Top surface weatherproofing structure of building unit

Abstract

To provide an upper surface rain prevention structure for building unit preventing rainwater infiltration while capable of lifting the building unit without rolling up the tarpaulin.SOLUTION: There is provided with an upper surface rain prevention structure for a building unit 2. An elongated draining sheet 13 is provided for covering an elongated unwaterproofed portion 12 formed along the upper edge 11 of the building unit 2. In the draining sheet 13, notches 25 are formed near both ends 14 and a height difference is formed so that the intermediate portion 26 between the cuts 25 is higher than the upper edge 11 with respect to the unwaterproofed portion 12 and both ends 14 have the same height as the upper edge 11. Under the draining sheet 13, a local cover 43 is provided around the notches 25 to partially protect the non-waterproof portion 12.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present invention relates to a top surface weatherproofing structure for a building unit. [Background technology]

[0002] Some buildings, such as houses, are made up of modular buildings. These modular buildings are constructed in a short period of time by transporting prefabricated rectangular parallelepiped building units to a construction site and assembling them there (see, for example, Patent Document 1).

[0003] In such modular buildings, it is necessary to prevent rainwater from getting inside the building units from the time the building units are shipped until the modular building is completed. To this end, in Patent Document 1, for example, when it rains, a waterproof sheet large enough to cover the entire top surface of the building unit is placed on top of the building unit, and the building unit is then shipped from the factory to the construction site. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-140997 Summary of the Invention [Problem to be solved by the invention]

[0005] As in Patent Document 1, if a building unit is shipped with a waterproof sheet covering the entire top surface of the building unit in case of rainfall, the waterproof sheet is a large component, making it difficult to handle. Furthermore, when lifting a building unit at a construction site, at least a portion of the large waterproof sheet must be rolled up in order to attach a lifting device to the building unit. If the building unit is lifted with the waterproof sheet rolled up, rainwater may seep into the building unit through the rolled-up portion of the waterproof sheet.

[0006] Therefore, a main object of the present invention is to contribute to improving the above-mentioned problems. [Means for solving the problem]

[0007] In response to the above problems, the present invention provides: A thin waterproof sheet is provided to cover the thin unwaterproofed portion formed along the upper edge of the building unit; The drainage sheet has cutouts near both ends, and a height difference is formed so that the middle part between the cutouts is higher than the upper edge part with respect to the non-waterproof part, and both ends have parts at the same height as the upper edge part, Under the drainage sheet, around the cutout, The building unit is protected from rainwater that has penetrated into the inside of the drainage sheet through the cutouts. The top surface weatherproofing structure of the building unit is characterized by a local cover that locally protects the non-waterproof portion. [Effects of the Invention]

[0008] According to the present invention, the above-mentioned configuration makes it possible to reduce the size of the waterproof sheet, and to prevent the infiltration of rainwater while allowing the building unit to be lifted without having to roll up the waterproof sheet. In addition, by providing a local cover around the cutout under the water-repellent sheet, the local cover can locally protect the unwaterproofed parts of the building unit from rainwater that has seeped inside the water-repellent sheet through the cutout. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an overall perspective view of a unit building having a top surface weatherproofing structure according to the present embodiment. FIG. [Figure 2] FIG. 2 is an overall perspective view of a lower floor building unit used in the unit building of FIG. 1. [Figure 3] This is an enlarged vertical cross-sectional view of the upper edge of the exterior wall (unwaterproofed area) of the top floor of a unit building. [Figure 4A] FIG. 10 is a partially enlarged perspective view showing the state before hangers are attached to both ends of the drain sheet. [Figure 4B] FIG. 10 is a partially enlarged perspective view showing the state in which hangers are attached to both ends of the drain sheet. [Figure 5] Component diagrams of the draining sheet, in which (a) is a plan view of both ends omitting the middle part, (b) is a longitudinal cross-sectional view of the vicinity of the hanger insertion holes at both ends of the draining sheet, and (c) is a longitudinal cross-sectional view of the outermost parts at both ends of the draining sheet. [Figure 6A] FIG. [Figure 6B] These are part diagrams of the local cover, where (a) is a plan view, (b) is a side view, and (c) is an end view. [Figure 6C] FIG. [Figure 7] This is an overall perspective view showing the state in which a water-repellent sheet is attached to the side of a roof panel to which a local cover has been attached. [Figure 8A] FIG. 10 is a partially enlarged perspective view showing a state in which a local cover is attached to a side surface of a roof panel. [Figure 8B] FIG. 10 is a partially enlarged end view showing the state in which a local cover is attached to the side of the roof panel. [Figure 9A] FIG. 10 is a partially enlarged vertical cross-sectional view showing the state in which the water-repellent sheet is attached to the roof panel. [Figure 9B] FIG. 1 is an enlarged vertical perspective view of both ends of a roof panel with a water-repellent sheet attached. [Figure 10] 10 is a perspective view showing the state in which a sheet receiving beam is attached to the unwaterproofed portion around the upper edge of the building unit. FIG. [Figure 11A] This is an oblique view showing the state in which a waterproofing sheet attached to a roof panel is spread over the unwaterproofed area around the upper edge of the building unit. [Figure 11B] This is a vertical cross-sectional view of the area around the upper edge on the exterior wall side of the building unit, showing the water-repellent sheet in an unfolded state. [Figure 12A] 10 is a partially enlarged perspective view of both ends of the drain sheet, showing the state in which the hanger insertion hole to which the hanger is attached is blocked with waterproof tape. FIG. [Figure 12B] 10 is a partially enlarged perspective view showing the state in which the mounting hole is closed and the drain sheet is attached to the sheet receiving beam. FIG. [Figure 12C] FIG. 10 is a partially enlarged vertical cross-sectional view showing the state in which the drainage sheet is attached to the sheet receiving beam. [Figure 12D] FIG. 10 is a partially enlarged perspective view of both ends of the drainage sheet, showing the cutouts being connected with waterproof tape. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, this embodiment will be described in detail with reference to the drawings. 1 to 12D are provided to explain this embodiment. [Example]

[0011] <Configuration> The configuration of this embodiment will now be described.

[0012] A building such as a detached house or an apartment building is composed of a unit building 1 as shown in FIG.

[0013] The unit building 1 is a building that can be constructed in a short period of time by manufacturing box-shaped (rectangular) building units 2 (Figure 2) in advance in a factory, transporting them to the construction site, and assembling and installing them at the construction site.

[0014] The unit building 1 is a multi-story building with a building unit 2 on an upper floor H placed on top of a building unit 2 on a lower floor L. A balcony 3 is also installed on the upper floor H. Note that the unit building 1 does not need to have the building units 2 installed in the vertical direction 4, and may be a single-story building.

[0015] The building unit 2 is a hexahedron with upper and lower surfaces that are approximately rectangular in plan view and four side surfaces that are approximately rectangular in side view. The four side surfaces include a pair of parallel side surfaces along the long sides of the building unit 2 and a pair of parallel side surfaces along the short sides.

[0016] Exterior walls 5 are attached to the exterior-facing side and corner portions of the unit frame. Note that the exterior walls 5 at the corner portions may not be shown in the drawings.

