GB2180286A - Cavity wall tie - Google Patents

Abstract

A replacement tie for use in a cavity wall comprises an inner metal tie element (10 Fig. 1) having keying formations 11 at each end and a generally channel shaped cavity bridging portion 16. The tie element carries a spacer element 19 of plastics which snap engages over and is located at the central portion of the tie element by cooperating formations 18, & 24 Fig. 6). The spacer element has enlarged end portions 22a which act to dam mortar or other settable material by means of which the tie is secured in drilled holes in the inner and outer leaf masonry. Other water shedding formations 22 are provided on the spacer element 19. The specification also describes a wall tie replacement method. <IMAGE>

Description

SPECIFICATION Cavitywalltie This invention relates to a cavity wall tie designed for use as a replacementtie in an existing cavity wall andto a method of using thetie. However in certain circumstances, the tie could be used as a conventional wall tie by conventional methods.

Old cavity wall ties may become unserviceable through corrosion oras a result of damagetothe wall due to fire, impact orunderground subsidencefor example. During structural alterations, it may also be necessaryto add or replace a masonryleafofa cavity ofa cavity wall.

In each case, new wall ties may need to be inserted either in mortar coursing joints of existing masonry or at other positions in holes specially drilled in the masonrytotakethe ties.

Various types of replacement ties have been proposed for use in such circumstances. However most of these replacement ties are of limited applicability.

Furthermore the methods of using such ties have not proved entirely satisfactory.

For example, some replacement ties rely on expan sion fixingsto securethem tothe inner leaf masonry in drilled holes. Where the inner leaf is made of breeze blocks or similar friable materials, such fixings are sometimes insecure and it is difficult to check the security ofthe fixing where the inner leaf is concealed by the outer leaf of the wall.

Other ties are secured in place by curable resins which are provided in capsules. The resin capsule is placed in a driiled hole of the inner leaf and pierced by the tie when it is placed in position to release the resin into the hole. However, performing this operation by remote control through the outer leaf ofthe wall can be tricky and itis not always possible to position the resin capsule correctly. It also may not provide a satisfactory bond ifthe masonry ofthe inner leaf is porous or wet or ifthe drilled hole is not of the correct size. Resin can also trickle into the cavity, particularly where the tie is placed in an upwardly slanting hole to assist in r moisture shedding.

It is an object ofthe present invention to provide a new or improved replacement tie and a method of using the tie in a cavity wall.

According to the first aspect ofthe invention, there is provided a replacementtie for use in a cavity wall, the tie comprising a pair of end portions including keying formations and a central cavity bridging portion, provided with spacer means including a pair of end members spaced by the intended width ofthe cavity and of a lateral size slightly less than or equal to the size ofthe intended opening in which the tie is to be inserted Thetie may comprise an assembly of a tie element comprising a metal strip affording said end portions and a cavity bridging portion; and a specer element having a profile adapted to engage over the central portion ofthe tie and provided with said end members toform spacer means.

The central cavity bridging portion of these element may be downwardly open generally channel shape.

The spacer element may snap engage over the central portion oftheelement.

Thetie element andthespacer element may have cooperating location means to centre the spacer element on the tie element in relation to its length.

The cooperating location means may comprise one or more notches in the underside ofthe tie element and one or more cooperating snap engagement elements on the spacer.

Thetie element may have a moisture barrier in the central cavity bridging portion. This may for example comprise a peripheral rib or groove capable of preventing moisture from seeping along the tie element under the spacer element.

From a further aspect, the invention provides a method of inserting a replacement tie in a cavity wall, the method comprising the steps of; drillingaholeintheinnerleafofthewall; inserting a dispensing tool into the hole and dispensing a settablecomposition therein; withdrawing the tool; inserting a replacement tie according to the fore going statements af i nvention into the filled hole so that an end member ofthe spacer means substantially abuts the inner leaf masonry to retain thesettable composition in the hole; and allowing the composition to set to secure the tie relativeto the inner leaf.

The method may also includethe steps of drilling a hole in the outer leaf of the cavity wall; inserting the replacement tie through said hole into the inner leaf ski that an end member ofthe spacer means substantially closes the hole in the outer leaf of thewall; inserting a dispensing tool into the hole ofthe outer leaf and dispensing asettable composition therein; withdrawing thetool and allowing the composition to set to secure thetie relative to the outer leaf.

