GB2230544A

GB2230544A - Wall tie

Info

Publication number: GB2230544A
Application number: GB8908687A
Authority: GB
Inventors: Roger James Scragg; David Laurence Starkey
Original assignee: STARKEY DAVID LAWRENCE
Current assignee: STARKEY DAVID LAWRENCE
Priority date: 1989-04-18
Filing date: 1989-04-18
Publication date: 1990-10-24
Also published as: GB8908687D0

Abstract

A wall tie has opposite ends for engaging in the skins of a cavity wall with the tie portion 11 or 23 being inclined downwardly towards the outer skin to drain any penetrating water. The tie can be of strip metal with the tie portion 11 twisted to minimize adhesion of dropped mortar, or can be of bent metal. The ends have holes 8 and flanges 9 or are bent 21, 22 to promote adhesion. <IMAGE>

Description

WALLING TIE This invention relates to an improved tie for use by builders in the construction of walls made of brick, stone or other forms of masonry.

One especially important form of wall construction which is employed in the building of domestic houses and public buildings entails a cavity wall construction. Walls made in this way comprise an outer and an inner wall separated by a small gap of, for example, about 7 cms. The outer wall is exposed to the weather and is made generally from high resistant materials for example bricks or stone. The inner wall which faces towards the interior of the building is not exposed to the same rigorous conditions.

Consequently whilst either brick or stone can be employed for making the inner wall in general blocks of lighter and less durable building materials, for example breeze blocks or blocks of thermalite are employed more frequently.

In order to ensure that a cavity wall has sufficient strength the two walls are secured together by metal ties which extend horizontally between the walls and the ends of the ties are anchored in the layer of cement binding the bricks or blocks of building material used in the construction of the walls.

Builders ties exist in different forms. However one that is used most frequently is a so called butterfly tie. This device is made by twisting a length of heavy gauge galvanized steel wire so as to form two loops horizontally disposed with respect to each other and having the shape resembling the wings of a butterfly. The two ends of the length of wire are twisted together and form what is in effect the body of the butterfly between the two wings. In use an operative builds one wall of a cavity wall and as he progresses he inserts a loop of a tie between two courses of bricks as he applies the cement. The remainder of the tie protrudes horizontally from the wall in the direction of where the second wall is to be built.When the first wall has reached a desired number of courses the operative then commences to build the second wall spaced sufficiently from the first so that as the second wall rises the exposed loops of the ties can be incorporated with the layers of cement used to bond courses of bricks or other building material forming the second wall.

Butterfly ties have a number of disadvantages which to some extent or other are shared by other known forms of ties. Thus butterfly ties in use extend horizontally between the two walls. Consequently when rain is driven against the outer wall water tends to penetrate the layers of cement between the bricks and to run along the horizontal tie to the inner wall where it tends to form a damp patch on the surface of the wall which faces the interior of the building. The tie has in effect bypassed the damp-proof course which normally forms part of a cavity wall.

A second disadvantage of a butterfly tie resides in the fact that during construction of the walls wet cement tends to fall between the walls and some of it adheres to the body of the tie. The readiness for this to happen stems in large measure on the fact that the body is fairly thick i.e. depending upon the design of the tie. The adhering cement forms an encrustation on the body which facilitates still further the transfer of water from the outer wall to the inner wall.

A further disadvantage of a butterfly tie stems from the fact that when one loop of the tie has been bonded into one wall the remaining exposed part of the tie protrudes horizontally from the wall and obstructs the building of the second wall. In order to overcome the difficulty the operative bends the free loop away from his working area and when he has built the second wall to the desired height he then bends the free loop back towards the new wall prior to embedding it in the layer of cement. This bending operation carried out twice results in cracking of the protective galvanizing coating and as a result, in the course of time, the tie corrodes. Eventually it can break in two with consequent weakening of the wall. The present invention is directed to overcome the disadvantages of existing ties.

Accordingly this invention provides a tie for strengthening two closely spaced walls comprising two wall engaging members each of which is connected to opposed ends of a connecting member the wall engaging members being in stepped relationship with respect to each other, the connecting member when the tie is in use being inclined edgewise upwards between the walls.

This invention is illustrated but not restricted by the following drawings: Figure 1 is an isometrical view of one preferred form of tie made according to the invention.

Figure 2 is a view taken in plan of an alternative form of tie Figure 3 is a side view of the tie shown in figure 2 The tie illustrated in figure 1 can be made conveniently by cutting a flat piece of metal, for example, steel strip having a thickness of from 1 - 3mm and then shaping it so as to form an integral structure described below. The tie when formed can then be galvanized. Other materials can be used for example aluminium. However they are usually more expensive and not necessarily more effective.

