GB2062719A - Linking Members - Google Patents

Abstract

The invention relates to a wall tie (2), which comprises two opposite end portions (4) each adapted to lie between courses of bricks in a wall, and an intermediate portion (6) adapted to bridge the cavity between the wall leaves (10) and lying in a vertical or substantially vertical plane passing perpendicularly through the end portions, said intermediate portion (6) comprising an upper narrow peripheral surface (18) and a lower narrow peripheral surface (20), each said surface including at least part thereof which is sloped upwardly with respect to the horizontal end portions of the member, the construction and arrangement being such that, in use, said intermediate portion (6) presents no horizontal or near-horizontal surfaces upon which material falling within the cavity may adhere and provides no path for transfer of moisture between the leaves (10) of the wall. <IMAGE>

Description

SPECIFICATION Linking Members The invention is concerned with improvements in or relating to linking members, particularly wall ties for use in linking leaves of a cavity wall in the building construction industry.

It is conventional practice to link the inner and outer leaves of a cavity wall at selected intervals in its construction by bridging the cavity with wall ties. Where cavity walls are liable to warp due to uneven loading, the lateral deflection of the leaves is likely to be unequal and wall ties play an important role in equalising the deflection to a large extent, particularly where only one leaf of the wall is loaded. Since ties should advantageously transmit tensile and compressive forces without appreciable buckling or stretching, it will be found that ideally the bending stresses are substantially the same in the two leaves where these are of equal stiffness.

However, it is possibie that, under certain circumstances, the presence of wall ties can have a deleterious effect on the weatherproof properties of a cavity wall. For example, water penetrating the outer leaf may run along the tie to the inner leaf in a situation where the brick courses are not accurately formed in the same horizontal plane. Although drip-forming means may be provided at an intermediate position on the tie to hinder this undesired travel of moisture, a more serious problem can arise where mortar has fallen onto the tie during construction of the wall. Thus, water can readily percolate through a mortar "bridge" inadvertently formed on and supported by the tie.

The invention provides an elongate linking member formed from stiffly flexible material for use in linking two leaves of a cavity wall, comprising two opposite end portions each adapted to lie in a horizontal plane and to be received entirely or substantially so between courses of building units in said wall, and an intermediate portion adapted to bridge the cavity between the wall leaves and lying a vertical or substantially vertical plane passing perpendicularly through the end portions, said intermediate portion comprising an upper narrow peripheral surface and a lower narrow peripheral surface, each said surface including at least part thereof which is sloped upwardly with respect to the horizontal end portions of the member, the construction and arrangement being such that, in use, said intermediate portion presents no horizontal or near-horizontal surfaces upon which material falling within the cavity may readily adhere and provides no path for transfer of moisture between the leaves of the wall.

Advantageously, the joint region between each end portion and the intermediate portion, while normally stiff, permits of some degree of bending, conveniently with a hand tool, so that the end portion may lie in different, but parallel, planes, to accommodate variations in the level of courses in two leaves of for example, a brick wall.

In an example of the invention the intermsdiere portion of the member may comprise two subportions each of which comprises one of said narrow peripheral surfaces. Conveniently, the material from which the member is made may be strip material, for example, stainless steel wire or galvanised steel strip, copper, or phosphor bronze, or may be moulded from suitable plastics material, for example polypropylene. It is necessary to choose materials such as these to minimise damage by corrosion or due to chemical action from the materials used in the construction of the wall. If necessary, linking members formed from strip material may be provided with a brace or strut extending between the two sub-portions of the intermediate portion to minimise the risk of undue distortion.Here again care must be taken to avoid providing a horizontal or near-horizontal surface onto which mortar may fall and adhere to form a "bridge" and to avoid providing a path for the transfer of moisture between the leaves of the wall.

In various examples of linking members according to the invention, the narrow peripheral surfaces are provided on a disc or plate which may be rhombic or circular, or by wire or other rod or strip shaped into a rhomb or circle or any other suitable two-dimensional shape which does not provide an uninterrupted straight-line surface bridging the cavity along which water may run. It is to be understood that, because of surface tension, surfaces along which water may travel are not only upwardly-facing surfaces. It is advantageous if the strip material is of circular cross-section, which minimises the risk of formation of a mortar "bridge".

