GB2198464A

GB2198464A - Insulated spacer for double skin walls and roofs

Info

Publication number: GB2198464A
Application number: GB08709663A
Authority: GB
Inventors: Geoffrey John Higgins
Original assignee: Stramit Industries Ltd
Current assignee: Stramit Industries Ltd
Priority date: 1986-12-04
Filing date: 1987-04-23
Publication date: 1988-06-15
Anticipated expiration: 2007-04-23
Also published as: GB8709663D0; GB8629060D0; GB2198464B

Abstract

A double skin roof or wall structure has an inner skin 10 separated from an outer skin 12 by an elongate composite spacer 18 of insulating material, one face of which abuts one skin and the other providing support for a metal strip 22 through which the spacer is fixed relative to both the skins. The metal strip 22 is preferably bonded to the body 20 of the spacer 18 and may be Z-shaped, in which event one limb is fixed by screws 32 passing through the spacer 20 and inner skin 10 to a purlin 16, while screws 28 secure the outer skin 12 through the outer limb to the spacer body 20. <IMAGE>

Description

Title Double Skin Roof or Wall Structure Field of the invention This invention relates to a roof or wall structure of the kind having spaced inner and outer skins of sheet material, commonly corrugated or ribbed sheet material.

Prior Art A known double skin roof or wall structure utilises elongate Z-shaped brackets to space apart the inner and outer skins. These known spacers are of galvanized steel, and thus constitute a potential thermally conducting path between the inner and outer skins, which commonly leads to condensation problems and may lead to heat loss, depending on the materials of which the inner and outer skins are made. The interpositioning of thermally insulating washers between the skin(s) and the spacers, for example at the points where the inner and/or outer skin is/are fixed to the spacers, tends to reduce compactness of the roof or wall assembly and also to reduce the rigidity and strength thereof. When the inner skin is corrugated or ribbed, the Z-shaped spacers have been slotted or recessed to accommodate the ribs or corrugations of the inner skin.

The invention According to one aspect of the present invention, there is provided a double skin roof or wall assembly wherein the inner and outer skins are separated by a composite spacer constituted by an elongate member of thermally insulating material which on one face abuts one skin and on the opposite face provides support for a metal strip through which the composite spacer is fixed relative to both the inner and outer skins.

According to another aspect of the invention, there is provided a spacer for the inner and outer skins of a double skin roof or wall structure, said spacer being a composite spacer comprising a body of thermally insulating material adapted on one face to abut one skin, and a metal strip supported on the opposite face of the said body, said strip being adapted to provide for fixing of the spacer relative to both the inner and outer skins.

Preferably the metal strip is shaped and is bonded or otherwise secured to the cooperating face of the body of the insulating material.

A preferred spacer has a body which on the one face is recessed to fit over the corruqations or ribs of the inner skin against which it abuts in use. The body is Preferably stepped on its opposite face, for example being of a thick L-shaped cross-section, so as to support a generally Z-shaped metal strip.

One limb of the Z-shaped strip, preferably that nearer the first mentioned one face of the thermally insulating body, then provides for fixing of the spacer to the inner skin, as by means of a self-drilling, self-tapping screw passing through the strip, the thermally insulating body and the inner skin into the main supporting structure of the building, i.e. into a roof purlin or rafter or into a wall stanchion or column.

The other limb of the Z-shaped strip, preferably that remote from the first mentioned one face of the thermally insulating body, provides for fixing to the outer skin.

Thermal insulation, for example of mineral wool, may be accommodated between the spaced inner and outer skins.

The body of the composite spacer is preferably made of high density, extruded polystyrene. Alternatively the spacer body may be made of polyurethane or polyisocyanurate foams; or of compressed mineral fibre or fibreglass.

The composite spacer in accordance with the invention has the advantage of providing a compact, rigid and strong double skin roof or wall structure, whilst thermally isolating the inner and outer skins from one another and thereby reducing risk of condensation problems and heat loss.

It remains possible that a relatively small degree of condensation may occur in the space between the inner and outer skins and, to enable drainage, the said one face of the thermally insulating body may be provided with drainage channels enabling water to flow past the spacer along the face of the inner skin. Clearances between the spacers and the sides of the ribs or corrugations of the inner skin may be sufficient for this purpose.

The invention is applicable to both walls and roofs, more often the latter, and especially roofs with relatively low pitch, as is common in buildings for industrial and/or agricultural usage. Such buildings qenerally have a main supporting structure of steel. However, the invention is also applicable to other types of building, wherein the main supporting structure, or at least that of the roof, is made of timber.

