WO1999049146A1

WO1999049146A1 - Wall structure

Info

Publication number: WO1999049146A1
Application number: PCT/CA1999/000235
Authority: WO
Inventors: Claude CÔTÉ
Original assignee: Cote Claude
Priority date: 1998-03-23
Filing date: 1999-03-19
Publication date: 1999-09-30
Also published as: AU2822899A

Abstract

A wall structure (34) designed to minimize thermal bridges between the external environment and the interior of a building is described herein. The wall structure (34) includes an outer wall structure (44) having a side exposed to the external environment and an inner wall structure (42) having a side exposed to the interior of the building. The inner and outer walls (42, 44) are separated and not in direct contact with one another. One of these inner and outer (42, 44) wall structures may support a roof (36) of the building. The inner and outer walls (42, 44) are preferably made of extruded aluminum studs (50) mounted between respective bottom and top rails (72, 74).

Description

TITLE OF THE INVENTION

WALL STRUCTURE

FIELD OF THE INVENTION

The present invention relates to wall structures. More specifically, the present invention is concerned with a wall structure where an inner wall and an outer wall are provided to minimize thermal bridges between an external environment and the interior of a building.

BACKGROUND OF THE INVENTION

The conventional method of constructing a building is to erect a peripheral wall of the desired dimensions and to install a roof on top of the wall to create an enclosed space providing shelter from the elements.

Conventional peripheral walls include a wall structure, an external wall covering and an internal wall covering. The wall structure is generally made of 2X6 inches wood studs mounted vertically at regular intervals (usually 16 inches, about 0,41 metre) between a horizontal bottom runner and a horizontal top runner. Furring strips made of 1X3 inches wood lumber are horizontally mounted on the external surface of the studs at regular intervals to receive the external wall covering. Heat insulating material is then placed between the adjacent studs before internal wood furring strips and wall covering (usually sheet rock panels) are installed. A major drawback of the conventional wall structure described hereinabove is that, even though the heat insulation material used between the studs may be very efficient, thermal bridges exist in the wooden studs and transfers heat from the inside of the building to the external environment or vice-versa. Indeed, it is generally known that a significant portion of a wall structure having an adequate R-factor, for example R-20, actually has a much lower R-factor, i.e. about R-7 created by the thermal bridges created by the studs.

OBJECTS OF THE INVENTION

An object of the present invention is therefore to provide an improved wall structure.

Another object of the invention is to provide a wall structure minimizing thermal bridges.

SUMMARY OF THE INVENTION

More specifically, in accordance with the present invention, there is provided a wall structure to be mounted to a substructure, the wall structure comprising : an outer wall including a longitudinal outer bottom rail, a longitudinal outer top rail and a plurality of first studs mounted to and between the outer bottom rail and the outer top rail; the outer bottom rail being configured and sized to be mounted to the substructure; an inner wall spaced from the outer wall and including a longitudinal inner bottom rail, a longitudinal inner top rail and a plurality of second studs mounted to and between the inner bottom rail and the inner top rail; the second studs being generally parallel to the first studs of the outer wall, the longitudinal inner bottom rail being configured and sized to be mounted to the substructure in a laterally spaced position from the longitudinal outer bottom rail; whereby (a) the inner and outer walls define a free space therebetween and (b) thermal bridges interconnecting the inner and outer walls are minimized.

According to another aspect of the present invention there is provided an open joist comprising: a longitudinal bottom rail having a generally U-shape cross-section defined by a bottom wall and two opposed side walls; a longitudinal top rail having a generally inverted U- shape cross-section defined by a top wall and two opposed side walls; at least one rail connecting element provided with a longitudinal bottom rail connecting portion, a longitudinal top rail connecting portion and an intermediate portion provided between and connected to the bottom and top rail connecting portions; the bottom rail connecting portion being mounted in the generally U-shaped bottom rail and the top rail connecting portion being mounted in the generally inverted U-shaped top rail.

It is to be understood that the term "wall", used herein and in the appended claims must be construed as including roofs and floors.

Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the appended drawings:

Figure 1 is a perspective view of a portion of a house structure built according to a first embodiment of the wall structure of the present invention;

Figure 2 is a sectional front elevational view of the house of Figure 1 ;

Figure 3 is a sectional top plan view of a window opening of the house of Figure 1 ;

Figure 4 is a sectional top plan view of a wall structure according to the embodiment of Figure 1 ;

Figure 5 is a sectional view taken along line 5-5 of Figure 4;

Figure 6 is a top plan view of a wall structure according to a second embodiment of the present invention, the wall structure illustrating inner and outer walls erected with different studs;

Figure 7 is a sectional view taken along lint 7-7 of Figure Figure 8 is a top plan view of a wall structure according to a third embodiment of the present invention, the wall structure illustrating elements provided between inner and outer walls to maintain a predetermined distance therebetween;

Figure 9 is a top plan view of a wall structure according to a fourth embodiment of the present invention, the wall structure shown being an internal partition provided with first and second spaced apart walls;

Figure 10 is a sectional side elevational view illustrating a two story house constructed according to the first embodiment of the present invention;

Figure 11 is a side elevational view of an open joist;

Figure 12 is a sectional view taken along line 12-12 of Figure 11 ;

Figure 13 is a side elevational view of an open joist mounted to an inner wall of a wall structure;

Figure 14 is a top elevational view taken along line 14- 14 of Figure 13;

Figure 15 is an exploded top plan view of a stud according to an embodiment of the present invention; Figure 16 is a top plan view of a stud according to another embodiment of the present invention;

Figure 17 is a top plan view of a stud according to yet another embodiment of the present invention;

Figure 18 is a side elevational view of an alternate truss according to an embodiment of the present invention;

Figure 19 is a sectional view taken along line 19-19 of

Figure 18; and

Figure 20 is a sectional view taken along line 20-20 of

Figure 18.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to Figures 1 to 5 of the appended drawings a house structure 30 constructed according to the general principles of the present invention will be described.

As discussed hereinabove, the present invention aims at providing a wall structure including an inner wall and an outer wall where the thermal bridges therebetween are minimized. To do so, the two walls are not in direct contact with one another. As will be discussed hereinafter, some connecting elements may be provided between inner and outer walls when necessary. However, these wall connecting elements are made of materials that are poor heat conductors. The studs used to erect inner and outer walls are therefore advantageously stiff and solid. It has been found advantageous to make the studs from aluminum using a conventional extrusion process. The studs are therefore very stiff and their strength may easily be modified by increasing the thickness of the stud walls.

In Figure 1 , the house structure 30 is mounted to a conventional concrete slab 32 and generally includes two assemblies: a wall assembly 34 and a roof assembly 36.

The wall assembly 34 generally includes four peripheral wall structures (only two shown: 38 and 40). As can be better seen from Figure 2, the peripheral wall structure 38 includes an inner wall 42 and an outer wall 44.

The inner wall 42 includes a plurality of studs 50 mounted between a generally U-shaped inner bottom rail 52 and a generally U-shaped inner top rail 54. Each stud 50 has a H-shaped portion 56 and an integral L-shaped portion 58 (see Figure 4). The H- shaped portion 56 provides two channels 60, 62 in which wall forming elements 64 may be inserted while the L-shaped portion 58 increases the strength of the stud 50 by increasing the area of the base of the stud. The internal stud wall 66 of the stud 50 is generally flat and may receive sheet rock panels 68 conventionally mounted via fasteners (not shown). It is to be noted that the wall forming elements 64 and the sheet rock panels 68 are not illustrated in Figure 1 for clarity purposes.

Similarly, the outer wall 44 includes a plurality of studs 70 mounted between a generally U-shaped outer bottom rail 72 and a 8

generally U-shaped outer top rail 74. Each stud 70 has a H-shaped portion 76 and an integral L-shaped portion 78 (see Figure 4). The H- shaped portion 76 provides two channels 80, 82 in which wall forming elements 84 may be inserted while the L-shaped portion 78 increases the strength of the stud 70 by increasing the area of the base of the stud. The external stud wall 86 of the studs 70 are generally flat and may optionally receive furring strips 88 mounted to the studs via conventional fasteners (not shown). It is to be noted that the wall forming elements 64 and the furring strips 88 are not illustrated in Figure 1 for clarity purposes. It is also to be noted that the furring strip 88 is provided with ridges 90 to increase the strength thereof. Exterior covering material (not shown), such as bricks or clapboards, may thus be installed and secured to the furring strips 88.

