Field of the Invention

This invention relates to construction systems and more particularly for systems for attachment of curtain wall perimeters to multi-level residential building developments including arrangements for attachment of brick cladding to the curtain wall.

Background of the Invention

For multi-unit residential buildings that extend over several floors, typical construction methods provide a concrete or a steel structure which supports the floors that are stacked to form the multi level or high rise building. The perimeter portion of the building is enclosed by a curtain wall which attaches to the structure to form a "weather screen". The construction methods heretofore employed provide for a framing arrangement, floor to floor supported by the structure, with a shelf angle attached to the structure at each floor to support the brick cladding extending around the perimeter of the building. Typically, the framing provided in residential high rise buildings includes light- gauge-metal (LGM) studs which extend between the floor and the ceiling of each level of the structure. The stud framing forms a cavity between the interior and exterior surfaces defined by the framing to receive insulation and accommodate any electrical wiring that is provided in the perimeter of the building. On the interior surface of the framing an interior finish such as drywall is applied and on the exterior surface of the framing, insulation, a wind barrier and weatherproof material such as brick is applied.

Window assemblies are subsequently incorporated into the wall to provide a source of natural light and ventilation into the residential units of the building. Brick ties are installed in two parts, the inner portion of which, is screwed into the web of the framing studs and protrudes through the subsequently applied exterior insulation and wind barrier. The exterior portion of the wall is finished by applying a weather resistant brick surface that is supported by a shelf angle attached directly to the structure at each floor and retained in its vertical plane by attachment of the second portion of the brick ties. During the placement of bricks, the brick ties extending from the framing can, and frequently do, cause head and eye injury to personnel working on the scaffolding to prepare for, and lay the brick. Thus the conventional system of building cladding results in a hazard to brick layers, insulators and others working on the scaffolds. The conventional cladding process also causes thermal bridging between the framing and the brick. The perforation of the insulation and wind barrier by the brick ties, even with subsequent caulking, will compromise the value of both energy conservation products.

During construction of a multiunit residential building, or high rise residential building, the floors and supporting columns of the structure are first constructed. Where concrete construction is used, the floors are poured sequentially, one after the other, until all of the floors of the structure are constructed. While the floors are being poured, the curtain wall framing can proceed on lower floors that have cured sufficiently through passage of time. Generally, however, the exterior surface of the curtain wall is not applied until all of the floors of the building have been completed as a safety measure to protect workers on the exterior of the building while forming, steel setting and concrete pouring is in process overhead.

The construction systems heretofore employed have a number of shortcomings. For example with conventional construction techniques, commencement of building cladding is not started until all of the floors of the superstructure have been completed. Consequently, interior trades are delayed pending protective enclosure of the structure. Interior work on the construction is also delayed due to the sequential nature of the cladding process Le.- framing between floors, exterior application of insulation and wind barrier, laying of brick and finally installation of exterior doors and windows.

Summary of the Invention

The present invention provides a construction system for use with multi-unit residential buildings that extend over several floors to provide the perimeter enclosure portion, or curtain wall, of the building.

In accordance with the invention, perimeter wall sections are constructed for attachment to the structure of the building. The perimeter walls sections are provided in wall panel assemblies that inter-fit to form the building perimeter wall. The wall panel assemblies are supported on the building by attachment to shelf angles that extend around the perimeter of each building floor slab. The shelf angles are attached to anchors provided in the edge portion of the building floor slabs. The preferred manner of attachment of the shelf angles to the anchors includes adjustment means to provide precise alignment of the shelf angles to horizontal and true straight lines to accommodate construction tolerances. The upper portion of each wall panel assembly is connected or attached to an upper shelf angle

using a pin that extends between the shelf angle and the wall panel that is installed after the wall panel is aligned. The lower portion of the wall panel rests on the shelf angle of the lower floor, which is also attached to the upper portion of the wall panel of the lower floor.

