GB2201977A - Structural ties for walls - Google Patents

Abstract

A cavity wall has an outer leaf 4 of conventional brick and mortar construction and an inner leaf built up from a number of large panels 1 of aerated concrete. Panels of insulation are included in the cavity. The cavity is maintained and the insulation positioned by a number of wall ties 3 embedded in mortar in the brickwork 4 and driven through the insulation 2 and directly into the aerated concrete 1 without a pilot hole having been bored first in the aerated concrete. <IMAGE>

Description

STRUCTURAL TIES This invention relates to the use of reinforcements and ties of the kind the subject of European Patent Application No. 85305405.4, filed on 29 July 1985 and published under the number 0171250 on 12 February 1986.

Various forms of tie are disclosed in that specification, but in essence the tie comprises a length of wire with a uniform cross-section consisting of a core and a number of externally projecting fins, with a uniform twist along its length so that effectively the tie has helical flanges. The length of the tie might be anything from a few centimetres to 1 or 2 metres. A preferred form is made from a cylindrical feed wire with a diameter of perhaps 2, 3, 4, 5 or 6 mm by deforming the feed wire in dies to define the flanges, each of which might be as wide as the core diameter.

That specification describes not only the ties themselves but methods of using them, for example, for tying together two spaced masonry walls or a masonry wall and timber cladding or decoration.

A problem in some applications was that for one end of the tie to be secured in a masonry wall, for example, built up from bricks and mortar or aerated concrete, that end of the tie had to be arranged to lie in the mortar bed between successive courses of bricks or of concrete blocks, or a block had to be drilled with a pilot hole to accommodate the core of the tie.

Although the ties performed perfectly well, the method of applying them tended to be a little laborious.

This problem has been solved by the discovery by the inventprs that, where such structural masonry comprises aerated concrete blocks, the ties can in fact be driven in without the necessity df previously drilling a pilot hole.

Although aerated concrete has been referred to because aerated concrete blocks are being used increasingly as the inner leaf of cavity brickwork, the invention applies equally to other members of compacted granular material, or pumice, for example.

Thus, provided one leaf of a double leaf masonry wall is of a material that can accept a tie without requiring a pilot hole, the ties can be used to tie the two leaves together, provided they are driven into, or through, the one leaf at positions corresponding to mortar beds between, say, courses of brick work in the other leaf. That enables fewer ties to be used with the positions of the ties not being critical so that the aerated concrete blocks or other structural members can be of substantial area and do not have to be small enough for there to be frequent interruptions between successive blocks containing a mortar bed.

Also, insulation material such as blocks or quilts positioned between the two leaves of such a double wall can easily be penetrated by the ties so that they can be secured in position readily even if they are also of substantial area.

Therefore, according to one aspect of the present invention, a layer of material is secured to a structural masonry wall by helically flanged ties driven into the body of the structural masonry. ' The layer of material could be another masonry layer, for example, of bricks and mortar, or could be a timber layer, or could be a protective or decorative layer.

The helically flanged tie is strongly resistant against withdrawal from structural masonry or from timber, even if it is driven into the end grain of timber, and according to another aspect of the invention, helically flanged ties are used to secure together the components of a multicomponent assembly merely by being driven through the various components.

In one embodiment of this aspect of the invention a preformed insulating slab which is not in itself self-supporting, can have timber or other-battens secured on either side, preferably opposite one another, with all the components being retained in assembly by helically flanged ties driven through the battens and the slab of material.

Preferably the ties extend at an angle to the general plane of the slab and preferably extend in different angular directions to produce a substantial bracing effect.

A self-supporting insulating layer for use in a building can be manufactured in that way and could include a layer of vapour-resisting material.

The invention may be carried into practice in various ways and certain embodiments will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a sketch showing the construction of c double leaf wall with intermediate insulation using helically flanged ties; Figure 2 is an end section showing a modification of Figure 1 with a different kind of intermediate insulation; Figure 3 is a view similar to Figure 2 of a modified double leaf wall construction method; Figure 4 is a sketch showing how a skirting board can be fixed to an aerated concrete partition wall; and Figure 5 is a series of sketches showing how a replacement wall tie can be introduced into a cavity wall, of which the inner leaf is of aerated concrete.

