GB2140481A

GB2140481A - Cavity wall ties

Info

Publication number: GB2140481A
Application number: GB08413612A
Authority: GB
Inventors: Patrick Joseph Ewens
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-05-26
Filing date: 1984-05-29
Publication date: 1984-11-28
Also published as: GB8413612D0

Abstract

A cavity wall tie suitable for building into cavity walls or repairing or reinforcing existing cavity walls comprises an elongate member (1) provided at each end with a planar member or element (4) shaped to conform to the transverse cross-section of a frog of a brick. One of the planar members may be adjustable. In another arrangement (Fig. 7) for use where the bricks of the wall are not provided with frogs, the planar elements are replaced by two blade-like elements arranged to be received in recesses previously cut into the bricks. In use, the tie is inserted into the cavity wall between opposing faces of first and second bricks in adjacent layers of each skin with the planar members or blade-like elements extending from the elongate member in a direction substantially parallel to the opposing brick faces so that one planar member or blade-like element extends into the other skin of the wall between the said adjacent brick layers. The one end of the elongate member is then rotated to cause the planar members to engage in respective frogs of the first and second bricks of the upper skin or in the alternative arrangement, to cause the blade like elements to engage in the previously formed recesses. <IMAGE>

Description

SPECIFICATION Improvements in or relating to cavity wall ties and the like This invention relates to cavity wall ties and the like.

In particular, the invention relates to cavity wall ties for insertion during the building of a cavity wall and cavity wall ties for use in repairing existing cavity walls.

Conventional cavity wall ties comprise an elongate planar member which may be of a butterfly shape or have forked ends which is laid on top of the bricks of a cavity wall during building as to extend between the two walls or leaves of the cavity wall. The cavity wall tie is held in place by the mortar between the bricks in the completed wall and by the weight of the bricks above the tie. However, the mortar tends to dry out and crumble with age. Accordingly, the fixing of the ties in the wall becomes less secure with age and the ties are liable to detach from the walls, which may, in some cases, collapse.

A cavity wall tie in the form of a bolt for use in repairing existing cavity walls has been designed which comprises an elongate member having screw threaded ends. In use, holes are drilled into corresponding bricks in the two skins of the cavity wall and expandable tapered sockets, similar to rawlplugs, are inserted into the holes. The elongate member is then inserted through one of the holes into the cavity and the corresponding hole in the other skin.

Insertion of the elongate member or bolt causes the sockets to expand to hold the bolt securely in the walls. However, the expansion of the sockets increases the stresses in the bricks containing the sockets and makes them more liable to fracture or cracks, particularly if the hole is drilled close to the indentation or 'frog' in the top of the brick.

According to a first aspect of the present invention, there is provided a cavity wall tie comprising means for linking first and second skins of a cavity wall, and means carried by the linking means for engaging in a recess in a building block in one of the first and second skins of the cavity wall.

In a second aspect, the present invention provides a cavity wall tie suitable for repairing or reinforcing an existing cavity wall, the tie comprising means for linking first and second skins of a cavity wall, each skin comprising a plurality of layers of building blocks, and means carried by the linking means for engaging in a recess in a building block, the engaging means being movable between a first position in which the same can be inserted between adjacent layers of a skin of the wall and a second position in which the engaging means can engage in a said recess.

The present invention also provides a cavity wall tie accordance with the first aspect suitable for use during the building of a cavity wall, wherein the recess engaging means is shaped to conform to at least part of the shape of the recess in a building block of one skin of the wall.

Preferably a further recess engaging means is carried by the linking means, the further recess engaging means being shaped to conform to at least part of the shape of a recess in a building block of the other skin of the wall.

The present invention further provides a cavity wall tie in accordance with the first aspect suitable for use during the building of a cavity wall, wherein the recess engaging means extends substantially transversely of the linking means and is formed with a plurality of teeth for engaging a surface of the recess of a building block of one skin of the cavity wall.

Preferably a further recess engaging means is carried by the linking means, the further recess engaging means extending substantiallytransversely of the linking means and being formed with a plurality of teeth for engaging a surface of the recess of a building block of the other skin of the cavity wall.

As an alternative to the further recess engaging means, the linking means may carry a tapered member for insertion in a building block of the other skin where that skin is formed of breeze or similar blocks or where the other skin of the cavity wall is formed by a timber framework, the linking means maybe a fastening member for securement to part of a timber framework forming the other skin of the cavity wall.

The phrase "building block" as used herein is intended to include bricks, breeze block, insulation blocks such as thermolite blocks and any other similar building elements.