A preferred manner of installing the curtain wall sections is to hoist a curtain wall section and it's associated upper shelf angle, to which the curtain wall section is preliminarily attached, up to the location of the building where it will be installed. Preliminary attachment of the curtain wall section to the upper shelf angle allows limited relative movement between the curtain wall section and the upper shelf angle. When the curtain wall section is initially positioned on the building, its lower portion will rest on the shelf angle of the floor below. The upper shelf angle is then attached to anchors provided on the perimeter of the building. Once the upper shelf angle is installed, the lower portion of the just positioned wall panel section will be installed on or attached to the lower shelf angle that it is resting on. The preferred manner of installation of the lower portion of the just positioned wall panel is effected by providing oversized holes in the bottom surface or track that are positioned over the bolts holding the lower wall panel section in place. The just positioned wall panel section is aligned and mated with its adjacent wall panel section and a horseshoe washer is placed over the oversized holes in the lower track and those bolts are tightened to install and secure the lower portion of the just positioned wall panel section.

Next the just positioned wall panel section is plumbed and its upper portion is permanently installed or secured to the upper shelf angle. Permanent installation to the upper shelf angle is accomplished by providing threaded holes in the upper shelf angle through which threaded pins that extend to engage mating holes in the upper track.

A drill guide is threaded into the threaded holes in the upper shelf angle to permit drilling of mating holes in the upper track.

In another of its aspects the invention provides apparatus to attach a brick cladding to a building exterior. The brick courses rest on a shelf angle arranged to extend around the perimeter of the building. A plurality of generally vertically extending channels is installed around the building. The channels provide channel engagement means extending along the length of the channel. As brick laying proceeds, elongate brick ties are installed in the channels. The elongate brick ties have complementary brick tie engagement means at one end that couple to the channel engagement means. In the preferred arrangement, symmetrical shoulder portions facing inwardly across the channel area embody the channel engagement means. The elongate brick ties have a complementary brick tie engagement means in the form of a tab extending across a head portion of the brick tie. The brick tie is snapped into the channel to secure the brick tie to the building. Thereafter brick is laid to sandwich the brick tie in the mortar used to hold the bricks in place.

Preferred embodiments of the invention will now be described with reference to the attached drawings. Like features of the invention are denoted by like reference numerals throughout the various figures of the drawings.

Brief Description of the Drawings

Figure 1 shows a cross-section elevation view of a structure that has an embodiment of an exterior curtain wall arranged in accordance with the present invention.

Figure 2 shows an exploded view of certain components of a curtain wall section constructed in accordance with the principles of the invention.

Figure 3 shows a cross-section of the shelf angle and upper track coupling arrangement taken along cutting line 3-3 of Figure 2.

Figure 4 shows a cross-section taken along line 4-4 of Figure 2 showing the placement of a drill guide that is used to drill pin receiving holes into the upper track

Figure 5 shows a cross-section view of the shelf angle and upper track coupling arrangement taken along cutting line 5-5 of Figure 2 showing the fixing means that fixes the upper track portion of a wall section to a shelf angle.

Figure 6 shows a cross-section corresponding to the cross-section of Figure 5 where curtain wall sections are shown stacked for two consecutive floors.

Figure 7 shows a portion of the cross section of Figure 6 further including a sealing element.

Figure 8 shows the cross-section of the curtain walls of Figure 6 further including providing an exterior finish of brick veneer.

Figure 9 shows a horizontal cross section of a brick-cladded curtain wall section constructed in accordance with the principles of the present invention.

Figure 10 is a sequence of perspective views of a brick tie channel and brick tie showing the insertion of a brick tie into the brick tie channel.

Figure 11 is a perspective view of a preferred embodiment of a wall section including brick tie channels and a portion of brick cladding.

