterproof sheet fastener 3 overlap.

[0058] Next, the waterproof sheet fastener 3 is fixed to the existing waterproof sheet fastener 13 (step S12). Specifically, as shown in Fig. 8, a rivet 11 is inserted into the outer through-hole 33b of the waterproof sheet fastener 3, and the waterproof sheet fastener 3 is fixed to the outer portion 13c of the existing waterproof sheet fastener 13 by the rivet 11. However, the waterproof sheet fastener 3 may be fixed to the existing waterproof sheet fastener 13 by other fixing members such as tapping screws.

[0059] Next, the waterproof sheet 2 is laid over the existing waterproof sheet 12 and waterproof sheet fastener 3 (step S13). The waterproof sheet 2 is also fixed to the front surface of the waterproof sheet fastener 3 (step S14). In this embodiment, the layer H made of thermoplastic synthetic resin of the waterproof sheet fastener 3 is melted by an electromagnetic induction heater to fuse the waterproof sheet 2 to the front surface of the waterproof sheet fastener 3. However, the waterproof sheet 2 may be fused to the front surface of the waterproof sheet fastener 3 by the layer H made of a solvent.

[0060] [2] As shown in Fig. 7, the outer groove portion 33a may extend at an angle in the circumferential direction of the outer portion 33. In addition, the outer groove portion 33a does not have to be adjacent to the vertices of the polygonal central portion 31 on the radially outer side.

[0061] [3] The outer groove portion 33 a may extend in a direction perpendicular to the radial direction of the outer portion 33 .

[0062] [4] As shown in Fig. 7, the interval between some of the outer groove portions 33a may be different from the interval between the other outer groove portions 33a. In other words, the outer groove portions 33a do not have to be arranged at equal intervals in the circumferential direction.

[0063] [5] The outer through-holes 33b do not have to be a pair. For example, the outer portion 33 may have one outer through-hole 33b, or three or more outer through-holes 33b.

[0064] [6] The distance L1 may be the same as the distance L2, or the distance L1 may be greater than the distance L2.

[0065] [7] The configurations disclosed in the above embodiments (including other embodiments, the same applies below) may be applied in combination with configurations disclosed in other embodiments, unless a contradiction arises. In addition, the embodiments disclosed in this specification are merely examples, and the embodiments of the present invention are not limited thereto. They may be modified as appropriate within the scope of the purpose of the present invention. [Industrial Applicability]

[0066] The present invention is applicable to tarpaulin fasteners. [Explanation of symbols]

[0067] 1: Waterproof base 2: Waterproof sheet 3: Tarpaulin fixing device 31: Central part 32: Central groove area 33 :Outer groove-like part 33:Outer part 33a: Lateral groove-like part 33b: Outer through hole 34: Central through hole 11: Rivet (fixing member) 13: Existing waterproof sheet fixing device 14: Tapping screw (fixing part) C3: Center point

Claims

1. A plate-shaped waterproof sheet fastener to which a waterproof sheet is fixed on the front surface, A groove-shaped central portion surrounding a central point is provided. The central portion surrounded by the central groove portion is polygonal in shape, A waterproof sheet fastener in which the number of interior angles of the central portion is 4 or more and 8 or less in plan view.

2. The waterproof sheet fastener according to claim 1, wherein the central portion has a pentagonal shape with five interior angles in a plan view.

3. The waterproof sheet fastener according to claim 1 , further comprising a central through hole located at the central point and through which a fastening member for fastening the waterproof sheet to a waterproof substrate is inserted.

4. Further comprising an outer portion located outside the central groove portion in a plan view, The waterproof sheet fastener described in claim 1, wherein the outer portion has a groove-shaped outer groove portion spaced from the central groove portion, and an outer through hole through which a fixing member for fixing the waterproof sheet to an existing waterproof sheet fastener is inserted.

5. 5. The waterproof sheet fastener according to claim 4, wherein a pair of said outer through holes are located symmetrically with respect to said central point.

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