JP7308535B2 - Waterproof sheet construction method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a waterproof sheet construction method.

For example, in the waterproof sheet construction method disclosed in Patent Document 1, multiple points of the waterproof sheet are fixed to the waterproof base ("roof base" in the document) so that the waterproof sheet does not swell due to the wind. When wind pressure acts on the waterproof substrate, the wind pressure generally acts more strongly on the outer peripheral area (“corner” in the literature) than the inner peripheral area (“other part” in the literature) of the waterproof substrate. . For this reason, in order for the waterproof sheet to withstand the wind pressure in the outer peripheral area, the point-like fixing points in the outer peripheral area (“corner” in the literature) of the waterproof substrate are the inner peripheral area (“other part” in the literature). ) are more densely arranged than the point-like fixing points in

JP 2006-077505 A

Due to factors such as climate change in recent years, there is a demand for a method that can fix the waterproof sheet more firmly than before, especially in the outer peripheral area. However, a method of simply increasing the number of point-like fixing points in the outer peripheral area and arranging them more densely than in the conventional method causes problems such as an increase in building material cost, complication of construction, and an increase in the risk of construction failure. It is also conceivable to attach the waterproof sheet to the entire surface of the waterproof substrate, but if the waterproof sheet is completely adhered to the waterproof substrate with dust remaining on the waterproof substrate, it will result in poor construction. It is necessary to clean the entire surface of the substrate, which complicates the construction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a waterproof sheet construction method capable of firmly fixing a waterproof sheet to a waterproof substrate by a simple method.

The waterproof sheet construction method according to the present invention includes an outer peripheral step of adhesively fixing the entire surface of the first waterproof sheet laid in the outer peripheral area of the waterproof base to be constructed to the waterproof base, and the inner side of the outer peripheral area of the waterproof base. and an inner peripheral step of fixing a plurality of locations of the second waterproof sheet laid in the inner peripheral region of the second waterproof sheet to the waterproof substrate in a point shape after the outer peripheral step, wherein the end of the second waterproof sheet The second waterproof sheet is superimposed on the first waterproof sheet from above so as to overlap the first waterproof sheet, and the overlapped portion of the second waterproof sheet is entirely adhered to the upper surface of the first waterproof sheet. do.

Wind pressure tends to act more strongly on the outer peripheral area than on the inner peripheral area, so if the first waterproof sheet is fixed to the waterproof base in points in the outer peripheral area, the first waterproof sheet tends to flutter with the wind. On the other hand, the wind pressure acting on the inner peripheral area tends to be weaker than the wind pressure acting on the outer peripheral area. And it is hard to flutter in the wind. According to the present invention, the first waterproof sheet is laid on the outer peripheral area of the waterproof substrate, and the second waterproof sheet is laid on the inner peripheral area. The first waterproof sheet laid on the outer peripheral area is fixed by full-surface adhesion. Therefore, even if the wind pressure is stronger in the outer peripheral area than in the inner peripheral area, the first waterproof sheet is fluttered by the wind compared to the method in which the first waterproof sheet is fixed in a plurality of points. It can withstand wind pressure without sticking. Also, even if the second waterproof sheet flutters in the wind, the fluttering of the second waterproof sheet converges while remaining weak, and the point-like fixing portion of the second waterproof sheet to the waterproof substrate is less likely to be subjected to a load.

In general, the method of adhesively fixing the entire surface of the waterproof sheet to the waterproof substrate is more complicated in terms of workability than the method of fixing the waterproof sheet to the waterproof substrate in points. In the present invention, the area to which the waterproof sheet is fixed by full-surface adhesion is only the outer peripheral area, and the construction of full-surface adhesion in the outer circumferential area is performed prior to the construction of the inner circumferential area. From this, even if the workability is somewhat deteriorated, the worker can adhere the first waterproof sheet only to the outer peripheral region over the entire surface, and after that, the inner peripheral region can be used without worrying about the state of the outer peripheral region. , the second waterproof sheet can be fixed in points.