Detailed Description of the Preferred Embodiments

Figure 1 shows a cross-section elevation view of a structure that has an embodiment of an exterior curtain wall arranged in accordance with the present invention. The structure has a foundation slab on grade or as part of a basement foundation 10, one or more floor slabs 12, and a roof slab 14. These slabs, 10, 12, 14 form the structure of the building to which the curtain wall arrangement of the present invention is attached. A plurality of anchor assemblies 16 are disposed around the outer perimeter of each slab 12 and 14 used to attach the curtain wall to the building structure.

In accordance with the invention, the curtain wall of the building is provided in panels or sections 20 and each of the curtain wall sections is attached to the building anchor assemblies 16. A shelf angle 18 is attached to the building anchor assemblies 16 and to an upper portion of the curtain wall section 20. Alignment means facilitate the attachment of the shelf angle 18 to the anchor assemblies 16 to facilitate precise alignment or placement of each wall section 20 on the perimeter of the building. As shown most clearly in Figures 1 and 3-6 an anchor wedge 19 is provided in the anchor assembly to prevent movement of the shelf angle under loading once the shelf angle is leveled, aligned and bolted in place.

In accordance with the invention, the curtain wall is formed in sections 20. Each curtain wall panel or section 20 may be fabricated or assembled at the construction site, however, the sections are preferably fabricated in a factory or manufacturing facility, which can be located remote or off-site from the construction area. The completed or fabricated curtain wall section 20 is delivered to the construction site, typically complete with windows, doors, insulation and wind-barrier installed. In the preferred embodiment, an interlocking 'male-female' connection, explained in more detail with reference to Figures 2 and 9, is provided in the vertical interface between adjoining panels to prevent differential deflection under wind loading. The application of a brick cladding or veneer 66 is an independent operation that can take place as weather permits and labour is available.

The curtain wall sections 20 provide a protective weather envelope for completing the building construction and facilitating early user occupancy. The curtain wall extends around the perimeter of the building and, generally, each of the sections 20 forming the curtain wall is attached to and rests on shelf angles 18. However, for the ground floor sections, there may be other arrangements for the support of the curtain wall sections. For example, where the building foundation is a slab 10 as shown in Figure 1 , the lowest or first curtain wall sections would be attached to and rest on the floor slab 10. The curtain wall extends up the exterior perimeter of the building to the roof slab 14. The roof curtain wall section 21 is attached to the roof slab 14 and is typically much shorter in height than the curtain wall sections for the lower floors. The roof curtain wall section 21 extends above the roof slab 14 forming a perimeter extension that surrounds the roof portion of the building. Typically, the roof curtain wall sections are supported in a cantilever fashion using a roof cantilever

angle 23 that is bolted to the top of the roof slab 14 and to the interior face of the framing of the roof curtain wall section. Depending on the manner of construction, other forms of roof curtain wall sections may be used, for example a concrete parapet wall. Also, the roof curtain wall may be attached to a concrete parapet wall that extends upwardly from the roof slab, for structural integrity will higher extensions of the roof curtain wall from the roof slab. Preferably the framing elements of the curtain wall sections are light gauge metal (LGM) construction studding.

Figure 2 shows an exploded view of the framing components of a curtain wall section constructed in accordance with the principles of the invention. The curtain wall section 20 has a lower track 22 and upper track 24 to which stud framing members 26 are attached on centers determined by anticipated structural loads. Preferably, a vertical side of each panel is provided with a female coupling 36 to provide a male-female interconnection between adjacent panels (Refer also to Fig. 9).

The upper track has an upper attachment 28 at each end, which preferably is a carriage bolt. Upper attachment 28 is used to attach a top portion of the curtain wall section 20, formed by the track or rail and stud member assemblies 22, 24, 26 and 36, to shelf angle 18. Shims 31 are provided when necessary to permit lateral or in and out alignment of the shelf angle 18 in relation to an anchor assembly 16. The shims 31 correct for discrepancies in the concrete structure. Allowance for further adjustment of the wall section 20 is provided by the oversized holes in the shelf angle to receive the bolts 28. The anchor assembly 16 includes a vertically extending slot 17 that facilitates vertical alignment of the shelf angle 18 in relation to the slab to which the shelf angle is attached. A horizontally extending slot 32

is provided in the shelf angle 18 to facilitate the lateral alignment of the shelf angle 18 in relation to the slab.