The external wall 44 may optionally be provided with spacing elements 92 provided with a longitudinal channel 94 and a transversal channel 96. The longitudinal and the transversal channels 94 and 96 are configured and sized to allow the insertion of a top or bottom portion of the studs 70 therein. Since the spacing elements 92 are all identical, the spacing between consecutive studs 70 will therefore be equal. Of course, when spacing elements 92 are used, the top or bottom rail must be designed to receive the spacing element 92. For example, the top rail 74' of Figure 5 includes a thicker top wall 75 provided with a longitudinal channel 77.

As will be apparent to one skilled in the art, the inner wall 42 and the outer wall 44 are not in direct contact with one another to prevent thermal bridges therebetween. It is also to be noted that even though each inner stud 50 of the inner wall 42 is illustrated as facing an outer stud 70 of the outer wall 44 the distance separating consecutive studs 50 could be different from the distance separating consecutive studs 70. For example, to follow conventional construction standards, the distance separating consecutive studs 50 could be 16 inches (about 0,41 metre), while the distance separating consecutive studs 70 could be 24 inches (about 0,62 metre) since the outer wall 44 is not subjected to the load of the roof assembly 36 as will be described hereinafter.

Returning to Figure 1 of the appended drawings, peripheral wall structures 38 and 40 are interconnected via a corner studs 98 and 100 mounted between respective bottom rails 52, 72 and respective top rails 54, 74. The corner stud 98 includes two U-shaped channels 102, 104 configured to receive the wall forming material 64 and an arrow shaped portion 106 designed to adequately contact the top and bottom rails 52, 54. Similarly, the corner stud 100 includes two U-shaped channels 108, 110 configured to receive the wall forming material 84 and a Y-shaped portion 112 designed to adequately contact the top and bottom rails 72, 74.

The wall structure 40 is provided with a window opening

114. The window frame 116 of the window opening 114 in the outer wall 44 consists of two E-shaped studs 118 and 120 provided on either side of the opening 114, two lower E-shaped studs 122 and 124 supporting an inverted U-shaped bottom window rail 126, two rectangular section tubes 128, 130 supporting a U-shaped top window rail 132 and three upper E- shaped studs 134, 136 and 138 mounted between the top window rail 132 and the top rail 74. It is to be noted that a supplementary lower E- shaped stud (not shown) could be provided between studs 122 and 124 depending on the width of the window opening 114. 10

The inner wall 42 also includes a frame similar to the window frame 116. For concision purposes, this frame of the inner wall

42 will not be described in details herein. It is however to be noted that the studs 140, 142 (see Figure 3) further include respective channels 144, 146 configured and sized to receive sheet rock panels 68.

As will be appreciated by one skilled in the art, a window 148 (shown in dashed lines in Figure 3) mounted to the frame 116 of the outer wall 44 has no direct contact with the inner wall 42. Indeed, the only contact between the window 148 and the inner wall 42 is made via finishing elements 150 connecting the inner, insulated, portion of the window 148 and the inner surface of the inner wall 42.

Returning to Figures 1 and 2, the roof assembly 36 will be described in greater details. The roof assembly 36 includes a plurality of rafters 152 (only one shown) mounted on top of the inner walls 42. More specifically, the inner wall 42 includes a thermal bridge limiting assembly 154 provided on top of the inverted U-shaped top rail 54. The rafter 152 are mounted on top of the thermal bridge limiting assembly 154. Therefore, no thermal bridge will exist between the rafter 152 and the inner wall 42.