[0017] The side of the unit frame facing the interior is left open. Therefore, the side facing the interior is temporarily covered with a temporary weatherproofing sheet 6. The building unit 2 in Figure 2 is installed on the lower floor L.

[0018] In addition to the basic configuration described above, this embodiment may also have the following configuration.

[0019] (1) As shown in Figures 3 to 4B (mainly see Figure 4A), the upper surface weatherproofing structure of the building unit 2 is A thin waterproof sheet 13 (FIG. 5) is provided to cover a thin unwaterproofed portion 12 formed along the upper edge 11 of the building unit 2. The drainage sheet 13 has cutouts 25 near both ends 14, and a height difference is formed so that an intermediate part 26 between the cutouts 25 is higher than the upper edge part 11 relative to the non-waterproof part 12, and both ends 14 have parts at the same height as the upper edge part 11. Under the draining sheet 13, a local cover 43 (FIGS. 6A to 6C) is provided around the cutout 25 to locally protect the non-waterproof portion 12.

[0020] Here, the top surface waterproofing structure of the building unit 2 is a structure for waterproofing the top surface and upper part of the building unit 2. Top surface waterproofing means protecting the top surface and upper part of the building unit 2 from rainwater. Waterproofing can be done temporarily before the construction of the unit building 1, or permanent waterproofing that continues after the construction of the unit building 1, but in this example, at least temporary waterproofing is assumed to be possible. Note that it is not limited to temporary waterproofing, and permanent waterproofing may also be possible at the same time.

[0021] Temporary weatherstripping is required at least during the period from when the building units 2 are transported from the factory to the construction site during rainfall, when they are installed at the construction site, until the outer shape of the unit building 1 is almost complete, and until the roof is completed. If temporary weatherstripping is not provided, the above work cannot be carried out during rainfall, which will extend the construction period accordingly. This embodiment is particularly concerned with temporary weatherstripping for the upper part of the building units 2 on the upper floor H (top floor).

[0022] The building unit 2 is a unit structure that makes up the unit building 1. As described above, the building unit 2 is roughly rectangular parallelepiped, and has a unit frame with a box-frame rigid frame structure inside. As shown in Figure 2, the unit frame is a box frame in which four ceiling beams 2b are connected in a rectangular shape between the upper ends of four columns 2a, and four floor beams 2c are connected in a rectangular shape between the lower ends of the four columns 2a. Joint pieces 2d are used to connect the columns 2a to the ceiling beams 2b and floor beams 2c, respectively.

[0023] The upper edge 11 is the edge portion of the upper surface of the approximately rectangular parallelepiped building unit 2, or each side that constitutes the upper surface that is approximately rectangular in plan view. The periphery of the upper edge 11 refers to the upper edge 11 and a certain range nearby it.

[0024] Specifically, the top surface of the building unit 2 is the inner surface of an area that is approximately rectangular in plan view and is formed by the upper ends of the four columns 2a and the upper surfaces of the four ceiling beams 2b (and the upper surface of the joint piece 2d). The upper edge 11 may include the upper ends of the columns 2a and the upper surfaces of the ceiling beams 2b (and the upper surface of the joint piece 2d). The upper edge 11 may be any of the four ceiling beams 2b, but in this example, the case where the target is two ceiling beams 2b that form the long sides of the rectangular top surface, or either one of the two ceiling beams 2b, will be described.

[0025] The non-waterproof portion 12 is the portion (around the upper edge 11) on the top surface of the building unit 2 that has not been waterproofed. The building unit 2 is manufactured in the factory so that almost the entire building unit 2 is waterproofed.

[0026] At this time, the portion along the periphery of the upper edge 11 must be used for lifting the building unit 2, so finishing work to make it waterproof cannot be carried out until installation at the construction site is complete, and it is left in an unfinished, unwaterproofed state. Note that the unwaterproofed portion 12 will be made completely waterproof (fully waterproofed) when finishing work on the roof is carried out once the rain has stopped after installation of the building unit 2 at the construction site.

[0027] The non-waterproof portion 12 has a long and narrow shape formed with a required width along the upper edge 11. The required width is, for example, approximately the same as the width of the ceiling beam 2b, or slightly (approximately 2 to 3 times) wider than that.

[0028] The water-repellent sheet 13 is a thin, flexible, waterproof sheet or film made of a resin such as polyethylene. The water-repellent sheet 13 is substantially the same as that installed, for example, as a roofing underlayment or on the inside (back side) of the exterior wall 5 of a building. The water-repellent sheet 13 has an elongated shape that is at least one size larger in width and length than the unwaterproofed portion 12 so that it can completely cover at least the unwaterproofed portion 12 around the upper edge 11. Therefore, the water-repellent sheet 13 does not need to be large enough to cover the entire top surface of the building unit 2.

[0029] The water-repellent sheet 13 may have waterproof adhesive tape 22 (Figures 4A, 5, etc.) pre-attached to at least one edge along its extension direction (in this embodiment, the direction of the long side of the building unit 2).

[0030] The adhesive tape 22 is attached continuously over almost the entire area of ​​the drain sheet 13 (for example, up to a position beyond the hanger insertion holes 16, which will be described later) except for the outermost portions of both end portions 14. The adhesive tape 22 is attached to the drain sheet 13 over at least a length that is approximately the same as the boundary line between the non-waterproof portion 12 and the waterproof portion 21, and is stuck so that its extension direction is aligned with the boundary line.

[0031] In this embodiment, the adhesive tape 22 is attached so that a portion of it extends beyond one edge of the draining sheet 13 in the width direction by a required width, and the extending adhesive portion is attached to the boundary line. The boundary line has a length that is approximately the same as or shorter than the long side of the building unit 2. Note that if the adhesive tape 22 is double-sided tape and attached to the back side of the draining sheet 13, it will not be necessary to attach it so that a portion of it extends beyond the draining sheet 13.

[0032] The adhesive tape 22 has release paper 22a (Fig. 5(b)) attached to the protruding adhesive portion, and by peeling off the release paper 22a, the water-repellent sheet 13 can be easily attached in the correct position aligned with the boundary line. Note that there is no particular need to attach adhesive tape 22 to the outermost part of the water-repellent sheet 13, such as the part that extends beyond the unwaterproofed part 12 to the outside of the building unit 2 (Fig. 5(c)).

[0033] The two end portions 14 are the terminal portions on both sides of the elongated drainage sheet 13 in the extension direction and the surrounding areas (the two end portions of the sheet). Specifically, the two end portions 14 are the portions that roughly overlap with the columns 2a and joint pieces 2d located on both sides of the long sides of the building unit 2, as well as the portions that are further outward than these. The two end portions 14 also include the portions that extend beyond the long sides of the building unit 2 in the extension direction.

[0034] The draining sheet 13 has the above-mentioned hanger insertion holes 16 at both end portions 14 thereof.

[0035] The hanger insertion holes 16 are through-holes formed directly in both end portions 14 (of upper edge contact surfaces 17, which will be described later) of the water-repellent sheet 13. The hanger insertion holes 16 are provided at positions that coincide with mounting holes 23 formed in the upper ends of the pillars 2a of the building units 2, for mounting hangers 18.