Preferably, the dispensing tool is progressively withdrawn as the settable composition is dispensed into the drilled hole inçthe inner andlor outer leaf of the wall.

The settable composition may be a mortar, a grout ora resin.

The mortar may be a specialist quick setting pointing mortar such as that marketed underthe trade mark EASIPOINTbyThoro Yorks arid Humber Limited.

A replacement cavity wall tie and the method of using the tie will now be described in more detail by way of example only with referencetotheaccom- panying drawings in which; FIGURE lisa plan view ofthetie element FlGURE2isa side elevational view of the tie element.

FIGURE 3 is an end elevational view of the tie element.

FIGURE4 is a side elevational view of a spacer elementforming partofthetie.

FlGURE5isan enlarged sectional viewontheline 5:5 of Figure 4.

FIGURE 6is a sectional view on the line 6:6 of Figure 4.

FIGURE 7 is a sectional view on the line 7:7 of Figure 4.

FIGURES 8 to 13 are diagrammatical sequence drawings illustrating a method of using the tie of Figures 1 to 7.

FIGURES 14 to20 are illustrations of possible alternative end formationsforthetie of Figures 1 to 3.

Referring firstlyto Figures 1 to 3 of the drawings, the main body of a wall tie for use as a replacementtie is a tie element 10 formed from a single stainless steel blank. Other materials might be suitable but it is of prime importance thatthetie should not be capable of corrosion in the damp and alkaline environment of a cavity wall. The tie element 10 comprises a pair of end portions 11 which are identical and which have a central axial spine 12 and a plurality of keying formations 13 of generally chevron shape pressed into the metal ofthetie.

The extreme free end portions i4areflattened and the region between the spine 12 and these flattened end portions 14forms a hollowed "hump" 15for added keying.

A central cavity bridging portion generally indicated at 16 is of inverted U or V shaped cross-section. The downwardly directed free edges are notched at 17 on either side ofthe centre line of the cavity bridging portion 6. At the centre of this cavity bridging portion, a waist 18 is providedtoactas a barrierto prevent moisture from passing from one end ofthetie to the other.

The metal tie element is used with a cavityspacer 19 shown in Figures 4to 7 ofthe drawings. This is formed as a plastics moulding in a springy material such as potupropylene.

As an alternative, the tie could include integral spacing means (not shown).

Thecavityspacer 19 is of generally circular outer profile 20 but has an inner profileofinverted U orV shape shown at 21 in Figure7 ofthe drawings. This corresponds to the outer profile ofthe central cavity bridging portion 16 ofthe metal tie element 10.

The cavity spacer 19 is snap engaged on the tie element 10 by formations which will be described in relation to Figure 6 of the drawings.

Thecavity spacer has a number of outwardly projecting part circularflanges 22 which tend to act as moisture drip formations, permitting moisture condensing in the cavity ofthe wall to drip offthe tie. Tbey also prevent moisture from travelling along the upper surface ofthe tie. However, these flanges have other functions and are oftwodifferenttypes, shown respectively in Figure Sand 5 and6 ofthe-drawings. Figure 5 ofthe drawings shows the flange provided at the centre and at each end of the cavity spacer and indicated at 22a. The underside ofthe flange has a simple opening 23to permitthe metaltie 10tote received inthecavity spacer.

Figure 6showsthe otherform offlange 22bwhich is provided at either side ofthe central flange of the cavity spacer. In this case, the downwardly facing opening of the flange has a pair of restricted sidewalls 24 which, together with internal notches 25 define a snap fixing which can snap onto the metal body ofthe tie element 10. The restricted portions 24 cooperate withthe notches 17 on the underside of the tie element and have the dual function of holding the cavity spacer ontothetie elementand of preventing it from being slid axially along the tie element. Thus, the cavity spacer is located centrally ofthe tie element for use in the method to be described in relation to Figures 8to 13 ofthe drawings.

This method is suitable for use where a cavity wall is to have ties replaced, with out the removal of the outer leaf of masonry. Where the outer leaf is removed and rebuilt, only the first part ofthe method will be carried out.