As can be better seen from Figure 2, the thermal bridge limiting assembly 154 includes a lower U-shaped support 156, an upper U-shaped support 158 and an insulating layer 160 provided between the lower and upper U-shaped supports. The lower support 156 is mounted onto the top rail 54 and the rafter 152 is mounted onto the upper support 158. Of course, the insulating layer 160 must be sufficiently strong to support the weight of the entire roof of the building for a number of years. 11

It is believed that the use of isocyanurate plastic, which is a good thermal insulator and may support great weight in compression, for the insulating layer 160 would be advantageous. Of course, other materials could be used, such as, for example, magnesium and metallic powders, Duralcan™, galvanized steel and even some plastics or wood.

Each rafter 152 includes a U-shaped bottom rail 162, a

U-shaped top rail 164, interconnecting elements 166 mounted between the top and bottom rails, an upper end plate 168, a finition element 170 mounted to the top rail 164 and a mounting element 172 provided between the top and bottom rails.

As illustrated in Figure 1 , the top and bottom rails 162, 164 are provided with inwardly facing lips 174 and the interconnecting elements 166 are provided with corresponding grooves (not shown) allowing the interconnecting elements 166 to be longitudinally inserted in the rails 162, 164. Fasteners (not shown) may then be used to secure the interconnecting elements 166 to the rails 162, 164.

Each interconnecting element 166 includes two aligned portions 176, 178 (see Figure 2) that are parallel with an opposite portion 180. The portion 176 is integrally connected to the portion 180 via a first angled portion 182 while the portion 178 is integrally connected to the portion 180 via a second angled portion 184.

The upper end plate 168 includes an inner portion 186 and a generally flat portion 188. The inner portion 186 enable the end plate 168 to be fixedly mounted to the rails 162 and 164 and the flat portion 188 enables each rafter 152 to be secured to an opposite rafter 12

(not shown) joining the rafter 152 to the peripheral wall structure (not shown) opposite the peripheral wall structure 38. Of course, fasteners (not shown) are advantageously used to connect the flat portions 188 of the opposite rafters.

The finition element 170 is provided to close the bottom end of the rafter 152.

The rafter mounting element 172 provides an adequate contact between the rafter 152 and the inner wall 42. As can be better seen in Figure 1 , the mounting element 172 is similar to the upper end plate 168 since it includes an inner portion 190 and a generally flat portion 192. The inner portion 190 enable the mounting element 172 to be fixedly mounted to the rails 162 and 164 and the flat portion 192 enables the rafter 152 to adequately contact the inner wall 42. Of course, fasteners (not shown) are advantageously used to connect the flat portion 192 to the top support 158 of the thermal bridge limiting assembly 154.

As will be apparent to one skilled in the art, a ceiling (not shown) is advantageously provided at the junction of the wall assembly

34 and the roof assembly 36. This ceiling enables the insulation of the living space from the roof assembly 36. Various possible configurations of this ceiling will be described hereinafter.

It has been found advantageous to use isocyanurate plastic having a thickness of about 1% inches (about 3 centimetres) as the wall forming elements 64 and 84 since this material is durable and a good insulator. Of course, other materials and/or other thicknesses could be used. 13

It is to be noted that the fastening of the different aluminum elements to one another may be done according to various known techniques. For example, the elements could be fastened via self- drilling screws or could be held by aluminum adhesives.

As will be understood by one skilled in the art, many modifications could be done to the house structure 30. For example, the house structure 30 could be erected onto a conventional substructure foundation (not shown) instead of on the concrete slab 32. It is also to be noted that any alternate elements illustrated in Figures 6-20 and described hereinbelow could be substituted to their equivalent illustrated in Figure 1-5 or added to the house structure 30. Of course, some design modifications could be required to allow the use of some elements together. It is however believed to be within the skills of one skilled in the art to do these design modifications.

It is also to be noted that the concrete slab 32 could be provided with embedded heating elements (not shown) provided below the inner wall 42 to enable heat to be transferred to the studs 50 to provide ambient heating.