[0036] A threaded portion 18a (FIG. 4A) provided at the bottom of the hanger 18 is passed through the hanger insertion hole 16. Therefore, the diameter of the hanger insertion hole 16 is approximately the same as or slightly larger than that of the threaded portion 18a and the mounting hole 23. One hanger insertion hole 16 is provided at each end of the draining sheet 13, approximately in the center of the upper edge contact surface 17 of each end 14. The hanger insertion hole 16 is simply an opening. The hanger insertion hole 16 is formed in the draining sheet 13 so that it is a hole that is completely exposed to the outside, without, for example, any lid-like attachment to cover the opening.

[0037] A reinforcing tape (reinforcing material 24) such as a waterproof acrylic tape may be attached to one or both sides of the portion (upper edge contact surface portion 17) of the draining sheet 13 where the hanger insertion hole 16 is formed. The hanger insertion hole 16 is formed in the same position and size so as to pass through both the draining sheet 13 and the reinforcing material 24.

[0038] Furthermore, the portions of the drain sheet 13 at both ends 14 where the reinforcing material 24 is attached are thickened and flattened, thereby partially improving the adhesion of the periphery of the hanger insertion hole 16 to the upper edge 11 of the building unit 2. Therefore, the reinforcing material 24 also serves as a member (sealing surface forming member) that forms a highly sealing portion on the upper edge contact surface 17. In this embodiment, the reinforcing material 24 has approximately the same shape and size as the upper end of the column 2a, and is attached to the position of the upper end of the column 2a, thereby bringing the upper edge contact surface 17 into close contact with the upper end of the column 2a.

[0039] The cut portions 25 are cuts formed in the draining sheet 13, and are formed in the draining sheet 13 so as not to completely separate both end portions 14 from the draining sheet 13, leaving connecting portions 13a.

[0040] The cutouts 25 are formed from the lower edge to the upper edge of the draining sheet 13, not reaching the upper edge. This separates the draining sheet 13 into both end portions 14 and a middle portion 26, allowing for a relatively free shape. The draining sheet 13 has a connecting portion 13a around the upper edge of the cutout 25 (almost up to the position where the adhesive tape 22 is attached).

[0041] The cutout 25 is provided in the water-repellent sheet 13 that covers the upper edge 11 (the unwaterproofed portion 12 around it) facing the outside of the unit building 1. Alternatively, the cutout 25 is provided in the water-repellent sheet 13 that is installed above the position where the exterior wall 5 of the building unit 2 is provided.

[0042] On the other hand, the cutouts 25 do not have to be provided in the water-repellent sheet 13 that covers the upper edge 11 (the unwaterproofed portion 12 around it) located between adjacent building units 2. Furthermore, a thick temporary rainproofing sheet 27 (Fig. 1) may be placed over at least the water-repellent sheet 13 that covers the upper edge 11 (the unwaterproofed portion 12 around it) located between adjacent building units 2 to double the temporary rainproofing means.

[0043] In this embodiment, the water-repellent sheet 13 having the cutout portion 25 is installed at two locations on the upper floor H of the unit building 1: the unwaterproofed portion 12 facing the balcony 3, and the unwaterproofed portion 12 on the opposite side farthest from the balcony 3 (Figure 1).

[0044] The middle portion 26 is the portion between both longitudinal end portions 14 of the draining sheet 13 (the middle portion of the sheet). In the case of Fig. 4A, the middle portion 26 is the portion (main portion) located between the two cut portions 25 formed on both longitudinal sides of the draining sheet 13.

[0045] The middle portion 26 occupies most of the length of the drain sheet 13 except for both end portions 14. The boundary between the middle portion 26 and both end portions 14 is generally located around the boundary between the end portion of the ceiling beam 2b and the joint piece 2d.

[0046] The middle portion 26 being higher than the upper edge portion 11 means that the middle portion 26 is set in a state where it is raised above the upper edge portion 11 at the position of the non-waterproof portion 12. This state is easily achieved by providing the notches 25, which increases the degree of freedom in the shape of the middle portion 26 and both end portions 14.

[0047] In this case, the water-repellent sheet 13 may be installed in such a way that the intermediate portion 26 between the cutouts 25 extends downward from the position of the side surface 32 of the roof panel 31 (Figure 7) toward the upper edge portion 11 of the building unit 2, as described below.

[0048] The downward shape is a shape in which the middle part 26 of the water-repellent sheet 13 installed in the unwaterproofed portion 12 slopes downward as a whole from the inside to the outside of the building unit 2. For example, a downward shape is a shape in which there are no horizontal or reverse-sloped parts. The downward shape can be any shape as long as the water-repellent sheet 13 slopes downward without rising in the middle. The inside is the indoor side of each building unit 2, and the outside is the outdoor side of each building unit 2.

[0049] As a result, the edge of the drain sheet 13 on the inside (roof panel 31 side) is higher and the edge on the outside (upper edge 11 side of the building unit 2) of the drain sheet 13 is lower, making it difficult for rainwater to accumulate and allowing it to be easily drained to the outdoors. Note that the drain sheet 13 may have an upward shape at the middle part 26 from the inside to the outside of the building unit 2, the opposite of the above, so that rainwater is drained towards the roof panel 31 side, but a downward shape is preferable.

[0050] In this case, the middle section 26 is installed at an angle so that it hangs naturally from the (upper part of) the side surface 32 of the roof panel 31 toward the upper edge 11 of the building unit 2. As a result, the middle section 26 is stretched in a state where it is almost raised (or separated from the upper edge 11) so that it is higher than the upper edge 11 relative to the unwaterproofed portion 12 of the building unit 2 (a spaced-apart stretching section).

[0051] The intermediate portion 26 may be stretched tightly to have a continuous inclined slope with a constant angle, or may be stretched loosely to have an uneven slope without a constant angle.

[0052] And, having both end portions 14 at the same height as the upper edge portion 11 means that a part of both end portions 14 is set along the upper edge portion 11. By setting both end portions 14 along the upper edge portion 11, a difference in height is formed between the middle portion 26 and both end portions 14.

[0053] As described above, the draining sheet 13 has different shapes at the middle portion 26 and both end portions 14 when placed on the non-waterproof portion 12, so that the difference in height causes the cutouts 25 to open, forming openings 42 (FIG. 4A) at the positions of the cutouts 25. The area around the openings 42 is protected by a local cover 43 provided on the inside (underside) of the draining sheet 13.

[0054] Specifically, the drain sheet 13 has both end portions 14, at least around the hanging device insertion holes 16, which are at the same height as the upper edge portion 11, and form an upper edge contact surface portion 17 that covers the periphery of the upper edge portion 11 of the building unit 2 in a surface contact state.

[0055] Covering the upper edge portion 11 in a face-to-face contact state means that most or a portion (at least around the suspension fixture insertion hole 16) of both end portions 14 of the water-repellent sheet 13 is placed from above in a face-to-face contact state with almost no gaps against the upper end portion of the column 2a (around the mounting hole 23), the upper surface of the joint piece 2d, and the upper surface of the end portion of the ceiling beam 2b.

