JP5220459B2 - Floor joist - Google Patents

Description

  The present invention relates to a joist in the case of a floor foundation structure.

  The floor foundation structure is suitably applied to a floor foundation such as the second floor of a wooden-type detached house or a floor foundation of the second or higher floor of an apartment house, and suppresses the propagation of living noise generated on the floor downstairs. Such a floor foundation structure is based on a thick plywood (for example, plywood having a thickness of 24 mm, 28 mm, etc.) laid on a large pull, or a 12 mm plywood laid on a large pull and a joist on it. It is provided on the top.

As a joist in such a floor foundation structure, there is one shown in Patent Document 1 below. In this patent document, with respect to the wall material 2 (symbol described in the same publication, hereinafter the same), the floor material 1 has a constant height and the wall material 2 is kept constant. , The joist 3 is provided (paragraph 0009). Further, a damping rubber 8 or the like is provided between the lower surface of the floor material 5 excluding the portion supported by the joist 3 and the facing surface of the floor base 1, and a support member 9 which can be expanded and contracted as necessary. Provided at predetermined intervals (paragraph 0010).
JP 2002-309757 A

  Since the conventional jokita has an adhesive sheet between the jokita and the wall material, the living noise generated by walking on the floor or falling objects on the floor is not Propagation downstairs is relatively good, but when heavy objects such as heavy furniture are placed along the wall surface, the depth of the heavy object is generally larger than the width of the joist floor. May be bent and the heavy object may be tilted forward (in a direction away from the wall surface), which may cause a squeak or vibration noise to propagate downstairs.

  Therefore, the problem to be solved by the present invention is that the heavy article such as furniture is installed along the wall in the floor foundation structure of the second floor of the wooden detached house or the second floor or more of the wooden apartment house. It is to provide a new joist structure that can prevent the squeezing to the near side or the generation of squeak noise and propagating downstairs.

In order to achieve the above object, the present invention according to claim 1 is a pair of vertical shafts which are joists when placed at the corners of the base and the wall in the floor foundation structure and extend in parallel at a predetermined interval. The outer surface of the longitudinal member that has a material and a transverse member that spans the entire surface length of the pair of longitudinal members, has a smooth surface, and is positioned at least away from the wall of the pair of longitudinal members. Is characterized in that a fruit is formed to connect the pier .

The present invention according to claim 2 is a pair of vertical members which are joists when placed at the corners of the base and the wall in the floor foundation structure, and extend in parallel at a predetermined interval. And a plurality of cross members spanned between the inner side surfaces of the pair of cross members formed in a ladder shape in plan view , and a pier can be connected to the outer surface of the vertical member located at least away from the wall of the pair of vertical members. It is characterized in that a fruit is formed for the purpose .

According to a third aspect of the present invention, in the case of the joist according to the first or second aspect, a step portion is formed so as to be actually adjacent to the outer surface of the vertical member on which the fruit is formed .

  In the case of the present invention, the joist is formed with a pair of vertical members extending in parallel at a predetermined interval, so even if a heavy object such as furniture is placed thereon, the entire weight is substantially reduced. It can be supported by joists. Therefore, it is possible to prevent the heavy object from being inclined to the near side and maintain a stable installation state for a long period of time.

  Further, since squeak noise and vibration sound caused by the heavy object tilting toward the front side are prevented, these noises do not propagate downstairs.

Since a fruit is formed to enable the pier to be connected to the outer surface of the vertical member located away from the wall of the pair of vertical members constituting the joist , this is actually provided at one end in the longitudinal direction of the pier. by fitting, when a plurality of桟木provided in the orthogonal direction can be securely connected to the joists when the relative joists, the strength of the underfloor structure is increased.

Further, according to the configuration in which the step portion is formed adjacent to the outer surface of the vertical member on which the fruit is formed (Claim 3 ), the pier can be supported by the step portion, and the pier and the pier are constructed. It is possible to stably support the floor board. In addition, since the joist and the crosspiece are supported not only by the actual but also the stepped portion when connecting and fixing, the work can be easily performed when fixing with a screw or the like, and a firm fixing state can be obtained.