Especially in the case of a timber main supporting roof structure, where the composite spacer is to fix through the inner skin into a timber purl in or rafter, a modification may be employed wherein the preferred composite spacer comprises two thick L-sections integrally formed back to back, and the metal strip is of an integrally formed S and Z shape, i.e. a flanged channel cross-section. The spacer is thus provided with twin steps on the face remote from the inner skin, and dual fixings through the inner skin to the underlying timber purlin or rafter are made possible.

When the fixing through the inner roof structure is made by means of self-drilling, self-tapping screws or like fixing elements, the heads of such fixing elements may be isolated from the metal strips by means of thermally insulating washers.

Description of drawings The invention is exemplified with reference to the accompanying drawings, in which: Figure 1 is a cross section through a double skin roof structure in accordance with the invention; Fiqure 2 is a ciit-away oerspective view of the roof structure; Figure 3 shows a modified double skin roof structure; Figure 3A shows a detail; and Figure 4 shows the roof structure of Figure 3 in cut away perspective view.

Description of embodiments Referring to Figures 1 and 2, a roof structure has a ribbed inner skin 10 and a ribbed outer skin 12.

Typically the inner and outer skins 10, 12 consist of plastics coated steel or aluminium panels, but various other sheet materials may be employed, often different materials for the inner and the outer skins. The outer skin has a weatherproofed finish. Rock wool or fibre glass or other suitable thermal insulation 14 is accommodated between the two skins 10, 12.

Figures 1 and 2 show a low pitched roof structure for an industrial or agricultural building having a main supporting structure of steel, which includes conventional Z purlins 16. The roof structure is required to fix to the steel purl ins in a manner which minimises transmission of heat from the warm building space into and through the cold roof space, thereby not only to avoid wastage of heat but also to avoid condensation, especially on the underside of the inner skin.

The inner and outer skins 10, 12 are separated by composite spacers 18 which comprise a thermally insulating elongate body 20, more especially of high density extruded polystyrene, and a metal strip 22. Alternative insulating materials for the body 20 may include polyurethane or polyisocyanurate foams, compressed mineral fibre or fibreqlass.

On one face, the body 20 is shaped with recesses 24 to fit over the ribs 26 of the inner skin 10 and abut the inner face of said inner skin in its principal plane.

Preferably, small clearances between the recesses 24 and the ribs 26 provide for drainage, in the event of condensation occurrinq between the two skins.

The opposite face of the body 20 is stepped to support the metal strip 22, which is of a Z shape analogous to that of a Z purl in.

The spacer has an intermediate face at which fixing elements in the form of self-drilling, self-tapping screws 32 extend through the strip 22, the body 20 and the inner skin 10 into the purlin 16, thereby to secure the double skin roof structure down on to the main supporting structure of the building. The said self-drilling, selftapping screws 32 are also conventional in the art. Heat transfer via the screen 32 is minimised by the use of thermally insulating washers which will be described in more detail in relation to Figure 3A.

The fixings 28, 32 are provided at suitable centres, and the composite spacer is assembled with fixing elements 28 and with predrilled holes in the intermediate face in accordance with the spacings of the centres which are required. It is to be noted that the screws 32 (or other fixinq elements employed in lieu thereof) extend through the composite spacer and inner skin at positions between the ribs 26 of the inner skin 10. The screws 28 may or may not align with the fixing screws 32.

The outer skin 12 is supported on the upper face of: the metal strip 22 and is secured thereto by screws 30 (or the like) in manner known per se.

Figures 3 and 4 show a modification applied to a double skin roof structure 10, 12 fixed down on to timber purlins or rafters 40.

The composite spacer 42 comprises a stepped thermally insulating body 44 having twin intermediate faces to enable the structure to be fixed to the timber nurlin 40 by two fixing screws 46. The metal strip 48 has a flanged channel section supported against the stepped, upper face of the body, and fixing screws 50 for the outer skin 12 are provided in the manner previously described.

It is also to be noted that, in the embodiment of Figures 3 and 4, flat inner roof panels are envisaged for the inner skin 10. The under face of the spacer 42 is thus also flat, except for the provision of drainage channels 52. Insulating material may be located between the inner and outer skins as shown.

The invention may be applied as an over-roof to an existing flat roof in which event items 10 and 40 would comprise part of the existing roof.

Figure 3A shows that heat insulating washers or hushes 60, for example of nylon, may he incorporated between the heads 62 of the fixing screws 46 and the metal strip 48 (or likewise the fixing screws 32 and metal strip 22 in the embodiment of Figures 1 and 2), in order to break the potentially heat conductinq connection through the screws across the roof space between the inner and outer skins.

Various modifications of the embodiments described with reference to the drawings are possible within the scope of the invention hereinbefore defined.