For a better understanding of the present invention, and to show how the same may be put into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure lisa schematic plan view of a cavity wall tie for repairing an existing cavity wall; Figures 2, 3 and 4 show three different forms of cavity wall ties for use when a cavity wall is being built; Figures 5A to 5/ show various different components of another cavity wall tie for repairing an existing cavity wall; Figure 6 shows the cavity wall tie of Figures 5A to 51 installed in a wall; Figures 6A to 6C illustrate an alternative recess engaging means for the cavity wall tie of Figure 5; Figures 7, 7a and 7b show a cavity wall tie for repairing an existing wall built with bricks formed without frogs.

Figures 8 and 9 illustrate two forms of cavity wall tie for use where one skin or leaf of the wall is formed by a timber frame.

Figures 10, it and 12 illustrate three further forms of cavity wall ties having a different type of recess engaging means; and Figures 13 to 15 illustrate three forms of another cavity wall tie having a further alternative form of recess engaging means.

Referring now to the drawings, Figure lisa schematic view of one version of a cavity wall tie 1 for use in repairing an existing cavity wall. The cavity wall tie 1 is stamped from a single sheet of material to provide linking means in the form of an elongate member 2 having at one end 2a recess engaging means in the form of a first planar member or element 3 shaped to engage in the frog of a brick extending transversely of the elongate member. A further recess engaging means in the form of a second planar member or element 4 also shaped to engage in the frog of a brick is provided along the elongate member 2 at a distance from the first planar member and spaced from the other end 2b of the elongate member 2.The portion of the elongate member 2 between the first and second planar members 3 and 4 has a V-shape, the arms of the V-shape converging in the direction in which the planar members 3 and 4 extend to provide a water drip ensuring that moisture does not seep into the mortar between bricks.

In use of the cavity wall tie 1 shown in Figure 1, a bore or hole is first drilled through the outer skin or leaf of the existing cavity wall through the mortar between two bricks of adjacent brick layers of the wall and into the opposing skin between two bricks of the corresponding two brick layers. A tool which is elongate and substantially planar having an end shaped to conform to the frog of a brick is inserted through the bore and rotated to clear the old mortar from the frog of one of the bricks of the two adjacent layers of the inner leaf of the cavity. The tool is then removed and the tie 1 is inserted into the bore so that the planar members 3 and 4 are substantially parallel to the brick layers.When the tie 1 has been inserted so that the end 2b is level with the brick faces of the outer leaf of skin and the planar members 3 and 4 are positioned over the frogs of the bricks in the lower of the two brick layers in the respective skin of the wall, the tie is rotated through 90" by turning the protruding end 2b of the elongate member 2 using a wrench or other device to cause the planar members 3 and 4 to engage in respective frogs of the two skins of the wall. The bore or bores is/are then filled with fresh mortar.

As will be appreciated from the description given above, the cavity wall tie 1 of Figure 1 is not adjustable and must therefore be made to fit the cavity wall. Accordingly, the cavity wall tie 1 cannot be used to restore the cavity in a wall where the inner and outer skins of the wall have bowed either inwardly or outwardly.

Figures 2 and 3 show cavity wall ties 5 and 6 both of which are for use during the building of a wall and are stamped from a single sheet of material 1/16" (0.16 cm) thick. The cavity wall tie 5 shown in Figure 2 is similar to that shown in Figure 1 and comprises an elongate member7 having a planar member 8 shaped to engage in a frog of a brick extending transversely therefrom at each end 7a of the elongate member 7. The centre portion of the elongage member is V-shaped as in the arrangement shown in Figure 1. The cavity wall tie shown in Figure 3 differs from that shown in Figure 2 in that it is provided for use where the outer leaf of the wall is formed of breeze or similar building blocks. Thus, one end 7a of the elongate member 7 is formed with an elongate tapered member or element 9 instead of a planar member 8.The elongate tapered member 9 is arranged to be inserted into a breeze block an insulation block, such as a thermolite block, or similar building block. In use of the cavity wall ties 5 and 6, the tie is placed across the cavity of the wall being built so that, in the case of the cavity wall tie 5, the planar members 8 engage in respective frogs of corresponding bricks in the top layer of bricks in the two skins of the wall and, in the case of the cavity wall tie 5, the planar member 8 engages in the frog of a brick in the top layer of one skin of the wall and the tapered elongate member 9 is inserted in a breeze block of the other skin of the wall. Mortar is then applied to the bricks to enable further layers of the wall to be constructed.Holes 4a and 8a are provided in the cavity wall ties of Figure 1 and Figures 2 and 3 respectively, through which motar can flow to increase the bonding of the tie to the wall.