  In the case of the present invention, the joists are placed at the corners of the base and the wall. For example, thick plywood (especially having a thickness of 24 mm, 28 mm or the like is used) laid on a large pull, It is provided on a 12 mm plywood laid on a large pull and a joist on this. In the case of the present invention, the joist includes a plurality of piers provided in a direction parallel or perpendicular to the longitudinal direction thereof, and elastic legs provided at regular intervals in the longitudinal direction of the pier between the lower surface and the base of these piers. It can be used for a floor foundation structure that is provided. Such a floor foundation structure is suitably applied to floor foundations such as the second floor of wooden detached houses, or floor foundations of the second and higher floors of apartment houses, etc. Suppress.

  In the case of the present invention, the joist is formed by having a pair of longitudinal members extending in parallel at a predetermined interval and a transverse member spanned between the pair of longitudinal members. Two embodiments are included: a case where a cross member is bridged over the entire length, and a case where a plurality of cross members are bridged between a pair of longitudinal members.

In any of the embodiments, the material of the joist is woody, and for example, LVL, plywood, MDF, or the like is used. The thickness and height (H ₁ in FIG. ₁ and H ₅ in FIG. 11) of the thick joist and the vertical member are generally 40 to 60 mm, and the plywood provided under the joist and the height of the joist or large pulling, etc. Select according to. When joists total width _{(D 1} in FIG. 1, _{D 3} of FIG. 11, _{D 4} in FIG. 12) is generally 250～500Mm, selected appropriately in accordance with the use purpose. When the entire length of the joists _{(L 1} in FIG. 1, _{L 3} in FIG. 11, _{L 4} in FIG. 12) are generally prepared as 500～2000Mm, used to cut the appropriate length as it at length or construction site, Is done. Depending on the construction site, it may be used with a length of 500 mm or less.

  The width of the vertical member is generally 30 to 80 mm, and the length is the same as the total length of the joist and is generally prepared as 500 to 2000 mm. A soft sheet such as a sound insulation sheet may be provided on the back surface (base material side) of the vertical member.

  The cross member in the case of spanning the cross member over the entire surface length of the pair of vertical members is plate-shaped. The length of the plate-shaped cross member is the same as the length of the vertical member (that is, the total length of the joist), and is generally 500 to 2000 mm. The width of the plate-like cross member does not exceed the full width of the joist (250 to 500 mm), but at least a part of both side edges must have a width dimension applied to the vertical members on both sides, and the thickness Is within the thickness range of the longitudinal member and is, for example, 7 to 20 mm. Specifically, a notch having a depth equal to the thickness of the plate-like cross member is formed in each of the upper corners on the inner surface side of the pair of vertical members, and both side edges of the plate-like cross member are extended over the entire length in the notch Then, they are fixed so as to be placed and fitted (FIG. 10A). Alternatively, a notch having a depth equal to the thickness of the plate-like cross member is formed at the upper corner on the inner surface side of one vertical member, and one side edge of the plate-like cross member is placed and fitted in this notch, The other vertical member may be formed in advance at a height lower by the thickness of the plate-like cross member, and the other side edge portion of the plate-like cross member may be simply placed and fixed (FIG. 10B). ). Alternatively, both vertical members may be formed in advance at a height that is lower than the thickness of the plate-like cross member, and both side edges of the plate-like cross member may be fixed in a state of being placed on these vertical members. Good (FIG. 10C). In addition, the configuration described in the embodiments described later and any other configuration can be adopted, but in any case, the surface of the joist (longitudinal material and / or plate) in a state where the plate-like cross member is bridged. The surface of the cross-shaped cross member is smooth and has no step. In this embodiment, since the cross member is plate-like, it is possible to fix the floor board anywhere as long as it is the upper surface of the joist, and it is possible to construct the floor board without worrying about the position of the floor board construction on the joist There is.

On the other hand, when a plurality of cross members are bridged between a pair of vertical members, the cross members are rod-shaped, and are configured as joists in a substantially ladder shape. The length of this bar-shaped cross member does not exceed the full width of the joist (500 to 2000 mm), but both ends must have a width dimension applied to the vertical members on both sides, and the thickness is the thickness range of the vertical members For example, it is 7 to 20 mm, and the width is arbitrary, but is generally about 30 to 80 mm, which is the same as that of the vertical member. (P ₂ in FIG. _11, P ₄ in FIG. ₁₂₎ the pitch of the case of providing a plurality of bar-shaped crossmember preferably be matched to the width of the floorboard. Also in this case, the surface of the joist (the surface of the vertical member and the bar-like horizontal member) is substantially smooth in a state where the bar-like horizontal member is bridged, and no step is generated. In this embodiment, since the bar-shaped cross member is spanned at intervals, the floor plate is constructed so that the side edge portion of the floor plate covers the bar-shaped cross member.

