GB2270937A - Cavity wall ties - Google Patents

Abstract

There is provided a wall tie for tying two leaves of a cavity wall. The tie 20 has angled end portions and an intermediate portion. The end portions are for insertion in respective holes formed in the two leaves, the holes then being filled with a grout/cement 18. A drip formation in the form of a notch 24 can also be provided. A brick is removed from the outer leaf of the wall to allow the holes to be drilled. <IMAGE>

Description

Improvements Relating to Cavity Walls This invention relates to cavity walls, a method of tying the inner and outer leaves of a cavity wall and a wall tie for use in the method.

In a cavity wall the two leaves are joined by a number of wall ties which span the cavity and have their ends embedded in the mortar joins between layers of bricks. Many wall ties, particularly older ones, are made from steel and may have corroded. This leads to expansion and bulging of the wall or even failure of the wall tie. It is, therefore, often necessary to remove old ties and replace them.

Removal is often effected by removing a brick from the outer leaf of the wall, which brick sits above part of the corroded tie, and pulling out the tie or remaining parts of the tie. It is possible to simply replace an old tie with a similar new one but there is a tendency for the grouting material, such as mortar or resin, to fall or pour out before setting.

This obviously impairs the bond and reduces the strength of the link. In an alternative system a horizontal or slightly upwardly inclined hole is drilled into a brick of the inner leaf and a tie of the sort described in UR Patent No. 2153892 is used.

Again there is a tendency for the grouting material to fall or pour out before setting, thereby impairing the bond.

According to a first aspect of the present invention there is provided a wall tie having two end portions at respective ends of an intermediate portion, at least one of said end portions being angled relative to the intermediäte portion and adapted to be secured in respective holes firmed in respective leaves of a cavity wall.

Preferably both two end portions are angled and also extend generally parallel to each other.

Conveniently the intermediate portion and the end portions are generally straight and the wall tie is bent from a single piece of wire. Preferably the intermediate portion is provided with a water drip, perhaps in the form of a V-shaped notch. In a preferred arrangement the notch is located in the same plane as the end portions.

According to the second aspect of the present invention there is provided a method of linking together the inner and outer leaves of a cavity wall, each leaf containing masonry elements, the method comprising the steps of: removing a masonry element from the outer leaf, forming a hole in the inner leaf, forming a second hole in the outer leaf inserting respective end portions of a wall tie into the holes, and replacing the masonry element in the outer leaf.

Preferably the holes extend generally downwardly, In a preferred embodiment they are in a vertical plane. In further preferred embodiments the holes are formed using a drill and an old wall tie is removed whilst the masonry element is temporarily removed.

Conveniently a grout is used to secure the end portions of the wall tie and the grout may comprise a sand/cement grout or a resin/cement grout.

An embodiment of the invention will now be described in more detail. The description makes reference to the accompanying diagrammatic drawings in which: Figure 1 shows a cross-section through a cavity wall at one stage in the method according to the present invention, Figure 2 is a side view of a wall tie according to the present invention, Figure 3 is a view similar to that shown in figure 1 at a later stage in the method, and Figure 4 is a view similar to that shown in figure 1 at a finished stage in the method.

In the figures there is shown a cavity wall 10 having an inner leaf 11 and an outer leaf 12. Each leaf is made up of a number of masonry elements in the form of bricks 14 joined by mortar 15. The leaves 11 and 12 are interlinked by old wall ties (not shown) which have corroded. Each corroded wall tie is exposed by removing the brick together with its associated mortar immediately above the tie in the outer leaf 12 and the tie is extracted and discarded.

A masonry drill is then used to drill two angled holes 16 and 17 in the inner and outer leaves 11, 12 respectively. In the embodiment shown, both holes 16, 17 extend into the bricks 14 and are generally parallel to each other. The holes 16, 17 shown are also angled downwardly relative to a horizontal axis but remain in a generally vertical plane.

A wall tie 20 has two angled end portions 21, 22 which are parallel and which extend at an angle from an intermediate portion 23. The wall tie 20 is forcibly bent from a piece of wire and the intermediate portion 23 is also formed with a V-shaped notch 24 which constitutes a water drip.

The wall tie 20 has its end portions 21, 22 inserted into the holes 16, 17 such that the intermediate portion 23 spans the cavity 25 and the notch 24 is disposed between the leaves 11, 12 so as to prevent moisture passing from the outer leaf to the inner leaf.

The holes 16, 17 are then packed using a suitable grout mixture 18 such as a sand/cement based grout or a resin/cement based grout. In the embodiment shown some of the brick and mortar above the hole 16 in the inner leaf is also removed to enable the wall tie to be inserted and a suitable grout 19 is also used to pack this area. It is, however, not always necessary to affect such areas.

