External ceiling structure, and external ceiling construction method

Abstract

To provide an external ceiling structure which can improve fire resistant performance with a simple configuration.SOLUTION: An external ceiling structure facing an external space (S1) of a building includes: first and second ceiling surface materials (3, 3) which are arranged so as to be adjacent to each other through a joint part (20); first and second support members (5, 5) which have openings fixed to end back faces on the joint part side (one end side) of each of the first and second ceiling surface materials while facing an opposite side (other end side), and have substantially U-shaped cross sections; and a joint back member (7) which is arranged so that its opening faces upward and has a substantially U-shaped cross section, on the back side of the joint part. The first and second support members have back face parts (51) which are offset and arranged from an end edge position on one end side to the other end side, and the joint back member has a pair of side plate parts (72, 73) which are connected and fixed to the back face parts of each of the first and second support members.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a ceiling structure, and more particularly to an exterior ceiling structure facing the exterior space of a building. [Background technology]

[0002] When providing a ceiling of a building with fire resistance, it is necessary to deal with the intrusion of heat through the joints between ceiling panels. Japanese Patent Application Laid-Open No. 2008-184788 (Patent Document 1) discloses a joint connection structure for a fire-resistant ceiling.

[0003] In this ceiling structure, adjacent ceiling panels (ceiling surface materials) are arranged with a joint between them, a connecting plate of a specified length is installed across both ceiling panels above the joint, a cover material with a U-shaped cross section is placed across both ceiling panels with the connecting plate housed inside, gypsum board is filled inside the cover material, and screws are passed through the connecting plate from above and screwed to the ceiling panel. A support plate is screwed to the top of the cover material and suspended from the ceiling by a hanging bolt, and the joints between adjacent ceiling panels are filled with gypsum board, and the joint joint is engaged with the fastening piece and screwed to the connecting plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-184788 A Summary of the Invention [Problem to be solved by the invention]

[0005] In cases where an external stairwell is provided in a building, a ceiling (hereinafter referred to as "external ceiling") may be placed facing the external space of the building. Patent Document 1 proposes a technology for improving the fire resistance of the ceiling, but it is not intended for external ceilings. In addition, the joint connection structure of Patent Document 1 is complicated, and there is also the problem that construction is time-consuming.

[0006] The present invention has been made to solve the above-mentioned problems, and its object is to provide an exterior ceiling structure that can improve fire resistance with a simple configuration.

[0007] Another object of the present invention is to provide a method for constructing an exterior ceiling that can improve workability on site. [Means for solving the problem]

[0008] An external ceiling structure according to one aspect of the present invention is an external ceiling structure facing an external space of a building, comprising first and second ceiling surface materials arranged adjacent to each other via a joint portion and having one end on the joint portion side and another end opposite the joint portion, first and second support members having a substantially U-shaped cross section fixed to the back surface of each of the one ends of the first and second ceiling surface materials with an opening facing the other end side, and a joint backing member having a substantially U-shaped cross section arranged on the back side of the joint portion with an opening facing upward. The first and second support members have a back surface portion arranged offset from the edge position of the one end side to the other end side, and the joint backing member has a pair of side plate portions connected and fixed to the back surface portions of the first and second support members, respectively.

[0009] Preferably, the joint backing member has a bottom plate portion arranged with a gap between it and the rear surfaces of the first and second ceiling surface materials, and the external ceiling structure further includes a heat insulating material that fills the gap.

[0010] Preferably, one side plate portion of the joint backing member and the back portion of the first support member are fixed by a first bolt and a first nut, and the other side plate portion of the joint backing member and the back portion of the second support member are fixed by a second bolt and a second nut.

[0011] The external ceiling structure desirably further comprises first and second upper face materials pre-fixed to the upper surfaces of the first and second support members. In one embodiment, the first and second upper face materials are provided with cutouts for exposing a space for fixing the first and second support members to the joint backing member.