In this figure the two wall spacing members (1 and 2) which abut the interior face of inner wall (3) and outer wall (4) are separated by a cavity (5) having a width of about 6 cms. The two wall spacing members (1 and 2) are each connected to a wall engaging member (6 and 7) comprising a generally flat strip which is modified to enable it to become more securely keyed into a layer of cement between two courses of bricks forming a wall. In this figure the keying means comprises holes (8) and the formation of a flange (9). However other means can be employed such as corrugations or tongues. The two wall spacing members (1 and 2) are secured together in stepped relationship by a connecting member (10) which is inclined edgewise upwards between the two walls (3 and 4).

In order to use the tie the inner wall (3) is built up for a few courses after which ties are placed at intervals on a layer of wet cement on the last course and pressed down slightly so as to ensure that cement enters keying hole (8). Each tie is positioned so that the connecting member inclines downwards towards where second wall is to be located. When the inner wall has been constructed to the desired height the outer wall is then built also in such a way that the layer of cement separating each course of bricks has been embedded into the free wall engaging members (6). During the construction wet cement is liable to fall down between the walls. However there is little tendency for any to adhere to the sharp edge (11) of the connecting member (10).Furthermore if rain drives against the outer face of wall (4) and penetrates the cement it is prevented from reaching the inner wall (3) because of the upwards inclination of the connecting member (11 ) Figures 2 and 3 illustrate an alternative form of tie which is made preferably from either stainless steel or ordinary steel wire having a diameter conveniently of about 3mm.

When ordinary steel is employed it is preferably shaped before being subjected to a galvanizing treatment. The tie comprises two loops (21 and 22) joined by connecting member (23) which in effect is part of a length of wire from which the tie has been made. The loops are disposed in stepwise relationship and assist the tie to become more firmly anchored in the cement used to bond courses of bricks together. The tie is dimensioned preferably so that when in use the loops do not extend from the wall and the distance AB which is formed by dropping a perpendicular to an extension of loop (22) corresponds to the width of the space between the wall (not shown). Whilst the wire connector does not possess an edge in the manner indicated when a metal strip is employed as a tie it nevertheless behaves in a similar way from the point of view of being resistant to retaining loose cement when used in its inclined position.

In a normal vertical cavity wall construction the wall engaging members are generally disposed parallel to one another. However in other circumstances they can be angled with respect to one another.

Claims

1. A tie for strengthening two closely spaced walls comprising two wall engag-ing members each of which is connected to opposed ends of a connecting member the wall engaging members being in stepped relationship with respect to each other the connecting member when the tie is in use being inclined edgewise upwards between the walls.

2. A tie according to Claim 1 comprising a shaped strip of metal.

3. A tie according to either of Claims 1 and 2 wherein each wall engaging member is connected to the connecting member through a wall spacing member.

4. A tie according to any one of the preceding claims wherein the wall engaging members incorporate means to enable them to become anchored more firmly within a layer of cement.

5. A tie according to Claim 4 wherein the means comprises a hole.

6. A tie according to Claim 4 wherein the means comprises a flange.

7. A tie according to Claim 1 comprising wire which has been shaped.

8. A tie according to Claim 7 wherein the wire is made of stainless steel.

9. A tie according to Claim 7 made of steel which has been galvanized after having been shaped.

10. A tie according to any one of Claims 7 to 9 comprising two loops connected together in stepped relationship.

11. Ties as hereinberore described with particular reference to the drawings.

11. Ties as hereinbefore described with particular reference to the drawings.

Amendments to the claims have been filed as follows 1. A tie for strengthening two closely spaced walls comprising two wall engaging members each of which is connected te opposed ends cf a connecting member the wall engaging members being in stepped relationship with respect to each other the connecting member when the tie is in use being inclined upwards between the walls.

2. A tie according to Claim 1 comprising a shaped strip of metal wherein the wall engaging members and the connecting member are of integral ccnstruction and when the tie is in use the connecting member is inclined edgewise upwards between the walls.

3. A tie according to either of Claims 1 and 2 wherein each wall engaging member adjoins a wall spacing member.

. A tie according to any one of the preceding claims wherein each wall engaging member incorporates means to facilitate anchorage of the member in one of the walls.

5. A tie according to Claim 4 wherein the means comprises a hole.

6. A tie accordIng to Claim d wherein the means comprises a flange.

7. A tie according to CI. Claim 1 comprising wire which has been shared.

L. A tie according to Cfflair , wherein the wire re is made fn & Ce of stainle0o- steel.

9. A tie according to Claim i made of steel which has been galvanized after having been shaped.

10. A tie according to any one of Claims , to 9 wherein each end of the wire connecting member terminates in a loop the two loops being disposed in stepped relationship.