GB2169939A

GB2169939A - Wall tie

Info

Publication number: GB2169939A
Application number: GB08600733A
Authority: GB
Inventors: Robert Taylor
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-01-22
Filing date: 1986-01-14
Publication date: 1986-07-23
Also published as: GB2169939B; GB8600733D0; GB8501533D0

Abstract

A cavity wall tie for use in a multiple skin masonry cavity wall has an outer end portion 15, an inner end portion 16 and a cavity bridging portion 14 which is upwardly inclined throughout the width of the cavity 13 from the outer leaf 10 to the inner leaf 11. This inclination is preferably at least equal to the height (H) of one standard brick. In use, the outer leaf 10 is built slightly ahead of the inner leaf 11 and the inner end portion 16 of the tie can be pulled downwardly by hand to lie in a coursing joint 12 of the inner leaf, irrespective of any unevenness between the coursing joints 12 of the inner and outer leaves. In a modification (Figure 2) a vertical portion 19 is provided adjacent the inner leaf 11 so that the inner and outer end portions 15, 16 are initially coplanar. The vertical portion 19 links the inner end portion 16 to the main cavity bridging portion 18. <IMAGE>

Description

SPECIFICATION Wall tie This invention relates to a wall tie for use in multi skin masonry cavity walls having at least two leaves of masonry spaced by a cavity.

It is general building practice to construct cavity walls using large sized blocks of breeze or THERMALITE (registered trade mark) for the inner leaf and using smaller standard facing bricks for the outer leaf. Where part of the outer leaf of the wall is concealed for example by a porch canopy or the like, both bricks and blocks may be used in the same masonry leaf.

It is essential for the security of the wall that the inner and outer leaves are tied together by wall ties capable of transmitting tension and compression forces from one leaf to the other. To avoid moisture running along the wall ties into the inner leaf, they are usually provided with a drip formation to prevent water crossing the cavity.

In theory, such wall ties are effective but in practical building difficulties are encountered.

Firstly, even where both inner and outer leaves are built of masonry elements such as bricks of the same size, they are not built at the same rate because it is usual to build up the outer leaf of the wall before bringing the inner leaf of the wall up to the same level. Thus, if the thickness of the mortar coursing joints is not kept absolutely constant, there is the danger that the inner leaf and outer leaf brickwork may become "out of step" and the wall ties introduced into the coursing joints of the outer leaf may not exactly meet the coursing joints of the inner leaf.

This problem is of course greatly aggravated where the inner and outer leaves are made of differently-sized masonry elements. It will then be appreciated that many of the coursing joints will not tally between the inner and outer leaves.

Under practical conditions, this often results in a wall tie which has been left projecting from the outer leaf masonry being bent downwardly to meet a coursing joint of the inner leaf masonry as the inner leaf is built up. Naturally, this means that the wall tie slopes downwardly towards the inner leaf of the cavity wall and is very likely to result in damp penetrating along the wall tie into the inner leaf.

Similarly, where mortar is allowed to fall down into the cavity, it is likely to lodge on one of the wall ties at a lower level and, particularly where the wall tie tends to slope downwardly towards the inner leaf of the wall, the mortar may form a bridge, tending to trap water against the inner leaf masonry.

It is an object of the present invention to provide a wall tie which overcomes or reduces these disadvantages met during practical use of conventional wall ties.

according to the invention there is provided a wall tie for use in multiple skin masonry cavity walls, the wall tie comprising an outer end portion adapted to be embedded in a mortar coursing joint of an outer masonry leaf of the cavity wall; an inner end portion adapted to be embedded in a mortar coursing joint of an inner masonry leaf of the cavity wall; and a cavity bridging portion extending from the outer end portion to the inner end portion of the tie and being upwardly inclined across substantially the entire cavity in use from the outer end portion to the inner end portion, the cavity bridging portion of the tie being capable being deformed by hand to adjust the level of the inner end portion relative to that of the outer end portion in use.

The tie may be made of wire or strip of corrosion resistant metal such as galvanised mild steel or stainless steel, or may be made of plastics material.

Preferably, the inclination of the cavity bridging portion is at least equal to the height of one standard brick, that is 75 mm.

A cavity bridging portion may include one or more vertically downwardly directed portions immediately adjacent the inner or outer end portions of the tie and linking the said inner or outer end portion and the upwardly inclined portion of the tie. In these versions of the tie, the cavity bridging portion is upwardly inclined across substantially the entire cavity but there may be one or more vertical portions adjacent the inner and/or outer leaf masonry so that the inner and outer end portions may at least initially be coplanar.

Preferably, the cavity bridging portion of the tie presents a narrow cross-section as viewed in plan to reduce the risk of mortar build up on the tie.

Two versions of wall tie embodying the invention will now be described in more detail by way of example only with reference to the accompanying drawings in which: Figure 1 is a diagrammatical side elevational view of a brick-block masonry wall having a wall tie according to the invention, the initial shape of the wall tie being shown in chain dotted lines.

Figure 2 is a view similar to that of Figure 1 showing a modified form of wall tie.

Figure 3 is a plan view of the tie of Figure 1.

Referring to Figure 1 of the drawings, there is shown a brick-block masonry cavity wall comprising an outer leaf 10 of brick and an inner leaf 11 of large sized blocks such as breeze blocks. The inner and outer leaves of the wall are built up in courses, with mortar 12 being used to secure the masonry elements together at coursing joints.

