GB2208399A

GB2208399A - Cavity wall ties and a method of manufacture

Info

Publication number: GB2208399A
Application number: GB8718462A
Authority: GB
Inventors: Ernest Baldwin
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-08-04
Filing date: 1987-08-04
Publication date: 1989-03-30
Anticipated expiration: 2007-08-04
Also published as: GB2208399B; GB8718462D0

Abstract

The ties are manufactured from separate elements to enable selection of the properties of each element to suit its function in the completed tie. Cavity spanning elements 1 have permanently affixed to them elements 3 for anchoring into mortar joints, element 2 providing the moisture drip and element 4 for retaining cavity insulation in position. A method for manufacture is described whereby a composite sheet of welded mesh is produced and the ties are formed by cutting the mesh along lines A - A and B - B. <IMAGE>

Description

WALL TIES AND A METHOD OF MANUFACTURE This invention relates to wall ties for use in cavity wall construction and a method for their manufacture. More particularly the invention relates to ties having one or more straight cavity spanning elements to which are permanently affixed additional members. each of which performs a function essential to the effectiveness of the assembly, The main function of a wall tie is to provide connecting links between opposite leaves of cavity wal)s 1capable of transferring loads from one leaf to the other, creating a strong and rigid structure. The stresses are transferred via cavity spanning elements which must be firmly anchored in or to the opposite leaves of the wall.In the case of masonry wall leaves the anchor is usually provided by embedding a deformed or distorted end of the wall tie into the mortar of the brickwork. In the case of a wall leaf constructed from timber, the anchorage is usually obtained by providing the end of the wall tie with a hole or loop through which a nail is driven in such a way that the tie is firmly anchored to a timber component of the leaf.

A further requirement of the tie is to provide some means of preventing moisture from passing across the cavity along the cavity spanning elements of the tie. It is usual to provide a kink in the cavity spanning element of the tie which induces the moisture to drip from the tie into the cavity.

A more recent requirement for ties used in constructions which have insulation positioned in the cavity, is to provide the tie with means to locate and hold the insulation in the desired position in the cavity. This is usually achieved by clipping a separate device on to the cavity spanning element such that the device holds the insulation in the desired position.

Previously the effectiveness of the tie in transmitting stresses from one leaf of the cavity wall to the other and the ammount of deformation in so doing, played little part in the design of wall ties, but recent proposals as instanced in the "Draft for Development Rscommendations for design of wall ties" DD lb0 Part 2 1987 issued by the British Standard Institution, have outlined the need for improving strength and deformation characteristics of wall ties.

According to the present invention there is a wall tie Provided comprising one or more cavity spanning elements to which are permanently affixed separate elements providing the means of anchoring the tie to the leaves of the cavity wall and the means for preventing moisture transfer across the cavity spanning elements of the tie qnd the means to locate and hold insulation in position in the cavity.

Tensile and Compression tests have shown that cavity spanning elements which are kinked to provide moisture drips are inferior in strength and deformation resistance to those where the cavity spanning element is straight and undeformed and the moisture drip is provided by permanently affixing a separate element. The weakening effect of kinking the cavity spanning element is particularly noticeable when they are constructed from light gauge materials - eg steel wires of 4.0 mm diameter or less, and especially when the ties are in compression.

By constructing the tie from several different elements it is possible to select the properties of the individual elements to suit their functional requirements. Thus in order to achieve high tensile and compression properties for the tie the cavity spanning elements can be constructed from high tensile material eg wires in the hard-drawn condition, whereas the usual material is less hard to allow for deformation needed , when the anchorage is provided by bent or shaped ends and when the moisture drip is formed by kinking the wires.

The material chosen for the separate element which provides the means to position and retain the insulation can be of smaller section and softer temper to provide the element with the flexibility needed to allow bending and forming by hand in order to apply pressure on the insulation.

The advantages gained by affixing separate elements to the cavity spanning elements may be outweighed to some extent by the increased cost of manufacturing the tie from several different elements but there is provided a means of manufacturing wall ties whereby separate elements are permanently fixed to cavity spanning elements by welding on standard welding muchines.

The welding machine can be d spot welding machine producing single ties but preferably an automatic welding machine as commonly used in producing welded mesh whereby the pattern of the mesh is so chosen that individual ties can be cut therefrom. The method of producing the ties by welding the separate elements together on welding machines forms part of the invention.

In order that the invention may be more readily understood reference is made to the accompanying drawings which illustrate by way of example only some embodiments of the invention.

Although the elements in the examples are stainless steel wires of various sizes and qualities, it should be understood that other forms such as strip or tube could be used and other materials such as mild steel coated with plastics could be used.

Figure 1 is a plan view of the first embodiment for use when both leaves of the cavity are masonry walls.

