GB2317194A - Wall tie - Google Patents

Abstract

A wall tie is pressed from a length of stainless steel strip. The tie has a central region (10) intermediate a pair of end regions (12). Each end region has pressed formations (46,60) to enhance its ability to be anchored in a mortar layer. The central region (10) has at least three distinct axially-extending fold lines, and is convex in cross section. When disposed in an orientation for use, all of the material of the central region (10) slopes transversely downwardly away from an axial central line (A). Flat edge sections (22) of the central region (10) slope less steeply than immediately adjacent material of the central region (20).

Description

WALL TIE The present invention relates to wall ties.

Most buildings constructed of brick or block have cavity walls. A cavity wall has two or more separate wall elements known as leaves which are built up parallel to, and spaced from, one another. In order to impart strength to the wall, the leaves are interconnected at intervals by wall ties.

A wall tie must meet performance standards laid down by building regulations. Such standards specify strength of the tie, as well as imposing limitations upon its dimensions. Additionally, there are relevant regulations regarding the spacing between the leaves. When taken together, these regulations make the proper construction of a wall tie a far from straightforward matter.

As a further problem, the cavity between the leaves is often quite damp. The wall tie must be designed such that it does not provide a direct path by means of which condensation is encouraged to run onto an inner leaf of the wall. This problem is increased by the tendency for amounts of mortar to fall onto the ties during construction of the wall.

Many different ties have been proposed to attempt to achieve these aims. Examples are shown in GB-A-2255989, GB-A-2251634, GB-A-2249816, GB-A-2215356, and GB-A 2267518. However, all of these exhibit some disadvantages, for example in strength, cost of production or convenience in use.

It is an aim of the invention to provide a highperformance wall tie which is convenient in use and of attractive cost in manufacture. A particular aim has been to reduce the amount of material required to manufacture a tie of a given strength.

According to the invention there is provided a wall tie formed of a length of metal strip, comprising a central region intermediate a pair of end regions, each end region having formations to enhance its ability to be anchored in a mortar layer, and the central region having at least three distinct axially-extending fold lines, and being convex in cross section such that, when disposed in an orientation for use, all of the material of the central region slopes transversely downwardly away from an axial central line.

The provision of three or more fold lines imparts strength to the tie, while the convex shape of the tie minimises the risk of water collecting on it. The convex shape also encourages wet mortar falling onto the tie (as happens inevitably as the wall is built up) to be shed from it.

Preferably, at one of the fold lines the material curves in a direction opposite to that at the or one other fold line. Such an embodiment may have a central axially extending fold line from which side portions slope downwardly, and spaced parallel fold lines at which the slope of the side portions is reduced.

One or more apertures may be provided through the central region, most preferably at its highest section.

Such apertures reduce the likelihood of water travelling along the tie.

The end regions may be of generally upward convex cross-section when in use. At least one portion of each end region may be deflected with respect to the material surrounding it so as to provide a key to enhance anchorage of the end region in mortar. Preferably, a plurality of such deflected portions are provided on each end region.

A transition region may be provided between each end region and the central region, at which transition region there is preferably a smooth transition of crosssectional shape between the respective end region and the central region.

Most conveniently, the wall tie may be pressed from steel. A preferred material is stainless steel.

An embodiment of the invention will now be described in detail, by way of example, with reference to the accompanying drawings in which: Figures 1 and 2 are, respectively, plan and side views of a wall tie embodying the invention; and Figures 3, 4 and 5 are sections along lines AA, BB and CC respectively of the wall tie of Figures 1 and 2.

For convenience of description, in the following, the terms "up", "down" and associated words will be used to refer to features of a wall tie as it is disposed in position in a wall.

With reference to all of the drawings, a wall tie comprises an elongate metal pressing comprising a central region 10 intermediate a pair of end regions 12. There is a respective transition region 14 between each of the end regions 12 and the central region 10. The end regions 12 are substantially identical to one another such that the tie is symmetrical about a centre line (not shown) of the central region 10. The tie is also symmetrical about a longitudinal axis A of the tie. In this embodiment, the tie is pressed from a strip of grade 304 stainless steel of 20mm x 1.2mm in section and one of 200mm, 225mm or 250mm in length.

In use, the central region 10 spans the cavity between the leaves of a cavity wall.

The central region 10 has, over much of its length, a cross section as shown in Figure 5. In this region, the strip is pressed such that it has a central section 20, which includes an axially central fold line, bordered by a pair of substantially flat sections 22. In use, the tie is disposed with the curved section 20 having its convexity uppermost.

In this region, the overall width W of the tie is approximately 16.78mm, and its height H is approximately 6.lmm. The flat sections 22 are disposed at an angle of approximately 30 to a horizontal datum. At the border regions of the central section 20, the material of the strip is at an angle of approximately 52" to the horizontal datum. The change between the angle of the material of the strip within the central section 20 and each flat section 22 occurs at a sudden transition.

Thus, each flat section 22 meets the curved section at a pair of parallel fold lines 24 are formed along boundaries of the central section 20.

It will be noted that the parallel fold lines 24 curve in a direction opposite to the fold line of the central section 20.

Close to each of the transition regions 14, a through hole 26 of approximately 4mm in diameter is formed through the central section 20, substantially centrally of the tie. The centre of the hole is approximately 80mm from the nearest end of the tie. This minimises the chance of water running from the central region 10 onto the transition regions 14.

