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Document Type and Number:
WIPO Patent Application WO/2019/140514
Kind Code:
An assembly of purpose-made components that individually and collectively provide a high performance thermal wall system for the exterior of buildings, functioning like a vertical truss, to accommodate up to 400mm of wall insulation or more, with near thermal - bridge-free construction, and providing support for an exterior wall cladding system. The system components include a factory-dimpled and milled intermediate steel girt attached with a specially threaded screw through insulation to the structure and vertically supported by a heavy-gauge bent wire tension strap that carries the wall loads onto the building structure; a die-formed bent steel clip to support the exterior part of the wall system onto the girt, with a thin plastic thermal break separating the clip from the girt. The system relates to architecture and building construction for use with a wide range of structural systems, insulation, and cladding types.

LEANING, Anthony (164 DRUMMOND STREET, Ottawa, Ontario K1S 1K4, K1S 1K4, CA)
Application Number:
Publication Date:
July 25, 2019
Filing Date:
January 15, 2019
Export Citation:
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LEANING, Anthony (164 DRUMMOND STREET, Ottawa, Ontario K1S 1K4, K1S 1K4, CA)
International Classes:
Foreign References:
Attorney, Agent or Firm:
MACRAE & CO. (222 Somerset St. West, Suite 600Ottawa, Ontario K2P2G3, K2P2G3, CA)
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1. A thermal wall assembly for buildings having an exterior layer of insulation, comprising:

a girt arranged external to the insulation;

a suspension strap connected and angled out from the wall to the girt; a screw attaching the girt to the wall; and

strapping for cladding, wherein the strapping is secured to the girt.

2. The thermal wall assembly of claim 1 further comprising a clip connected to the girt, wherein the girt is adapted to support the clip and a second layer of insulation.

3. The thermal wall assembly of claim 2 wherein the strapping is attached to the clip.

4. The thermal wall assembly of any one of claims 1 to 3 wherein the screw has a reduced diameter shank for a portion of length.

5. The thermal wall assembly of any one of claims 1 to 4 wherein the girt further comprises one or more factory punched dimples for receiving the screw therein. 6. The thermal wall assembly of any one of claims 1 to 4 wherein the suspension strap, girt, strapping, and screws form a triangulated and rigid structural frame.

7. The thermal wall assembly of any one of claims 2 to 6 wherein the clip extends outward from the girt in a direction away from the wall.

8. The thermal wall assembly of claim 2 wherein the thermal clip further comprises slotted holes for screw fasteners, die-formed ribs and dimples at points of contact with the girt.

9. The thermal wall assembly of any one of claims 1 to 8 wherein the girt has an L- shape.

10. The thermal wall assembly of any one of claims 1 to 8 wherein the girt has a Z- shape.

11. The thermal wall assembly of any one of claims 1 to 10 wherein the suspension strap has flanges on one or both ends for attachment of the strap to the wall or girt.

12. The thermal wall assembly of claim 11 further comprising one or more screws attaching the suspension strap to the wall or girt through the flanges. 13. The thermal wall assembly of claim 1 wherein the screw attaches the girt to the wall through the insulation.

14. The thermal wall assembly of any one of claims 1 to 13 wherein the insulation is rigid or semi-rigid and contributes to structural rigidity of the assembly.

15. The thermal wall assembly of any one of claims 1 to 14 wherein the girt is horizontal and the strapping is vertical.

16. The thermal wall assembly of claim 5 wherein the dimples increase an effective thickness of girt material at threads of the screw.

17. The thermal wall assembly of claim 6 wherein the strapping is offset on the girt from the suspension straps and screws attaching the girt to the wall. 18. The thermal wall assembly of claim 8 wherein the dimples at points of contact with the girt provides rigid support and minimizes heat losses due to thermal bridging.


Technical Field

The present invention relates to a thermal wall assembly system for buildings.


In building construction, an important component of the building is the exterior building envelope which consists of walls, roof, exposed floors and foundations. The building envelope has several functions, such as appearance, keeping out weather, noise and pests, controlling heat loss during cold weather, heat gain during hot weather, as well as controlling moisture migration and damaging condensation within the exterior envelope.

One of the most critical and costly functions of the envelope is controlling heat loss during cold weather, and a range of construction technologies exist for this purpose, all of which rely on insulation of some form located within the building envelope. Most insulation is placed either in the space created by the exterior structure, or outside of the structure and in the case of exterior walls, just behind the cladding where it has the advantage of keeping the structure warm, and minimizing interruptions through the insulation by structural penetrations. As building codes get stricter in response to the cost of energy and efforts to reduce climate change impacts from buildings, more insulation is being used in a continuous layer on the outside of buildings.