[0056] The upper edge contact surface portions 17 are formed on all or part of both end portions 14 of the drainage sheet 13. The upper edge contact surface portions 17 are installed almost horizontally so as to cover from above in a state of almost surface contact with almost horizontal and almost flat surfaces such as at least the upper end portions of the pillars 2a, the upper surfaces of the joint pieces 2d, and the upper surfaces of the ends of the ceiling beams 2b.

[0057] As long as the upper edge contact surface 17 has the highest degree of contact with at least the upper end of the column 2a, the degree of contact with other parts may be somewhat lower. As a result, the upper edge contact surface 17 acts as a seal that covers at least the periphery of the mounting hole 23 with almost no gaps, sealing the mounting hole 23.

[0058] A suspender 18 is attached to the building unit 2 through the suspender insertion hole 16.

[0059] The hoisting fixtures 18 are auxiliary jigs that are temporarily attached to the four corners of the top surface of the building unit 2 when the building unit 2 is hoisted by a crane or the like. There are various types of hoisting fixtures 18, but in this embodiment, as described above, the hoisting fixture 18 has a threaded portion 18a at the bottom and the mounting holes 23 are screw holes that are directly screwed into the mounting holes 23.

[0060] The upper part (hanging tool main body) of the hanger 18 is larger than the threaded portion 18a, and the underside has a flat surface that is perpendicular to the threaded portion 18a and surrounds the periphery of the threaded portion 18a. When the hanger 18 is attached to the building unit 2, the underside of the upper part presses against the upper surface of the building unit 2 with the upper edge contact surface portion 17 sandwiched between them, forming a sealing surface that more reliably seals the mounting hole 23.

[0061] The hoisting device 18 has an engaging portion 18b at its upper part for engaging the hook of a crane. The engaging portion 18b may be installed in a fixed state relative to the upper part of the hoisting device 18, or may be installed so as to be movable. The hoisting device 18 is attached from above to the four corners of the upper surface of the building unit 2 when the building unit 2 is shipped from a factory, for example, and is removed from the upper surface of the building unit 2 after the building unit 2 is installed at the construction site.

[0062] Furthermore, the water-repellent sheet 13 may be installed in an L-shape, with both ends 14 having vertical surface portions 34 extending downward along the side surfaces 32 of the roof panel 31 and upper edge contact surface portions 17 extending horizontally along the periphery of the upper edge 11 of the building unit 2.

[0063] The vertical surface portions 34 at both end portions 14 of the drain sheet 13 are portions that are above the upper edge contact surface portions 17. The vertical surface portions 34 are portions (vertical descending portions) that descend vertically almost directly downward from an upper position (upper flange surface 35b) of the roof frame 35 that forms the side surface 32 of the roof panel 31. The vertical surface portions 34 have a length (width) that matches the height of the side surface 32 of the roof panel 31, for example. Then, by its own weight or by forming an appropriate shape, they are formed into a vertical descending shape that almost follows the side surface 32.

[0064] The upper edge contact surface portion 17 is a portion or part of a substantially horizontal surface formed in the middle portion in the width direction (below the vertical surface portion 34) of both end portions 14 of the water-repellent sheet 13. The upper edge contact surface portion 17 has a length (width) that matches the distance from the side surface 32 of the roof panel 31 to the upper edge portion 11 of the building unit 2 (the width of the unwaterproofed portion 12). Then, by its own weight or by forming an appropriate shape, it is formed into a horizontal, transverse shape that is substantially aligned with a horizontal surface such as the upper end portion of the pillar 2a.

[0065] In particular, in the upper edge contact surface portion 17, the hanger insertion hole 16 is aligned with the mounting hole 23. Therefore, by attaching the hanger 18 to the top of the building unit 2 from above through the hanger insertion hole 16, at least a portion of the upper edge contact surface portion 17 is pressed down by the underside of the upper part of the hanger 18, and is maintained in a horizontal shape.

[0066] The vertical surface portions 34 (vertically descending portions) and the upper edge contact surface portions 17 (horizontal portions) form both end portions 14 as a whole in a generally downwardly concave L-shape in side view.

[0067] The area below the drainage sheet 13 is between the back surface of the drainage sheet 13 and the upper edge 11 of the building unit 2. Therefore, the local cover 43 is installed around the cutout 25 in the area below the drainage sheet 13 and above the upper edge 11 of the building unit 2.

[0068] The local cover 43 is a member that locally protects the unwaterproofed portion 12 of the building unit 2 from rainwater that has seeped inside the water-repellent sheet 13 through the cutout 25. The local cover 43 will be described later. The unwaterproofed portion 12 is protected by the local cover 43 from the periphery of the upper end of the column 2a to the periphery of the end of the ceiling beam 2b beyond the position of the cutout 25.

[0069] (2) The unwaterproofed portion 12 may be formed in a long, narrow shape along the upper edge 11 by installing a waterproof roof panel 31 on top of the building unit 2, shifting it inward from the upper edge 11 (Figures 3 and 10). The water-repellent sheet 13 may be attached to the side 32 of the roof panel 31 facing the unwaterproofed portion 12. A sheet support beam 41 may be installed below the middle portion 26 of the water-repellent sheet 13 to hold the middle portion 26 at a height halfway between the upper surface of the roof panel 31 and the upper edge 11 of the building unit 2. The local cover 43 may be installed at the end of the seat receiving beam 41 .

[0070] Here, the roof panels 31 are panels that make up the roof portion of the unit building 1. In this embodiment, the roof panels 31 are installed in a line on the top (corner portions of the upper surface) of the building units 2 on the upper floor H (top floor), so that the roof portion of the unit building 1 is constructed directly on the building units 2. Because the roof panels 31 are waterproof, most of the upper surface of the building units 2 becomes the waterproof portion 21.

[0071] Installing the roof panel 31 by shifting it inward from the upper edge 11 means installing the roof panel 31 a required amount toward the inside of the top surface of the building unit 2 so that the roof panel 31 does not cover the mounting holes 23 for attaching the hanging fixtures 18 of the building unit 2.

[0072] As a result, the roof panel 31 is installed on the top surface of the building unit 2 so as not to overlap the upper edge 11 and mounting holes 23 of the building unit 2. And, because there is no roof panel 31 above, the top surface of the building unit 2 has an unwaterproofed portion 12 in the narrow area around the upper edge 11. The unwaterproofed portion 12 is formed to a width equal to the amount of misalignment of the roof panel 31 from the upper edge 11 of the building unit 2 (for example, approximately 2 to 3 times the width of the ceiling beam 2b).

[0073] Any waterproof roof panel 31 may be used. For example, the roof panel 31 is formed by connecting and integrating surface materials 36, such as sheathing boards 36a and waterproof steel base plates 36b, between a pair of parallel roof frames 35, forming a flat surface. The sheathing boards 36a are supported and fixed from below on both sides by braces 36c attached to the inside surfaces of the roof frames 35.