[0012] Preferably, each of the first and second ceiling facing materials includes a gypsum board and a ceramic siding that is overlaid on the gypsum board and exposed to the exterior space.

[0013] The above-mentioned external ceiling construction method preferably includes the steps of preparing a first panel unit having a first support member pre-fixed to both widthwise sides of a first ceiling surface material, a second panel unit having a second support member pre-fixed to both widthwise sides of a second ceiling surface material, and a joint backing member, and fixing the first support member and one side plate portion of the joint backing member with a fastening means, and fixing the second support member and the other side plate portion of the joint backing member with a fastening means. This can improve the ease of construction of the external ceiling. Effect of the Invention

[0014] According to the present invention, the joint backing member also serves as a connector for the first and second ceiling surface materials, so that the fire resistance can be improved with a simple configuration.

[0015] In addition, by using a panel unit that combines the ceiling surface material and supporting members into a unit, the ease of installation of the exterior ceiling can be improved. [Brief description of the drawings]

[0016] [Figure 1] 1 is a vertical cross-sectional view showing a schematic view of a building (an apartment building having a stairwell as an external space) according to an embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view (plan view) showing a schematic diagram of a building according to an embodiment of the present invention. [Diagram 3] 1 is a plan view showing a schematic example of an arrangement of panel units that constitute an exterior ceiling in an embodiment of the present invention. FIG. [Figure 4] FIG. 2 is a vertical cross-sectional view illustrating a schematic configuration of a panel unit. [Diagram 5] FIG. [Figure 6] FIG. 2 is an exploded view showing a method of constructing an exterior ceiling using panel units. [Figure 7] 1 is a perspective view showing a joint backing member used to connect panel units. FIG. [Figure 8] FIG. 4 is a vertical cross-sectional view showing a connected state of the panel units. [Figure 9] 1 is a vertical cross-sectional view showing a main part of an exterior ceiling according to an embodiment of the present invention. [Figure 10] 4 is a vertical cross-sectional view showing a schematic connection structure of the end portion of the panel unit. FIG. [Figure 11] FIG. 2 is an explanatory diagram of the fire resistance performance of an exterior ceiling according to an embodiment of the present invention. [Figure 12] FIG. 2 is a vertical cross-sectional view showing a comparative example (floor structure) of an exterior ceiling according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0018] In this embodiment, for example, the structure of the ceiling of an external staircase 10 of an apartment building 1 as shown in Figures 1 and 2, i.e., the external ceiling 11, will be described. The external staircase 10 shown in Figure 2 is a vertical section surrounded on three sides by exterior walls 12 in a plan view. The bottom surface (ceiling surface) of the external ceiling 11 is exposed to the external space (outdoor space) S1 formed by the external staircase 10. The space S2 above the external ceiling 11 may be an attic space or may be a room as shown in Figure 1.

[0019] As shown in Fig. 3, the external ceiling 11 in this embodiment includes a plurality of panel units 2 each having a rectangular shape in a plan view. The plurality of panel units 2 are arranged adjacent to each other in at least one direction (for example, the x-axis direction). Fig. 3 shows, as an example, an example in which the plurality of panel units 2 are arranged adjacent to each other in two directions, the x-axis direction and the y-axis direction. In the following description, the x-axis direction is also referred to as the width direction (indicated by arrow A1), and the y-axis direction is also referred to as the depth direction (indicated by arrow A2).

[0020] <Outline of panel unit configuration> Fig. 4 is a vertical cross-sectional view showing a schematic configuration of the panel unit 2. As shown in Fig. 4, the panel unit 2 includes a ceiling surface material 3 facing the external space S1, support members 5, 5 fixed to both widthwise ends of the ceiling surface material 3, and an upper surface material 4 fixed to the upper surfaces of the support members 5, 5 and facing the ceiling surface material 3. The upper surface material 4 is located on the upper space S2 side.

[0021] 3, the panel unit 2 of the present embodiment further includes support members 5', 5' fixed to both depth-direction ends of the ceiling surface material 3. The support members 5, 5 at both width-direction ends and the support members 5', 5' at both depth-direction ends are arranged in a rectangular frame shape.