For exterior walls, this has triggered a new range of building construction technologies for supporting exterior cladding while providing a deep space to fit the increased insulation. A desire of all of these new technologies is an ability to support the exterior cladding with a minimum of material penetrating the insulation that will conduct heat through and bypass the thermal performance of the insulation. Most of these systems are described as thermally broken wall cladding support systems. Most thermally broken wall cladding support systems, while reasonably effective, add significant cost to the exterior wall envelope, as they use purpose-made specialized components and require dedicated manufacturing processes involving multiple components. Less expensive, simpler solutions are needed in the market.

The current systems function as brackets and metal support rails secured to the structural wall and cantilevered through the insulation to support the cladding. They require robust profiles to provide sufficient strength of support through the wall. They also require two or more screw fasteners to secure the separate components of the system together and then secure the entire assembly to the wall. Since the systems must work as cantilevers, they have limited reach, and can only accommodate up to l50mm for most and up to 200mm for a very few systems. This depth is just enough for insulation thickness under current codes for most cold climates, but will not be sufficient should code requirements increase over the next several years. As a new generation of low-energy buildings is developing to reduce energy demand to the level that can be supplied with on-site renewable energy (Net Zero Buildings), insulation thickness will increase to 300mm and greater depending on location. Commercial systems are either non-existent or very costly to meet this need.

Existing systems have robust components with multiple screw fasteners penetrating the insulation layer. These components are made with materials such as steel and fiberglass which variously have greater thermal conductivity than insulation and therefore create thermal bridges which increase the heat loss through the entire system. Compensation for these additional heat losses is desired. Thermal bridging occurs when insulation support structures convey heat from the building wall to the exterior side of the insulation. It is desirable to minimize thermal bridging. All current systems rely on support from the building structure which often is provided by steel or wood framing. As it is difficult to co-ordinate location of the wall framing members with the required location of support behind the cladding panels, most of these systems rely on additional intermediate components to address offsets between the cladding support and the wall framing. These additional components add material and labour cost to these systems. Few of these systems are designed to use locally available components that would improve cost and competitiveness in more regional and remote locations.

It is common for building structures to be constructed out of plumb by l2mm (1/2”) framing and most cladding support systems have developed means to accommodate these discrepancies so that the outside cladding is straight and vertical. Some systems achieve this with the addition of components and features to permit adjustability, but these often add material, labour and/or compromises in thermal performance and cost. Most existing systems are placed in a relatively frequent pattern of between 405mm (16”) and 610mm (24”) horizontally and between 610mm (24”) and 1220mm (48”) vertically in order to provide enough support for the insulation and cladding. If insulation is installed in multiple thicknesses, the insulation must have its joints lined up through the wall, which causes a weakness in the insulation performance if workmanship is not careful. Also, for systems where the bracket has thickness or profile, the insulation must be pushed aside or manually cut away to fit around the bracket resulting in risk gaps which will reduce thermal performance and additional labour.

Systems are known for attaching insulation to the exterior of a building for the purpose of insulating the building, particularly in cold climates. Some methods rely on extra insulation. For example, US8898984 teaches installation of a second heat insulation panel in order to provide additional thickness to a traditional first insulation panel. This system uses a traditional dense insulation panel as the second insulation panel, spaced apart from the wall in order to hold in place a first lighter insulation panel between the wall and the second denser insulation panel. The patent requires a complicated spacer and L-bracket system for attachment to the wall along with a plurality of support rails that span the entire length of the outer wall and angled tension brackets that are attached between the wall and the support rails. The support rails are individual elements requiring complicated individual installation. In addition, the system requires a dense insulation panel on the exterior surface, thereby limiting the forms of insulation that can be used. Current systems of cladding and insulation are limited to 200mm overall depth. There is a need for thicker insulation in cold-weather climates in order to improve building thermal efficiency, and to comply with increasingly demanding Building Code requirements. . Current systems rely on rigid brackets fastened with at least two screws to the structural wall and cantilevered out through the insulation layer to support the exterior wall cladding. The cross-sectional area of the attachments permits heat loss through the insulation layer by thermal bridging as well as careful placement and cutting of insulation around the brackets.