  In any case, a fruit for enabling the pier to be connected is formed on the outer surface of the vertical member positioned at least away from the wall of the pair of joists. A fruit may be provided on each outer surface of both longitudinal members. As the actual shape, any actual shape, such as a real one, an agitation, and a short one, can be adopted. The fruit formed on the vertical member is formed as a female fruit of a shape that can fit the male fruit when the fruit at the end of the pier is a male fruit, and fits into the female fruit when the fruit at the front of the pier is a female fruit. It is formed as a solid of shape that can be combined.

On the outer side surface of the vertical member on which the joist seeds are provided, a step portion is formed adjacent to each other. The height of the step (H _{2 in} FIG. 1) is a dimension obtained by subtracting the thickness of the pier from the thickness of the vertical member, that is, the same dimension as the height of the supporting leg (H _{3 in} FIG. ₃ ) described later. . The width of the step portion is generally set within a range of 10 to 30 mm.

  The jokita is placed on the base, but it is not always necessary that the lower surface of the jombo is in full contact with the base. It may be supported on the base via the substrate (FIG. 12). In this case, a gap is provided between the longitudinal member and the transverse member and the base. Moreover, a soundproofing property can be improved by sticking or attaching a soft sheet to the lower surface of the vertical member or the lower surface of the piece or block constituting the joist.

A joist 10 according to one embodiment of the present invention is shown in FIG. At this time, the joist 10 has a pair of longitudinal members 11a and 11b extending in parallel at a predetermined interval, and a plate-like transverse member 12 spanning the entire surface of the pair of longitudinal members 11a and 11b. Configured. The size of the joist 10 in this example is length L ₁ = 1818 mm, width D ₁ = 353 mm, and thickness H ₁ = 49.2 mm. The width B ₁ of the vertical member 11a is 50 mm, the width B ₂ of the vertical member 11b is 75 mm, and the thicknesses of the vertical members 11a and 11b are both 48 mm. The thickness of the sound insulation sheet (not shown) attached to the back surface of the vertical members 11a and 11b is 1.2 mm. The cross member 12 has a width C ₁ = 258 mm and a thickness of 12 mm. The material of the vertical members 11a and 11b is LVL, and the material of the cross member 12 is plywood. In this embodiment, the vertical members 11a and 11b are both formed by joining two upper and lower members, but may be constituted by one member.

Of the pair of vertical members 11a and 11b, a female member 13 extending over the entire length is provided on the outer surface of the vertical member 11b disposed away from the wall surface, and a stepped portion 14 is further provided on the outer lower side thereof. . Height _{H 2} of the step portion 14 is 25.2 mm. Cutouts 15a and 15b are formed at the upper corners of the inner side surfaces of the vertical members 11a and 11b, and the side ends of the cross member 13 are placed on the cutouts 15a and 15b so as to be bridged. The vertical members 11a and 11b and the cross member 12 are integrated by fixing with a nail, a screw, an adhesive, an adhesive tape, or the like, and the joist 10 is obtained.

  At this time, the joist 10 is used in a floor foundation structure as shown in FIGS. The floor foundation structure 1 is provided on a thick plywood 3 (24 mm thick) laid on a large pull 2 on a floor of a house, and a floor board 4 is laid thereon. Reference numeral 5 denotes a skirting board. In the floor foundation structure 1, the joist 10 is provided along the four corners of the corner formed by the thick plywood 1 and the walls 9 a and 9 b of the room. In addition, the floor foundation structure 1 has a plurality of piers 6 connected to the joists 10 so as to extend in a direction orthogonal to the joists 10 when extending in a direction coinciding with the longitudinal direction of the floor board 4. Support legs 7 are provided on the lower surface of the pier 6 at regular intervals in the longitudinal direction, and the pier 6 is supported on the thick plywood 3 as a floor base via the support legs 7. The floor board 4 is laid on the joists 10 and the piers 6 with nails or an adhesive (not shown).