Claims

1. A double skin roof or wall assembly wherein the inner and outer skins are separated by a composite spacer constituted by an elongate member of thermally insulating material which on one face abuts one skin and on the opposite face provides support for a metal strip through which the composite spacer is fixed relative to both the inner and outer skins.

2. A spacer for the inner and outer skins of a double skin roof or wall structure, said spacer being a composite spacer comprising a body of thermally insulating material adapted on one face to abut one skin, and a metal strip supported on the opposite face of the said body, said strip being adapted to provide for fixing of the spacer relative to both the inner and outer skins.

3. A spacer according to claim 2 in which the metal strip is Z-shaped and is bonded or otherwise secured to the cooperating face of the body of the insulating material.

4. A spacer according to claim 2 or claim 3 in which said body has one face which is recessed to fit over any corrugations or ribs of the inner skin against which it abuts in use.

5. A spacer according to claim 4 as dependent on claim 3 in which said body is stepped on its opposite face, being of a thick L-shaped section to support said Z-shaped strip.

6. A spacer according to claim 4 or claim 5 in which a limb of said Z-shaped strip nearer said one face is provided with screws passing through the strip, the thermally insulating body and the inner skin into supporting structure.

7. A spacer according to claim 6 in which the heads of said screws are isolated from the metal strips by means or thermally insulating washers.

9. A spacer according to claim 6 or claim 7 in which the other limb of said Z-shaped strip has the outer skin secured thereto.

9. A spacer according to any of claims 2 to 8 in which said body is made from any of a range of thermal insulation materials comprising high density extruded polystyrene, polyurethane foan, polyisocyanurate foam, compressed mineral fibre and fibreglass.

10. A spacer according to any of claims 4 to 9 in which said one face of said body is provided with drainage channels enabling water to flow past the spacer along the face of the inner skin.

11. A spacer according to any of claims 6 to 10 in which said body comprises two thick L-sections integrally formed back to back, and the metal strip is of a correspondingly shaped flanged channel cross-section.

12. A double skin roof or wall assembly according to claim 1 in which a thermal insulation material is accommodated in the space between the inner and outer skins.

13. A double skin roof or wall assembly according to claim 12 in which said material comprises mineral wool.

14. A spacer for a double skin roof or wall structure substantially as herein described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.

14. A double skin roof or wall assembly substantially as herein described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.

15. A spacer for a double skin roof or wall structure substantially as herein described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.

Amendments to the claims have been filed as follows Claims 1. A double skin roof or wall assembly wherein the inner and outer skins are separated by a composite spacer constituted by an elongate member of thermally insulating material which on one face abuts one skin and on the opposite face provides support for a metal strip through which the composite spacer is fixed relative to both the inner and outer skins.

2. A spacer for the inner and outer skins of a double skin roof or wall structure, said spacer being a composite spacer comprising a body of thermally insulating material adapted on one face to abut one skin, and a Z-shaped metal strip supported on the opposite face of said body and beng bonded or otherwise secured thereto, said strip being adapted to provide for fixing of the spacer relative to both the inner and outer skins.

3. A spacer according to claim 2 in which said body has one face which is recessed to fit over any corrugations or ribs of the inner skin against which it abuts in use.

4. A spacer according to claim 3 as dependent on claim 3 in which said body is stepped on its opposite face, being of a thick L-shaped section to support said Z-shaped strip.

5. A spacer according to claim 3 or claim 4 in which a limb of said Z-shaped strip nearer said one face is provided with screws passing through the strip, the thermally insulating body and the inner skin into supporting structure.

6. A spacer according to claim 5 in which the heads of said screws are isolated from the metal strips by means or thermally insulating washers.

7. A spacer according to claim 5 or claim 6 in which the other limb of said Z-shaped strip has the outer skin secured thereto.

8. A spacer according to any of claims 2 to 7 in which said body is made from any of a range of thermal insulation materials comprising high density extruded polystyrene, polyurethane foam, polyisocyanurate foam, compressed mineral fibre and fibreglass.

9. A spacer according to any of claims 3 to 8 in which said one face of said body is provided with drainage channels enabling water to flow past the spacer along the face of the inner skin.

10. A spacer according to any of claims 5 to 9 in which said body comprises two thick L-sections integrally formed back to back, and the metal strip is of a correspondingly shaped flanged channel cross-section.

11. A double skin roof or wall assembly according to claim 1 in which a thermal insulation material is accommodated in the space between the inner and outer skins.

12. A double skin roof or wall assembly according to claim 11 in which said material comprises mineral wool.

13. A double skin roof or wall assembly substantially as herein described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.