The shelf angle 18 is used to attach the curtain wall section to a slab and support the curtain wall section on the exterior portion of the building. The shelf angle is attached to the building using any suitable attachment means, such as for example, slab attachment bolts 30, which extend from anchor assembly 16. The shelf angle could also be attached to the anchor assembly by welding.

In the preferred embodiment, vertical adjustment means are provided to enable exact horizontal alignment of the shelf angle irrespective of the precise or exact locations of the anchor assemblies on the slab. The anchor assemblies need not be placed precisely horizontally and precise horizontal placement is unlikely if not impossible with structure construction tolerances. In the preferred embodiment, vertical adjustment means are constructed using a square headed bolt 30 extending through a vertically oriented slot 17 provided in anchor assembly 16, which permits the adjustment of self angle 18 up or down relative to the slab. After the shelf angle is adjusted or positioned to horizontal alignment, nut 34 is tightened on the bolt 30 extending from the anchor assembly 16. Once the bolt is tightened, the shelf angle can not move down. An anchor wedge 19, as is shown, for example, in Figures 1 , 3, 4, 5 or 6, is preferably used to provide a wedging action under subsequent loading that further ensures that there is no relative movement of the shelf angle after alignment and tightening.

Where the shelf angle is not welded to the anchor assembly, at least one aperture 32 is provided in the shelf angle to receive a slab attachment bolt 30 therethrough to attach the shelf angle to the slab.

Of course, in practice at least two or possibly several apertures would be provided in each shelf angle to permit multiple attachment points between a shelf angle and the slab. Preferably, each aperture 32 is provided as a slot that extends generally longitudinally or horizontally to permit horizontal alignment of the shelf angle and its corresponding wall section. The length of aperture 32 is sufficient to permit the shelf angle of a wall section 20 to be mounted on the desired slab attachment bolts 30 yet provide some freedom of horizontal movement to allow the wall section to be adjusted horizontally with respect to the slab. Moreover, the longitudinal or horizontal direction of the apertures 32 permits alignment of each aperture 32 to the bolt extending from its corresponding anchor assembly 16. Construction tolerances for location or placement of each of the anchor assemblies 16 around the perimeter of the slab will not result in uniform exact spacing of each and every anchor assembly from adjacent ones. Consequently, providing longitudinally extending apertures in the shelf angle will permit alignment of the attachment bolts to each corresponding aperture and overall alignment of each curtain wall section to an adjacent section, including alignment at the exterior corners of the building. As will be understood, the number of slot and bolt assemblies 32, 30 that are provided to attach a curtain wall section 20 to the slab will vary depending on the weight and width of the curtain wall section. Once shelf angle 18 is properly aligned and leveled, the nuts 34 are tightened to fix the shelf angle to the slab.

As will be understood, the anchor assemblies 16 may not all extend in an exactly straight line. Therefore, there may be the need to interpose shims 31, such as washers, between the shelf angle and the anchor assemblies to provide for lateral adjustment of the shelf angle to each of the anchor assemblies and maintain the shelf angle extending along a true straight line.

Generally, a lifting mechanism such as a crane is used to hoist an assembled curtain wall section up to the slab to which it will be attached. Any suitable coupling of the crane to the curtain wall section may be used. For example using a spreader with 'horse shoe quick-connect brackets' that are inserted under shelf angle 18 through bolts 28. This permits subsequent fixing of the self angle 18 to the anchor bolt 30 before disconnection of the hoisting assembly.