Figure 2 is a side view of the wall tie illustrated in Figure 1 Figure3ais a perspective view of a second embodiment of the invention for use when one leaf of the cavity wall is of timber constructions and the other is of masonry construction, Figure 3b is a perspective view of an alternative tie for use when the internal leaf of the cavity is timber and the externai leaf is of masonry construction.

Figure 4 is a side view of the wall tie illustrated in Figure 3a Figure 5 is a plan view of the composite mesh produced from an automatic welded mesh machine.

Figure 6 is a plan view of the mesh illustrated in Figure 5 after being cut into ties illustrated in Figure 1.

Figure 7 is a plan view of the composite mesh used to produce ties as illustrated in Figure ya) after cutting.

Figure 8 and 9 illustrate alternative constructions of moisture drips.

The tie illustrated in Figure 1 shows the cavity spanning element 1 which is 3.5mm diameter stainless steel wire in the hard drawn condition with a moisture drip 2 consisting of a 2mm diameter stainless steel wire welded underneath the wire 1. With this simple type of moisture drip construction the drip will only function when the tie is positioned in the cavity with the wire 2 on the underside of the cavity 6parlning element 1.

If ties are required which function regardless of which side is placed upwards across the cavity then two alternatives are illustrated in Figures 8 and 9.

Figure 8 illustrates a moisture drip comprising the elements.

2 a and 2 b being hard drawn stainless steel wires of 2.0 mm diameter and where 2 a is welded above the wire 1 and 2 b is welded below the wire 1 Figure 9 illustrates a moisture drip comprising the wire 2 being a soft annealed stainless steel wire of 1.5mm diameter welded to wire 1 and mibsequently wrapped around wiL 1 so as to form protrusions all around the circumference of the wire 1 The wires 3 in Figure 1 provide the anchor when embedded in the mortar of a masonry wall and comprise hard stainless steel wire of 2.0mum diameter.

When the tie is required to provide insulation retaining elements, then extra wires may be provided and it may be necessary to alter the position of the moisture drip 2 so that it is clear of the inSulation The wire 4 in Figure 1 is the insulation retaining element and is constructed from 1.5mm diameter stainless steel wire in the soft annealed condition.

Figure illustrates a tie which is capable of being fastened to a timber wall at one end and a masonry wall at the other end.

The two cavity spanning wires 1 in this embodiment are 2.0mm diameter stainless steel wires in the inter-annealed condition to give a "medium-temper" hardness. The anchor to the timber wall is provided by welding two wires 3a across the wires 1 so as to form an aperture 5 through which a nail can be driven. The end section of the tie at this timber anchoring side is bent upwards so as to form a perpendicular portion lying in the same plane as the timber wall and capable of being held closely against the timber by a nail 6 driven through the aperture 5 into a timber component of the wall. The opposite end of this tie consists of one wire 3 acting as anchor to the masonry leaf of the cavity in the same manner as illustrated in Figure 1.

If it is required to use two nails to fasten the tie to the timber then the aperture can be extended to allow for the extra nail or extra wires 3 can be provided to form two apertures 5 Figure 3b illustrates an alternative tie produced according to the invention for use with cavity walls having one leaf timber and one leaf masonry. In this example the cavity spanning elements 1 are bent upwards to lie flush with the timber leaf in the same manner as in Figure 3a but only one cross wire element 3a is welded to the wires 1. The wires 1 are themselves bent at right angles to the timber and provided with points and ring shanks to enable them to be driven into the timber thus eliminating the need for separate nails.

Figure 4 is a side view o the tie illustrated in Figure 3a.

In a third embodiment of the invention the composite mesh produced from an automatic welded mesh machine is illustrated in Figure 5. In this embodiment the cavity spanning wires 1 are fed continuously as "line wires" to the welding section which consists of four individual welding heads.Two of the welding heads are fed with anchoring wires 3 as "cross wirese2, one welding head provides the cross wire 2 as a moisture drip wire and one welding head provides the cross wire 4 for insulation retainIng elements0 It will be appreciated by those skilled in the art that this arrangement of separate welding heads hollows tore control of the welding parameters ana enables wires of different diameters and physical properties to be welded together, however, welding machines with only one cross wire feed can be used preferably by making the cavity spanning wires feed as cross wires to the mesh.

The composite mesh illustrated in Figure 5 has three line wires 1 but a simple form could have only one line wire.

Figure 6. illustrates in plan how the composite illustrated in Figure 5 is cut along lines A - A and B - B so that each line wire 1 forms the cavity spanning element of a tie as illustrated in Figure 1 with its various affixed elements 2, 3, 4 as required. Clearly the spacing between line wires and cross wires can be adjusted to provide the most advantageous design of ties.