Figure 8 shows a cavity wall having an inner masonry leaf 2,6 which may be ofbrickworkor blockworkfor example, and an outer masonry teat27, separated by a cavity 28. In order to replace a tie,the first stage which is undertaken isto drill a holethrough the outer leaf 27 and into the inner leaf 26 using a conventional masonry drill 29. For adequate fixing, it is desirablethatthe inner leaf masonry 26 is drilled to a depth of between 70 and 80 mm. The hole is drilled either horizontally or inclining slightly upwardly so that the replacement tie will slope down towards the outer leaf.In this way, the penetration of moisture into the inner leaf 26 along the tie is avoided Figure 9 ofthe drawings shows a mortar injection tool 30 having a long nozzle, inserted through the outer masonry 27 into the hole 31 formed by drilling the inner leaf masonry 26. Mortar is injected through the nozzle 30 and the injection tool is simultaneously withdrawn so that the mortar 32 builds up in the bore 31 ofthe inner leaf as shown in Figure 10 ofthe drnwings.Thetool may have metering meansto ensure that the correct amount of mortar is injected to fill the bore 31.

In Figure 11 of the drawings, the next stage of inserting the tie is illustrated.-The complete tie with its cavity spacer 19 is inserted into the drilled hole 31 containing the mortar32 in the inner leaf 26 ofthewall.

An application tool 34 having an adjustable stop flange 35 may be used to ensurethatthe tie is inserted fully intothewall.The mortar keying formations 13, not shown in detail in Figure 11, engage with the mortar 32 in the inner leaf bore 31. As the tie is pushed into the mortar, a small amount may tend to be squeezed out of the borne into the cavity at 33. However the flange 22awhich is of a lateral size similarto that of the drilled hole 31 tends to restrain the mortar and prevent excessive amounts being squeezed out of the drilled hole 31.

The application tool 34 with its adjustable stop flange 35 also has atie enclosing portion36which assists in centralising the tie in the auter, and hence in the aligned inner drilled hole. Thetool can be left in place until the mortar 32 in the inner leaf has cured sufficiently to hold the tie in position. The application tool 34is then withdrawn prior to the injection of mortar into the outer leaf 27.

Clearly,the outer leaf 27 has a through bore made by the drill 29. Forthis reason both ends ofthe cavity spacer are provided with flanges 22a. That adjacent the outer leaf masonry 27 tends to block off the through holeto some extent and enables the mortar injecting tool 30 to be used to fill the drilled hole 37 in the outer leaf with a further quantity of mortar38. The tool 30 is again withdrawn as the mortar is injected into the drilled hole 37 and finally, as shown in Figure 13 ofthe drawings,the outer surface ofthe outer leaf 27 is made good by trowelling off any excess mortar as illustrated diagrammatically at 39.

The mortar may be the specialist pointing mortar marketed underthetrade nameEASIPOINTbyThoro Yorks and Humber Limited. This mortar is made up of a specific grade of white silica sand, high grade portland cement and certain additives and can be applied using a handgun fitted with a plastics exten sion tube to permitthe mortarto be injected into the inner leafofthe wall. The mortar is substantially waterproof and shrink resistant in use and water based, so that it can be applied to damp or porous materials. The mortar is preferably chosen to be of a suitable colourto blend with the outer leaf masonry.

The mortar has a fairly quick initial set depending on the porosity ofthe brickwork and on the water content ofthe mix, within 30to 60 minutes. On full cure it reaches a strength in excess of 25 newtons.

It might also be possible to use other forms of mortar, grout or resin as thesettable composition to secure the tie. The tie can of course also be used instead of a conventional wall tie in initial construction of a cavity wall but it has been specifically designed for use as a replacement tie.

In use, the tie element is intrinsically rustproof by being made of stainless steel and the plastics cavity spacer also covers the tie element. The flanges 22 provide drip formations to shed any moisture which may condense on a tie in the cavity. The metal body of the tie element 10 has the central waisted portion 18 which is disposed centrally beneath the plastics cavity spacer. This is intended to prevent any moisture seeping along the tie element 10 underthe cavity spacer 19.

The tie can be used in methods which involve the demolition ofthe outer leaf masonry 27 to insertthe new ties. In this case, the cavity spacer 19 may have at least one greatly enlargedflange 22 to support thermal insulation material within the cavity.