[0074] The roof frame 35 is a member (side surface forming member) that forms the side surface 32 of the roof panel 31, and is made to be approximately the same length as the ceiling beams 2b that form the long sides of the building unit 2. The roof frame 35 located on the outdoor side of each building unit 2 forms the boundary between the unwaterproofed portion 12 and the waterproofed portion 21.

[0075] The roof frame 35 is a member with an inwardly facing C-shaped cross section, having a vertical web surface 35a and horizontal upper and lower flange surfaces 35b, 35c. The flange surfaces 35b, 35c extend laterally from the upper and lower edges of the web surface 35a toward the inside of the roof panel 31.

[0076] For example, a single solar cell panel 37 or multiple solar cell panels (for example, four panels) are installed on the upper side of the base steel plate 36b along the roof frame 35. The solar cell panel 37 is attached from above to the roof frame 35 (to the upper flange surface 35b) with screws via mounting brackets 38. At the time of shipment, the solar cell panel 37 is covered on its upper surface with a protective sheet 37a. Furthermore, the solar cell panel 37 is not necessarily required, so it may be omitted, or a dummy panel that resembles the solar cell panel 37 may be used instead.

[0077] The roof panels 31 are arranged one or more (for example, two) on top of the connecting beams 39 and fixed to the connecting beams 39. The multiple roof panels 31 are integrated into a rectangular shape with a length approximately the same as the long sides of the building units 2 and a width shorter than the short sides of the building units 2.

[0078] The integrated roof panel 31 is then installed from above at the center of the top surface of the building unit 2 on the (top) upper floor H together with the connecting beam 39, with the orientation of the roof panel 31 aligned with the top surface of the building unit 2.

[0079] The connecting beam 39 is installed at a position that is approximately the same as or slightly lower than the top surface of the building unit 2. The end 39a of the connecting beam 39 protrudes laterally from the side surface 32 of the roof panel 31 and is engaged from above onto the ceiling beam 2b of the unit frame, and is fixed in the vertical direction 4 by fastening fixtures 39b such as bolts and nuts. The end 39a of the connecting beam 39 is stepped so that it is slightly higher than the main body of the connecting beam 39.

[0080] The roof panel 31 has a solar cell panel 37 or the like on its upper surface, and is higher than the upper edge 11 of the building unit 2 by at least the thickness of the roof frame 35 (the height of the web surface 35a). The position of the side surface 32 of the roof panel 31 to which the water-repellent sheet 13 is attached may be, for example, above the center of the roof frame 35 in the vertical direction 4, but it is particularly preferable to attach it to a high position such as the upper flange surface 35b of the roof frame 35.

[0081] The side surface 32 is the portion of the roof panel 31 located on the outdoor side (panel side surface), and forms the roof frame 35. With the middle portion 26 of the water-repellent sheet 13 aligned with the roof frame 35, the adhesive tape 22 attached to one edge is stuck to (the upper portion of) the roof frame 35 so that it runs continuously over almost the entire length of the roof frame 35.

[0082] At this time, the drain sheet 13 is placed with the adhesive tape 22 side facing up. The drain sheet 13 is then attached to the upper flange surface 35b of the roof frame 35 or, where the mounting bracket 38 is located, to the upper end surface of the mounting bracket 38 using the adhesive tape 22 (the protruding adhesive portion thereof). The width of the protruding adhesive portion of the adhesive tape 22 is slightly wider than the width of the upper flange surface 35b of the roof frame 35. Therefore, it is preferable to apply the tip of the protruding adhesive portion of the adhesive tape 22 so that it faces downward against the edge of the upper flange surface 35b or the vertical surface of the mounting bracket 38 by pushing it downward with a tool T such as a pointed spatula, as shown in FIG. 9A.

[0083] Then, as shown in Figure 3, by attaching a sheet support beam 41 to the unwaterproofed portion 12, a portion of the width of the middle portion 26 of the water-repellent sheet 13 is supported from below by the sheet support beam 41, thereby maintaining the middle portion 26 at an intermediate height.

[0084] The intermediate height may be any height between the top surface of the roof panel 31 and the top surface of the building unit 2, but it is preferable to set it at a position approximately in the middle of the roof panel 31 in the vertical direction 4 or a position higher than that.

[0085] The sheet receiving beams 41 are attached in a single or multiple rows along the ceiling beams 2b on top of the ceiling beams 2b. The sheet receiving beams 41 are provided so as to be almost continuous in an area that almost coincides with the middle portion 26 of the water-repellent sheet 13. However, the sheet receiving beams 41 may be cut out or divided as necessary in the areas that interfere with the end portions 39a of the connecting beams 39.

[0086] In this embodiment, the sheet receiving beam 41 is a member that is shorter than the ceiling beam 2b and wider than the ceiling beam 2b. The sheet receiving beam 41 is a member that is shorter in height than the roof frame 35 of the roof panel 31.

[0087] The sheet receiving beam 41 is a C-shaped cross-section member that has a vertically oriented web portion 41b and horizontally oriented upper and lower flange portions 41a, 41c and is open to the outside.

[0088] The sheet support beam 41 is installed so that the outdoor edge of the lower flange portion 41c is aligned with the outdoor edge (upper edge 11) of the upper surface of the ceiling beam 2b. The sheet support beam 41 is fixed in the vertical direction 4 to the upper surface of the ceiling beam 2b with fasteners 41d (FIG. 11B) such as rivets or screws. As a result, the web portion 41b is positioned more inward than the ceiling beam 2b. The web portion 41b is spaced apart from the web surface 35a of the roof frame 35.

[0089] An upper flange portion 41a, which forms the upper surface of the sheet receiving beam 41, projects slightly outside beyond the ceiling beam 2b (to the extent that it does not exceed the position of the outer surface of the exterior wall 5).

[0090] Then, by installing the sheet receiving beam 41, the intermediate portion 26 is installed so that at least a part of the width direction thereof contacts the upper surface (flange portion 41a) of the sheet receiving beam 41 from above.

[0091] The upper surface (flange portion 41a) of the sheet support beam 41 is inclined downward from the indoor side to the outdoor side. Furthermore, the outdoor side portion of the upper surface (flange portion 41a) of the sheet support beam 41 is higher than the line connecting the upper flange surface 35b of the roof frame 35 and the upper edge portion 11 or the upper end of the exterior wall 5. Therefore, the middle portion 26 is supported from below by the sheet support beam 41, thereby reliably forming a downward shape. The middle portion 26 is maintained in a raised state so that it is higher than the upper edge portion 11 relative to the unwaterproofed portion 12 of the building unit 2.

[0092] The intermediate portion 26 may be installed so that it is loosely stretched to contact the entire upper surface (flange portion 41a) of the sheet support beam 41, or it may be installed so that it is taut to contact only a portion of the flange portion 41a.

[0093] For example, when the middle portion 26 of the drain sheet 13 is stretched loosely, the slope is relatively steep from the upper end to where it contacts the upper surface (flange portion 41a) of the sheet receiving beam 41. The middle portion 26 has a gentle slope where it contacts the upper surface (flange portion 41a) of the sheet receiving beam 41, and a steep slope in the portion beyond the sheet receiving beam 41.