As shown in phantom lines in Figure 1, tabs 4' which are, for example,1/4" (0.64 cm) wide may be provided on the planar members 4. In use, the tabs are bent along the score lines 4D so as to extend perpendicularly of the planar members 4. Similar tabs may be provided on the ties shown in Figures 2 and 3.

Figure 4 shows an alternative cavity wall tie for use during the building of a wall wherein the cavity wall tie 10 is formed from an elongate sheet of suitable material bent transversely of its length to provide a V-shaped configuration 11 between opposing bricks 12 of two skins of a cavity wall being built and to provide at each end of the sheet a brick engaging element 13 shaped, as shown in Figure 4to conform to the frog of the brick. Such a cavity wall tie has a width of, for example, 3/4" (1.9cm) along the length of the brick.

Figures 5A to 51 shows the various components of a further different cavity wall tie for use in repairing a cavity wall. Figure 6 shows the cavity wall tie 14 in position in a cavity wall.

The cavity wall tie 14 comprises an elongate member or shaft 15 (Figure 5c) which maybe of square cross-section being /4" (6.4 mm) square in cross-section and 83/8" (21.3 cm) in length. The shaft may alternatively have a circular cross-section. One end 1 5a of the shaft 15 is threaded for a length of 23/4" (9.5 cm) and the other end 15b of the shaft is drilled with holes to enable a substantially planar member or element 16 to be rivetted to the end 15b.

The planar member 16 is trapesoidal in shape, the two parallel edges 16a and 16b of the planar member being 1 3/16" (3 cm) and 5/a" (1.6 cm) in length, respectively. The edge 16c perpendicular to the edges 16a and 16b is 1 3/8" (3.5 cm) in length. As shown in Figure 5F, tabs 17 may be provided on the sloping edge 16d and the shorter parallel edge 16b of the planar member. The tab 17s extends outwardly from their respective edges for a distance of " (0.64cm). The tab 17a provided on the edge 16b is 3/8" (0.95cm) wide and is situated adjacent the corner between the edges 16b and 16d so as to leave a distance of 1/4" (0.64 cm) between the upper edge of the tab 17a and the edge 16c of the planar member 16. The tab 17b on the edge 16d runs along the length of the edge 16d. A plurality of planartriangu- lar or tapered teeth 18 having a height of3/16" (0.5 cm) are provided along the upper edge 16c of the planar member.

The planar member 16 is drilled with two holes 19 to correspond to the holes in the end of the shaft 15 so that the planar member 16 may be bolted or rivetted to the shaft 15. Of course, the planar member 16 could be welded to the shaft 15, in which case the holes would not need to be provided. The tabs 17 on the planar member are bent, for example by scoring the planar member, to extend perpendicularly of the planar member. Figure 5d is an end view of the shaft 15 showing the planar member 16 secured thereto.

A substantially planar element or butterfly 19 is mounted on the shaft 15 as shown in Figure 5A.

Thus, the butterfly is formed with two slits 19' and is deformed to accept the shaft 15 through the slits 19' so that the butterfly is rotatable on the shaft.

The butterfly 19 is substantially rectangular in shape. However, each edge of the butterfly is V-shaped. Thus, the upper edge 19a ofthe butterfly is inwardly V-shaped while the lower edge 19b is outwardly V-shaped, the point of the V being " (0.64 cm) lower than the corners of the edge 19b. The edges 19c and 19d of the butterfly extending transversely of the shaft are also inwardly V-shaped, the minimum width of the butterfly 19 occurring art a distance of approximately 1" (2.54cm) from the upper edge 19a. The slots 19' are positioned so that the axis of the shaft is approximately 11/8" (2.9 cm) from the corner upper edge 19a. The butterfly 19 has a maximum width of 1 7/8" (4.8 cm) and a maximum depth of 2 3/8" (6 cm).Of course, the dimensions of the butterfly 19 will be determined by the cavity size of the wall to be repaired. A tab 20 is provided at each corner of the butterfly. Each tab is 3/8'1 (0.95cm) long and " (0.64 cm) wide. Figure 5B is an end view of the butterfly 19 showing the tabs 20 bent to their position of use. As shown each upper tab 20' is bent in one direction, and each lower tab 20" is bent in the opposite direction, so as to extend perpendicularly of the butterfly.

Figures 5G to 51 show a further substantially planar member or element 21 for the cavity wall tie 14. The planar member 21 is substantially trapesoidal in shape having a width of 13/8" (3.5 cm). A score mark 24 is formed across the planar member 21 at a distance of 1" (2.5 c) from the corner between the edges 21 band 21 c thereof and a distance of " (0.95 cm) from the corner between the edges 21c and 21d.