As shown in FIG. 5, the pier 6 has a square bar shape made of LVL provided with a male fruit 61 at one end in the longitudinal direction thereof and a female fruit 62 having a shape capable of fitting the male fruit 61 at the other end. It is a member.桟木thickness _{H 4} of 6 when a smaller than the height _{H 1} of the joist 10, as a guide for about 1/2 of the height _{H 1} of the joists 10 upon. For example, length L ₂ = 910 mm, width D ₂ = 50 mm, and thickness H ₄ = 24 mm. On the lower surface of the pier 6, holes 63 are provided at three positions with a predetermined pitch P ₁ = 303 mm. The upper end protrusions 72 (FIG. 3) of the support leg 7 are inserted into these holes 63. Since the floor board 4 is attached to the upper surface of the pier 6 and the support legs 7 are attached to the lower surface, it is preferable that at least the upper and lower surfaces thereof are flat. The tip side of the length of桟木6 (from the center of the most distal end of the bore 63 to the tip length) Q is, Q + (vertical member 11a 1/2 of the width B ₁ of the time joist 10) floorboards For example, when the width dimension B ₁ of the longitudinal member 11a is 75 mm and the floor board width dimension is 303 mm, Q can be set to 126.5 mm.

  The support leg 7 is made of an elastic material such as synthetic rubber, natural rubber, or soft synthetic resin, and has a columnar, prismatic, or other columnar body 71, and an upper end protrusion 72 formed so as to protrude from the upper surface thereof. Are integrally formed. The main body 71 of the support leg 7 is placed on the thick plywood 3 which is a floor base, and the protrusion 72 is attached to the pier 6 by being inserted into the hole 63 on the lower surface of the pier 6. One or more annular grooves 73 may be formed on the side surface of the main body 71.

  The support leg 7 preferably has a durometer hardness (JIS K6253: 2006) of A50 to A90. If the supporting leg 7 has a hardness of less than A50, the floor deflection becomes large and the flatness of the floor cannot be maintained. If the supporting leg 7 has a hardness exceeding A90, the soundproofing property of the floor becomes inferior. In this embodiment, one having a hardness of A75 is used.

  As shown in FIG. 2, in this embodiment, the support legs 7 are attached to the lower surface of the pier 6, but the seam (actual position) of the floor board 4 is not overlapped with the attachment position of the support leg 7 when the floor board 4 is constructed. It is preferable to do. This is because when the floor plate fixing nail is driven into the actual part of the floor plate 4 in order to fix the floor plate 4 to the pier 6, if the nail is driven into the support leg 7, the buffering action of the support leg 7 is impaired. This is to avoid this.

  Referring to FIG. 3, gaps are provided between the wall-side surface of wall joist 10 and wall surface 9 a and between the end surface of floor board 4 and wall surface 9, and a cushioning material having a thickness of about 1 to 5 mm is provided in this gap. 8a is provided. That is, the edge joist 10 is placed on the thick plywood 3 in a state in which the side surface of one vertical member 11 a is in contact with the wall surface 9 via the cushion material 8. The cushion material 8a may be attached in advance to the side surface of the vertical member 11a of the joist 10 in advance. The cushion material 8a may be made of a known material. For example, a resin foam such as polyolefin resin, urethane resin, acrylic resin, or foam rubber such as neoprene rubber or butyl rubber can be used.

When the joist 10 is arranged in this manner, the vertical member 11b is positioned away from the wall surface 9a, and the female fruit 13 is opened to the indoor side. By fitting the male fruit 61 at one end in the longitudinal direction of the pier 6 to the female fruit 13, the pier 6 is connected to the border joist 10. The pier 6 is supported on the thick plywood 3 via a support leg 7 attached by inserting an upper end protrusion 72 into a hole 63 on the lower surface thereof. The height H ₃ of the support leg 13 in such a mounting state is substantially equal to the difference between the thickness H ₁ = 49.2 mm of the joist 10 and the thickness H ₂ = 24 mm of the bridge 6, and in this embodiment, H ₃ = 26 mm.

  On the other end in the longitudinal direction of the pier 6, a female fruit 62 having a shape that can fit the male fruit 61 (and therefore substantially the same shape as the female fruit 13 provided on the outer surface of the vertical member 11 b of the joist 10) is formed. Therefore, a plurality of male seeds 61 and female seeds 62 can be connected and extended in the longitudinal direction through the fitting of the male seeds 61 and the female seeds 62 (see FIG. 2).