In the embodiment of Figure 1, a double leaf wall has an inner leaf built up from load bearing but light weight aerated concrete blocks' 1 and an outer leaf 4 conventionally built from bricks and mortar. In the cavity between the inner and outer leaves and 4 is a layer built up from blocks of insulation board 2 which fill or substantially fill the cavity.

The three layers 1, 2 and 4 are tied together by a number of helically flanged ties 3. Preferably, the ties are of a metal which will not corrode, being of stainless steel or steel with a corrosion-resistant coating. The ties are straight ties, for example, of the kind described with reference to Figures 1 and 2 of the European Patent Specification published under the number 0171250 on 12 February 1986 and consist essentially of a central core and two diametrically opposed flanges which are of helical form with a substantial pitch, possibly formed merely by twisting the core which has been produced with flanges in a common plane on opposite sides of the core. The core may be between 2 and 6 mm in diameter and the tie will have a sharpened point on one, or possibly both, ends.

There is no difficulty in driving such a tie through the light insulation board 2, but the inventors have discovered that it is possible to drive the tie 'into - and even through - the body of the aerated concrete block 1 and, indeed, some other masonry blocks which are strong enough to be vertical-load-carrying structural members. This discovery means that the leaves of the wall can be tied together merely by driving ties into, or through, the masonry inner leaf and through the intermediate insulation boards.

After a certain number of courses of the brick leaf 4 have been completed, ties can be driven from the outside through the insulation layer 2 and into the aerated concrete layer 1, without requiring predrilling of the concrete, and without needing to locate in the mortar between adjacent concrete blocks, the outer parts of the ties can then be embedded in the mortar for the next course of bricks.

Pilot holes do not have to be drilled and there is a good choice of positions of the ties, provided they line up with the bed joints indicated at 5 in Figure 1.

Alternatively, the ties may be driven through the layers 1 and 2 from the inside, to be positioned just above a completed brick course.

Since the ties can be driven directly into and through the aerated concrete block 1, it is not necessary for there to be many bed joints between adjacent blocks and, therefore, the blocks can' be of a substantially larger area than would otherwise be the case. They might be 1 metre square or even larger.

For similar reasons the insulation board 2 can be of large area. Assembly is very quick so that erection is cheaper and quicker than in previously proposed methods.

In most cases, it will be possible merely to hammer the ties into position, but dense concrete blocks might require driving by ballistic means.

It will be noted that a minimum of bedding material between blocks is needed. Another advantage is that, with large intermediate insulation blocks and few joints between insulation blocks, the loss of heat and penetration of moisture through the insulation layer will be reduced.

The arrangement of Figure 2 is quite similar, but in that case, the insulation boards are replaced by rolls of insulation quilting 6. Once again, the helically flanged ties 3 are driven into the concrete inner leaf blocks 1 through the quilt 6, and are then set in the bed joints 5 of the outer brick leaf.

In the embodiment of Figure 3, the external leaf is not of conventional brick work 4, as in Figures 1 and 2, but, in the upper part of the Figure, is of timber cladding strips 8, extending horizontally and located one above another. The cladding strips are secured to horizontally spaced vertically extending battens 9 which hold the insulation 2 against the inner aerated concrete wall blocks 1 by the same helically flanged ties 3 which extend at angles to the vertical and the horizontal, both inwardly and upwardly, and inwardly and downwardly. After the ties have been inserted from the outside and driven through the battens, and the insulation, and part way through the inner aerated concrete blocks 1, the external cladding strips 8 are secured to the battens 9 conventionally.

The upper part of Figure 3 shows intermediate insulation boards 2 similar to those in Figure 1, while in the lower part of Figure 3, the insulation is provided by quilting 6 as in Figure 2. In the latter case, pieces of quilting 6 sit on horizontally extending timber components 10, and the battens 9, components 10 and inner leaf blocks 1 are tied together by the helically flanged ties 3 driven in from the outside again at oblique angles upwards and downwards.

In that example, instead of timber cladding strips 8, tiles 11 are held on horizontally extending timber strips 7 secured to the battens 9 conventionally.

Although the ties can be very easily driven straight into the components to be tied together, there is a consistently high withdrawal strength provided by the ties driven directly into the aerated blocks. The aeration, of course, enables the blocks to provide maximum thermal insulation, but, although the aeration weakens the block, it is nevertheless strong enough in compression to support structural weights and transfer them to the ground. The ties extending upwards and downwards in a sort of triangulated arrangement are quite capable of transferring the vertical loads of the cladding to the structural blocks 1.