[0094] The sheet support beams 41 can be used as support materials for attaching final finishing materials (such as girder covers and gutters) to the roof portion of the unit building 1, and can be left as they are and used even after temporary waterproofing.

[0095] The end (of the sheet support beam 41) is the part of the sheet support beam 41 that is closest to the pillar 2a. The position of the end is near the boundary between the end of the ceiling beam 2b and the joint piece 2d, or slightly closer to the center.

[0096] 6A to 6C, local cover 43 is formed by processing a waterproof resin thin plate material, etc. Local cover 43 is placed below both end portions 14 and a position on the middle portion 26 side that is a required distance beyond cutout portion 25 of draining sheet 13, and directly covers the periphery of both side portions of non-waterproof portion 12.

[0097] The local cover 43 is attached to the roof panel 31 in advance (Figs. 7 to 8B). Then, by attaching the roof panel 31 to the top of the building unit 2, the local cover 43, together with the roof panel 31, is locally installed on the upper edge 11 of the building unit 2 (Fig. 11A). The local cover 43 does not have to be particularly connected to the water-repellent sheet 13. The local cover 43 will be described later.

[0098] The waterproof sheet 13 placed over the unwaterproofed portion 12, sheet support beam 41, and local cover 43 has its lower edge (protruding portion) (at both ends 14 and middle portion 26) formed larger than the unwaterproofed portion 12 temporarily fastened (FIG. 4A). The protruding portion is attached to the upper side of the building unit 2 (for example, column 2a or exterior wall 5) with adhesive tape 44.

[0099] Similarly, the outer portions (extending portions) of the drain sheet 13 (at both ends 14), which are formed larger than the non-waterproof portion 12, are folded appropriately and temporarily secured with adhesive tape 44 (FIG. 4B). For example, the protruding portions are attached to the upper side of the side of the building unit 2 (for example, the outer wall 5 on the short side) or the top surface of the roof panel 31.

[0100] (3) The local cover 43 may have a water blocking surface (step surface 43b) facing the cutout portion 25 at a position deeper than the cutout portion 25.

[0101] Here, the position deeper than the cutout 25 refers to a position closer to the center of the cutout 25 in the extension direction of the ceiling beam 2b.

[0102] Facing the cutout 25 means that the water-stopping surface (step surface 43b) of the local cover 43 installed on the underside of the drainage sheet 13 is formed to face the opening 42 formed by the cutout 25. The step surface 43b is then in a state where it can block the infiltration of rainwater by substantially closing the opening 42 from an inside position.

[0103] The local cover 43 integrally has at least a step lower surface 43a, a step surface 43b, a step upper surface 43c, and vertical surface portions 43d and 43e. The step lower surface 43a, the step surface 43b, and the step upper surface 43c are the main parts of the local cover 43, and are formed continuously in the long side direction of the building unit 2. Of these, the step surface 43b serves as a water-stopping surface facing the cutout portion 25. The water-stopping surface is a surface that blocks rainwater from entering through the cutout portion 25. The vertical surface portions 43d and 43e are formed on both side portions of the local cover 43.

[0104] The step undersurface 43a is a rectangular horizontal surface that covers from above the upper end surfaces of the columns 2a and the upper surfaces of the joint pieces 2d of the building units 2. The step undersurface 43a is sized to slightly protrude outward (in the extension direction of the ceiling beams 2b) from the upper end surfaces of the columns 2a.

[0105] The stepped upper surface 43c has a rectangular horizontal surface and covers the upper surface of the end of the sheet receiving beam 41 from above (FIG. 12B). The width of the stepped upper surface 43c is, for example, approximately the same as or slightly larger than the height of the stepped surface 43b.

[0106] The step surface 43b is a rectangular vertical surface that connects the step lower surface 43a and the step upper surface 43c. The step surface 43b is at approximately the same height as the sheet receiving beam 41. The step surface 43b abuts approximately against the end of the sheet receiving beam 41, preventing the end of the sheet receiving beam 41 from directly hitting the drain sheet 13 and protecting the drain sheet 13 from damage. The step surface 43b is formed, for example, at a position rearward from the cutout portion 25 by a distance approximately equal to or less than the width of the step upper surface 43c.

[0107] The first vertical surface portion 43d has a length spanning the entire area of ​​the local cover 43 and a height approximately equal to that of the roof frame 35. The lower portion of the vertical surface portion 43d on the sheet receiving beam 41 side is convexly cut out in the shape of the step surface 43b and the step top surface 43c. The vertical surface portion 43d is located on the roof panel 31 side and covers the roof frame 35 from the outside. In other words, the vertical surface portion 43d is positioned in contact with the outer surface of the web surface 35a of the roof frame 35.

[0108] The second vertical surface portion 43e is rectangular, is located on the side of the upper edge portion 11 of the building unit 2, and connects the step upper surface 43c and the step surface 43b. The vertical surface portion 43e has the same width as the step upper surface 43c and is slightly taller in the vertical direction than the step surface 43b.

[0109] Furthermore, communication holes 43f (FIGS. 9B and 11A) are formed in step-down surface 43a at positions that coincide with suspender insertion holes 16 and mounting holes 23. Communication holes 43f are approximately the same size as suspender insertion holes 16 and mounting holes 23, or slightly larger.

[0110] Furthermore, the local cover 43 may be provided with a flange portion of a required width along the periphery. For example, the flange portion may be a downward flange 43g formed downward on the edge opposite the stepped surface 43b of the stepped lower surface 43a or the vertical surface 43d. This downward flange 43g serves as a drain.

[0111] The flange portion may be an inward flange 43h (FIG. 6A) formed laterally on the upper edge of the vertical surface portion 43d. This inward flange 43h serves as an engaging portion or an attachment margin for the upper flange surface 35b of the roof frame 35.

[0112] The joints between the various parts of local cover 43 are waterproofed with waterproof tape 43i or the like. Local cover 43 is fixed with adhesive tape 45 or the like by, for example, abutting vertical surface portion 43d against web surface 35a of roof frame 35 with inward flange 43h engaged from above with upper flange surface 35b of roof frame 35 (FIG. 8A).

[0113] <Operation> The operation of this embodiment will now be described.

[0114] First, the roof panel 31 is placed on and fixed to the connecting beam 39 to be integrated (panel integration step). The number of roof panels 31 to be integrated may be one or more.

[0115] As shown in FIG. 7 (FIG. 8A), local covers 43 are attached in advance to both ends of the side surface 32 of the roof panel 31 (local cover attaching step).

[0116] 7 and 9B, a thin, long drain sheet 13 is attached to the roof panel 31 in advance along the side surface 32 (the upper part of the roof frame 35) of the roof panel 31 (a drain sheet attaching step). Either the local cover attaching step or the drain sheet attaching step may be performed first.

[0117] As shown in Fig. 9B, the draining sheet 13 has cutouts 25 between both end portions 14 and the middle portion 26. The cutouts 25 may be provided before installation, simultaneously with installation, or after installation.