[0022] The width and depth of the panel unit 2 are, for example, 900 mm to 2000 mm. Depending on the planar dimensions of the panel unit 2, one or more horizontal foundation bars 61 extending in the width direction between the support members 5, 5 provided at both widthwise ends are included (shown by imaginary lines in FIG. 4). One or more vertical foundation bars may also be provided that are perpendicular (intersect) with the horizontal foundation bars 61 (not shown). These foundation bars are, for example, wooden bars.

[0023] The panel units 2 are manufactured in advance in a factory or the like. This simplifies the construction of the exterior ceiling 11 on-site. The construction method of the exterior ceiling 11 using the panel units 2 and the structure of the exterior ceiling will be described later.

[0024] (Ceiling surface materials) An example of the configuration of the ceiling surface material 3 will be described with reference to FIG.

[0025] The ceiling surface material 3 in this embodiment is composed of one water-resistant gypsum board 32 and a ceramic siding 31 overlaid on the gypsum board 32. The gypsum board 32 and the ceramic siding 31 are fixed to the horizontal base rails 61 or the vertical base rails with screws, respectively.

[0026] The above-mentioned configuration of the ceiling surface material 3 is more advantageous than using a material conforming to the notification specifications for a "floor" having quasi-fire resistance. Here, the notification specifications for a "floor" that requires quasi-fire resistance will be explained with reference to Fig. 12. As shown in Fig. 12, the floor 100 includes a front side surface material 104, a rear side surface material 103, and a load-supporting member (joist and base) 105 arranged between the double-sided materials 103, 104.

[0027] Floors 100 that require quasi-fire resistance must have load-supporting members 105 made of wood or steel and rear and side members 103 constructed to meet the following standards: (1) A gypsum board that is 12 mm or more thick is laid on top of another gypsum board that is 12 mm or more thick, and then a layer of rock wool that is 50 mm or more thick is laid on top of that. (2) A reinforced gypsum board with a thickness of 12 mm or more attached to another reinforced gypsum board with a thickness of 12 mm or more. (3) A reinforced gypsum board having a thickness of 15 mm or more, covered with rock wool or glass wool having a thickness of 50 mm or more. (4) A reinforced gypsum board having a thickness of 12 mm or more and a rock wool sound-absorbing board having a thickness of 9 mm or more attached to the top.

[0028] The rear surface material 103 of the floor 100 is finished with fire-resistant gypsum board. Therefore, when this specification is adopted for an exterior ceiling, it becomes necessary to attach a finishing material separately. In contrast, in this embodiment, the surface material of the ceiling surface material 3 is ceramic siding 31, so that a finishing material is not required. In addition, since the ceramic siding 31 is formed from a non-combustible or semi-non-combustible material, fire resistance can be maintained without overlapping gypsum board as in (1) and (2) above. Therefore, manufacturing costs can be reduced.

[0029] In addition, when filling with non-flammable insulation material as in (3) and (4) above, water absorption during rainfall becomes an issue, but since the ceiling surface material 3 does not contain insulation material, it can be designed to be water-resistant.

[0030] (About support members) The configuration and fixing position of the support member 5 will be described with reference to Figures 4 and 5. Figure 5 is a perspective view of the panel unit 2.

[0031] The support member 5 is a metal member (channel steel) that extends in the depth direction and has a generally U-shaped cross section. The support members 5, 5 on both sides in the width direction are fixed inward (facing the center in the width direction) so that their openings face each other. Both longitudinal ends of the horizontal base rail 61 are fitted into the openings of the support members 5, 5.

[0032] Each support member 5 has a back portion 51 facing outward in the width direction, a lower flange portion 52 extending inward from the lower end of the back portion 51, and an upper flange portion 53 extending inward from the upper end of the back portion 51. The lower flange portion 52 is fixed to the ceiling surface material 3 (gypsum board 32), and the upper flange portion 53 is fixed to the upper surface material 4. The support member 5 can be fixed to each surface material 3, 4 by a fastening means such as an adhesive.