A 1/4" (0.64 cm) wide tab 22 is provided along the length of the edge 21 c while a 3/8" (0.95 cm) long, 1/4" (0.64 cm) wide tab 23 is provided on the edge 21d.

The tabs 22 and 23 are then bent so as to be perpendicular to the planar member (Figure 5H). The part 21' of the planar member 21 above the score line is then bent into a substantially circular crosssection.

In orderto insert the cavity wall tie 14, the pointing is cleared between two brick layers from the space of the outer skin into which the tie 14 is to be inserted and three or more aligned bores are drilled through the outer skin to the frog of a corresponding brick in the inner skin of the wall. Preferably, the holes are drilled to a depth of 21.5 cm using a 12.7 mm masonary bit drill.

The eroded mortar along the path of the tie 14 is then cleared to the frog of the corresponding brick in the inner skin of the wall and an elongate tool having a frog-shaped planar member at its end is inserted into the wall through one of the holes drilled into the wall unit the frog-shaped planar member reaches the frog of the corresponding brick in the inner skin or leaf of the wall. The tool is then rotated through 90" and turned back again to remove mortar from the frog. The tool isthen removed.

The butterfly 19 is then inserted onto the shaft 15 with a nylon washer either side of the butterfly and the shaft 15 is inserted into the wall through one of the holes with the planar member 16 and the butterfly 19 extending parallel to the brick layers.

The shaft 15 is pushed into the cavity as far as it will go and then an elongate tool is inserted into the cavity to engage the butterfly. The tool is pushed into the cavity until a mark provided on the tool is level with the faces of the bricks of the outer skin or leaf so that the planar member 16 is positioned correctly over the frog of the corresponding brick in the inner leaf of the wall. The butterfly is then rotated through 90" using the tool engaging the butterfly so that the butterfly is substantially vertically positioned in the cavity. The tool is then removed and the other planar member 21 is slid onto the shaft 25 together with a washer and nut. The nut is run onto the screw threaded end of the shaft until it reaches the end of the thread to prevent rotation of the planar member 21 on the shaft.A further elongate tool is then engaged with the shaft 15 and rotated through 90" so that the planar members 16 and 21 engage in the respective frogs of bricks in the two skins of the wall and the teeth of the planar member 16 engage the brick above. The tool is then removed and the nut is tightened to lock the planar member 21 in place. Fresh mortar may then be applied to the wall.

Figure 6 is a cross-section through a cavity wall into which the tie 14 has been inserted. As shown in Figure 6, the tabs on the butterfly 19 engage the bricks of the skins of the cavity to maintain the cavity while the planar members 16 and 21 serve to prevent the skins of the cavity bowing outwardly. The V-shaped edges of the butterfly provide a water drip and the edges 19cant 19d in particular serve to ensure that moisture does not seep into the mortar between the bricks.

The planar members 16 and 21 and the butterfly are preferably made of 1/16" (0.16 cm) gauge plate and all the components of the tie 14 are preferably made of type 316 Molybdenum stabilized stainless steel.

Figures 6A, 6B and 6C illustrate an alternative form of recess engaging member 40 which may be used to replace the planar member 16 and 21 shown in Figures 5D to 51.

As shown in Figure 6A, the alternative recess engaging member 40 comprises a substantially rectangular planar member which is stamped out from sheet metal. Two parallel edges 40A and 40B are serrated or formed with teeth 40C and the member 40 is scored parallel to the said edges 40A and 40B to divide the member 40 into two edge sections 41A and 41B and a middle section 41 C. The middle section 41 C is further scored and cut to form two flaps 42A and 42B, each flap 42A and 42B being formed with an aperture 43.The two edge sections 41A and 41 B are bent or folded along the score lines so as to extend in opposite directions as shown in Figure 6B and the two flaps 42A and 42B are bent or folded along the score lines so that the flaps extend perpendicularly of the member 40. One of the thus-shaped recess engaging members 40 is slid onto the shaft and then mounted to the shaft 15 by means of a bolt or the like so that the recess engaging member can pivot with respect to the shaft 15. Of course, unlike the arrangement shown in Figures 5D to 51, only a single aperture is required in the shaft 15 to mount the recess engaging member on the shaft.As mentioned above, a similar recessing engaging member is provided at the other end of the shaft but this recess engaging member is not fixed to the shaft but merely slid onto the shaft and held in place bythetightening of a nut washer on the shaft.

