GB2289074A - Wall tie - Google Patents

Abstract

A wall tie (5) has two conventional planar ends (5A, 5B) separated by a linking section (5C) having a right angle bend (5D) in it at a predetermined distance D from one end (5E) of the wall tie (5) and in a plane perpendicular to both of the planar end portions (5A, 5B) such that the bend (5D) can be straightened out to make the end portions (5A, 5B) coplanar without making a kink in the tie (5). <IMAGE>

Description

WALL TIE This invention relates to improvements to wall ties and in particular to improvements to wire wall ties.

Wall ties are employed to tie together the separate leaves of masonry cavity walls as shown in figure 1. In figure 1 a cavity wall is formed by a first leaf or skin 1 and a second leaf or skin 2 separated by a cavity 3. Each leaf 1, 2 is made up of a plurality of bricks or blocks 1A, 2A separated by layers of mortar 1B, 2B respectively and wall ties 4 are placed with one end embedded in a mortar layer 1B of the first leaf 1 and the other end embedded in a mortar layer 2B of the second leaf 2.

Masonry walls can be constructed from either bricks or blocks, the distinction between the two types of unit being essentially only one of size. Wall ties may be used with either bricks or blocks and in particular may be used to link a leaf of bricks with a leaf of blocks. For simplicity, only bricks will be referred to in this application but any reference to bricks should be understood as applying equally to blocks.

Wall ties provide a connection between the two leaves of the cavity wall and so increase its structural strength by causing the two leaves to act together as a single structure. The horizontal and vertical spacing of the wall ties and the pattern in which they are arranged can be varied to provide the desired structural strength for the cavity wall as a whole.

In general, cavity walls are built by laying a first leaf with the wall ties embedded in the mortar layers between the bricks and projecting horizontally out of the first leaf.

After allowing the mortar of this first leaf to harden, the second leaf is laid incorporating the wall ties projecting from the leaf already erected into the mortar layers between the bricks of the second leaf.

A number of problems have been encountered with such wall ties, particularly as there has been a tendency to use wider cavities for improved insulation.

The first problem is that the weight of the wall tie causes it to sag away from the horizontal due to the stiffness of the mortar being insufficient to keep the wall tie in place. This problem is inevitably worsened by wider cavities because these require longer and heavier ties.

One solution to this problem is to simply place the tie further into the mortar layer when the first leaf is erected, but this can reduce the length of the wall tie within the mortar layer of the second leaf to an unacceptable level when the second leaf is assembled.

Even where sagging is not a problem, there is a general problem of ensuring that the length of the wall tie placed within the mortar layer in the first leaf is correct in order to provide the required length of wall tie within the mortar layers of both leaves.

The amount of the wall tie situated within the mortar layer is critical to the cavity wall structure as a whole having its designed structural strength and at least 50mm of the wall tie length within the mortar layers of each leaf is a normal minimum requirement.

The required penetration of the wall tie into the mortar is the subject of a British Standard, as are the specifications of the wall ties themselves.

Generally, wall ties are placed in the mortar layer in the first leaf of a cavity wall structure manually with their position in the mortar being judged by eye. This leads to problems with ensuring that the necessary minimum penetration into the mortar occurs at both ends of the wall tie.

This invention was intended to provide a wall tie overcoming the above problems of ties sagging and being placed with inadequate penetration into the mortar, at least in part.

This invention provides a wall tie comprising first and second substantially planar portions separated by a portion including a bend at a predetermined distance from the end of the first substantially planar portion and in a plane perpendicular to both the first and second substantially planar portions.

Preferably the bend is substantially 90".

Preferably the wall tie is a wire tie formed integrally from a single piece of wire and in this case the substantially planar portions can advantageously be formed by bending the wire to define a substantially planar shape.

A detailed description of the invention will now be made by way of example only with reference to the accompanying diagrammatic figures in which: Figure 1 shows a typical cavity wall structure employing wall ties; Figures 2A and 2B show plan and side views of a conventional wall tie; Figures 3A, 3B and 3C show plan, side and end views of a wall tie according to the invention; Figure 4 shows a perspective view of the wall tie of figures 3 in use; and Figures 5A and 5B show how the wall tie of figures 3 is used identical parts having the same reference numerals throughout.

Referring to figures 2A and 2B, a typical known double triangle type wall tie 4 is shown in plan and side view respectively. The wall tie 4 is formed by bending from a single piece of wire. In use, the triangular end pieces 4A and 4B of the wall tie 4 are embedded within the mortar layers of the first and second leaves of a cavity wall structure, while the substantially straight linking wire section 4C extends across the cavity. The amount of the linking wire section 4C within the mortar layers of the two leaves of the cavity wall structure will depend on the precise geometry selected and the relative dimensions of the cavity and wall tie. The wall tie 4 includes a kink 4F in the linking wire section 4C to act as a "drip" to prevent water passing along the wall tie 4 from the outside leaf to the inside leaf of the wall.