The roof assembly 36 is illustrated as being supported by the inner wall 42. However, it would be within the skills of one skilled in the art to design a house structure where the roof assembly is supported by the outer wall. Of course, if this the case, the thermal bridge limiting assembly 154 is no longer required since the roof assembly and the outer wall would be subjected to the same external temperature. 14

As will be understood by one skilled in the art, the following general steps could be followed for the construction of the house structure 30 onto a concrete slab 32:

• lay the bottom rail 52 so as to provide desired spacing between the inner and outer walls 42 and 44;

• secure the bottom rail to the concrete slab 32;

• erect the inner wall 42 (including the studs 50, the wall forming elements 64 and the top rail 54);

• install the thermal bridge limiting assembly 154 on top of the inner wall 42;

• mount the rafter 152 to form the roof assembly 36;

• lay the bottom rail 72;

• secure the bottom rail 72 to the concrete slab 32; and

• erect the outer wall 44 (including the studs 70, the wall forming elements 84 and the top rail 74).

Of course, if the outer wall 44 supports the load of the roof assembly 36, this outer wall 44 is erected first.

Turning now to Figures 6 and 7 of the appended drawings, a wall structure 200 according to a second embodiment of the present invention will be described. The general principles of the wall structure 200 are the same as the general principles of the wall structure 30 of Figure 1-5, i.e. providing an inner wall and an outer wall configured 15

and positioned to limit the thermal bridges therebetween. Indeed, the wall structure 200 includes an inner wall 202 and an outer wall 204.

The inner wall 202 includes studs 206 provided with two channels 208, 210, configured and sized to receive wall forming material

212, and a flat inner surface 214 to receive interior wall covering such as sheet rock panels 216. Each studs 206 is also provided with an internal strengthening portion 218.

The outer wall 204 includes studs 220 similar to the studs 206. The major difference between the studs 220 and the studs 206 concerns the strengthening portion 222 which is wider and provided with inwardly facing winglets 224, 226 further providing strength to the stud 220. Referring more specifically to Figure 7, the flat outer surface 228 of the studs 220 allow the installation of furring strips 230. It is to be noted that the particular shape of the furring strips 230 is not critical. However, the generally C-shape of the furring strips 230 provides air space between the outer wall 204 and the external covering material (not shown) that is conventionally installed to the furring strips 230.

The wall structure 200 illustrates that the particular shape of the studs used to erect the inner and outer walls is not critical as long as the studs provide adequate and lasting support for the roof installed thereon. Furthermore the wall structure 200 illustrates that the studs of the inner wall and the studs of the outer wall are not necessarily identical since the purpose of the inner and outer walls is different.

Figure 8 is a top plan view of a wall structure 250 according to a third embodiment of the present invention. Again the wall 16

structure 250 includes an inner wall 252 and an outer wall 254. Both walls 252 and 254 include studs 256 identical to the studs 206 of Figure 6 and mounted in U-shaped rails 258, the description of which will not be repeated here. The corner stud 260 of the external wall 254 is identical to the corner stud 100 illustrated in Figure 1.

The wall structure has the following features that are different from the wall structures 30 and 200 described hereinabove. First the wall structure 250 uses spacing elements, for example elements 262 and 264, to maintain the spacing between the inner wall 252 and the outer wall 254 constant. This feature may be advantageous during the erection of the outer wall 254 when the inner wall 252 is already erected. Of course, at least a portion of the spacing elements used is advantageously made of a heat insulator to prevent the formation of a thermal bridge between the inner and the outer walls.

More specifically, the spacing element 262 is made of two stud contacting portions 266, 268 provided with respective threaded rods 270, 272. A relatively long nut 274 made of heat insulating material such as, for example Nylon™ is connected to the threaded rods 270, 272 to allow the length of the spacing element 262 to be adjusted as required.

The spacing element 264 is much simpler. It consists in a piece of the wall forming material, for example isocyanurate plastic, that is configured and sized to provide the desired spacing between the walls 252 and 254.

Of course, the spacing elements 262 and 264 are secured to the studs 256 via fasteners (not shown). 17

The wall structure 250 is also provided with an internal corner stud 276. The stud 276 may be viewed as being two studs 256 integrally formed at right angle. If a corner stud 276 is used, an angled piece of wall forming material 178 is advantageously used to insulate the internal corner 276.

Turning now to Figure 9 of the appended drawings, an internal wall structure 300 according to a fourth embodiment of the present invention will be described.