Between the central region 10 and the transition region 14, small section of the material of each flat section 22 is displaced downwardly so as to form a short furrow 28 extending part-way into the respective flat section 22 from its edge. The furrow 28 acts as a channel along which water on the upper surface of the flat section 22 will be encouraged to run, so guiding it off the wall tie. Additionally, moisture droplets on the underside of the flat section 22 will have great difficulty in travelling past the downwardly-displaced material which makes up the furrow. In some embodiments, it has been found to be advantageous to provide an additional furrow 28 substantially mid way along the length of the tie. Furthermore, it may be advantageous to provide, alternatively or additionally, furrows within the central region, for example at locations approximately mid-way between the centre of the tie and the transition region.

The end regions 12 of the wall tie are intended to be embedded in a mortar layer between courses of the leaves of a cavity wall.

The basic cross-sectional shape of the end regions 12 is shown in Figure 3. At this region, the height H' of the tie is approximately 5.6mm and its width W approximately 17.4mm. This shape is upwardly convex, having an arcuate central section 40 bounded by relatively flatter side regions 42, each of which side regions 42 has a small, downwardly curved end section 44.

A first section 46 of the end region 12 is punched to form a downwardly-projecting convex part 50 extending across the central section 40 and part way into the side regions 42 for a length of approximately 20mm, starting approximately 8.3mm from the nearby end of the tie.

The cross-sectional shape of the first section 46 can be thought of as a spread-out M-shape, and is shown in Figure 4. The downwardly-projecting part 50 is formed, at its lowest extent, in a relatively small radius curve, while the material transversely adjacent the lowest extent is substantially planar. Furthermore, a similarly small radius of curvature is formed at transition zones 58 between the side regions 42 and the punched-out material of the first section 46.

The height H" of this section is reduced to approximately 3.5mm. At axial ends, the downwardly projecting part is bounded by transverse cut lines 52,54 such that it is separated from adjacent material of the tie.

A second section 60 of the end region 12 is punched, also to form a downwardly-projecting convex part 50 extending across the central section 40 and part way into the side regions 42. A first end of the second section 60 is defined by a transverse cut line 62 spaced approximately 8mm from the adjacent cut line 54 of the first section, the intervening section 56 having the undistorted profile, as described with reference to Figure 3. Adjacent the cut line, the material of the second region has a cross-sectional shape substantially the same as that of the first section 46.

The second section 60 extends into the transition region 14. Within the transition region 14 there is a smooth transition of cross-sectional shape of the tie between that described for the central region 10 and the end region 12. Additionally, there is no cut line to separate the material of the second section 60 form the transition region 14. Transition zones 64 between the side regions 42 and the punched-out material of the first section 46 taper together within the transition zone 14 to meet on the axis A, and to blend into the central section 20 of the central region 10 at a longitudinallysloping section 66.

In use, each end region 12 is embedded in a mortar layer between courses of bricks or blocks, as the case may be, in respective leaves of a cavity wall to anchor the tie. Mortar closely surrounds the material of the end regions 12, and enters into the first and second sections 46,60. It will be seen that tie cannot readily be pulled out of the mortar once it has hardened, the shape of the end region securely keying it into place.

It will be understood that the particular shape and dimension of the above-described embodiment is not limiting upon the scope of the invention. Working within the scope of the invention, a person of ordinary skill in the art will be readily able to vary the particular configuration of a wall tie embodying the invention so suit a particular purpose.

Claims (16)

1. A wall tie formed of a length of metal strip, comprising a central region intermediate a pair of end regions, each end region having formations to enhance its ability to be anchored in a mortar layer, and the central region having at least three distinct axially-extending fold lines, and being convex in cross section such that, when disposed in an orientation for use, all of the material of the central region slopes transversely downwardly away from an axial central line.

2. A wall tie according to claim 1 in which at one of the fold lines the material curves in a direction opposite to that at the other or one other fold line.

3. A wall tie according to claim 2 having a central axially extending fold line from which side portions slope downwardly

4. A wall tie according to claim 2 or claim 3 having spaced parallel fold lines at which the slope of the side portions is reduced.

5. A wall tie according to any preceding claim in which one or more apertures are provided through the central region.

6. A wall tie according to claim 5 in which the or each aperture is provided at the highest section of the central region of the tie when in use.

7. A wall tie according to any preceding claim in which the end regions are of generally upward convex crosssection when in use.

8. A wall tie according to any preceding claim in which at least one portion of each end region is deflected with respect to the material surrounding it so as to provide a key to enhance anchorage of the end region in mortar.

9. A wall tie according to claim 8 having a plurality of such deflected portions on each end region.

10. A wall tie according to any preceding claim having a transition region between each end region and the central region, at which transition region there is a smooth transition of cross-sectional shape between the respective end region and the central region.

11. A wall tie according to any preceding claim having a plurality of furrows constituted by regions of downwardly extending material extending laterally into the tie from an edge.

12. A wall tie according to claim 11 having, on each edge of the tie, a plurality of furrows disposed symmetrically about a mid-point of the tie.

13. A wall tie according to any preceding claim in which one of the three distinct fold lines is disposed coincident with the axial central line.

14. A wall tie according to any preceding claim formed as a one-piece steel pressing.

15. A wall tie according to any preceding claim formed from stainless steel.

16. A wall tie substantially as described herein with reference to the accompanying drawings.