In use of a cavity wall tie recess engaging members 40, the recess engaging members 40 are first positioned so that the edge sections 41 and 41B are thereof are substantially parallel to the shaft 15.

When the tie is inserted into the wall as described above in relation to Figure 5 and each recess engaging member reaches the frog of a brick in the respective inner or outer skin or leaf of the wall, the recess engaging members 40 will pivot under gravity, (because the teeth of the edge 41 B are heavier than those of the edge 41A) to the position shown in Figure 6C. Thus, when the nut and washer is tightened as described above in relation to Figure 5, the teeth of the edge 41 B will bite into the wall of the frog 44 of the brick of the respective skin of the cavity wall. It should be appreciated that, because of the shape of the recess engaging members 40 and the fact that these can lie substantially parallel to the shaft of the cavity wall tie, it is not necessary in the present case to rotate the shaft through 90" when the recess engaging members reach the correct position.Rather, the recess engaging members will fall naturally into position under the influence of gravity.

Figure 7 shows a cavity wall tie 30 for use in repairing an existing cavity wall when the wall was built with bricks not formed with frogs. The cavity wall tie 30 comprises an elongate member 31 which may be of square or circular cross-section but is preferably of " (0.64 cm) square cross-section having a V-shaped dip 32 in the centre to provide a water drip. First and second brick engaging elements 33 and 34 forming planar members are secured to an end 31a of the cavity wall tie 30 for example by rivetting or welding and third and fourth brick engaging elements 33' and 34' are secured to the elongate member 31 at a distance from the other end 31 b thereof. Figure 7b shows a brick engaging element which is preferably stamped from sheet metal, preferably stainless steel as mentioned above.The brick engaging element is substantially rectangular in shape but has a curved blade end 35 at one end. A score line 36 is provided across the brick engaging element so that the blade end 35 may be bent upwardly to extend perpendicularly of the remainder of the brick engaging element. Holes are provided in the brick engaging element to accept rivets or bolts. Figure 7a is a view from one end of the elongate member 31 showing the opposed arrangement of the two brick engaging elements at each end of the elongate member 31.

In order to insert the cavity wall tie shown in Figure 7, a tool comprising an elongate member carrying two circular cutting blades or saws is inserted into a hole formed through the wall as described above in relation to Figures 5A to 51 to a distance determined for example by a mark provided on the elongate member and then rotated through 90" so that one of the circular scores cuts an arcuate similar groove in the brick in the layer of the inner skin beneath the elongate member of the tool and the other cuts a parallel groove in the brick above.

The tool is then returned to its initial position and withdrawn until a second mark provided on the tool is level with the brick faces of the outer wall. The tool is then rotated through 90" to cut arcuate grooves in the bricks above and below the tool so that the arcuate grooves in the bricks of the inner and the outer skins of the wall are separated by the same distance as the two pairs of brick engaging elements provided on the cavity tie. The tool is then removed and the tie inserted with each pair of brick engaging elements lying parallel to the brick layers. When a mark provided on the end of the tie protruding from the outer skin of the wall is level with the brickfaces of the outer wall, a tool, for example a wrench, is used to rotate the cavity wall tie through 90" so that the brick engaging element engage in their respective grooves.The tool is then removed and the free end of the cavity wall tie may be either levelled with the wall or capped with a nut or similar means. Fresh mortar is then applied to the wall.

Figures 8 and 9 illustrate two forms of cavity wall ties for use during the building of a wall wherein one leaf or skin of the cavity is formed by a timber frame and the other leaf or skin is formed of conventional building blocks.

Figure 8 shows a cavity wall tie 50 for use in building a wall of a timber framed building wherein the outer skin of the wall is constructed from bricks or other building blocks having frogs. As shown in Figure 8, the cavity wall tie 50 is stamped from metal sheet so that one end 51 of the cavity wall tie is shaped to conform to at least part of the crosssection of a frog of a brick and the other end of the cavity wall tie is formed with a transversely enlarged fastening plate 52. The fastening plate 52 is formed with a plurality of apertures 53 for receiving screws orthe like to allowthefastening plate 52to be secured to part of the timber frame of the building.

As shown in Figure 8, the frog-shaped end 51 of the tie 50 is scored or otherwise bent to form a tab 54 which in use of the tie 50 extends in a direction perpendicular to the length of the tie so that, when the tie is inserted into the cavity wall being built, the tab 54 extends across the frog of the brick to increase the degree to which the frog-shaped end 51 is secured in the brick when the wall is completed.