  After appropriately extending in this way, the pier 6 is not connected to the joist 10 when it is installed near the wall surface 9b on the opposite side of FIG. In the state where it cut | disconnected, it is constructed in the state which mounted the end part of the end on the step part 14 of the vertical member 11b of the thick joist 10 (FIG. 4). A gap is provided between the wall-side surface of the joist 10 and the wall surface 9 and between the end surface of the floor plate 4 and the wall surface 9b, and the cushion material 8b similar to that described with reference to FIG. 3 is provided in this gap. In FIG. 4, the female fruit 13 is provided on the side surface of the vertical member 11 b of the joist 10, but the female fruit 62 side of the pier 6 is cut for dimension adjustment as described above. The female fruit 13 is not used as a fitting for the male fruit 62 of the crosspiece 6, and the cut end of the crosspiece 6 is placed on the stepped portion 14 leaving a gap 22.

  Next, with reference to FIGS. 6-9, the construction method of this floor foundation structure is demonstrated. As will be understood from the following description, this floor foundation structure has an advantage that simple construction can be performed.

  First, as shown in FIG. 6, the base of the room in which the floor base structure is provided is adjusted. That is, inking 16 is performed on a 24 mm thick plywood 3 (Tokyo plywood industrial association, Tohoku plywood industrial association “Nedanon” (trademark), etc.) laid on the draw 2 or the like.

  After inking 16, as shown in FIG. 7, a clearance of 3 mm is formed between the base joist 10 and the wall surface 9 a from the reference surface and between the connecting portions of the hot joists 11 with screws 17 having a length of 75 mm or more. Fix to the thick plywood 3.

Then, as shown in FIG. 8, the male fruit 61 at one end in the longitudinal direction of the pier 6 is inserted into the female fruit 13 that opens on the outer surface of the vertical member 11 b of the joist 10, and the real part is fixed with a screw 18. When a sound absorbing material is used, a sound absorbing material 19 is spread between the piers 6 and 6. The sound absorbing material 19 is glass wool or polyester, and the density is, for example, 32 kg / m ³ .

  Next, as shown in FIG. 9, an adhesive (not shown) is applied to the surface of the joist 10 and the pier 6 in a beat shape, and the flooring 4 is placed on this with a gap of 3 mm from the wall surface 9a. And it fixes with the fixing tools 20, such as a floor nail or a staple. Next, the crosspiece 6 is connected in the longitudinal direction through the fitting of the male fruit 61 and the female fruit 62, and a screw 21 having a length of about 25 mm is driven into and fixed to the actual fitting part. In this way, when the male fruit 61 is inserted and fixed with the screw 18, the female fruit 62 of the pier 6 so that there is a gap 16 of about 3 to 5 mm between the joist 10B and the joist 10B. Cut the side edge. This cut pier is shown as 6 '.

  And after constructing the flooring 4 to the whole floor foundation structure 1 as shown in FIG. 2, the skirting board 5 is attached and it cures until an adhesive agent dries. In this way, the floor is completed.

  FIGS. 10A to 10D show modified examples of the configuration of the joist 10. FIG. 10A shows an example in which the pair of longitudinal members 11a and 11b of the joists 10 are formed as a single member in the first embodiment. FIG. 10B shows the longitudinal member 11b as in the embodiment of FIG. 10A, but the longitudinal member 11a has a thickness of the transverse member 12 instead of providing the notch 15a at the inner upper corner. This is an example in which the height is low by the amount and the side edges of the cross member 12 are placed on the upper surface. In FIG. 10 (c), the vertical members 11a and 11b are both low in height by the thickness of the cross member 12, and are constructed so that both side edges of the cross member are placed on the upper surface of the cross members 11a and 11b. It is an example. In this example, the female fruit 13 is formed by extending the side edge portion of the cross member 12 spanning the vertical member 11b so as to cover the stepped portion 14. In FIG. 10D, the vertical member 11a is formed of three members to form a notch 15a for receiving the side edge of the horizontal member 12, and the vertical member 11b is the same as the embodiment of FIG. 10C. This is an example in which the shape is formed of two members.

FIG. 11 shows another configuration example of the joist in the present invention. At this time, the joist 30 is formed in a substantially ladder shape by a plurality of bar-like cross members 32 being spanned at appropriate intervals between a pair of vertical members 31a and 31b. At this time, the thickness of the vertical members 31a and 31b of the joist 30 is equal to the thickness of the cross member 32. Therefore, the upper and lower surfaces of the joist 30 are flush with the vertical members 31a and 31b. The size of the joist 30 in this example is length L ₃ = 1818 mm, width D ₃ = 328 mm, and thickness H ₅ = 48 mm. Further, the mounting pitch P ₂ of the cross member 32 is 303 mm, the width B ₃ of the vertical members 31 a and 31 b is 50 mm, and the width of the cross member is 228 mm. The materials of the vertical members 31a and 31b and the horizontal member 32 are all LVL. On the outer surface of the vertical member 31b on the side located away from the wall surface, a female fruit 33 for fitting the male fruit 61 at the end of the pier is formed.