Lower track 22 is provided with a plurality of oversized holes 38 and 40 that allow the lower track to be positioned flat on the lower shelf angle 18 of the corresponding lower wall section. The oversized holes 38 and 40 permit freedom of movement of the lower track 22 with respect to the lower angle and protruding bolt heads 28 and 48. When a wall section is attached to the edge of a slab using the nut, slot and bolt arrangement 30, 32 and 34, the carriage bolt 28 provided on the upper track 24 is loosely retained with respect to shelf angle 18 by nut and washer pair 42 and 44. In this manner, when shelf angle 18 is fixedly attached to the slab during construction, the upper track 24 retains the ability to be adjusted with respect to shelf angle 18 as the carriage bolt and corresponding nut and washer 42 and 44 are not tightened. Consequently, the upper track 24 and corresponding curtain wall section 20 still retains minor freedom of movement, in and out, with respect to the slab. Immediately after placement, the upper track 24 is not completely tightened. Consequently, the bottom rail or lower track 22 merely rests on either the corresponding shelf angle 18 of the curtain wall section 15 of the floor below or the foundation slab of the building.

Once the shelf angle and corresponding suspended curtain wall section 20 has been lifted into place and bolted to the slab, the lower

track 22 of the curtain wall section 20 is secured in place. The lower track 22 has oversized apertures 38 and 40 to enable the lower track to fit over the bolt and washer 28, 42 and 44 sit on a level plane of the shelf angle 18. These oversize holes permit alignment of the curtain wall section 20 prior to fixing in place over the assemblies that secure the curtain wall panel section 15 below the one of interest. In this way, the lower track 22 can be lowered onto the shelf angle 18 of the curtain wall section 15 of the floor below. The lower portion of the curtain wall section 20 is now aligned to the outside surface of the curtain wall section 15 located immediately below it and thus is in alignment with the exterior surface of the building. After alignment, the horse shoe shims 46 are inserted under the locating pins 48 and the locating pins 48 are tightened.

The upper track 24 of the curtain wall section retains freedom of movement in relation to shelf angle 18 to which it is mounted as the threaded carriage bolts 28 are not completely tightened to the shelf angle 18. Once the lower track 22 has been fastened with the horse shoe shims 46 in the manner described above, the wall section can be plumbed and aligned in relation to the desired exterior surface of the building. When the wall section has been plumbed and aligned, it is secured in place by tightening nut 42 which places the wall section in tension with its lower track 22 affixed to the shelf angle 18 and curtain wall section 15. The upper track 24 is now in a fixed relation to the shelf angle 18 proximal to the upper track 24 due to the tightening of nut 42 on bolt 28 that extends through the upper track 24.

When the upper track 24 has been aligned, a drilling sleeve 54 is threaded into each successive threaded hole 52 of the upper shelf angle 18 to permit a pin receiving hole 56 to be drilled into the upper

track 24 as described more fully with reference to Figure 4. Thus when the corresponding threaded pin coupling 48 is threaded into the upper track 24, the pin portion 58 of the threaded pin coupling will be received into the pin receiving hole 56. Mating of the pin portion 58 of the threaded pin coupling in the receiving hole 56 secures the upper track and hence the curtain wall section 20 in fixed relation to the upper shelf angle 18. However, the upper track 24, as a fixed part of the curtain wall section 20 remains free to absorb structural movement up or down relative to the shelf angle 18 within the limits of anticipated deflections and shrinkage of the building structure.

Figure 3 shows a cross-section of the shelf angle and upper track coupling arrangement taken along cutting line 3-3 of Figure 2. The carriage bolt 28 is preferably secured to upper track 24 by means of a square washer 60 that is provided to grip the head portion of the carriage bolt 28 to prevent its rotation within the channel formed by the upper track 24. To retain the carriage bolt within the upper track 24, a spring clip washer 62 is provided. In this manner, the threaded portion of the carriage bolt 28 extends upwardly from upper track 24 where it can be attached to a shelf angle 18 by threading a nut and washer 42, 44 over the end of carriage bolt 28 as shown in the figure.