Figure 9 shows an alternative form of the tie 50 of Figure 8 wherein the frog-shaped end 51 is replaced by a substantially rectangularly shaped enlarged end 51'. This cavity wall tie is intended for use in the building of timber framed houses wherein the outer skin or leaf of the cavity wall is formed of building blocks formed with recesses of rectangular crosssection rather than frogs. The tie shown in Figure 9 is otherwise used in the same manner as the tie shown in Figure 8. As can be seen from Figures 8 and 9, each of the ties 50 and 50' has an angled or V-shaped centre section 55 which provides a moisture drip in a similar manner to the butterfly of the arrangement shown in Figures 5 and 6.

Figures 10 to 12 show further forms of cavity wall ties for use wherein at least one skin or leaf of the wall is formed of bricks or building blocks having rectangular cross-section recesses rather than frogs.

In particular, Figure 10 shows a cavity wall tie 56 which is stamped from sheet metal and has at each end an enlarged substantially rectangularly shaped section 57 for engagement in a rectangular-shaped recess of a building block of a skin or leaf of a cavity wall. Each of the large rectangularly shaped end sections 57 has a tab 58 similar to the tab 54 shown in Figures 8 and 9 so that, in use, the tab 58 is bent to extend perpendicularly of the tie 56 to provide better purchase for the tie in the wall being built. Figure 11 shows a cavity wall tie 56' similar to that shown in Figure 10 but for use where one skin of the wall is formed of breeze or similar building blocks.Thus, on end of the tie 56' is formed with an elongate tapered member or element 59 extending transversely of the tie 56' so that, in use, the elongate tapered member 59 is inserted into a breeze block, or other insulation block such as a thermolite block, or other simlar building blockforming one skin of the wall being built.

Figure 12 shows a cavity wall tie 56" similar to that shown in Figure 10. However, the cavity wall tie 56" shown in Figure 12 is for use in repairing existing walls ratherthan for use during the building of a new cavity wall. Thus, as shown in Figure 12, one end of the cavity wall tie is extended beyond the rectangularly shaped enlarged section 57 so that the end 56a of the cavity wall tie which extends beyond the rectangularly shaped enlarged section 57 can be engaged by a tool to allow the cavity wall tie to be inserted into an existing wall. It should, of course, be appreciated that the cavity wall tie shown in Figure 12 is inserted into an existing wall in a manner similar to that described above in relation to the embodiment shown in Figure 1 of the accompanying drawings.As can be seen from Figures 10 to 12, each of the cavity wall ties 56, 56' and 56" is provided with a V-shaped middle section 60 which provides a water drip in a similar manner to the V-shaped middle section 55 of the cavity wall ties shown in Figures 8 and 9.

Figures 13 to 15 show various forms of cavity wall ties having a further alternative form of recess engaging means. Thus, Figures 13A and 13B show a cavity wall tie 61 for use during the building of a cavity wall having one skin or leaf formed from breeze, insulation or similar blocks, Figures 14A and 14B show a cavity wall tie 61' for use where the wall being built is formed of two skins or leafs of brick or similar building blocks having frogs or other recesses therein while Figures 15A and 15B show a similar form of cavity wall tie 61" but modified for use when one skin or leaf of the cavity wall is formed by a timber frame of the building.

Referring now to Figure 13A, there is shown a cavity wall tie 61 having at one end an elongated tapered spike or member 62 for insertion in a breeze block or similar insulation block of one skin of a cavity wall and having at the other end a substantially trapezoidal member 63 arranged so that the parallel sides thereof extend transversely of the length of the cavity wall tie. The free edge 63a of the trapezoidal member 63 is serrated or formed with teeth and the trapezoidal member 63 is scored in a direction parallel to the parallel edges thereof. In use of the tie shown in Figure 1 3A, the trapezoidal section 63 is first bent or folded along the score line and then the tie is twisted from the point 64 so that, as shown in Figure 13B, the trapezoidal section 63 extends in a direction substantially perpendicularly of the plane of paper.In use of the tie shown in Figure 13B, the teeth 63A will engage in the frog or recess of a brick forming one skin or leaf of the wall being built while the spike 62 will be inserted into a breeze or other insulation block from which the other skin or leaf of the cavity wall is being formed.

Figures 14A and 14B illustrate a tie 61' for use during the building of a cavity wall wherein each leaf or skin of the wall is formed of bricks formed with frogs or recesses. Thus, each end of the cavity wall tie 61' shown in Figure 14A has a trapezoidally shaped section 63 and, in order to shape the tie 61, for use each end of the tie is deformed about a respective point 64 to produce the shape shown in Figure 14B. Again, each of the trapezoidal sections 63 is scored in a direction parallel to the two parallel edges thereof allowing the serrated or toothed section 63A can be bent under as shown in Figure 14B so that, in use, the teeth engage the walls of the frog or recess of a brick in a respective skin or leaf of the cavity wall being built.