[0033] As shown in FIG. 4, the support member 5 is disposed offset toward the center (the other end) from the edge position T (indicated by a dashed line) of the ceiling surface material 3. The edge position T coincides with the position of the widthwise end face 301 of the ceiling surface material 3. The distance (offset dimension) D between the position of the back surface portion 51 of the support member 5 in the width direction and the edge position T is typically about half the height dimension L1 (the vertical length of the back surface portion 51) of the support member 5. If the height dimension L1 of the support member 5 is, for example, 60 mm, the distance D is, for example, 25 to 35 mm. The width dimension L2 of the joint backing member 7 described later is about twice the distance D.

[0034] 5, a plurality of holes 50 are provided at a constant pitch along the longitudinal direction in the back surface portion 51 of the support member 5. The holes 50 are bolt holes that penetrate the back surface portion 51 in the plate thickness direction.

[0035] The configuration and fixed position of the support member 5' perpendicular to the support member 5 are also the same as those of the support member 5. That is, the support member 5' has a substantially U-shaped cross section, and the support members 5', 5' on both sides in the depth direction are fixed facing inward (towards the center in the depth direction) so that their openings face each other. In a case where the panel unit 2 includes a vertical foundation bar, both longitudinal ends of the vertical foundation bar are fitted into the openings of the support members 5', 5'.

[0036] (About the upper surface material) The upper panel 4 in this embodiment may have a similar structure to the front side panel 104 of the floor 100 shown in Fig. 12. In this case, the upper panel 4 is made of, for example, a wooden plywood with a waterproof sheet attached underneath. The plywood of the upper panel 4 is fixed to the horizontal base rails 61 or the vertical base rails with screws.

[0037] As shown in Fig. 4, the overall width dimension of the upper panel material 4 is approximately equal to the width dimension of the ceiling panel material 3. In this embodiment, as shown in Fig. 5, a plurality of cutout portions 40 are provided at a constant pitch on both widthwise edges of the upper panel material 4. The cutout portions 40 are provided at positions corresponding to the holes 50 in the support member 5. In other words, the arrangement pitch of the cutout portions 40 is equal to the arrangement pitch of the holes 50 in the support member 5. Note that the cutout portions 40 are not shown in Fig. 3.

[0038] The cutout portion 40 is desirably formed by cutting out the upper panel 4 from its widthwise edge position (equivalent to position T shown in FIG. 4) to a position beyond the tip position of the upper flange portion 53 of the support member 5. As a result, a part S3a of the air layer (space between the ceiling panel 3 and the upper panel 4) of the panel unit 2 is exposed from the cutout portion 40. This space S3a is a space used for the fixing work described below (hereinafter referred to as the "work space"). In this way, the cutout portion 40 is provided at the widthwise edge of the upper panel 4 to expose the work space S3a. The work space S3a is desirably large enough for a person's hand to enter.

[0039] <Construction method for exterior ceilings using panel units> A method for constructing an external ceiling 11 using the panel units 2 will be described with reference to Figs. 6 to 8. Fig. 6 is an exploded view showing a method for constructing an external ceiling 11 using the panel units 2. Fig. 7 is a perspective view showing a joint backing member 7 used to connect the panel units 2. Fig. 8 is a cross-sectional view showing the connected state of the panel units 2.

[0040] First, prepare a plurality of panel units 2 that have been manufactured in advance in a factory, and joint backing materials 7 to be used for connecting the panel units 2. Also prepare bolts, which will be described later.