When a single waterproof sheet is laid over the outer peripheral area and the inner peripheral area, if the fixing method of the same waterproof sheet is different between the outer peripheral area and the inner peripheral area, the workability tends to deteriorate. In the present invention, separate waterproof sheets are laid in the outer peripheral area and the inner peripheral area, so there is no concern that workability will be impaired. As described above, according to the present invention, a waterproof sheet construction method capable of firmly fixing a waterproof sheet to a waterproof substrate is realized by a simple method.
In general, when a worker stacks and bonds a plurality of waterproof sheets, if the lower waterproof sheet is flat, the worker can easily bond the upper and lower waterproof sheets to each other without gaps. . In the present invention, since the entire surface of the first waterproof sheet is adhesively fixed to the waterproof substrate in the outer peripheral process, the upper surface portion of the first waterproof sheet is easily formed flat.
For example, when a plurality of second waterproof sheets are laid in parallel, irregularities are formed in the overlapping portions of the adjacent second waterproof sheets. In such a case, if the first waterproof sheet is superimposed on the uneven part from the upper side, this part will be defective in construction, and the waterproof will not start from the overlapped part of the first waterproof sheet and the second waterproof sheet. There is a risk of water leakage to the base.
With this configuration, the top surface of the first waterproof sheet can be easily formed flat. By superimposing the second waterproof sheet on top of the top surface of the first waterproof sheet, it becomes difficult for the first waterproof sheet and the second waterproof sheet to be adhered poorly.

The "adhesion" in the present invention may be adhesion by an adhesive, fusion by heat, or fusion by a welding agent. In other words, "adhesion" in the present invention includes adhesion by adhesive, fusion by heat, fusion by welding agent, and the like.

In the present invention, it is preferable to lay the second waterproof sheet in the inner peripheral region after the outer peripheral step.

If the second waterproof sheet is laid before the entire surface of the first waterproof sheet is adhesively fixed in the outer peripheral area, the workability of the first waterproof sheet tends to deteriorate. With this configuration, since the second waterproof sheet is not laid when the entire surface of the first waterproof sheet is adhesively fixed in the outer peripheral region, the operator can easily perform the adhesively fixing of the first waterproof sheet.

In the present invention, the first waterproof sheet and the second waterproof sheet are long sheets, and the first waterproof sheet is arranged such that the longitudinal direction of the first waterproof sheet follows the outer peripheral shape of the waterproof base. and laying the second waterproof sheets in parallel in a plurality of rows with the longitudinal direction of the second waterproof sheets along any one side of the inner peripheral region.

Typically, the generally elongated sheet is rolled into a roll prior to laying. Therefore, the operator can deploy the first waterproof sheet along the outer peripheral shape of the waterproof base, and deploy the second waterproof sheet along any one side of the inner peripheral region. Therefore, the worker can easily lay the first waterproof sheet and the second waterproof sheet.

In the present invention, it is preferable to finish laying the second waterproof sheet at a position inside the outer peripheral edge of the waterproof substrate.

With this configuration, the second waterproof sheet is located inside the area where the first waterproof sheet is laid, so that the work of bonding the first waterproof sheet and the second waterproof sheet is facilitated. In addition, since the first waterproof sheet is entirely adhered and fixed to the waterproof substrate in the peripheral process, the top surface of the first waterproof sheet can be easily formed flat. Therefore, even when the parapet is provided outside the outer peripheral region, the waterproof sheet laid on the rising portion of the parapet can be easily adhered to the flat first waterproof sheet in the outer peripheral region.

FIG. 2 is a plan view showing a flat roof on which a waterproof sheet is laid; FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1 showing adhesion between the first waterproof sheet and the second waterproof sheet; It is a top view which shows an outer periphery process. It is a top view which shows a metal fittings fixing process. It is a top view which shows an inner periphery process. FIG. 2 is a cross-sectional view taken along the line VI-VI of FIG. 1 showing adhesion between the first waterproof sheet and the second waterproof sheet; FIG. 2 is a cross-sectional view taken along line VII-VII in FIG. 1, showing adhesion between the first waterproof sheet and the second waterproof sheet; FIG. 2 is a cross-sectional view taken along the line VIII-VIII of FIG. 1, showing the case where the first waterproof sheet is laid over the parapet. FIG. 3 is a cross-sectional view taken along line VIII-VIII of FIG. 1, showing a case where a first waterproof sheet is laid as another embodiment;

[Regarding the fixing structure of the waterproof sheet]
FIG. 1 shows a flat roof, for example made of concrete. In this embodiment, a flat roof is provided with a floor 1 having a water gradient and a parapet 2 on the outer peripheral side of the floor 1 .
The parapet part 2 is provided along the four sides of the flat roof and covers the entire circumference of the outer peripheral portion of the flat roof in plan view. The part surrounded by the parapet part 2 is the floor part 1 . The vertical position of the parapet part 2 is positioned higher than the vertical position of the floor part 1 . A wall surface portion 2 a is formed in the parapet portion 2 and rises upward from the floor portion 1 . The floor 1 is the "waterproof base" of the present invention.