The wall structure 300 includes a first wall 302 and a second spaced wall 304. These two walls are interior walls since the wall structure 300 is intended to be used to erect internal partition walls.

The first and second walls 302, 304 include two types of studs. A first stud 306 is generally H-shaped and a second stud 308 is also H-shaped but includes two L-shaped projections 310, 312 to receive sheet rock panels 314 as will be described hereinafter.

It is to be noted that since the wall structure 300 is intended to be used to form internal partition walls, the panels of wall forming an insulating material (see for example 64 and 84 in Figure 3) are not provided between consecutive the studs.

It has been found advantageous to alternate the studs

306 and 308 every about two feet (about 0,62 metre) so as to enable the installation of standard sheet rock panels 314 of four feet (about 1 ,23 metres). Each sheet rock panel 314 is therefore inserted in a channel defined by the L-shaped projection 310 of a stud 308, is adjacent to a 18

stud 306 and is inserted in a channel defined by the L-shaped projection 312 of a subsequent stud 308. The need for joints between adjacent sheet rock panels being eliminated and the need for joints to hide the fasteners used to secure the sheet rock panels to the studs being therefore greatly reduced.

It is to be noted that decorative strips 316 may be mounted in the space separating the L-shaped projections 310 and 312 of the studs 308. However, this space may also be left empty or provided with a decorative paper strip (not shown).

It is also to be noted that the corner stud 318 is also provided with L-shaped projections 320 and 322 and that a decorative corner strip 324 is mounted to the corner stud 318. Similarly, the corner stud 326 is provided with channels 328, 330 configured and sized to receive sheet rock panels.

As will be easily understood by one skilled in the art, it is advantageous to erect a partition wall provided with spaced apart first and second walls since electrical wires and plumbing conduits may be installed within the space separating the first and second walls without requiring a plurality of apertures to be done. Furthermore, the installation of further electrical wires or plumbing conduits, once the construction of the wall is completed is greatly simplified.

Figure 10 of the appended drawings illustrate a sectional side elevational view of a two story house 350 constructed using the wall structure illustrated in Figures 1-5. For concision purposes, only the 19

differences between the house 350 illustrated in Figure 10 and the house 30 illustrated in Figure 2 will be highlighted hereinafter.

The house 350 is erected on a foundation 352 provided with a first subfloor 354 made of a plurality of discrete extruded aluminum elements 356. The first subfloor 354 is mounted to the foundation 352 via a longitudinal mounting element 355 provided with a channel 357 receiving the first of the aluminum elements 356.

It is to be noted that the configuration, size and interconnecting system of the discrete extruded aluminum elements 356 are shown in Figure 10 for illustration purposes.

The outer wall 358 is mounted onto the foundation 352 while the inner wall 360 is mounted onto the first floor 354.

As will be understood by one skilled in the art, since the aluminum studs 362 of the inner wall 360 are in contact with the aluminum subfloor 356, it is possible to simultaneously heat the inner wall 360 and the floor 356 with contact heating elements (not shown).

An open joist 364, having a structure similar to the structure of the rafter 152 described hereinabove, is mounted to the inner wall 360 to provide a second subfloor. As can be better seen from Figure 11 , the open joist 364 includes a bottom rail 366, a top rail 368, a plurality of interconnecting elements 370 and a pair of end plates 372 and 374. Each end plate 372, 374 includes a respective rail connecting portion 376, 378 and generally flat portions 380, 382 laterally projecting from either sides of the rails 366, 368 providing fastening surfaces that enable 20

the open joist 364 to be mounted to the inner wall 360 via fasteners (not shown). It is to be noted that a L-shaped bracket 384 is provided on the inner wall 360 to provide additional support to the open joist 364.

It is to be noted that while the interconnecting elements 370 are shown herein as being solid elements, they could be hollow, provided that the thickness of the walls of these elements are thick enough to ensure an adequate support. For example, rectangular tubes could be used.