The removed brick from the outer leaf 12 can then be replaced in the outer leaf and bedded in using mortar in the known manner and the mortar joints repointed if necessary.

This arrangement offers considerable advantages over known replacement methods. Firstly the downwardly extending nature of the holes 16, 17 means that there is no tendency for the grout to fall out or run away. Thus the mixing of the grout to a suitable viscosity is not so vital. Secondly the effective cleaning of the holes 16, 17 is not so vital because any dust is more likely to settle at the base of the hole, not all along its length, Furthermore, any tendency for the leaves to separate in the event of grout failure, for example, is resisted because of the staple-like qualities of the wall tie and the downwardly extending end portions which prevent the leaves from separating.

The precise angle of the end portions 21, 22 of the tie relative to the intermediate portion 23 is a matter of design choice. The greater the angle the better for resisting the parting of the leaves 11, 12. However, the larger the angle the more difficult it is to drill the holes 16, 17.

Around 450 has been found to be practical but a wide range of angles above and below this figure are suitable. For example a 900 angle for the outer end portion 22 has been found to be effective where the end portions are not parallel.

The S-notch 24 could be replaced by any other suitable formation in the wire or a rubber ring rolled into position along the tie 20. Alternatively the tie 20 could be oriented such that the intermediate portion 23 is downwardly inclined towards the outer leaf 12. Also the end portions 21, 22 may incorporate formations or be roughened to enhance their retention in the grout. For example, the end portions may incorporate undulations.

It is also possible for the end portions 21, 22 to be inserted into holes formed in the side wall of an exposed brick in the outer leaf after the first brick has been removed. The holes could still be drilled somewhat downwardly to ensure the grout remained in place whilst setting although this is not essential. In addition the resistance to the separation of the leaves would still be present.

With the illustrated method the two holes 16, 17 are preferably formed in a plane which is perpendicular to the two leaves 11, 12 to ensure strength. Whilst it is possible for the angles of the end portions 21, 22 relative to the intermediate portion 23 to be different, it is sometimes preferable for them to be the same as this makes insertion simpler. The end portions 21, 22 can also be in different planes if desired.

In further applications it is possible to use the wall tie in other situations. For example, the wall tie could be used when a second wall is being constructed adjacent an existing wall so as to form a cavity wall construction. The ties could be secured as the second wall is constructed, the holes in the existing leaf being drilled either before construction of the outer leaf or as and when a suitable location is reached.

The system could also be used during the construction of a new cavity wall, holes being drilled and ties inserted at chosen locations. In addition the system could be used in masonry cladding incorporating a cavity between leaves.

It is also envisaged that the end portions could be of different length to each other. Also, the grout 19 securing either or both end portions could be replaced by forcibly inserting the end portions in tight fitting holes 16, 17 drilled into the leaves.

Other forms of packing or securing could be used.

Claims (16)

1. A method of linking together the inner and outer leaves of a cavity wall, each leaf containing masonry elements, the method comprising the steps of: removing a masonry element from the outer leaf, forming a hole in the inner leaf, forming a second hole in the outer leaf,inserting respective end portions of a wall tie into the holes, and replacing the masonry element in the outer leaf.

2. A method as claimed in claim 1 wherein the end portions of the wall tie are secured in the holes.

3. A method as claimed in claim 2 wherein the securing is by inserting a grout into the holes around the end portions of the wall tie.

4. A method as claimed in claim 3 wherein the grout comprises a sand/cement grout or a resin/cement grout.

5. A method as claimed in any one of claims 1 to 4 wherein the hole in the innter leaf is not perpendicular to the inner leaf.

6. A method as claimed in claim 5 wherein the holes are horizontal.

7. A method as claimed in any one of claims 1 to 6 wherein the holes extend generally downwardly.

8. A method as claimed in claim 7 wherein the holes are in a vertical plane.

9. A method as claimed in any one of claims 1 to 8 wherein the holes are formed using a drill and an old wall tie is removed whilst the masonry element is temporarily removed.

10. A wall tie having two end portions at respective ends of an intermediate portion, at least one of said end portions being angled relative to the intermediate portion and adapted to be secured in respective holes formed in respective leaves of a cavity wall.

11. A wall tie as claimed in claim 10 wherein both end portions are angled relative to the intermediate portion.

12. A wall tie as claimed in claim 11 wherein the two ends extend generally parallel to each other.

13. A wall tie as claimed in claim 11 or claim 12 wherein the end portions are generally straight and the wall tie is bent from a single piece of wire.

14. A wall tie as claimed in any one of claims 10 to 13 wherein the intermediate portion is provided with a water drip.

15. A wall tie as claimed in claim 14 wherein the water drip is in the form of a V-shaped notch.

16. A wall tie as claimed in claim 15 wherein the notch is located in the same plane as the end portions.