GB2453716A - A thermal break connection for use between structural elements - Google Patents

Abstract

The invention relates to a thermal insulation load bearing connector 11 for use between construction elements 13 and 15 such as cantilever beams which support balconies. The connector comprises a load transferring, heat insulating gasket 12 having a first face adapted to be secured against a first heat conductive structural element 13 and a second face adapted to be secured against a second structural element 15, such that no conductive path exists between the first and second elements. The gasket may comprise a laminate of insulating layers 17, 18 and 19 and stainless steel layers 20 and 21 between the insulating layers. The steel layer 20 may have bolts 23 welded to it, which pass through insulating layer 18 and through oversize holes in the steel layer 21. Countersunk bolts 24 pass through the inner insulating layer 18 and through oversize bolts in the steel layer 20. The steel layers act primarily as washers preventing the bolt heads or nuts from penetrating the insulation layers. The insulation layer is preferably a resin-impregnated wood material.

Description

1 2453716 Thermal Break Arrangements for Construction Elements This invention relates to insulation arrangements for construction members, particularly for thermal insulation.

Building regulations may require -and it is in any event clearly desirable -that thermal conductivity of elements that penetrate the insulation layers of buildings should be broken. Such elements may comprise, for example, cantilever beams that support balconies.

Conventional constructional methods, however, do not generally involve a true thermal break in such a constructional element. In one suggestion, M16 stainless steel bolts pass through an insulated cloak containing a stainless steel compression block. The average conductivity taken over the whole cross section is said to be low enough to meet some building regulations, but the bolts still a provide a heat conductive path through which heat is lost causing condensation and mould growth.

The present invention provides improved insulation arrangements, which can be realised for steel and/or reinforced concrete structures.

The invention comprises an insulating, wall-penetrating connector comprising a load transferring, insulating gasket having a first face adapted to be secured against a first conductive structural element and a second face adapted to be secured against a second such element with no conductive path between the first and second said elements.

It is recognised, of course, that, strictly speaking, any material is heat conductive to a greater or lesser degree. By conductive' herein is meant heat conducting to a similar extent as steel or like load-transferring constructional material, and by insulating' is meant conducting to at least an order of magnitude less than that.

The gasket may be adapted to be secured against the first and/or the second conductive structural element by bolts, and may comprise oversize bolt holes, leaving an air gap between bolts and material they pass through.

A suitable heat insulating material is resin-impregnated wood. The wood may be impregnated with, for example, phenolic resin, and impregnation may be carried out in a vacuum tank. A gasket made using this material has been found suitable for supporting balconies and significant structural loads for other types of wall penetrating structural connections.

Another suitable insulation material is a non-compressible glass foam, which may be used in conjunction with the resin-impregnated wood. Such a gasket will carry moderate loads, with good insulation.

The gasket may comprise captive bolts for engaging said second element. Such bolts may be embedded in the gasket and may be welded, for example, to an inner steel plate.

The steel plate may serve primarily as a washer to prevent the bolt head embedding in the insulating material, and individual washers may be used instead of a washer plate.

For use in reinforced concrete structures, the connector may be bolted to a steel member having reinforcing bar projections adapted to be cast and embedded into a structural concrete slab. The projection may be of suitable anchorage to comply with relevant design codes..

The comlector may, however, be secured directly to a steel framework member of a steel frame building.

A typical size for the connector is 250 x200 x 80mm.

Insulating, wall-penetrating connectors according to the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is front elevation (A), side elevation (B) and plan (C), showing one embodiment of connector; Figure 2 is a perspective view of the connector set between typical structural elements to be connected thereby; and Figure 3 is a perspective view of the connector in a typical wall-penetrating situation.

The drawings illustrate an insulating, wall-penetrating connector II comprising a load transferring, insulating gasket 12 adapted to be secured against a first conductive structural element 13 and a against a second such element 15, Figure IC with no conductive path between the first and second said elements 13, 15.