The area of the floor 1 on the side where the edge portions of the four sides are located is the outer peripheral area A, and the area inside the outer peripheral area A is the inner peripheral area B. As shown in FIG. Waterproof sheets 3 and 4 are laid on a floor portion 1. - 特許庁
The waterproof sheets 3 and 4 are long sheets. A waterproof sheet 3 is laid on the outer peripheral area A, and a waterproof sheet 4 is laid on the inner peripheral area B.

The waterproof sheet 3 is the "first waterproof sheet" of the present invention. In this embodiment, one waterproof sheet 3 is laid on each of the four sides of the floor 1 . The worker lays down the waterproof sheet 3 so that the longitudinal direction of the waterproof sheet 3 follows the outer peripheral shape of the floor portion 1 . The waterproof sheet 4 is the "second waterproof sheet" of the present invention. The operator lays a plurality of rows of waterproof sheets 4 in parallel in the inner peripheral area B with the longitudinal direction of the waterproof sheets 4 along the direction of the water gradient of the floor 1 .

As shown in FIGS. 1 and 2, the portion where the waterproof sheet 3 and the waterproof sheet 4 overlap is the joint portion 5 between the waterproof sheet 3 and the waterproof sheet 4 . The area where the joint 5 is located is the boundary area C between the outer peripheral area A and the inner peripheral area B. As shown in FIG. The worker overlaps the waterproof sheet 4 with the waterproof sheet 3 from above so that the ends of the waterproof sheet 4 overlap the waterproof sheet 3 . At the junction 5, the waterproof sheets 3 and 4 are bonded to each other. In a state where the edge of the waterproof sheet 4 on the side where the waterproof sheet 3 is located overlaps with the edge of the waterproof sheet 3 on the side where the waterproof sheet 4 is located, the waterproof sheets 3 and 4 are separated from each other. The edges are joined by gluing.

[About the construction method of the waterproof sheet]
A construction method for the waterproof sheets 3 and 4 will be described with reference to FIGS. 3 to 5. FIG.
(1. Periphery process)
First, as shown in FIG. 3, the worker lays the waterproof sheet 3 in the outer peripheral area A. As shown in FIG. The process of laying the waterproof sheet 3 in the outer peripheral area A is called "peripheral process". In this embodiment, the waterproof sheet 3 is laid in the outer peripheral area A by an adhesion method. Before laying the waterproof sheet 3, the worker applies an adhesive such as a primer to the floor 1 of the outer peripheral area A. As shown in FIG. The waterproof sheet 3 before laying is wound in a roll shape, and the operator unfolds the roll-shaped waterproof sheet 3 along the outer peripheral shape of the floor portion 1 . In this embodiment, since the floor 1 has four sides, the worker lays four waterproof sheets 3 in the outer peripheral area A. As shown in FIG. The laid waterproof sheet 3 is adhered to the floor 1 via an adhesive. In this manner, in the outer peripheral step, the worker adheres and fixes the entire surface of the waterproof sheet 3 laid in the outer peripheral region A of the floor 1 to be constructed to the floor 1 .

(2. Metal fitting fixing process)
After the waterproof sheet 3 is laid in the outer peripheral area A by the outer peripheral process described above, as shown in FIG. do.
The step of fixing the fixture 6 to the floor 1 is called a "fixing step". The upper surface of the fixture 6 is formed in a substantially disc shape. A worker fixes the fixture 6 to the floor 1 by driving a screw into the floor 1, for example. Note that the metal fixture fixing step may be performed before the outer peripheral step. In short, the metal fixture fixing step should be performed before the inner peripheral step described later.