Figures 15A and 1 5B show a cavity wall tie 61" which is similar to that shown in Figures 13A and 13B with the exception that the tapered spike 62 is replaced buy a substantially rectangular fastening plate 65 formed with a plurality of apertures 66 to enable the fastening plate to be secured by screws or the like to be part of a timber frame forming the inner leaf of the cavity wall. Each of the cavity wall ties shown in Figures 13 to 15 is, of course, formed with a V-shaped middle section 67 which provides a water drip in use of the tie.

Each of the ties described above is preferably made of type 316 Molybdenum stabilized stainless steel or alternatively alloy steel rust and corrosion EN56 although they could be made of any stainless or galvanised steel or any other substantially rust and corrosion proof material having the necessary strength properties, for example a plastics material.

It should also be appreciated that the various dimensions given above are given by way of example only and that the dimensions of a cavity wall tie embodying the invention will depend on the wall into which the tie is being inserted.

Claims

1. A cavity wall tie comprising means for linking first and second skins of a cavity wall, and means carried by the linking means for engaging in a recess in a building block in one of the first and second skins of the cavity wall.

2. A cavity wall tie suitable for repairing or reinforcing an existing cavity wall, the tie comprising means for linking first and second skins of a cavity wall, each skin comprising a plurality of layers of building blocks, and means carried by the linking means for engaging in a recess in a building block, the engaging means being movable between a first position in which the same can be inserted between adjacent layers of a skin of the wall and a second position in which the engaging means can engage in a said recess.

3. A cavity wall tie according to claim 2 wherein a further engaging means is carried on the linking means, the further engaging means being movable between a first position in which the same can be inserted between adjacent layers of a skin of the wall and a second position in which the further engaging means can engage a said recess, so that, in use, when the tie is inserted between adjacent layers of a skin of the wall, the engaging means can engage a recess in one skin and the further engaging means can engage a recess in the other skin of the wall.

4. A cavity wall tie according to Claim 3, wherein the position of the further engaging means on the elongate member is adjustable.

5. A cavity wall tie according to Claim 2,3 or 4 wherein the engaging means and/or the further engaging means is/are manually movable into the second position thereof.

6. A cavity wall tie according to Claim 5, wherein the engaging means and/or the further engaging means is fixed for rotation with the linking means so that rotation of the linking means moves the engaging means and/or the further engaging means to the second position.

7. A cavity wall tie according to Claim 2,3 or 4 wherein the engaging means and/or the further engaging means is biased on the second position.

8. A cavity wall tie according to Claim 7, wherein the engaging means and/or the further engaging means is movable under gravity into the second position.

9. A cavity wall tie according to claim 7 or 8, wherein the engaging means and/or the further engaging means is pivotally mounted to the linking means.

10. A cavity wall tie according to Claim 9 wherein the engaging means and/orthefurther engaging means comprises two opposed members each formed with a plurality of teeth for engaging a wall of a recess of a building block.

11. A cavity wall tie according to any one of claims 2 to 9 wherein the or each recess engaging means is shaped to conform to the shape of the recess in a building block.

12. A cavity wall tie according to Claim 11, wherein the or each recess engaging means is shaped to conform to the shape of a frog in a brick.

13. A cavity wall tie according to Claim 12 wherein the or each recess engaging means is shaped to extend across half the transverse dimension of the frog of a brick.

14. A cavity wall tie according to claim 11, 12 or 13 wherein the or each recess engaging means is planar recess engaging element.

15. A cavity wall tie according to claim 14 wherein a building block engaging means extends at substantially 180" to the or each recess engaging element so that, during use of the tie, when the or each recess engaging element engages in the recess of a building block, the or each building block engaging means engages in an opposing block of the same skin.

16. A cavity wall tie according to Claim 13 wherein the or each building block engaging means comprises a plurality of teeth.

17. A cavity wall tie according to claim 15 or 16 wherein the or each building block engaging means is integral with the or each respective recess engaging element.

18. A cavity wall tie according to any of Claims 2 to 8 wherein a recess is formed in a building block of one skin or both skins prior to insertion of the cavity wall tie and the or each recess engaging means comprises a blade-like member for engaging in the recess or the respective recess.

19. A cavity wall tie according to Claim 18, wherein a recess is formed prior to insertion of the cavity wall tie in each of two opposing building blocks of one skin or both skins and the or each recess engaging means comprises two opposed blade-like members, each blade like member being arranged to engage in a respective one of the recesses formed in the two opposing building blocks of a skin of the wall.