The gasket 12 is a laminate of outer and inner insulating layers 17, 18, 19 and stainless steel layers 20, 21 squeezed tightly together on assembly. The stainless steel layer 20 has bolts 23 welded to it passing through the inner insulating layer 18 and through oversize bolt holes in the stainless steel layer 21. Countersunk bolts 24 pass through the inner insulating layer 18 and through oversize bolt holes in the stainless steel layer 20.

The stainless steel layers 20, 21 act primarily as washers, preventing bolt heads or nuts from penetrating the insulating layer 1 8. Regular circular washers may be used in place of the layers 20, 21, provided they do not make contact with a passing bolt.

The gasket 12 is adapted to be secured against the first conductive structural element I 3 by the bolts 23, and against the second conductive structural element 15 by the bolts 24.

Passing through oversize bolt holes in the gasket, the bolts 23 do not make thermal contact with the steel layer 22, and the bolts 22 do not contact the steel layer 21, so there is no direct conductive path through the gasket 12.

The upper bolts 23, 24 essentially bear the load of a cantilevered appendage such as a balcony. The lower bolts primarily serve to hold the connector's layers together, and may be smaller than the upper bolts. The upper bolts may be Ml6 bolts, as used widely in construction.

The layers may be adhesively secured together, but primarily for ease of assembly. It may well be better to rely mainly if not exclusively on the bolts, suitable tightened, for the integrity of the cormector.

Figures 1 and 2 illustrate a thermal break connector 11 constructed as above described, which has a thermal resistance of about 0.3 m2KJW, adapted to support balconies from a reinforced concrete structure.

The first structural element 13 comprises a steel beam 27 with reinforcing bar loops 28 and a lap plate 29 that can be welded to structural steelwork and in use cast into the concrete of an outer wall of a building. The second structural element 15 comprises a bracket 31, shown as attaching to a beam 32 of a balcony.

Clearly, the nature of the first and second elements 13, 15 will depend on the application of the thermal break connector.

The insulating layers 1 7, 1 8, 19 need, of course, to have physical and mechanical properties appropriate to the loads they will be required to bear and the conditions under which they will be deployed. A suitable heat insulating material for general building purposes is resin-impregnated wood, which can be formulated to have minimal or no shrinkage, will not crack or warp under a wide range of loadings, is impervious to water and resistant to salt water, oils and chemicals and can tolerate wide temperature variation.

Suitable resins include phenolic resins, and impregnation may take place under vacuum conditions.

The connector may have inherent fire safety features. The resin used to impregnate the wood, for example, may have self-extinguishing properties. Wood itself may char on its outer faces, but such charring forms an insulating layer, which can protect the internal wood against degrading for an hour or more, and thus the connector will remain viable.

Figure 3 shows the connector 1 1 attached to a steel beam 13 and Supporting a balcony 30 secured on a steel beam 31 with the structural element 15 penetrating the outer brick cladding 32 of a building.

Claims (9)

1. Claims: A thermal break, wall-penetrating connector comprising a load transferring, heat insulating gasket having a first face adapted to be secured against a first heat conductive structural element and a second face adapted to be secured against a second such element with no heat conductive path between the first and second said elements.
2. 2 A connector according to claim I, of which the gasket inner and outer insulating layers and structural, e.g. steel, layers intermediate the outer and inner insulating layers.
3. 3 A connector according to claim 1 or claim 2, adapted to be secured against the first and/or the second heat conductive structural element by bolts.
4. 4 A cormector according to claim 3, of which the gasket comprises internal structural layers.e.g. of steel with captive bolts welded or otherwise secured thereto and projecting from the gasket to serve as means to secure the gasket to structural elements.
5. A connector according to claim 4, of which the gasket comprises oversize bolt holes, leaving an air gap between bolts and any thermally conductive element they pass through.
6. 6 A connector according to any one of claims I to 5, of which the gasket comprises insulating material comprising resin-impregnated wood.
7. 7 A connector according to claim 6, of which the wood is impregnated with phenolic resin.
8. 8 A cormector according to claim 6 or claim 7, of which the wood is impregnated under vacuum conditions.
9. 9 A connector according to any one of claims 1 to 8, having a reinforcing bar projection adapted to be embedded in concrete.

   A connector according to claim 9, in which the projection is in the form of a loop.