The oblique ties provide bracing against horizontally applied forces. The helically flanged ties provide much better pull out resistance when driven into the end grain of timber than do nails or screws. The helically flanged ties can fasten components together effectively even if there is a gap, as at 13 in Figure 3.

As a tie is driven into a batten 9, it turns due to its helical flanges, and continues to turn as it is driven throught he component 10, and across the gap (containing quilting 6) in the angle between the component 10 and the concrete block 1. When it reaches the concrete, it continues to screw itself with the cement, but does not tend to reduce the gap; because it is screwing simultaneously into brick components 10 and 1. Thus, the gap is maintained.

In Figure 4, a timber skirting board 15 is to be secured through plaster 16 into an aerated concrete block 17 constituting a wall in a building.

Wall ties of the kind described are first driven into the skirting board while it is lying flat in what will be two vertically spaced horizontal rows. Then the skirting board is lifted into position against the lower edge of the plaster, and the upper line of ties is hammered through the plaster and into the aerated concrete block. The lower line of ties is driven through the skirting board while a gap is maintained between the aerated concrete and the skirting board where there is an absence of the plaster.After the pointed or inner ends of the lower ties are in contact with the aerated concrete, they are then driven in further, and, since they will automatically be turned and screwed by their helical flanges into both the skirting board and the aerated concrete block, the gap between the two will be maintained and there will be no danger of distorting the arrangement or releasing the upper ties.

In Figure 5, four successive stages in the introduction of a replacement wall tie of the kind described already are shown. The inner leaf is a block of aerated concrete 21 and the outer leaf is a conventional brick and mortar leaf, of which, in each of the four sketches, a single brick is shown.

First, a hole is bored with a masonry drill 12 mm in diameter through the brick 22. Then, the replacement tie 23 is passed through the bore in the brick until it extends across the cavity and it is then driven directly into the aerated concrete inner leaf 24 using a hammer and a special tool 25. A sleeve 26 is fitted into the bore around the outer end of the tie, which is set in a little from the outer edge of the brick, and, finally, grout or some other adhesive which can flow and bond is forced into the bore to bond the outer end of the tie to the brick.

Claims (18)

1. A method of securing a component in relation to a piece of aerated concrete or other compacted granular material, in which a tie having external helical flanges is driven into the material without preforming a hole in the granular material.

2. A method as claimed in Claim 1, in which the tie is driven in by hammering.

3. A method as claimed in either of the preceding claims, in which the tie is also driven through the said component in a single driving operation.

4. A method as claimed in Claim 3, in which there is a gap between the component and the piece of granular material, which gap is maintained as the tie is driven in.

5. A method as claimed in Claim 4, in which the gap includes quilting or other insulation.

6. A method as claimed in any of the preceding claims, in which the tie is of uniform cross-section, with the possible exception of having a pointed end.

7. A method as claimed in any of the preceding claims, in which the outer end of the tie is embedded in mortar.

8. A method of securing a component in relation to a piece of aerated concrete other compacted granular material, performed substantially as herein specifically described with reference to any Figure of the accompanying drawings.

9. A structure including a piece of aerated concrete or other compacted granular material and an additional component held in position in relation to the granular material by means of a tie having external helical flanges screwed into the granular material.

10. A structure as claimed in Claim 9, in which the tie is of uniform cross-section, with the possible exception of having a pointed end.

11. A structure as claimed in either of Claims 9 and 10, in which the tie is of stainless steel, or of steel with a corrosion-resistant coating.

12. A structure as claimed in any of Claims 9 to 11, in which the said component is an insulating board or quilting.

13. A structure as claimed in any of Claims 9 to 12, in which the component is a batten through which the tie is also screwed.

14. A structure as claimed in any of Claims 9 to 13, in which the component is a wall of bricks and mortar spaced from the piece of granular material, with one end of the tie embedded in the mortar.

15. A structure as claimed in any of Claims 9 to 14, in which the tie extends at an angle to the vertical.

16. A structure as claimed in any of Claims 9 to 15, in which the tie or an additional tie is at an angle to the horizontal.

17. A structure as claimed in any of Claims 9 to 16, in which there is a gap between the piece of granular material and the component, with the tie extending across the gap.

18. A structure including a piece of aerated concrete or other compacted granular material, and an additional component held in position in relation to it in a manner substantially as herein specifically described with reference to any Figure of the accompanying drawings.