(3. Inner circumference process)
After the waterproof sheet 3 is laid in the outer peripheral area A by the above-described outer peripheral process, and all the fixing metal fittings 6 are fixed to the floor 1 by the above-described metal fitting fixing process, as shown in FIG. , a waterproof sheet 4 is laid on the floor portion 1 of the inner peripheral area B inside the outer peripheral area A. The process of laying the waterproof sheet 4 on the floor portion 1 of the inner peripheral area B is called an "inner peripheral process". The waterproof sheet 4 before laying is wound into a roll, and the operator unfolds the roll-shaped waterproof sheet 4 along the direction of the water gradient of the floor section 1 . In addition, the worker finishes laying the waterproof sheet 4 at a position inside the outer peripheral edge of the floor portion 1 . When all the waterproof sheets 4 have been deployed, the plurality of waterproof sheets 4 are arranged in parallel, and the longitudinal direction of each waterproof sheet 4 is along the direction of the water gradient of the floor section 1 . The operator presses an induction heating device (not shown) from above the waterproof sheet 4 against each of the locations where the fixtures 6 are located, thereby heating the fixtures 6 . When the metal fittings 6 are heated to a predetermined temperature, the temperature of the portion of the waterproof sheet 4 that contacts the metal fittings 6 reaches the melting point, and the portion of the waterproof sheet 4 that contacts the metal fittings 6 is fused to the metal fittings 6. . In this way, in the inner peripheral process, the worker spreads the waterproof sheet 4 at a plurality of points on the inner peripheral area B inside the outer peripheral area A of the floor 1 to the floor 1 after the outer peripheral process. fixed to

(4. Sheet bonding process)
After the waterproof sheet 4 is laid in the inner peripheral area B by the inner peripheral process described above, the worker bonds the waterproof sheets 3 and 4 to each other. The process of adhering the waterproof sheets 3 and 4 to each other is called a "sheet adhering process". Specifically, the operator bonds the edges of the adjacent waterproof sheets 4 in the lateral direction to each other. The lateral edges of the waterproof sheet 4 may be fused together by, for example, a hot air blower or a welding machine, may be fused together by a welding agent, or may be bonded together by an adhesive. can be Further, the worker bonds the edge of the waterproof sheet 3 on the side where the waterproof sheet 4 is located and the edge of the waterproof sheet 4 on the side where the waterproof sheet 3 is located. In other words, in the sheet bonding process, the worker joins the waterproof sheets 3 and 4 in the boundary area C to form the joint 5 . The waterproof sheet 3 is already adhered to the floor 1 over the entire surface with an adhesive in the outer peripheral process. For this reason, the operator adheres the overlapping portion of the waterproof sheet 4 to the upper surface of the waterproof sheet 3 over the entire surface. The overlapped portions of the waterproof sheet 3 and the waterproof sheet 4 in the boundary region C may be fused to each other by, for example, a hot air blower or a welding machine, may be fused to each other by a welding agent, or may be bonded together. They may be adhered to each other by an agent.

Since unevenness is formed in the portion where the adjacent waterproof sheets 4 are overlapped, when the waterproof sheet 3 is overlapped from the upper side on the unevenness-formed portion, construction failure is likely to occur in this portion. On the other hand, in this embodiment, as shown in FIGS. 6 and 7, the waterproof sheet 3 is adhesively fixed over the entire surface before the waterproof sheet 4 is laid, and the upper surface of the waterproof sheet 3 is a flat surface. It has become. In this state, since the waterproof sheet 4 is superimposed from the upper side, the construction failure of the adhesion between the waterproof sheet 3 and the waterproof sheet 4 is unlikely to occur, and the overlapped portion of the waterproof sheet 3 and the waterproof sheet 4, that is, the joint 5 Therefore, it becomes difficult for water to leak to the waterproof substrate.

Moreover, since the waterproof sheet 4 has been laid at a position inside the outer peripheral edge of the floor 1, a large amount of the flat upper surface portion of the waterproof sheet 3 is exposed. Therefore, as shown in FIG. 8, when the waterproof sheet 7 is laid on the parapet portion 2, the waterproof sheet 7 is folded back between the floor portion 1 and the wall surface portion 2a of the parapet portion 2, and the waterproof sheet The lower end of 7 overlaps the waterproof sheet 3 . In this state, the worker can easily bond the entire surface of the overlapped portion of the lower end of the waterproof sheet 7 and the upper surface of the waterproof sheet 3 without defective work. The operator applies an adhesive such as a primer to the wall surface portion 2a before laying the waterproof sheet 7, and then lays the waterproof sheet 3 on the wall surface portion 2a.