[0041] As shown in FIG. 7, the joint backing member 7 is a metal member (channel steel) that extends in the depth direction and has a substantially U-shaped cross section, similar to the support member 5. In the attached state, the joint backing member 7 is arranged so that the opening faces upward. The joint backing member 7 has a bottom plate portion 71 and a pair of side plate portions 72, 73 that rise upward from both ends of the bottom plate portion 71 in the width direction. The height dimension L3 of the joint backing member 7 (the vertical length of the side plate portions 72, 73) is equal to or smaller than the height dimension L1 of the support member 5 shown in FIG. 4, and is preferably slightly shorter. If the difference between the dimensions L1 and L3 is "ΔL", the dimensional difference ΔL is preferably, for example, 1 mm or more and 5 mm or less.

[0042] One side plate portion 72 has a plurality of holes 70a at a constant pitch along the longitudinal direction. The other side plate portion 73 has a plurality of holes 70b at a constant pitch along the longitudinal direction. The arrangement pitches of these holes 70a, 70b are the same as each other and are also the same as the arrangement pitch of the holes 50 of the support member 5. The holes 70a, 70b are bolt holes.

[0043] It is desirable that the heat shielding material 8 is fixed in advance to the bottom plate portion 71 of the joint backing member 7. The heat shielding material 8 is composed of a sheet-like heat-foaming material (fireproof sheet) that foams when heated. The above-mentioned dimensional difference ΔL is determined according to the thickness dimension L4 of the heat shielding material 8 (so as to be approximately equal to the dimension L4). Specifically, the dimensions of each part are adjusted so that the sum of the height dimension L3 of the joint backing member 7 and the thickness dimension L4 of the heat shielding material 8 is approximately equal to the height dimension L1 of the support member 5.

[0044] The heat shielding material 8 is provided on the entire lower surface of the bottom plate portion 71. That is, the heat shielding material 8 having the same width as the bottom plate portion 71 is disposed from one end to the other end in the longitudinal direction of the bottom plate portion 71. The heat shielding material 8 can be fixed by a fastening means such as an adhesive or double-sided tape.

[0045] Next, as shown in FIG. 6, the ends of the two panel units 2, 2 are brought close to each other so as to sandwich the joint backing member 7 with the heat shielding material 8 therebetween. At this time, the joint backing member 7 is tightly sandwiched between the support member 5 of one panel unit 2 (left side of the drawing) and the support member 5 of the other panel unit 2 (right side of the drawing). As described above, the support members 5, 5 of both panel units 2, 2 are offset toward the center, so that the joint backing member 7 is accommodated in the outer space of the support members 5, 5 of both panel units 2, 2. In this state, the end surface 301a of the ceiling surface material 3 of one panel unit 2 and the end surface 301b of the ceiling surface material 3 of the other panel unit 2 are in contact with or close to each other. The width of the joint portion 20 (FIG. 8) formed between the end surfaces 301a, 301b of the two ceiling surface materials 3 is determined by the relationship between the width dimension L2 of the joint backing member 7 and the offset dimension D shown in FIG. 4.

[0046] 8, in a state in which the joint backing member 7 is sandwiched and positioned between the support members 5, 5 of both panel units 2, 2 (hereinafter referred to as the "positioned state"), the heat shielding material 8 fixed to the bottom plate portion 71 of the joint backing member 7 comes into contact with the back surfaces 302 of the ceiling surface materials 3, 3 on both the left and right sides. In other words, the bottom plate portion 71 of the joint backing member 7 is positioned with a "gap" between it and the back surface 302 of the ceiling surface material 3, and this gap is filled by the heat shielding material 8. The bottom plate portion 71 and the heat shielding material 8 of the joint backing member 7 are positioned on the back side (above) of the joint portion 20, spanning the joint portion 20.

[0047] In the positioned state, one side plate portion 72 of the joint backing member 7 is in surface contact with the back surface portion 51 of the support member 5 of one panel unit 2 (the left side of the paper), and hole 70a of the side plate portion 72 overlaps with hole 50 of the back surface portion 51. In addition, the other side plate portion 73 of the joint backing member 7 is in surface contact with the back surface portion 51 of the support member 5 of the other panel unit 2 (the right side of the paper), and hole 70b of the side plate portion 73 overlaps with hole 50 of the back surface portion 51.