One aspect of the present invention provides a system of supporting exterior cladding and exterior insulation in at least a first layer for conventional construction with an optional second layer of insulation for high performance low-energy construction. The system includes horizontal girts attached through the insulation to the building with special screws and angled suspension straps attached directly to the building, along with an optional clip for a second layer of insulation. In one aspect, a single horizontal girt can support a first layer of insulation, while additional clips enable a second layer of insulation. In addition, the present invention includes the ability to install cladding or strapping so that the cladding and strapping are independent of wall structure layout. Furthermore, the present invention can include staggered insulation joints so as to reduce heat loss through the gaps in the dual layer of insulation.

The exterior thermal insulated wall system for buildings includes components which when constructed together on the outside of an exterior building wall, and when combined with rigid and semi-rigid insulation, can support exterior building cladding while providing at least 300mm of insulation and avoiding thermal bridges that lose heating energy to the outside. Variability in the dimensions, spacing, and thickness gauge provide flexibility to suit each application to the thermal design objectives; weight and structural requirements of the cladding, and climate conditions including wind loads, selection of insulation type and thickness. The system has options that can be chosen to suit the required level of thermal performance, and adjustability to compensate for irregularities in construction tolerances.

One aspect of the basic system includes a primary layer of insulation, horizontal girts that are secured to the structural substrate, and suspension straps for a moderate level of thermal and constructability performance that provides up to about 200mm of insulation. For enhanced performance and higher insulation levels the system adds a thermal clip and an optional secondary layer of insulation. One feature of the basic system is the combination of special purpose designed components into a triangulated system of brackets with minimal penetrations that would conduct heat. These special components consist of girts with specific features, an angled suspension strap, and specially threaded screws that provide support in both compression and tension. A secondary and optional layer of the system extends support for exterior cladding using a special purpose-designed thermal wall clip that is cantilevered from the exterior strapping. The two layers are integrated at a metal Z-shaped girt within the assembly to provide rigidity in two directions and to transfer loads between the two layers.

Brief Description of the Drawings

The device will be further understood from the following description with reference to the drawings in which:

FIG. 1 shows a first step having insulation on a building wall;

FIG. 2 shows a second step having girts, screws and suspension straps;

FIG. 3 shows a detailed view of the screws and suspension straps;

FIG. 4 shows a third step having secondary layer clips;

FIG. 5 shows a detailed view of a cross-section through a wall showing the suspension strap, girt and clip;

FIG. 6 shows a closeup view of a clip attached to the strapping;

FIG. 7A shows a detailed top view of a clip;

FIG. 7B shows a detailed front view of a clip; FIG. 7C shows a detailed side view of a clip;

FIG. 8 shows a fourth step having strapping, a second layer of insulation, weather barrier and cladding;

FIG. 9 shows another embodiment of a first step having insulation on a building wall;

FIG. 10 shows another embodiment of a second step having girts, screws and suspension straps;

FIG. 11 shows a detailed view of the screws and suspension straps of Figure 10; and

FIG. 12 shows a third step having strapping, an optional second layer of insulation, weather barrier and cladding for the embodiment of Figures 9 to 11.

Detailed Description of Preferred Embodiments

Figure 1 shows a first stage having insulation 3 on a building wall. The insulation is typically panels that are 600mm wide and l200mm in long, but any width or length of insulation can be accommodated. The building structural wall substrate 1 onto which the assembly is constructed should have wood or steel stud framing; or, alternatively, concrete, reinforced masonry, or laminated wood panels can be used. Generally, a standard conventional air and/or vapour barrier 2 is applied over the building structural wall substrate wall 1, with continuity at windows, doors, and penetrations for building services. The thermal-bridge-free wall system of the present invention can be constructed over the air and/or vapour barrier 2. Alternatively, the air and/or vapour barrier can be omitted. In one embodiment of the present invention, a primary layer of conventional rigid or semi rigid insulation 3 boards (typically 6l0mm wide x l220mm long x lOOmm up to 200mm thickness, for example) is installed using adhesive, impale clips 4, or a conventional equivalent, see Figure 2. These can be installed in either a horizontal or vertical orientation depending on the particular structural support requirements for the selected cladding system. A horizontal Z-shaped girt 5 for the enhanced two layer system, or a modified L-shaped girt 5B for the basic system, is installed over the insulation, as shown in Figures 2 and 10. The girt can be installed as each row of insulation board is installed, or afterwards. These girts are of a gauge suited to the structural requirements of each building application. In one aspect, the girts are placed over the top outside edge of the primary layer of insulation boards and screwed through the insulation to the building structure behind. The girts can optionally have factory-punched dimples at both 305mm (12”) and 405mm (16”) spacing in order to aid lining up with the standard spacing of wall framing if wood or steel framing is used in the building. The dimples can be used to guide the screws as well as increase the effective depth of the screw thread in contact with the girt metal thickness.