There will now be described an example of a linking member according to the invention. It will be understood that the description, which is to be read with reference to the accompanying drawings, is given by way of example only and not by way of limitation.

In the drawings Figures 1, 2 and 3 are perspective, top plan and side views respectively of the link member; and Figures 4 and 5 are top plan and side view respectively of the member in position in a cavity wall.

The link member, hereinafter referred to as the wall tie 2, is constructed from shaped stainless steel heavy gauge wire and comprises two opposite end portions 4 lying initially in the same plane. These end portions are, in the present example, substantially triangular. An intermediate portion 6, which lies in a plane perpendicular to that of the end portions 4, is formed in approximate shape of a rhomb which is the present example is substantially a square.

The wire comprising the tie 2 is formed into twists at joint regions 8 to maintain the tie 2 in shape. The wire although tough and rigid has a slight amount of flexibility to allow shaping also to allow adjustment of the end portion 4 relative to the intermediate portion so that the end portions may lie in different horizontal planes. This is necessary where courses of two leaves 10 of a wall, as shown in Figures 4 and 5, are not accurately constructed with respect to one another.

Figure 5 shows this situation clearly in that the mortar filler 12 of one course in slightly higher than the mortar 14 of the other. It will be appreciated that the presence of a plain tie in the position identified at 1 6 in chain dotted lines would encourage moisture to travel from left to right as viewed in the drawing and transmit water from the outer leaf 10 to the inner leaf.

Use of a tie as shown obviates this problem by providing narrow peripheral surfaces, an upper surface 18 and a lower surface 20. Water running along the lower surface 20 will drip harmlessly from the lowest point 22, since it cannot travel upwardly to complete the span of the tie portion 6. Water cannot normally rise up the initial portion of the surface 18 for the same reason.

However, on occasions where mortar has been dropped from courses further up the wall, there may be some adhering to the tie portion 6. This will however, be very small in amount because of the narrowness of the plan layout as viewed in Figure 4. This is so slender that mortar simply falls off and does not normally lodge. Even if it did lodge, it would do so in such small quantities it would be extremely unlikely to cover the entire upwardly sloping portion of the surface 18, so that water would still be unable to reach the highest point 24 to be able to descend to the innerleaf.

If desired, a narrow vertical wire strut may be secured on the portion 6, arranged to act as a brace between the points 22 and 24 to minimise the risk of distortion.

Various modifications may be made within the scope of the present invention as defined in the following claims.

Claims (9)

Claims

1. For use in linking two leaves of a cavity wall, an elongate linking member formed from stiffly flexible material, comprising two opposite end portions each adapted to lie in a horizontal plane and to be received entirely or substantially so between courses of building units in said wall, and an intermediate portion adapted to bridge the cavity between the wall leaves and lying in a vertical or substantially vertical plane passing perpendicularly through the end portions, said intermediate portion comprising an upper narrow peripheral surface and a lower narrow peripheral surface each said surface including at least part thereof which is sloped upwardly with respect to the horizontal end portions of the member, the construction and arrangement being such that, in use, said intermediate portion presents no horizontal or near-horizontal surfaces upon which material falling within the cavity may readily adhere and provides no path for transfer of moisture between the leaves of the wall.

2. A member as claimed in claim 1, wherein the intermediate portion comprises two subportions each of which comprises one of said narrow peripheral surfaces.

3. A member as claimed in claim 1, wherein the narrow peripheral surfaces are provided on a disc or plate.

4. A member as claimed in claim 3, wherein the disc or plate is rhombic.

5. A member as claimed in claim 3, wherein the disc or plate is circular.

6. A member as claimed in claim 2, comprised by shaped heavy gauge wire.

7. A member as claimed in claim 6, wherein the wire is of galvanised or stainless steel or circular cross-section.

8. A member as claimed in either one of claims 2, 6 and 7, wherein a brace or strut is provided to extend between the two sub-portions of the intermediate portion to minimise the risk of distortion in use.

9. An elongate linking member for use in linking two leaves of a cavity wall, constructed and arranged substantially as hereinbefore described with reference to and as shown in the accompanying drawings.