Wind pressure tends to act more strongly in the outer peripheral region A than in the inner peripheral region B. Therefore, when the waterproof sheet 3 is fixed to the floor 1 in the outer peripheral region A in a dotted manner, the waterproof sheet 3 tends to flutter with the wind. Become. On the other hand, the wind pressure acting on the inner peripheral region B tends to be weaker than the wind pressure acting on the outer peripheral region A, and the waterproof sheet 4 is fixed to the floor 1 in a point-like manner. It is hard to flutter in the wind. In the present embodiment, the waterproof sheet 3 is completely adhered to the outer peripheral area A, so that the waterproof sheet 3 hardly flutters. Further, even if the waterproof sheet 4 flutters with the wind, the fluttering of the waterproof sheet 4 converges weakly, and the point-like fixing portion (the portion where the fixing metal fittings 6 are positioned) of the waterproof sheet 4 to the waterproof substrate is less likely to be subjected to a load.

[Another embodiment]
The present invention is not limited to the configurations exemplified in the above-described embodiments, and other representative embodiments of the present invention will be exemplified below.

(1) FIG. 1 shows a flat roof made of concrete, for example, but a heat insulating material may be laid on the flat roof, and the waterproof sheets 3 and 4 may be laid on the heat insulating material. Also, the flat roof may not be made of concrete, and may be made of metal (folded plate, deck plate, etc.), for example. Also, the roof may be a wooden roof having a wooden base made of rafters, sheathing boards, and the like.

(2) In the above-described embodiment, the waterproof sheet 4 is not laid in the outer peripheral area A. However, if the waterproof sheet 4 is positioned on the waterproof sheet 3, the waterproof sheet 4 is placed on the inner peripheral area B and the outer peripheral area. It may be laid over the area A. In short, it is preferable for the worker to finish laying the waterproof sheet 4 at a position inside the outer peripheral edge of the floor portion 1 .

(3) In the above-described embodiment, a plurality of waterproof sheets 4 are laid in parallel in the inner circumferential area B with the longitudinal direction of the waterproof sheets 4 along the direction of the water gradient of the floor 1. may not be along the direction of the water gradient of the floor 1. In short, the operator should lay the waterproof sheets 4 in parallel in a plurality of rows with the longitudinal direction of the waterproof sheets 4 along one side of the inner peripheral region B. As shown in FIG.

(4) In the above-described embodiment, the waterproof sheet 4 is fused and fixed to the fixing bracket 6 in the inner peripheral region B, but the waterproof sheet 4 may be fixed by, for example, an extension construction method (patch construction method). . The extension construction method (patch construction method) is, for example, a configuration in which the fixing bracket 6 is positioned above the waterproof sheet 4, and the waterproof sheet 4 and another expansion sheet (not shown) cover over the fixing bracket 6. means a construction method in which the fixing bracket 6 presses the waterproof sheet 4 downward to fix it. Further, in the inner peripheral region B, a region where the waterproof sheet 4 is fused and fixed to the fixture 6 and a region where the waterproof sheet 4 is fixed by the patch construction method may be mixed. In other words, in the inner circumference process, the worker fixes a plurality of points of the waterproof sheet 4 laid in the inner circumference area B inside the outer circumference area A of the floor 1 to the floor 1 after the outer circumference process. do it.

(5) In the above embodiment, the worker lays the waterproof sheet 4 in the inner peripheral area B after the outer peripheral process, but the worker lays the waterproof sheet 4 in the inner peripheral area B before the outer peripheral process. You can Moreover, the worker may lay the waterproof sheet 4 in the inner peripheral area B before the metal fitting fixing process, or may lay the waterproof sheet 4 in the inner peripheral area B concurrently with the metal fitting fixing process. Furthermore, the laying of the waterproof sheet 4 and the fusing of the waterproof sheet 4 to the fixture 6 may be performed simultaneously.

(6) In the outer circumference process described above, the worker applies an adhesive to the floor 1 of the outer circumference area A before laying the waterproof sheet 3, but the present invention is not limited to this embodiment. For example, the laying of the waterproof sheet 3 and the application of the adhesive may be performed in parallel. Further, after laying the waterproof sheet 3, an adhesive may be applied to at least one of the rear surface portion of the waterproof sheet 3 and the floor portion 1 to bond the rear surface portion of the waterproof sheet 3 and the floor portion 1 together.