Referring to Figures 14to 20 ofthe drawings, these illustrate alternativeforms of ending forthe tie. It will be appreciated thatthe centrat portion ofthe tie element should be formed to the shape shown in Figure 1 and 2 ofthe drawings butthe alternatives shown in Figures 14to20forthe mortarkeying formations may be adopted in particular circumst ances.

Figure 14 employs perforated tubular ends for the tie. Figure 15 has a fishtail formation in the upright plane. Figure 16 illustrates a tube having waisted formations adapted to key into the mortar. Figure 17 is similarlywaisted but has a solid ratherthan a hollow cross-section. Figure 18 iltustrates a tie of generally elliptical orcircular cross-section which is formed to a crimped orwavy shape to key with the mortar.

In Figure 19, a metal strip ending is provided on the tie and tags or barbs are punched from the material of this strip. Figure 20 similarly uses a strip of metal but in this case curved to an arcuate profile disposed upright in the mortar, the tie also being crimped to form the end portion into a wavy, mortar engaging formation.

Claims (18)

1. A replacement tie for use in a cavity wall, the tie comprising a pair of end portions including keying formations and a central cavity bridging portion provided with spacer means including a pair of end membersspace by the intended width ofthe cavity and of a lateral size slightly less than or equal to the size ofthe intended opening in which the tie is to be inserted.

2. A replacement tie according to Claim 1 comprising an assembly of a tie element comprising an elongate metal strip affording said end portions and a cavity bridging portion; and a spacer element having a profile adapted to engage overthecentral portion of the tie and provided with said end members to form spacer means.

3. A replacement tie according to Claim 2 wherein the central cavity bridging portion ofthetie element is of downwardly open generally channel shape.

4. A replacement tie according to Claim 2 or Claim 3 wherein the spacer element snap engages overthe central portion of the tie element.

5. A replacement tie according to any one of Claims 2to 4wherein the tie element and the spacer element have cooperating location means to centre thespacerelementonthetie element in relation to its length.

6. A replacement tie according to Claim 5 wherein the cooperating location means comprises one or more notches in the underside of the tie element and one or more cooperating snap engagement elements on the spacer.

7. A replacement tie according to any one of Claims 2to 6 wherein the tie element has a moisture barrier inthe central cavity bridging portion.

8. A replacementtie according to Claim 7 wherein the moisture barrier comprises a peripheral rib or groove capable of preventing moisture from seeping alongthetie element underthe spacer element.

9. Amethodofinsertinga replacement tie in a cavity wall, the method comprising the steps of: drilling a hole in the inner leaf ofthe wall; inserting a dispensing tool into the hole and dispensing a settable composition therein; withdrawing the tool; inserting a replacementtie according to any one of Claims 1 to 8 into the filled hole so that an end member ofthe spacer means substantially abuts the inner leaf masonry to retain the settable composition in the hole; and allowing the composition to setto secure the tie relative to the inner leaf.

10. A method according to Claim 9 also including the steps of drilling a hole in the outer leaf of a cavity wall; inserting the replacement tie through said hole into the inner leaf so that an end member of the spacer means substantially closes the hole in the outer leaf of the wall; inserting a dispensing tool into the hole of the outer leaf and dispensing a settable composition therein; withdrawing the tool and allowing the composition to set to secure the tie relative to the outer leaf.

11. A method according to Claim9 or Claim 10 wherein the dispensing tool is progressively withdrawn asthesettable composition is dispensed into the drilled hole in the inner and/or outer leaf ofthe wall.

12. A method according to any one of Claims 9 to 11 wherein the settable composition is a mortar.

13. A method according to Claim 12 wherein the mortar is a quick setting pointing mortar ofthe type marketed underthetrade markEASIPOINT.

14. Amethodaccordingto anyoneoflaimssto 11 wherein the settable composition is a grout.

15. A method according to any one of Claims 9 to 11 wherein the settable composition is a resin.

16 A replacementtie substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 13 ofthe accompanying drawings.

17. A replacementtie substantially as hereinbe- fore described with reference to and as illustrated in Figures 1 to 13 ofthe accompanying drawings as modifiedbyanyone of Figures 14to 20.

18. A method of inserting a replacementtie in a cavity wall according to Claim 9and substantially as hereinbefore described.