Figure 4 shows a cross-section taken along line 4-4 of Figure 2 showing the placement of a drill guide 54, which is used to drill pin receiving holes 56 into the upper track 24. Once the drill guide 54 has been mounted by threading it into the threaded hole 52 in the shelf angle 18, a drill bit 55 is passed through the drill guide 54 to drill a pin receiving hole 56 into the upper track 24. Once the pin receiving hole is drilled, the drilling sleeve 54 is removed from the shelf angle 18, and a threaded pin coupling 48 is then partially screwed into the threaded hole 52 of the shelf angle 18. As shown in Figure 5, once

the threaded pin coupling is screwed into the threaded hole, the upper track 24 is fixed to the shelf angle 18. When the threaded pin coupling is mounted, it prevents the upper track from lateral movement with respect to the shelf angle 18 but does not constrain the track from movement up or down as the concrete structure moves as a consequence of heating, loading and aging.

Figure 5 shows a cross-section view of the fixing means that fixes the upper track 24 securely, in final lateral aligned position, to shelf angle 18 by means of the threaded pin coupling 48. The threaded pin coupling 48 is partly turned into the threaded hole 52 provided in the lower reach of shelf angle 18. A pin receiving hole 56 was previously drilled into upper track 24 when the curtain wall section 20 was aligned and plumbed in its final desired positioning with respect to the structure that to which it is attached. Thus, the threading of the threaded pin coupling 48 into the shelf angle 18 causes the pin portion 58 of the threaded pin coupling to protrude into the pin receiving hole 56 of the upper track and fix the position of the upper track with respect to the shelf angle 18. At the point of construction shown in Figure 5, where only the lower wall section is placed, the threaded pin coupling 48 is not fully tightened into shelf angle 18. The threaded pin coupling 48 is not fully tightened pending placement of the next level of curtain wall sections for the floor above. That is, the threaded pin coupling is not fully tightened since the lower track 22 and accompanying horseshoe washer 46 of the wall section of the next floor up has not yet been mounted on the structure.

Figure 6 shows a cross-section corresponding to the cross-section of

Figure 5 where curtain wall sections are shown stacked for two consecutive floors. The upper curtain wall section 20 has its lower track 22 secured in place by means of a horseshoe washer 46

tightened into contact with the lower track by tightening the threaded pin coupling 48. An outer surface element 65 is attached to the outer or exterior surface formed by stud framing members 26 to construct an outside wall. Preferably the outer surface element is pre-attached. The outer surface element is a combination of rigid panel material such as wood or fiber cement board that provides backing to a rigid insulating material. These materials are fixed to the studs of the structural element of the wall section 20 by means of coated self tapping screws extending through dimpled flat washers, the rigid insulation and the backing material. An inner surface element 64 is attached to the inner or interior surface formed by stud framing members 26. Preferably the inner surface element 64 is a rigid board material such as gypsum board to provide an interior wall surface that can be finished and incorporated into the interior wall material provided elsewhere in the room or rooms of the building interior. The interior space between the stud elements 26 may be filled with insulating material such as fibre batts to provide additional insulating value to the composite curtain wall section 20. Each curtain wall panel or section 20 may be fabricated or assembled from the stud framing elements, 26, outer surface element 65 and inner surface element 64 at the construction site. However, the sections are preferably fabricated in a factory or manufacturing facility, located remote or off-site from the construction area. Consequently, access at least to the lower interior portion of each curtain wall panel is required to attach it to the building that it will form part of. A bottom portion of the inner surface element 64 is left open to permit access to threaded pins 48 for insertion of the horseshoe washers 48 and tightening of the pins 48. With the interior surface access, the curtain wall panel sections can be installed without any need for scaffolding.

Figure 7 is an enlarged portion of the cross section of Figure 6 further including a resilient seal 72 placed between two wall sections. The lower track 22 is held in fixed relation to the shelf angle 18 by means of horseshoe washer 46 that is compressed by the threaded pin coupling, to lock the lower track 22 from movement relative to the lower shelf angle 18. The resilient seal 72 is able to fill continuously the space between the upper and lower curtain wall sections 20, 15 as shelf angle 18 moves up or down under varying live loads and structural aging.

