GB2152993A

GB2152993A - Installing wall-tie in existing cavity wall

Info

Publication number: GB2152993A
Application number: GB08431877A
Authority: GB
Inventors: Andrew Kenneth Langlands-Brown; John Leslie Allen; John Fordham Speaight Pryke
Original assignee: Pynford Ltd
Current assignee: Pynford Ltd
Priority date: 1983-12-22
Filing date: 1984-12-18
Publication date: 1985-08-14
Also published as: GB8334248D0; GB8431877D0

Abstract

A hole 4 is drilled through a leaf 1 of the wall and part of the way 4'' into the second leaf 2 across the cavity 3. A settable bonding composition 5 is pumped into the hole 4'' in leaf 2 and an elongate reinforcing element 7 is inserted into hole 4''. Discs 8,9 are on element 7, one 8 lying centrally in the cavity to form a drip point and the other 9 lying at the inner end of hole 4 in leaf 1, to support element 7 spaced from the sides of the hole and also to provide a stop for settable bonding composition which is thereafter injected into hole 4 in leaf 1 around the end of element 7. <IMAGE>

Description

SPECIFICATION Method of installing wall ties The present invention relates to the insertion or installation of wall ties which are used to tie together a pair of leaves of a cavity wall or the like. More particularly the invention relates to a method of installing such wall ties in an existing wall.

Wall ties are normally built into a cavity wall during its construction and are typically positioned at about one per square metre over the whole wall.

The ties normally comprise twisted metal strips or bent wire forms which are laid in adjacent courses of mortar in the two skins of the wall and which are thus bonded into the skins of the wall as the mortar sets. However, in the past it was not always a requirement of Building Regulations that wall ties be provided and also, in the past, relatively easily corrodable materials were used for the wall ties.

Thus, in walls which have no ties between the two leaves, in walls where the ties have corroded, or in cavity walls where additional ties are required, for example as a result of forming openings in the wall, there is a requirement to insert wall ties in an existing wall.

In the past this requirement has been met by wall ties with expandable end portions which are positioned in aligned holes drilled in the wall and then expanded into a tight fit within the holes. This method, however, suffers from the disadvantage that considerable stresses are imposed in the blockwork or brickwork forming the leaves of the wall by the expansion of the ends of the ties and this in itself may lead to cracking of the blockwork or brickwork and thus weaken the wall.

GB-A-1515162 describes a method of installing a wall tie in a cavity wall which comprises drilling aligned holes, usually through a mortar joint, across the cavity wall outer leaf and part of the way into the inner leaf; inserting a perforated plastic tube into the hole and pumping a resin composition into the tube so that it fills the tube, bonds to the brickwork and forms a drip point on the tie in the cavity; and thereafter inserting a steel reinforcing rod within the plastic tube. The hole is then plugged and the resin sets within a few hours bonding the tie strongly to the brickwork in both leaves. Whilst this method is generally satisfactory in operation it does involve a number of steps and uses plural elements, both of which tend to make the method somewhat expensive.

According to the present invention a method of installing a wall tie in a cavity wall comprises drilling a hole through a first leaf of the wall and part of the way into the second leaf across the cavity; pumping a settable bonding composition into the hole in the second leaf; and inserting an elongate reinforcement element into the hole, a pair of disc elements being positioned on the element, one positioned to lie substantially centrally in the cavity to form a drip point and the other positioned to lie at the inner end of the hole in the first leaf when the element is in position, to support the element spaced from the sides of the hole and also to provide a stop for settable bonding composition which is thereafter injected in the hole in the first leaf around the end of the element.

A third disc element may additionally be provided positioned to prevent the bonding composition from oozing from the hole in the second leaf to any appreciable extent and/or to centre the element in the hole in the second leaf. The disc elements may comprise plastic washers which are a tight fit on the elongate reinforcement element. Alternatively the disc elements may be formed integrally connected to one another, for example being formed as flanges on a plastics tube which may have one or more apertures formed into its wall. If a third disc element is provided then it may be tapered or otherwise reduced in cross-section to form a guide for guiding the disc element into position at the end of the hole in the second leaf.

Preferably the elongate reinforcement element comprises a stainless steel rod which is thus resistant to moisture, but the element may be a tube or other form and may be formed of mild steel or other suitable materials in particular circumstances.

Preferably the bonding composition is a synthetic resin compound such as a two-part epoxy resin, but it may comprise other materials capable of providing the required bond to the blockwork or brickwork or the like, for example polymer cement mortar, cement grout, or polyester compositions.

After the bonding composition has cured the ends of the tie rod will be bonded firmly into the leaves of the wall. Even before the bonding composition has set the exposed face of the hole, which would normally be in the external leaf can be re-pointed to suit the original finish.

Preferably the bonding composition is pumped into the hole in the second leaf through a tube having a diameter only slightly less than that of the hole, the tube being forced back from within the hole by the pressure of the bonding composition as it is injected into the hole from the end of the tube. Similarly, the bonding composition is preferably injected into the hole in the first leaf through the same tube, in this case the tube being positioned around the tie rod and again the tube being forced back towards the exit of the hole by the pressure of bonding composition as it is injected. This ensures that bonding composition completely fills the annular gap between the tie rod and the side of the hole, surrounding the tie rod and providing a complete bond into the brickwork or blockwork.

One example of a method according to the present invention will now be described with reference to the accompanying drawings, Figures 1 to 5, which show a partially sectioned view of a cavity wall at various stages of the method in sequence.