[0048] In this state, the worker passes his / her hand through the cutout portion 40 of the upper panel 4 into the working space S3a, and passes the bolt 62a as fastening means through the hole 70a of one side plate portion 72 and the hole 50 of the rear surface portion 51, and tightens it with a nut 63a. Similarly, the bolt 62b as fastening means is passed through the hole 70b of the other side plate portion 73 and the hole 50 of the rear surface portion 51, and tightens it with a nut 63b. This connects and fixes the two panel units 2, 2 adjacent in the width direction.

[0049] In this manner, adjacent panel units 2 in the width direction (or depth direction) can be connected and fixed in sequence. The end of the panel unit 2 near the exterior wall 12 shown in FIG. 1 is fixed to a structural member such as the exterior wall 12 as shown in FIG. 10. The panel unit 2 away from the exterior wall 12 may be suspended from a structural member such as a beam by a suspension device (not shown) if necessary. In this case, the suspension device may be hooked to the upper flange portion 53 of the support member 5.

[0050] When the installation of the panel unit 2 is completed, as shown in Fig. 9, a sealant 9 is applied to the joints 20 from below the panel unit 2. The sealant 9 may be of a dry type or a wet type.

[0051] A floor finishing material (not shown) is applied on the underfloor material serving as the upper surface material 4. As a result, the joints 41 (FIG. 8) between adjacent upper surface materials 4, 4 and the above-mentioned cutout portions 40 are covered with the floor finishing material, completing the external ceiling 11. The upper surface material 4A in FIG. 9 includes the underfloor material and the floor finishing material.

[0052] As explained above, by producing the panel units 2 in advance at a factory, it is possible to reduce the work of driving upward screws on site (the work of fixing the ceiling surface material 3 to the base rail). In addition, by locating the support members 5 of the panel units 2 at a position away from the end of the ceiling surface material 3, the joint backing members 7 can be used as connectors for connecting adjacent panel units 2, 2. This improves the ease of construction of the external ceiling 11. In addition, it is possible to simplify the connection structure of the joints 20 between adjacent ceiling surface materials 3, 3.

[0053] The upper surface material 4 may be attached on-site. In other words, the panel unit produced in a factory needs to include at least the ceiling surface material 3 and the support member 5. In this case, the upper surface material 4 does not need to have the cutout portion 40 as shown in FIG.

[0054] <External ceiling structure> FIG. 9 is a cross-sectional view showing a main part of the completed external ceiling 11, and corresponds to a vertical cross-sectional view of the P1 portion (where the two panel units 2 are adjacent to each other in the width direction) in FIG.

[0055] The external ceiling 11 includes first (left side of the drawing) and second (right side of the drawing) ceiling surface materials 3,3, each of which has one end on the joint portion 20 side and the other end opposite the joint portion 20, first and second support members 5,5 having a substantially U-shaped cross section fixed to the end back surface 302 on one end side of each of the first and second ceiling surface materials 3,3 so that the opening faces the other end side, and a joint backing member 7 having a substantially U-shaped cross section arranged on the back side of the joint portion 20 so that the opening faces upward. The first and second support members 5,5 have a back surface portion 51 arranged offset from the edge position T on one end side to the other end side. The joint backing member 7 has a pair of side plate portions 72,73 connected and fixed to the back surface portion 51 of each of the first and second support members 5,5. The joint backing material 7 also has a bottom plate portion 71 that is arranged with a gap between it and the rear surfaces 302 of the first and second ceiling surface materials 3, 3, and the heat shielding material 8 is arranged to fill this gap. Note that the P2 portion in Fig. 3 (the portion where the two panel units 2 are adjacent to each other in the depth direction) also has a similar cross section.