Figure 8 shows the cross-section of the curtain walls of Figure 6 further including provision of an exterior finish of brick veneer 66. The brick veneer 66 is supported on the exterior of the curtain wall assembly by resting on a shelf angle 68 attached to the flange of framing member stud 26 by means of a bolt assembly 70. Preferably, the bolt assembly 70 passes through a compression block 71 provided to reduce thermal bridging between the shelf angle 68 and the flange of the stud member 26. Compression block 71 may be constructed from any suitable material, such as for example, fiberglass material. A resilient seal 72 is placed in the expansion gap between curtain wall sections. The expansion gap may be sealed using any suitable sealing agent such as expandable polypropylene foam rope. The joint is subsequently caulked with a weather resistant caulking as required during field installation. Similarly the gap extending on the outer face of the building around shelf angle 68 may be caulked with a suitable foam, caulking or combinations of materials or agents.

Figure 9 shows a horizontal cross section of the brick-cladded curtain wall sections 20. The male-female interface is shown in the relationship of the 'male' stud 26 of panel 20 inserting into the 'female'

track or coupling 36 of the adjacent panel 20. This provides a tight interface for the full height of the joined sections or panels of the curtain wall and prevents differential deflection between panels that could cause infiltration and damage to the brick cladding. No other mechanical bolting or screwing is required as the positioning of the panels is directly controlled by the threaded pin coupling through top and bottom tracks of each panel and the shelf angle attached to the concrete structure.

The invention provides apparatus for attachment of a brick cladding to the exterior portion of the wall channels. Metal channels 76 are attached to the exterior surface of the wall sections. The preferred manner of attachment is with screws 78 that extend through the channel 76, outer surface element 65 to attach to the stud framing members 26. The channels have channel engagement means 82 adapted to couple with complementary brick tie engagement means 84. In the preferred embodiment, symmetrical shoulder portions facing inwardly across the channel area and extending along the length of the channel provides the channel engagement means 82. Each brick tie has a tab extending across the width of the head portion of the brick tie 86 that forms a complementary brick tie engagement means 84. The brick tie 86 is a substantially flat elongate object typically constructed from metal. The wall section 20 is readied for brick ties when the outer wall sections 20 are secured to the building structure. There are no brick ties extending from the curtain wall sections as they are placed onto the building structure. Consequently, there is no possibility of injury to construction personnel through inadvertent or accidental contact with pre-placed brick ties that extend from the wall surface during the construction of a curtain wall in accordance with this aspect of the invention.

As shown most clearly with reference to Figures 10 and 11 , to apply a brick cladding, vertical runs of channel 76 are screwed to the outer wall of the wall sections 20. Figure 10 is a sequence of perspective views of a brick tie channel and brick tie showing the insertion of a brick tie into the brick tie channel. Figure 11 shows a perspective view of a preferred embodiment of a wall section including brick tie channels and a portion of brick cladding.

The lower course of bricks rests on shelf angle 68 and brick ties are inserted as needed when the brick is laid in courses. The brick ties 86 are snapped in place only as the laying of brick progresses. The brick ties 86 are inserted into channel 76 and rotated to engage the brick tie tabs 84 within the shoulders 82 of the channel. The end of the brick tie distal from the brick tie engagement means is sandwiched in the mortar between brick layers during construction and preferably includes serrations 87 to assist in adherence of the brick tie to the mortar. The inside facing surface of the brick is laid against the vertically aligned channels 76 which serve as spacers to provide an air space for equalization of internal and exterior air pressure and thus reduce potential leaking in the curtain wall.

Now that the invention has been described with reference to preferred embodiments and the attached drawings numerous substitutions and equivalents will occur to those skilled in the art. The invention is not, - however, limited to the specific embodiments described, but rather is defined by the claims appended hereto.