In generally known manner, a cavity 13 separates the inner and outer leaves 10 and 11 of the wall.

Awall tie 14, also shown in Figure 3 in plan view, is used to link the inner and outer leaves of the wall together so as to transmit tensile and compressive forces between the two leaves of the wall and unify the wall structure. In the example shown, the tie 14 is made of wire which may be stainless steel or corrosion resistant (e.g. galvanised) mild steel wire for example. Alternatively, the tie could be produced in strip metal or in a plastics material having suitable strength characteristics such as polypropylene.

The tie comprises an outer end portion 15 which is embedded in use in a mortar coursing joint 12 of the outer leaf 10. It also comprises an inner end portion 16 which is embedded in use in a coursing joint 12 of the inner leaf 11. Between the inner and outer end portions 16 and 15, a cavity bridging portion 17 is provided. In the form shown in Figures 1 and 3 of the drawings, this cavity bridging portion 17 is straight but it is inclined upwardly as seen in side elevation in Figure 1 so as to slope upwardly across substantially the entire width of the cavity 13.

The chain dotted line in Figure 1 shows the initial form of the wall tie, that is its initial shape on manufacture. The inner end portion 16a is at a level spaced from that of the outer end portion 15 by approximately the height H of one standard brick, that is 75 mm.

In use, however, the inner end portion 16 is pulled downwardly by hand so as to sit in the mortar coursing joint 12 of the inner leaf masonry which is closes to its natural level. Even in a very extreme case, the inner end portion 16 would not be pulled downwardly below the level of the outer end portion 15. Thus, there is never a condition in which the cavity bridging portion 17 slopes downwardly towards the inner leaf 11. It always slopes downwardly towards the outer leaf 10 of the wall, although the angle of inclination may vary according to the relative positions of the inner and outer leaf coursing joints 12.

In this way, the normal building practice of building up the outer leaf slightly ahead of the inner leaf can be continued. The ties are left projecting from the coursing joints 12 of the outer leaf, with the cavity bridging portions 17 inclined upwardly. As the inner leaf masonry is built up to that level, the ties can be pulled downwardly by hand so as to lie in the coursing joints 12 of the inner leaf.

In order to key the wall tie thoroughly into the mortar of the coursing joints 12, suitable formations are provided on the inner and outer end portions 16 and 15, for example the triangular folded formation shown in Figure 3.

Referring to Figure 2 of the drawings, a modified form of wall tie is shown in which, although the cavity bridging portion 18 inclines upwardly across substantially the entire cavity from the outer leaf 10 to the inner leaf 11, it has an additionally vertical part 19 extending downwardly from adjacent the inner leaf masonry 11 to merge with the inner end portion 16.This vertical downward portion enables the tie to be manufactured with the inner and outer end portions 15 and 16 substantially coplanar but still ensures that the cavity bridging portion 18 inclines upwardly across the cavity from the outer leaf 10 to the inner leaf 11 In use, the inner end portion 16 can still be pulled downwardly to align with an appropriate coursing joint of the inner leaf 11 while the cavity bridging portion 18 still provides the correct inclination to cause any moisture condensing on itto trickle towards the outer leaf 10.

It is known, in the context of timber frame construction, to provide a wall tie having an upwardly inclined slope across a cavity of a timber frame cavity wall, the inner end portion of the tie then extending vertically upwardly and being secured to the inner timber frame leaf of the wall.

The present invention does not seek to cover this form of timber frame wall tie.

Claims

1. A wall tie for use in multiple skin masonry cavity walls, the wall tie comprising an outer end portion adapted to be embedded in a mortar coursing joint of an outer masonry leaf of the cavity wall; an inner end portion adapted to be embedded in a mortar coursing joint of an inner masonry leaf of the cavity wall; and a cavity bridging portion extending from the outer end portion to the inner end portion of the tie and being upwardly inclined across substantially the entire cavity in use from the outer end portion to the inner end portion, the cavity bridging portion of the tie being capable of being deformed by hand to adjust the level of the inner end portion relativeto that of the outer end portion in use.

2. A tie according to Claim 1 made of corrosion resistant metal wire.

3. Atie according to Claim 1 made of corrosion resistant metal strip.

4. A tie according to Claim 2 or Claim 3 wherein the metal is galvanised mild steel.

5. A tie according to Claim 2 or Claim 3 wherein the metal is stainless steel.

6. A tie according to Claim 1 made of plastics material.

7. Atie according to any preceding claim wherein the inclination of the cavity bridging portion is at least equal to the height of one standard brick.

8. A tie according to any preceding claim wherein the cavity bridging portion includes one or more vertically downwardly directed portions immediately adjacent the inner or outer end portion of the tie and linking the said inner or outer end portion and the upwardly inclined portion of the tie.

9. Atie according to any preceding claim wherein the cavity bridging portion presents a narrow cross section as viewed in plan.

10. A cavity wall tie for use in a multiple skin masonry cavity wall substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 3 of the accompaning drawings.

11. A cavity wall tie for use in a multiple skin masonry cavity wall substantially as hereinbefore described with reference to and as illustrated in Figure 2 of the accompanying drawings.