[0056] According to this structure, as shown in Fig. 11, when the joint portion 20 is heated from below (from the external space S1) and the heat passes through the sealant 9, the heat-shielding material 8 disposed in the gap foams, so that the transfer of heat to the joint backing material 7 located behind it can be delayed. In addition, since the joint backing material 7 has heat resistance, it is possible to suppress the temperature rise of the support member 5 with which the joint backing material 7 interfaces. As a result, it is possible to suppress the temperature rise of the air layer S3, so that it is possible to effectively improve the fire resistance of the external ceiling 11, despite the simple structure.

[0057] In this embodiment, the upper surface material 4 of the external ceiling 11 has the same structure as the front side surface material 104 of the floor 100 shown in Fig. 12, so the ceiling of the external staircase 10 can be treated as a "floor" having quasi-fire resistance. Therefore, a room (such as a dwelling unit) can be arranged in the upper space S2 above the external ceiling 11.

[0058] If the external ceiling 11 does not need to function as a "floor", the upper surface material 4 may be omitted. Furthermore, the configuration of the external ceiling 11 is not limited to the ceiling portion of the external staircase 10, but can be applied to various types of ceiling portions facing the external space (outdoor space) of a building.

[0059] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0060] 1 Apartment house, 2 Panel unit, 3 Ceiling surface material, 4, 4A Upper surface material, 5 Support member, 7 Joint backing material, 8 Heat shielding material, 9 Sealing material, 10 External staircase, 11 External ceiling, 12 Exterior wall, 20, 41 Joint portion, 31 Ceramic siding, 32 Gypsum board, 40 Notch portion, 50, 70a, 70b Hole, 51 Back portion, 52 Lower flange portion, 53 Upper flange portion, 61 Base rail, 62a, 62b Bolt, 63a, 63b Nut, 64 Joint metal fitting, 71 Bottom plate portion, 72, 73 Side plate portion, 100 Floor, 103 Back side material, 104 Front side material, 105 Load support member, S1 External space, S2 Upper space, S3 Air layer, S3a Working space, T Edge position.

Claims

1. An exterior ceiling structure facing the exterior space of a building, First and second ceiling surface materials are arranged adjacent to each other via a joint portion and have one end on the joint portion side and the other end on the opposite side to the joint portion; a first support member and a second support member, each of which is a member having a substantially U-shaped cross section and fixed to a back surface of one end side of each of the first and second ceiling surface materials so that an opening faces the other end side, and each of which has a back surface portion disposed offset from an edge position of the one end side to the other end side; An external ceiling structure comprising a joint backing member, which is a member having an approximately U-shaped cross-section arranged with its opening facing upward on the back side of the joint portion, and which has a pair of side panel portions connected and fixed to the back portions of each of the first and second support members.

2. The joint backing member has a bottom plate portion disposed with a gap between the bottom plate portion and the back surface of the first and second ceiling surface materials, The exterior ceiling structure of claim 1 , further comprising a heat shield filling the gap.

3. One side plate portion of the joint backing member and a rear portion of the first support member are fixed by a first bolt and a first nut, The external ceiling structure according to claim 1 , wherein the other side plate portion of the joint backing member and the rear portion of the second support member are fixed together by a second bolt and a second nut.

4. The device further includes first and second upper panels pre-fixed to the upper surfaces of the first and second support members; The external ceiling structure as described in claim 3, wherein the first and second upper surface members are provided with cutouts for exposing a space for fixing the first and second support members and the joint backing member.

5. The exterior ceiling structure according to claim 1 , wherein each of the first and second ceiling surface materials includes a gypsum board and a ceramic siding layered on the gypsum board and exposed to an exterior space.

6. The method for constructing an exterior ceiling according to claim 1, A step of preparing a first panel unit having the first support member pre-fixed to both sides in the width direction of the first ceiling surface material, a second panel unit having the second support member pre-fixed to both sides in the width direction of the second ceiling surface material, and the joint backing member; A construction method for an external ceiling, comprising the steps of fixing the first support member and one side plate portion of the joint backing member with a fastening means, and fixing the second support member and the other side plate portion of the joint backing member with a fastening means.

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