Turning briefly to Figure 12, the bottom rail 366 is generally U-shaped to receive the interconnecting elements 370 and includes lateral projections 386, 388 providing fastening surfaces that enable ceiling covering (not shown) to be fastened to the open joist 364 without weakening the open joist. It is to be noted that the top rail 368 could also be provided with such projections to enable floor forming elements (not shown) to be fastened thereto.

The bottom and top rails 366 and 368 may optionally be provided with longitudinal ribs strengthening the rails, thus strengthening the open joist 364. As better seen in Figure 12, the bottom rail 366 includes six longitudinal ribs 390. As will be easily understood by one skilled in the art, the number, size, shape and position of these longitudinal ribs 390 is a function of the required strength of the open joist 364.

It is to be noted that open joist 364 could also be used to replace the aluminum extrusions 356 to form the first floor along with conventional flooring material. If this is the case the top rail of the open 21

joist could advantageously be provided with lateral projections similar to lateral projections 386, 388 of the bottom rail 366 to define a surface where the flooring material may be secure without compromising the structure of the open joist.

Turning now to Figures 13-15 of the appended drawings, an alternate method of mounting the open joist 364 to an inner wall 400 and an alternate structure for an inner wall 400 will be described.

The inner wall 400 includes a plurality of studs 402 made of three distinct elements: a structural element 404, an insulation mounting element 406 and a sheet rock panel mounting element 408. These elements are interconnected via clips 410 made of slightly deformable material such as, for example, galvanized steel.

It is to be noted that when studs 402 are used, a bottom rail 412 provided with separate longitudinal channels 414, 416 and 418, configured and sized to respectively receive the structural element 404, the insulation mounting element 406 and the sheet rock panel mounting element 408 is advantageously used.

The advantage of using separate elements in the formation of the studs 402 is that the structural elements 404 may be installed at the construction of the inner wall 400 and has sufficient strength to structurally support the roof. The insulation panels and the insulation mounting element 406 may be secured to the structural elements 404 during a second step of the building construction. Finally, in a third step, the sheet rock panels and the sheet rock panel mounting element 408 may be secured to the insulation mounting elements 406. 22

Furthermore, the clips 410 provide air space between each element which increase the insulation of the inner wall 400.

As will be understood by one skilled in the art, when studs 402 are used to construct an inner wall 400, the open joists 364 may be directly mounted to the structural elements 404 as illustrated in Figure 13.

Figures 16 and 17 of the appended drawings illustrate alternate devices to replace the clips 410 to secure the various elements of the studs 402' and 402" and illustrate other configurations of the elements of these studs. For example, air spaces 414 and 416 are defined between the elements of the stud 402" illustrated in Figure 17.

Longitudinally slidable securing elements 418 are used to secure the various elements of the studs 402' and 402" to one another. Indeed, the elements of the studs 402' and 402" are provided with longitudinal lips 420 that are maintained in a predetermined relationship by the generally C-shaped securing elements 418.

Figure 16 also illustrates a spacing element 422 provided with a heat insulating portion 424. This spacing element 422 may replace the spacing elements 262, 264 illustrated in Figure 8 when the lips 420 are present.

Turning now to Figures 18-20 of the appended drawings, a truss 450 designed according to the present invention will be described. 23

The truss 450 includes a ceiling joist under the form of a l-shaped beam 452, a generally U-shaped channel 454 mounted to the ceiling joist 452 and provided with inwardly projecting elements 456, 458, first and second insulated rafters 460, 462, first and second struts 464, 466 and first and second side posts 468, 470.

As can be better seen from Figure 20, each rafter includes an outer U-shaped channel 472, an intermediate insulating layer 474 and an inner U-shaped channel 476 receiving the struts 464, 466 and posts 468, 470. Since the inner and outer channels are not in direct contact with one another, but are separated by an insulating layer 474, there will be no thermal bridges between the inner and outer channels. For example, the insulating layer 474 may be made of isocyanurate plastic.

The struts 464 and 466 and of the side posts 468 and 470 are under the form of U-shaped channels and have a lower portion provided with adequate grooves (not shown) configured and sized to cooperate with the lips 456 and 458 of the channel 454.