The cavity wall in which the tie is to be installed has an outer leaf 1 and an inner leaf 2 separated by a cavity 3. The leaves 1, 2 may be brick, block or other building materials. A hole 4 is drilled from the outside through the outer leaf 1 across the cavity 3 and part of the way into the inner leaf 2. To simplify the description the hole in the outer leaf will be referred to by the reference numeral 4' and the hole in the inner leaf by the reference numeral 4". The hole 4 is preferably drilled through a mortar joint so that after completion of installation and re-pointing the pattern of brickwork is not defaced by plural holes, but rather the appearance of the brickwork is left substantially unchanged.

As a first stage in the process a synthetic resin 5, for example a two-part epoxy resin, is pumped into the hole 4". The resin 5 is pumped into the hole 4" through a plastic tube 6 (see Figure 4) which is first positioned fully in the hole 4" and which, as the resin 5 is pumped through the end of the tube is gradually forced out of the hole under the pressure of the pumped resin. Pumping in the resin in this way ensures that the hole 4" is completely filled.

After the hole 4" has been filled with the resin 5 the tube 6 is removed and a stainless steel tie rod 7 formed from studding which is fully helically threaded over its whole length, is inserted through the hole 4' and into the hole 4". A first tight-fitting plastic washer 8 is positioned on the rod at a point such that when the rod is fully inserted in the hole 4" the washer 8 lies substantially centrally of the cavity 3 to provide a drip point for any moisture forming on the rod 7 or running down the inside of the outer leaf onto the rod 7. A second tight-fitting plastic washer 9 is positioned on the rod so as to lie just within the inner end of the hole 4' when the rod is fully inserted.

To insert the rod satisfactorily it is normally twisted during insertion as the resin is a highly viscous thixotropic liquid. As the rod 7 is inserted a portion 10 of the resin 5 is forced out of the hole 4", but due to its nature does not drip all the way down the inside of the cavity, but rather forms a blob of material adjacent the hole.

The washer 9 not only spaces the rod so that it lies substantially centrally in the hole 4' but also provides a stop to at least partially retain resin which is next pumped into the hole 4', and prevent it from escaping into the cavity. In the next part of the method the tube 6 is again inserted in hole 4' and this time it also surrounds the rod 7. It is initially positioned against the washer 9 and as fluid resin is pumped into the hole 4' surrounding the rod 7 again it is forced outwards under pressure, thus ensuring complete filling of the hole 4' and ultimately complete bonding between the rod 7 and the block or brick work in the leaf 1.

After the resin has been back-filled to the end of the rod 7 the hole can be pointed up with mortar 11 to suit the original finish. The resin will cure over a period of 12 to 18 hours and after this time the tie will be fully operative within the cavity wall.

As mentioned above a third washer or other disc element could be provided both to locate the rod centrally in the hole in the second leaf and to prevent too much of the resin from exiting from the hole in the second leaf as the rod is inserted, and could be tapered to ensure an accurate location in the end of the hole. If the disc element is formed by a separate washer it would be inserted onto the rod prior to the first washer described above.

It is envisaged that the same method may be used in solid walls where the facing has detached leaving a void, or in other similar situations where a tie is required between two components separated by a void.

Claims

1. A method of installing a wall tie in a cavity wall, the method comprising drilling a hole through a first leaf of the wall and part of the way into the second leaf across the cavity; pumping a settable bonding composition into the hole in the second leaf; and inserting an elongate reinforcement element into the hole, a pair of disc elements being positioned on the element, one positioned to lie substantially centrally in the cavity to form a drip point and the other positioned to lie at the inner end of the hole in the first leaf when the element is in position, to support the element spaced from the sides of the hole and also to provide a stop for settable bonding composition which is thereafter injected in the hole in the first leaf around the end of the element.

2. A method according to claim 1, wherein a third disc element is provided positioned to prevent the bonding composition from oozing from the hole in the second leaf to any appreciable extent and/or to centre the element in the hole in the second leaf.

3. A method according to claim 1 or claim 2, wherein the disc elements comprise plastic washers which are a tight fit on the elongate reinforcement element.

4. A method according to claim 1 or claim 2, wherein the disc elements are formed integrally connected to one another.

5. A method according to claim 4, wherein the disc elements are formed as flanges on a plastics tube.

6. A method according to claim 5, wherein the plastics tube has one or more apertures formed into its wall.

7. A method according to claim 2 or any of claims 3 to 6 when dependant thereon, wherein the third disc element is tapered or otherwise reduced in cross-section to form a guide for guiding the disc element into position at the end of the hole in the second leaf.

8. A method according to any of claims 1 to 7, wherein the elongate reinforcement element comprises a stainless steel rod.

9. A method according to any of claims 1 to 7, wherein the reinforcing element is a tube.

10. A method according to any of claims 1 to 9, wherein the bonding composition is a synthetic resin compound.

11. A method according to any of claims 1 to 10, wherein the bonding composition is pumped into the hole in the second leaf through a tube having a diameter only slightly less than that of the hole, the tube being forced back from within the hole by the pressure of the bonding composition as it is injected into the hole from the end of the tube.

12. A method according to claim 11, wherein the bonding composition is preferably injected into the hole in the first leaf through the same tube, in this case the tube being positioned around the tie rod and again the tube being forced back towards the exit of the hole by the pressure of bonding composition as it is injected.

13. A method of installing a wall tie in a cavity wall, substantially as described with reference to the accompanying drawings.

14. A wall tie installed by a method according to any of claims 1 to 13.

15. A wall having one or more wall ties according to claim 14.