20. A cavity wall according to any preceding claim, wherein a substantially planar body is mounted on the linking means so that, in use of the tie, the body extends from the elongate member between the skins of the cavity wall.

21. A cavity wall tie according to Claim 20 wherein the planar body is shaped so that, in use, the planar body contacts at least one building block of each skin of the cavity wall but is spaced from the mortar between the building blocks.

22. A cavity wall according to any one of Claims 1 to 9 wherein an intermediate part of the linking means which in use of the tie extends across the cavity of a cavity wall is shaped so that, in use, the linking means inclines downwardly toward the centre of the cavity.

23. A cavity wall tie according to Claim 1 suitable for use during the building of a cavity wall, wherein the recess engaging means is shaped to conform to at least part of the shape of the recess in a building block of one skin of the wall.

24. A cavity wall tie according to Claim 23, wherein a further recess engaging means is carried by the linking means, the further recess engaging means being shaped to conform to at least part of the shape of a recess in a building block of the other skin of the wall.

25. A cavity wall tie according to Claim 1, suit able for use during the building of a cavity wall, wherein the recess engaging means extends sub stantiallytransversely of the linking means and is formed with a plurality of teeth for engaging a surface of the recess of a building block of one skin of the cavity wall.

26. A cavity wall according to Claim 25, wherein a further recess engaging means is carried by the linking means, the further recess engaging means extending substantially transversely of the linking means and being formed with a plurality of teeth for engaging a surface of the recess of a building block of the other skin of the cavity wall.

27. A cavity wall tie according to Claim 23 or 25 wherein the linking means carries a tapered elongate member for insertion into a building block of the other skin of the cavity wall when the outer skin is formed of breeze or similar building blocks.

28. A cavity wall tie according to Claim 23 or 25 suitable for use where the other skin of the cavity wall is formed by a timber framework, wherein the linking means carries a fastening member for se curementto part of a timber framework forming the other skin of the cavity wall.

29. A cavity wall tie according to any one of Claims 23 to 28 wherein a body which is enlarged relative to linking means is mounted on the linking means so that, in use of the tie, the body extends from the linking means between the skins of the cavity wall.

30. A method of reinforcing or repairing an existing cavity wall, comprising inserting a linking means for linking first and second skins of the cavity wall between adjacent layers of building blocks in one skin of a cavity wall with a recess engaging means carried by the linking means in a first position so that the linking means extends across the cavity between the first and second skins of the cavity wall and causing or allowing the recess engaging means to move to a second position in which the recess engaging means engages a recess of a building block in one skin of the cavity wall.

31. A method according to Claim 30, wherein the linking means carries a further recess engaging means and is inserted between the adjacent layers of building blocks in one skin of the cavity wall with the recess engaging means and the further recess engaging in the first position so that the linking means extends across the cavity and wherein the recess engaging means and the further recess engaging means are caused or allowed to move to the second position in which the recess engaging means engages in a recess of a building block in one skin and the further recess engaging means engages in a recess of a building block in the other skin.

32. A method according to Claim 30 or 31, wherein the recess engaging means and/or the further recess engaging means is moved to the second position by rotating the linking means.

33. A method according to Claim 30 or 31, wherein the recess engaging means and/orthe further recess engaging means is positioned over the recess or the respective recess and allowed to move under gravity to the second position.

34. A cavity wall tie suitable for repairing or reinforcing an existing cavity wall substantially as hereinbefore described with reference to, and as illustrated in, Figure 1 or Figures 7A to 7C or Figure 10 of the accompanying drawings.

35. A cavity wall tie suitable for repairing or reinforcing an existing cavity wall substantially as hereinbefore described with reference to, and as illustrated in, Figures 5A to 51 and 6, or Figures 5A to 51 and 6 when modified by Figures 6A to 6C of the accompanying drawings.

36. A cavity wall tie suitable for use during the building of a cavity wall substantially as hereinbefore described with reference to, and as illustrated in any one of Figures 2 to 4,8to 11 and 13 to 15 of the accompanying drawings.

37. A method of repairing or reinforcing an existing cavity wall substantially as hereinbefore described with reference to Figures 5A to 51 and 6 or Figures SAto 51 and 6when modified of by Figures 6A to 6C.

38. A method of repairing or reinforcing an existing cavity wall substantially as hereinbefore described with reference to Figure 1 or Figures 7, 7A and 7B or Figure 10 of the accompanying drawings.

39. Any novel feature or combination of features described herein.