It is to be noted that the various elements described herein as being made of extruded aluminum could easily be made of other extruded material. The extrusion process, while not being essential to the present invention, is believed the most advantageous since it allows the various elements to be produced at costs significantly lower than with other processes. Furthermore, it is relatively easy to make modifications to the shape and size of the elements with the extrusion process. 24

The wall structure of the present invention has many advantages, such as, for example:

• thermal bridges between outer and inner walls are minimized which enables one to erect a building that is energy efficient, i.e., that requires less energy to cool or to heat;

• the studs and various other elements may be inexpensively made of aluminum extrusions without leading to a thermally inefficient construction; and

• when the wall structure is used to erect internal walls, electrical wires, plumbing conduits or the like may easily be installed in the free space present between the walls without requiring further apertures in the studs.

Although the present invention has been described hereinabove by way of preferred embodiments thereof, it can be modified, without departing from the spirit and nature of the subject invention as defined in the appended claims.

Claims

25WHAT IS CLAIMED IS:

1. A wall structure to be mounted to a substructure, the wall structure comprising : an outer wall including a longitudinal outer bottom rail, a longitudinal outer top rail and a plurality of first studs mounted to and between said outer bottom rail and said outer top rail; said outer bottom rail being configured and sized to be mounted to the substructure; an inner wall spaced from said outer wall and including a longitudinal inner bottom rail, a longitudinal inner top rail and a plurality of second studs mounted to and between said inner bottom rail and said inner top rail; said second studs being generally parallel to said first studs of said outer wall, said longitudinal inner bottom rail being configured and sized to be mounted to the substructure in a laterally spaced position from said longitudinal outer bottom rail; whereby (a) said inner and outer walls define a free space therebetween and (b) thermal bridges interconnecting said inner and outer walls are minimized.

2. A wall structure as recited in claim 1 , wherein said inner and outer walls are generally vertical.

3. A wall structure as recited in claim 1 , wherein said inner wall includes first and second opposed longitudinal ends; at least one of said first and second longitudinal ends including a corner stud configured and sized to connect said inner wall to another similar inner wall having a different longitudinal direction. 26

4. A wall structure as recited in claim 1, wherein said outer wall includes first and second opposed longitudinal ends; at least one of said first and second longitudinal ends including a corner stud configured and sized to connect said outer wall to another similar outer wall having a different longitudinal direction.

5. A wall structure as recited in claim 1 , further comprising means for maintaining a predetermined distance between said inner and outer walls.

6. A wall structure as recited in claim 1 , wherein said outer wall includes means for maintaining a predetermined distance between adjacent first studs.

7. A wall structure as recited in claim 1 , wherein said inner wall includes means for maintaining a predetermined distance between adjacent second studs.

8. A wall structure as recited in claim 1 , wherein each said second studs include a panel portion configured and sized to receive wall forming panels.

9. A wall structure as recited in claim 8, wherein each said second studs include a finition receiving portion configures and sized to receive a finition panel.

10. A open joist comprising: a longitudinal bottom rail having a generally U-shape cross-section defined by a bottom wall and two opposed side walls; 27

a longitudinal top rail having a generally inverted U- shape cross-section defined by a top wall and two opposed side walls; at least one rail connecting element provided with a longitudinal bottom rail connecting portion, a longitudinal top rail connecting portion and an intermediate portion provided between and connected to said bottom and top rail connecting portions; said bottom rail connecting portion being mounted in said generally U-shaped bottom rail and said top rail connecting portion being mounted in said generally inverted U-shaped top rail.

11. An open joist as recited in claim 10, wherein said rail connecting element is tubular and has a generally rectangular cross- section.

12. An open joist as recited in claim 10, wherein said open joist includes first and second opposed longitudinal ends; at least one of said first and second longitudinal end being provided with an end plate provided with lateral projections defining fastening surfaces.

13. An open joist as recited in claim 10, wherein said lateral walls of at least one of said bottom and top rails are provided with integral external longitudinal ribs strengthening said at least one of said bottom and top rails.

14. An open joist as recited in claim 10, wherein at least one of (a) said bottom wall of said bottom rail and (b) said top wall of said top rail is provided with lateral projections defining fastening surfaces.