[0118] The water-repellent sheet 13 is temporarily folded or rolled up and attached to the top surface or side surface 32 of the roof panel 31 with adhesive tape 22. This prevents the water-repellent sheet 13 from interfering with the attachment of the roof panel 31 to the building unit 2 (water-repellent sheet temporary attachment process).

[0119] Then, a waterproof roof panel 31 is installed on top of the building unit 2, shifted inward from the upper edge 11, to form an unwaterproofed portion 12 that extends in a long, narrow manner along the upper edge 11 (roof panel installation process, Figure 10).

[0120] In the (roof panel installation process), the roof panel 31 is installed on top of the building unit 2 using a hanging jig while still integrated with the connecting beams 39. This forms an unwaterproofed portion 12 and a waterproofed portion 21 on the top surface of the building unit 2. The roof panel 31 may also be integrated using the connecting beams 39 immediately before being installed on top of the building unit 2.

[0121] After the (roof panel installation process), a sheet support beam 41 is installed at a position corresponding to the middle portion 26 along the upper edge 11 (ceiling beam 2b) at the position where the exterior wall 5 of the building unit 2 is installed (sheet support beam installation process).

[0122] Then, the unwaterproofed portion 12 is covered with a thin waterproof sheet 13 attached to the side surface 32 of the roof panel 31 facing the unwaterproofed portion 12 (water-repellent sheet installation step, Figs. 11A and 11B).

[0123] In this case, the water-repellent sheet 13 is installed in a downward shape from the side 32 of the roof panel 31 to the upper edge 11 of the building unit 2, with the middle part 26 located between the cut-out parts 25 provided near both ends 14 floating above the unwaterproofed part 12 of the building unit 2.

[0124] In addition, the water-repellent sheet 13 is installed so that both ends 14 located outside the cutout 25 are in surface contact with the periphery of the upper edge 11 of the building unit 2, thereby forming a (nearly horizontal) upper edge contact surface 17 (Figure 4A).

[0125] Specifically, in the (water-repellent sheet installation process), the adhesive tape temporarily fastening the water-repellent sheet 13 to the roof panel 31 is removed, and the water-repellent sheet 13 is spread over the unwaterproofed portion 12 and then hung down toward the side of the building unit 2.

[0126] At this time, at the position where the sheet support beam 41 is attached, the middle section 26, which makes up the majority of the waterproofing sheet 13, is placed over the sheet support beam 41, and is set afloat relative to the unwaterproofed portion 12 of the building unit 2. Thereafter, the lower part of the middle section 26 of the waterproofing sheet 13 is hung down along the exterior wall 5 on the side of the building unit 2, and the lower edge is attached to the upper part of the exterior wall 5 with adhesive tape 44.

[0127] The drain sheet 13 has both end portions 14, which are partially separated from the middle portion 26 by the notches 25, hanging almost straight down along the side surface 32 (the outer surface of the roof frame 35) of the roof panel 31 (vertical surface portions 34). Furthermore, the both end portions 14 are placed almost horizontally along the upper ends of the columns 2a and the upper surfaces of the joint pieces 2d (upper edge contact surface portions 17).

[0128] Then, hangers 18 are attached from above to the building unit 2 (mounting holes 23) through the hanger insertion holes 16 (or communication holes 43f) provided in the upper edge contact surface portion 17 of the water-repellent sheet 13 (hanger attachment step, FIG. 4B).

[0129] Thereafter, the lower portions of both end portions 14 of the drain sheet 13 are hung down along the exterior wall 5 on the side of the building unit 2, and the lower edge is attached to the upper portion of the exterior wall 5 with adhesive tape 44. Note that it does not matter whether the hanging fixture 18 is attached or the adhesive tape 44 is attached first.

[0130] The above-described steps are carried out in the factory after the building unit 2 is manufactured in the factory to provide temporary weatherproofing in preparation for rainfall.

[0131] Next, after the building unit 2 has been installed at the construction site, the hoisting fixture 18 is removed (from the building unit 2) as shown in FIG. 12A (hoisting fixture removing step). Then, the suspender insertion hole 16 from which the suspender 18 has been removed is closed with waterproof tape 61 (hole filling step).

[0132] In the (hole filling step), the suspender insertion hole 16 can be easily closed by simply applying waterproof tape 61, thereby ensuring waterproofing.

[0133] After waterproofing the hanger insertion holes 16 by sealing them with waterproof tape 61 in the (hole filling process), the lower edges of both end portions 14 are temporarily removed from the upper portions of the sides of the building unit 2 and rolled up to expose the unwaterproofed portions 12, as shown in Figure 12B. Then, the mounting holes 23 are sealed with waterproof tape 63 from above the communication holes 43f. It is also possible to remove the local cover 43 and directly seal the mounting holes 23 with waterproof tape 63.

[0134] At the same time, the lower edge of the middle part 26 is temporarily removed from the upper part of the side surface of the building unit 2 and rolled up to expose the non-waterproof part 12. Then, the release paper 64a of the double-sided tape 64 that was previously attached to the upper surface of the sheet receiving beam 41 is peeled off.

[0135] 12C, the entire waterproofing sheet 13 is hung back over the unwaterproofed portion 12, and the middle portion 26 is attached to the upper surface of the sheet receiving beam 41 using the double-sided tape 64 that was previously attached to the upper surface of the sheet receiving beam 41. The entire lower edge of the waterproofing sheet 13 is then reattached to the side of the building unit 2 with the adhesive tape 44.

[0136] In this state, as shown in FIG. 12D, the cutouts 25 are joined with waterproof tape 62, and both end portions 14 of the draining sheet 13 are formed downward to match the middle portion 26 (integration step).

[0137] In the (integration step), it is preferable to align the middle portion 26 and both end portions 14 in a substantially flush state with each other, and then apply the waterproof tape 62 across the cutout 25. The waterproof tape 62 is applied continuously along the entire length of the cutout 25. This ensures that the cutout 25 is neatly connected by the waterproof tape 62, and the middle portion 26 and both end portions 14 are joined together and waterproofed.

[0138] Furthermore, since there are no sheet support beams 41 below both end portions 14, even when connected to the middle portion 26, the both end portions 14 do not have exactly the same downward shape as the middle portion 26, but they do have a downward shape similar to that of the middle portion 26.

[0139] After that, when the rain stops, finishing work is done on the roof portion of the unit building 1 to waterproof the unwaterproofed portion 12 around the upper edge 11 of the building unit 2 and complete the roof portion. The water-repellent sheet 13 may be left as it is or removed depending on the situation.

[0140] The above-mentioned steps are carried out at the construction site after the building unit 2 is installed. The waterproof tapes 61 to 63 are adhesive tapes 22 that are waterproof.

[0141] <Effects> According to this embodiment, the following effects can be obtained.

[0142] (Effect 1) The top surface waterproofing structure of the building unit 2 may be provided with a long, narrow, non-waterproof portion 12 formed along the upper edge 11 of the building unit 2, and a thin, long, water-repellent sheet 13 that covers the non-waterproof portion 12. This allows the water-repellent sheet 13 to cover only the long, narrow, non-waterproof portion 12 formed along the upper edge 11 of the building unit 2. This makes the water-repellent sheet 13 smaller, making it easier to handle.