Figure 7 illustrates a composite mesh cut into individual ties as illustrated inire3a

Claims

CLAIMS 1 A wall tie for use in cavity walls comprising one or more cavity spanning elements to which are permanently affixed separate elements providing the means to anchor the tie to the leaves of the cavity wall.
2 A wall tie for use in cavity walls comprising one or more cavity spanning elements to which are permanently affixed one or more separate elements providing the means to prevent moisture transfer across the cavity spanning elements.
3 A wall tie as claimed in Claim 1 or Claim 2 wherein the means to hold and locate insulation in position in the cavity wall is provided by permanently affixing separate elements to the cavity spanning elements.
4 A wall tie as claimed in Claim 1 or Claim 2 or Claim 3 wherein the cavity spanning elements are straight undeformed lengths of material.
5 A wall tie as claimed in Claim 1 or Claim 2 or Claim 3 wherein the cavity spanning elements comprise material in the form of wire, strip or tube, preferably of high tensile strength and stiffness value.
6 A wall tie as claimed in Claim 1 or Claim 2 or Claim 3 wherein the affixed separate elements vary in cross-sectional area and strength from those of the cavity spanning elements and from each other affixed separate element.
7 A wall tie as claimed in Claim 1 or Claim 2 or Claim 3 wherein two parallel cavity spanning elements have two elements affixed to them at one end positioned in parallel to each other and lying across and perpendicular to the cavity spanning elements thereby forming an aperture through which a nail can be driven into timber when the aperture end of the tie is bent to lie in the plane of a timber leaf of a cavity wall.
8 Wall Ties as claimed in Claims 1 - 5 wherein the wires used in the assembly are steel and the completed tie is zinc-coated by a galvanizing process.

8 A wall tie as claimed in Claim 1 or Claim 2 or Claim 3 wherein two cavity spanning elements are pointed at one end and provided with ring shanks to allow them to be driven into timber after being suitably formed and held in parallel location by at least one separate element affixed across the cavity spanning elements.

9 A wall tie as claimed in any of the previous claims wherein all the materials used in the assembly are stainless steel elements.

10 A wall tie as claimed in Claims 1 - 8 wherein the materials used in the assembly are steel and the completed tie is plastic coated.

11 A wall tie as claimed in Claims 1 - 8 wherein the materials used in the assembly are steel and the completed tie is zinc coated by a galvanizing process.

12 A method of manufacturing wall ties as claimed in Claims 1 - 8 whereby the separate elements are permanently affixed to the cavity spanning elements by welding.

13 A method of manufacturing wall ties as claimed in Claims 1 - 8 whereby a plurality of ties are welded together in the form of a composite sheet of welded mesh from which the individual ties are subsequently separated by cutting.

Amendments to the claims have been filed as follows CLAIMS 1 Wall Ties for use in cavity walls produced on a welding machine and having one or more straight cavity - spanning wires with cross-wires welded thereto providing the means of anchoring the tie to the leaves of the cavity wall, the means of preventing transfer of moisture across the cavity - spanning wires and the means if so required of locating and retaining insulation in the cavity.

2 Wall Ties as claimed in Claim 1 produced by feeding wires of different diameters and strengths into the welding machine, the resulting ties having cavity spanning wires and cross-wires selected for size and strength to ensure high physical performance of tjie ties and good cost effectiveness.

3 Wall Ties as claimed in Claim 1 having two straight parallel cavity spanning wires and cross-wires providing the means of anchoring one end of the tie to the brick leaf of the cavity wall, the means of preventing transfer of moisture across the cavity-spanning wires, and the means of anchoring the other end of the tie to the wooden leaf of a cavity wall achieved by welding two cross-wires suitably spaced from one another so as to form an aperture through which a nail can be driven into the wooden leaf of the wall after the aperture end of the tie is bent to lie in the plane of the wooden leaf of the wall.

4 Wall Ties as claimed in Claim 1 having two straight parallel cavity spanning wires both of which are pointed and provided with ring shanks at one end, welded cross-wires providing the means of anchoring one end of the tie to a brick leaf of the cavity wall, the means of preventing moisture transfer across the cavity-spanning wires and the means of holding the pointed ends of the cavity-spanning wires in parallel location to allow the pointed ends to be driven into a wooden leaf of the cavity wall after suitably bending the welded tie.

5 A method of manufacturing Wall Ties as claimed in Claim 1 whereby a plurality of line wires are fed into a welding machine and one or more cross-wires are welded thereto to form strips of welded wire mesh which is cut into individual wall ties preferably continuously on the welded mesh machine but alternatively in a subsequent cutting operation on the sheets or strips of welded wire mesh.

6 Wall Ties as in any of the previous claims wherein the wires used in the assembly are stainless steel.

7 Wall Ties as claimed in Claim 1 - 5 wherein the wires used in the assembly are steel and the completed tie is plastic coated.