  Except for the above, this embodiment is the same as the first embodiment. In this case, the floor foundation structure using the joists 30 and the construction thereof are also the same, and thus the description thereof will be omitted.

FIG. 12 shows still another configuration example of the joist in the present invention. At this time, the joist 40 is formed by a plurality of rod-like cross members 42 having the same thickness (H ₆ ) between the pair of vertical members 41 a and 41 b and appropriately spanned (attachment pitch P ₄ ). Is substantially the same as that of the second embodiment in that it is formed in a ladder shape, but on the lower surfaces of the vertical members 41a and 41b, the pitch P ₄ = the same as the horizontal member mounting pitch corresponding to the mounting position of the horizontal member 42 = A rectangular parallelepiped block 44 is fixed at 303 mm, and a soft sheet 45 having a thickness of about 1 mm is attached to the lower surface of the block 44. In this embodiment, the joist 40 has a length L ₄ = 1818 mm, a width D ₄ = 328 mm, a thickness H ₆ = 24 mm of the longitudinal members 41 a and 41 b, and a thickness H ₇ = 24 mm of the block 44. is there. The point that the female fruit 43 is formed on the outer surface of the vertical member 41b is the same as the joist 30 described above. The vertical members 41a and 41b have a width of 50 mm, and the horizontal members 42 have a length and a width of 228 mm and 100 mm, respectively. The materials of the vertical members 41a and 41b and the horizontal member 42 are all LVL.

  Except for the above, this embodiment is the same as the first embodiment. In this case, the floor foundation structure using the joists 40 and the construction thereof are also the same, and thus the description thereof will be omitted.

It is the top view (a), front view (b), and right view (c) which show the joist according to one Example of this invention. It is a perspective view which shows the floor foundation structure which uses joist at this time in the state which removed most floor boards. It is AA sectional drawing in FIG. FIG. 4 is a cross-sectional view similar to FIG. 3 near the wall on the opposite side of FIG. 3. It is the front view (a) and top view (b) which show the crosspiece used for this floor foundation structure. It is a figure which shows the construction method of this floor foundation structure. Similarly, it is a figure which shows the construction method of this floor foundation structure. Similarly, it is a figure which shows the construction method of this floor foundation structure. Similarly, it is a figure which shows the construction method of this floor foundation structure. It is a right side view similar to FIG.1 (c) which shows the modification about the structure of an edge joist. It is a front view (a), a top view (b), and a right side view (c) showing another configuration example of the joist in the present invention. It is a front view (a), a top view (b), and a right side view (c) showing still another configuration example of the joist in the present invention.

Explanation of symbols

1 Floor foundation structure 2 Large draw 3 Thick plywood (base)
4 Floor board 5 Skirting board 6 Pier 7 Support leg 8a, 8b Cushion material 9a, 9b Wall surface 10 Edge joist 11a, 11b Vertical member 12 Horizontal member 13 Female fruit (actual)
14 Step part 30 Ink joist 31a, 31b Vertical member 32 Horizontal member 33 Female fruit (actual)
40 Junkita 41a, 41b Longitudinal member 42 Lateral member 43 Female fruit (actual)
44 Block 45 Soft sheet

Claims (3)

A pair of vertical members, which are joists when placed at the corners of the base and walls in the floor foundation structure, and extend across the entire surface length of the pair of vertical members, extending in parallel at a predetermined interval. It has a cross member, the surface is formed smoothly, and the fruit for enabling the pier to be connected is formed on the outer surface of the vertical member located at least away from the wall of the pair of vertical members. When it comes to features. A pair of vertical members, which are joists when placed at the corners of the base and wall in the floor foundation structure, and extend in parallel at a predetermined interval, and a plurality of bridges spanned between the inner surfaces of the pair of vertical members The cross member is formed in a ladder shape in plan view, and a fruit is formed on the outer surface of the vertical member positioned at least away from the wall of the pair of vertical members so that the crosspiece can be connected. When it is characterized by. 3. A joist according to claim 1 or 2, wherein a step portion is formed adjacent to the outer surface of the longitudinal member on which the fruit is formed .

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