In another aspect, the horizontal flanges of the girts can be optimized at about 30mm horizontal depth to reduce thermal bridging and about 75mm vertical height to provide rigidity as well as support for the next layers of insulation. These girts may be installed at 610mm or 1220mm vertical spacing, for example, depending on the structural requirements for each application. The girts can have a milled surface on the outer flange to aid in preventing the point of the self-tapping screw for the clip slipping while it is being fastened.

In a further embodiment, purpose-made screws 6 can be used for fastening the girt 5 and 5B to the wall, see for example Figures 3 and 11. The screws 6 can have standard threading for wood, steel, or concrete application or can be specially threaded in three sections, for example: a threaded portion of 30-50mm (length be sized to suit the structural substrate wall material and structural considerations) at the point to grip the wall; a reduced diameter shank for most of its full length to permit the screw point to penetrate the structural substrate (such as a steel stud) without stripping the inside thread at the girt; and a threaded portion of about l5mm right up to the screw head in order that the threads catch the girt to provide resistance to compression in the wall, due to loading and wind. Additional resistance to compression may be provided by the insulation. An optional soft plasticized washer in the shape of a sleeve can be provided on the screw 6 where additional air-tightness sealing is required around the screw penetration through the air and/or vapour barrier membrane on the wall. The sleeve shape will reduce the risk of distortion on the insulation where the screw penetrates it.

After the girts 5 and 5B are installed and before the next layer of optional insulation boards are installed, an angled suspension strap 7, fabricated from a metal strap or a heavy-gauge wire can be used for fastening between the wall 1 and the girt 5. The suspension strap 7 in a preferred embodiment can be bent at each end to lay flat against the wall and the girt or bent into a loop or equivalently arranged to receive a screw 7A for fastening to the wall 1 and a screw 7B for fastening to the girt 5. These suspension straps can be installed between adjacent insulation boards 3 or alternatively arranged. The spacing of the suspension straps both horizontally and vertically can be arranged to suit the structural requirements, and insulation board size and orientation. A great amount of flexibility is possible.

For seismic restraint in locations where earthquakes are a risk, an additional set of horizontal and vertical suspension straps can be added to resist uplift and side-to-side movement.

In the enhanced system with the secondary layer, in one embodiment, a clip 8 is fastened with a single screw or other form of fastening onto the exposed flange of the girt 5, see for example Figures 4, 6 and 7A, 7B and 7C. The clip can optionally have die-formed stiffener ribs 8A along the primary web for structural stiffness; punched elongated slotted holes 8B for the screws that secure the clip to the Z-girt; and slotted holes 8D for the screw(s) that secure the outer strapping 10 to the girt 5, allowing for adjustability perpendicular to the wall. The clip can further have die-formed dimples 8C on the contact surface with the girt 5 which holds the clip in position when screw-tightened into place. The dimples also serve to minimize the contact surface between the clip and girt providing a thin air film therebetween which contributes to reduced thermal bridging. An optional thin 2mm plasticized thermal gasket 13 (Figure 7C) can be added to the contact surface with the Z- girt 5 to increase thermal resistance across the junction between the clip 8 and the Z-girt 5. The clip can be dimensioned to receive any thickness of insulation, for example the clip can be between 50 to l50mm in length extending from the girt, with a bottom flange 8E for rigidity having a width of 22mm, for example. The front flange 8F of the clip that attaches to the strapping can be of any suitable size, for example 50mm by 50mm.

The clip should be located in line with the strapping 10 that supports the cladding 12 so it is aligned with cladding joints, lines of support, and sides of window and door openings, see for example Figure 5. The spacing of the clips can typically be at 407mm (16”) or 610mm (24”) to suit insulation board sizes although other spacing is easily accommodated.

A secondary and outer layer of insulation 9 is installed over the first in the enhanced system, see Figure 8. The outer layer of insulation 9 can be supported during installation on the exposed flange of the intermediate Z-girt 5. It may also be temporarily held in place until the assembly is completed using adhesive, straps, or sequenced with the installation of the outer cladding strapping 10. The cladding system includes vertical strapping 10 fastened to the girts 5 or clips 8 with a pair of screws 10 A, although more or less screws can be used as required. A weather barrier membrane 11 and cladding panels 12 are installed last. Figures 5 and 8 illustrate the preferred order of installation. The strapping 10 is preferably screwed onto the clips 8 using two screws per clip for a rigid connection, although other fastening forms may be used. The components of the cladding system, such as the strapping 10, weather barrier 11 and cladding 12 are conventional components.