[0143] The draining sheet 13 may have cutouts 25 near both end portions 14. The draining sheet 13 may have a height difference formed such that the middle portion 26 between the cutouts 25 is higher than the upper edge portion 11 relative to the unwaterproofed portion 12, and both end portions 14 have portions at the same height as the upper edge portion 11.

[0144] As a result, the draining sheet 13 can be easily and naturally given different shapes and functions by separating the middle section 26 and both end sections 14 by the cut sections 25. The middle section 26 and both end sections 14 can also be made to have fewer wrinkles and tension.

[0145] Furthermore, the drainage sheet 13 can be installed such that the middle portion 26 is higher than the upper edge portion 11 and, for example, in a downward shape extending from the top surface of the roof panel 31 to the upper edge portion 11 of the building unit 2, thereby promoting the drainage of rainwater.

[0146] Furthermore, by installing the drainage sheet 13 so that both ends 14 have portions at the same height as the upper edge 11, it is possible to ensure that there is a portion that comes into surface contact with the upper edge 11 of the building unit 2.

[0147] By bringing at least a portion of each end 14 into surface contact with the upper edge 11 of the building unit 2, gaps through which rainwater can seep in can be eliminated. Furthermore, the water-repellent sheet 13 can be attached to the building unit 2 with a hanger 18 through the portion that is in surface contact with the upper edge 11 of each end 14. This makes it possible to easily and reliably attach the hanger 18 to the building unit 2 without having to roll up the water-repellent sheet 13.

[0148] As described above, the cutouts 25 allow one sheet of the drainage sheet 13 to be used three-dimensionally. The cutouts 25 simultaneously form an intermediate section 26 suitable for draining rainwater and upper edge contact surfaces 17 at both ends 14 suitable for attaching the slings 18 to the drainage sheet 13.

[0149] A local cover 43 may be provided under the drain sheet 13 around the cutout 25 to locally protect the non-waterproof portion 12 from rainwater.

[0150] As a result, the non-waterproof portion 12 can be protected by the local cover 43 from rainwater that has seeped inside the drain sheet 13 through the cutouts 25. Therefore, even if cutouts 25 are provided in the drain sheet 13 to create a difference in height between the middle portion 26 and both end portions 14, the drain sheet 13 is less susceptible to the infiltration of rainwater. Therefore, even during rainfall, the building unit 2 can be transported and lifted with the lifting device 18. Furthermore, because the local cover 43 covers the non-waterproof portion 12, it does not need to be connected to the drain sheet 13, making installation easy.

[0151] (Effect 2) In the top surface waterproofing structure of the building unit 2, the unwaterproofed portion 12 may be formed in an elongated shape along the upper edge 11 by installing a waterproof roof panel 31 on top of the building unit 2, shifting it inward from the upper edge 11. The water-repellent sheet 13 may be attached to the side surface 32 of the roof panel 31 facing the unwaterproofed portion 12.

[0152] This allows the majority of the upper part of the building unit 2 to be a waterproofed portion 21 by the roof panel 31. The portion of the building unit 2 where the roof panel 31 is not installed can then be a long, narrow, unwaterproofed portion 12. The unwaterproofed portion 12 has a long, narrow shape that follows the upper edge 11 of the building unit 2, and is minimized.

[0153] Therefore, the draining sheet 13 can be made small and elongated to fit the unwaterproofed portion 12, and the elongated unwaterproofed portion 12 can be easily and reliably covered with just the small draining sheet 13. Furthermore, the compact size makes the elongated draining sheet 13 easier to handle. The draining sheet 13 can be easily installed in the unwaterproofed portion 12 by attaching it to the side surface 32 of the roof panel 31.

[0154] In addition, a sheet support beam 41 may be installed below the middle portion 26 of the water-repellent sheet 13 to hold the middle portion 26 at a height halfway between the upper surface of the roof panel 31 and the upper edge portion 11 of the building unit 2.

[0155] As a result, by receiving the middle portion 26 of the water-repellent sheet 13 on the sheet support beam 41, the water-repellent sheet 13 can be kept lower than the upper surface of the roof panel 31 and higher than the upper edge portion 11, maintaining a stable downward shape. Therefore, the middle portion 26 of the water-repellent sheet 13 has a shape that allows rainwater to be drained well.

[0156] In addition, the sheet support beam 41 does not need to be removed by using a support material for attaching the final finishing material to the roof part of the building.

[0157] The local cover 43 may be installed at the end position of the sheet support beam 41. This allows the local cover 43 to be supported from below by the end of the sheet support beam 41, and the end of the sheet support beam 41 can be covered from above with the local cover 43 to protect it from rainwater. In addition, the local cover 43 can prevent damage to the water-repellent sheet 13 by the end of the sheet support beam 41.

[0158] (Effect 3) In the top flashing structure of the building unit 2, the local cover 43 may have a water-stopping surface facing the cutout 25 at a position further back than the cutout 25. This allows the local cover 43 to block rainwater that has entered through the cutout 25 using the water-stopping surface located further back than the cutout 25. In this case, since the water-stopping surface is located further back than the cutout 25, an eave-like portion is formed around the cutout 25 that protrudes from the water-stopping surface, and the eave-like portion hangs slightly downward due to its own weight. Therefore, the opening 42 formed in the cutout 25 is naturally narrowed and small, which is expected to have the effect of reducing the amount of rainwater that enters through the opening 42. [Explanation of symbols]

[0159] 2 Building Units 11 Upper edge 12 Unwaterproofed parts 13 Water draining sheet 14 Both ends 25 Cutout 26 Middle section 43 Private parts cover 31 Roof Panel 32 Side 41 Sheet support beam 43b Step surface (water stop surface)

Claims

1. A thin waterproof sheet is provided to cover the thin unwaterproofed portion formed along the upper edge of the building unit; The drainage sheet has cutouts near both ends, and a height difference is formed so that the middle part between the cutouts is higher than the upper edge part with respect to the non-waterproof part, and both ends have parts at the same height as the upper edge part, A top surface rainproofing structure for a building unit, characterized in that a local cover is provided under the water-repellent sheet around the cut-out portion to locally protect the unwaterproofed portion of the building unit from rainwater that has penetrated inside the water-repellent sheet through the cut-out portion.

2. The top surface weatherproofing structure of the building unit according to claim 1, The non-waterproof portion is formed in an elongated shape along the upper edge by installing a waterproof roof panel on the building unit and offsetting it inward from the upper edge, The water-repellent sheet is attached to the side of the roof panel facing the unwaterproofed portion, The roof panel is then fitted with a support beam, which supports the roof panel at a height intermediate between the upper surface of the roof panel and the upper edge of the building unit. A top surface rainproofing structure for a building unit, characterized in that the local cover is installed at the end position of the sheet support beam.

3. The upper surface weatherproofing structure of the building unit according to claim 1 or 2, A top surface rainproofing structure for a building unit, characterized in that the local cover has a water-stopping surface facing the cutout at a position deeper than the cutout.

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