(7) In the above-described embodiment, the worker adheres and fixes the entire surface of the waterproof sheet 3 laid in the outer peripheral area A of the floor 1 to the floor 1 in the outer peripheral process, but is not limited to this embodiment. In the outer peripheral area A of the floor 1, the inner corner portion adjacent to the parapet portion 2 is particularly susceptible to wind. In addition, since the internal corner portion is located near the area where the wall surface portion 2a rises, it is also a portion where workability tends to deteriorate. Therefore, if the waterproof sheet 3 is only adhered to the floor 1 with an adhesive at the inside corner, the waterproof sheet 3 tends to rise over time, and the waterproof performance of the waterproof sheet 3 against the floor 1 decreases. there is a risk of

In order to avoid such inconvenience, as shown in FIG. good. The longitudinal direction of the fixture 8 extends along the parapet portion 2 in plan view. The fixing metal fitting 8 is fixed to an internal corner portion of the outer peripheral edge of the outer peripheral region A adjacent to the parapet portion 2 with a screw 8a. As a result, the fixing bracket 8 is firmly fixed to the floor 1, and the floor 1 and the fixing bracket 8 form an integral waterproof base. The operator unfolds the roll-shaped waterproof sheet 3 along the outer peripheral shape of the floor part 1 in a state where the waterproof sheet 3 is positioned on the fixing metal fittings 8 . Then, the operator uses an induction heating device (not shown) to fuse the edge portion of the waterproof sheet 3 on the side where the parapet portion 2 is located to the fixing bracket 8 over both ends in the longitudinal direction of the waterproof sheet 3. Let In addition, the worker adheres the portion of the waterproof sheet 3 on the inner peripheral side of the portion to be fused with the fixing metal fitting 8, that is, the portion in contact with the floor portion 1 to the floor portion 1 via an adhesive.

In this way, in the peripheral process, the worker fuses the waterproof sheet 3 to the fixture 8 with heat and adheres the waterproof sheet 3 to the floor 1 with an adhesive, thereby forming the waterproof base ( The entire surface may be adhesively fixed to the floor 1 and the fixing metal fittings 8). As a result, the waterproof sheet 3 is firmly adhered to the fixtures 8 compared to the structure in which the waterproof sheet 3 is adhered to the floor 1 with an adhesive. The fixture 8 is fixed to the floor 1 with screws 8a. As a result, even when strong wind acts on the inside corner, the waterproof sheet 3 is not easily peeled off from the fixture 8, and the adhesion state between the waterproof sheet 3 and the waterproof substrate is maintained for a long period of time. Moreover, the waterproof property of the waterproof sheet 3 against the waterproof substrate is maintained for a long period of time.

It should be noted that the configurations disclosed in the above-described embodiments (including other embodiments; the same shall apply hereinafter) can be applied in combination with configurations disclosed in other embodiments unless there is a contradiction.
Moreover, the embodiments disclosed in this specification are merely examples, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the scope of the present invention.

The waterproof sheet construction method can be used not only for newly installing a waterproof sheet but also for repair work.

1: Floor (waterproof base)
3: Waterproof sheet (first waterproof sheet)
4: Waterproof sheet (second waterproof sheet)
A: Outer peripheral area B: Inner peripheral area

Claims (4)

A peripheral step of adhesively fixing the entire surface of the first waterproof sheet laid in the outer peripheral area of the waterproof substrate to be constructed to the waterproof substrate;
and an inner peripheral step of fixing a plurality of locations of the second waterproof sheet laid in the inner peripheral area inside the outer peripheral region of the waterproof substrate to the waterproof substrate after the outer peripheral step. ,
Overlapping the second waterproof sheet on the first waterproof sheet from above such that the end of the second waterproof sheet overlaps the first waterproof sheet;
A waterproof sheet construction method in which the overlapping portion of the second waterproof sheet is entirely adhered to the upper surface of the first waterproof sheet . 2. The waterproof sheet construction method according to claim 1, wherein the second waterproof sheet is laid in the inner peripheral region after the outer peripheral step. The first waterproof sheet and the second waterproof sheet are long sheets,
Laying the first waterproof sheet in a state in which the longitudinal direction of the first waterproof sheet follows the outer peripheral shape of the waterproof base,
The waterproof sheet construction method according to claim 1 or 2, wherein the second waterproof sheets are laid in parallel in a plurality of rows with the longitudinal direction of the second waterproof sheets along any one side of the inner peripheral region. The waterproof sheet construction method according to any one of claims 1 to 3, wherein the second waterproof sheet is finished at a position inside the outer periphery of the waterproof substrate.

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