In the basic system, a second layer of insulation 9 can be applied directly over the first layer of insulation 3, if required, see Figure 10, with the screws 6 extended in length to go through both layers of insulation. The cladding system of the basic system also includes vertical strapping 10 which is fastened to the girts 5B with screws. Weather barrier membrane 11 and cladding panels 12 are installed last. Figure 12 illustrates the preferred order of installation. The strapping 10 is preferably screwed onto the girts 5B using two screws per clip for a rigid connection, although more or less screws can be used as required. This system readily accommodates up to 400mm insulation thickness or more using multiple layers of conventional insulation, particularly in the enhanced insulation system. For example, this is the insulation required in parts of Canada to meet the International Passive House Standard, one of the most stringent energy performance standards in the world and considered a pre-requisite for Net- Zero Buildings. The basic form of the present invention uses suspension straps in tension, using the compressive strength of the insulation in combination with the screw that secures the girt to the wall, to create a light-weight truss within the wall that efficiently supports the insulation and cladding loads. The present invention permits considerably thicker insulation than other available systems.

The single screw securing the intermediate girt to the building wall reduces the thermal bridging over prior systems. Conventional systems that rely on wall-mounted clips to carry the insulation and cladding typically use at least two screws per insulation panel. In the enhanced system with the secondary layer, the screw 6 does not penetrate the entire thickness of the insulated assembly, i.e. it does not penetrate the second insulation panel 9, which makes the system more economical and again assists with reducing thermal bridging from the screw 6. In one aspect, the screw 6 can be provided with a reduced diameter shank for most of its length so that when the screw advancement is slowed at the point where the tip penetrates the structural wall substrate 1, the threading at the Z-girt 5 is not stripped. This provides a benefit in that the screw threads secure the girt against compressive loads. In the embodiment using a factory punched dimple in the girt 5 or 5B for receiving the screw 6, the effective depth of metal for screw threads to’’grab” is increased which aids in the performance of the system in compression due to wind loads and weight of the system. This is an improvement in ease of installation over conventional systems. The angled suspension strap 7, when secured to the structural wall substrate 1 and secured to the girt 5, creates a triangulated structural bracket, which provides greater capacity for support with less material than the cantilevered methods used in other systems. It also reduces the cross-section thickness of material required for structural support as the angled suspension strap 7 operates in tension rather than bending, and thereby reduces thermal losses through the material due to its smaller cross-sectional area. This is an improvement over conventional systems. Other systems have employed angled struts to achieve similar structural advantages, but these run completely through the entire assembly and use more elaborate components and cross-sections which are more costly than the present invention which uses only a heavy gauge wire or a flat strap. Unlike other thermal insulation systems, the present invention places the thermal clip 8 only part way through the insulation thereby reducing the thermal bridging. The attachment of the thermal clip 8 to the girt 5 instead of the structural wall substrate 1 reduces the cantilevered span of the clip 8 and thereby reduces the size and thickness of material needed to provide rigidity under loading. Also, the rigid connection between clip 8 and strapping 10 is located on the outside of the first insulated zone, where the greater amount of metal in contact has less thermal impact. As well, this reverse configuration with a rigid connection at the strapping 10 results in the thermal losses at the connection between the clip 8 and the Z-girt 5 being minimized due to the small overlap between these, and the heat losses are not carried through to the building structure. This is an improvement as current systems have a large area of contact between the connector and the building resulting in more heat loss, and greater measures required to reduce the heat loss. Furthermore, the thermal clip 8 has slotted holes 8B and 8D for screw fasteners, die-formed ribs 8 A for strength, and projecting dimples 8C at the point of contact with the girt 5 to reduce thermal transfer as well as help lock the clip 8 to the girt 5 when secured.

Layout of the strapping 10 is independent of wall structure layout, e.g. studs of the wall. Thus, the cladding can be applied independently of the building structure underneath. Insulation joints can be staggered to reduce heat losses through gaps at the joints. The system provides adjustability in three dimensions to compensate for out-of-plumb construction and other construction tolerances. It will be appreciated by one skilled in the art that variants can exist in the above-described arrangements and applications. The specific examples provided herein relate to a thermal wall assembly system for buildings; however, the materials, methods of application and arrangements of the invention can be varied. For example, the system can be turned 90 degrees so that the girts are running vertically. As another example, standard screws or other fasteners can be used to replace the specially designed screws described. The girt members could be fabricated without milling or pre-set holes for screws. The suspension straps could have a different form with a change in cross-section or fabrication. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.