The wire wall tie design shown is exemplary only, although it is a standard wall tie design.

A wall tie incorporating the invention is shown in plan view, side view and end view in figures 3A to 3C respectively.

The wire wall tie 5 is formed from a single piece of wire bent to shape and is formed with first and second triangular end portions SA and SB, formed by bending the ends of the wire into equilateral triangles and separated by a bent portion 5C. The first and second triangular end portions 5A and SB are identical. The bent portion SC has a single bend SD through a 90" angle in a plane perpendicular to the planes of both of the triangular end portions SA and SB. The bend SD in the bent portion SC is at a prearranged distance D from the end SE of the first triangular end portion SA.The radius R of the bend SD in the bend portion SC is selected such that the wire tie S can be restraightened, eliminating the bend 5D in the bent portion SC, to make the triangular end portions SA and SB coplanar without leaving a kink in the wire. Generally, a radius R of approximately lSmm can be used but this will depend on the material properties and gauge of wire used to make the wire tie. In addition to the bend 5D, the bent portion SC also includes a kink 5F to act as a "drip" in the same way as a conventional wire tie.

The overall length when straightened L. width B and length and corner radius y and r respectively of the triangular end portions of the wire tie S and the size of the drip are substantially the same as a conventional wire tie of the same general design intended for the same use.

The use of the wire tie S will now be explained with reference to figure 4, where a wire tie S is shown in perspective view in position on a brick 6. In order to allow the wire tie S to be clearly seen, the mortar layer on top of the brick 6 has been omitted in figure 4, also the kink SF is omitted for claritv.

The wire tie 5 is placed with the first triangular end portion SA in a mortar layer (not shown) on top of the brick 6 with the bent portion 5C on the edge of the brick 6 and the second triangular end portion SB hanging down the side of the brick 6. As a result, the penetration of the first end portion 5A of the wire tie S into the mortar layer between the brick 6 and the brick above is controlled by and equal to the prearranged distance D between the end SE of the first triangular end portion 5A and the bend 5D in the bent portion SC. Furthermore, it has been found that the problem of sagging of the wall tie can be effectively eliminated by producing a wire tie with z bend portion of this type. It is believed that this is because the couple on the wire tie 5 due to its weight acting around the edge 7 of the brick 6 where the wire tie 5 crosses it is much smaller than for a conventional straight wire tie of the same length and weight and as a result it is easier for this couple to be resisted by the mortar layer in which the first end portion 5A of the wire tie S is embedded. Furthermore, if the wire tie does begin to sag it will only be possible for a very small amount of sagging to occur before the second end portion SB or kink SF forming the "drip" of the wire tie S comes into contact with the brick 6, or the brick leaf below the brick 6, thus stopping any sagging movement.

Referring to figure SA a cross-section through a first leaf 10 of a cavity wall containing a bent wire tie S is shown with the wire tie S on top of a first brick 6 and below a second brick 8 with its first end portion 5A embedded in the mortar layer 9 between the bricks 6 and 8. Once the mortar has hardened the wire tie 5 can be easily straightened by hand and the second end SB of the tie can then be incorporated into the second leaf 11 of the cavity wall unit as is conventional.

Since the penetration of the wire tie S into the mortar of the first leaf 10 is controlled by the predetermined distance D between the first end SE of the wire tie S and the bend SD and the overall length of the tie S and the width of the cavity are also predetermined, the penetration of the wire tie S into the mortar of the second leaf 11 is also controlled by the predetermined distance D from the end SE of the wire tie S to the bend 5D.

Thus the use of a bent wall tie according to the invention, allows the penetration of the wall tie into the mortar in both leaves of the cavity wall to be controlled without the use of any additional equipment or measurement to carry out the brick laying operation. Furthermore, the problem of sagging of the wall ties is effectively eliminated.

The use of a 90" bend is preferred, but an angle of nearly or approximately 90" is acceptable.

The wire tie 5 illustrated includes the central kink 5F to act as a drip similar to that shown in the conventional wire tie 4 in figures 2A and 2B. Alternatively, other forms of drip could be included in the wire tie 5 if desired.

The feature of the provision of a 90" or near 90" bend at a predetermined distance from one end of a cavity wall tie could be usefully incorporated in most designs of cavity wall ties and in particular to most designs of wire tie, the illustrated example of a triangular ended tie is intended as an example only.

Claims (5)

1. A wall tie comprising first and second substantially planar portions separated by a portion including a bend at a predetermined distance from the end of the first substantially planar portion and in a plane perpendicular to both the first and second substantially planar portions.

2. A wall tie as claimed in claim 1 in which the bend is substantially 90".

3. A wall tie as claimed in claim 1 or claim 2 in which the wall tie is a wire tie formed integrally from a single piece of wire.

4. A wall tie as claimed in claim 3 in which the substantially planar portions are formed by wire bent to define a substantially planar shape.

5. A wall tie substantially as shown in or as described with reference to any one of figures 3 to 5 of the accompanying drawings.