GB2542977A

GB2542977A - Wall tie

Info

Publication number: GB2542977A
Application number: GB1622420.6A
Authority: GB
Inventors: Williams Benjamin
Original assignee: Magmatech Ltd
Current assignee: Magmatech Ltd
Priority date: 2011-08-30
Filing date: 2011-08-30
Publication date: 2017-04-05
Anticipated expiration: 2031-08-30
Also published as: GB201114906D0; GB2494135A; GB201622420D0; GB2494135B; GB2542977B

Abstract

A wall tie 501 for tying two structural skins has a portion of relatively low thermal conductivity polymer-based material, for affixing to a first structural skin and a relatively ductile portion for affixing to a second structural skin. The polymer based material may be fibre reinforced polymer comprising basalt fibre and/or glass fibre in an epoxy, vinyl ester or polyurethane resin, the relatively ductile portion may be of steel, including stainless steel. The two portions are secured together and immobilized, by an adhesive resin or mechanical means. The ductile portion 533 is of a planar sheet shape with two indents 545 at side edges. The wall tie provides low thermal conductivity whilst being sufficiently ductile to compensate for any structural movement as a result of settlement or to compensate for inexact positioning during the building process. The wall ties of the present invention also offer the significant advantage of being adaptable and/or adapted for tying skins of various structural materials, e.g. wooden frame skins or steel frames, to masonry skins.

Description

Wall Tie

FIELD OF THE INVENTION

This invention pertains generally to the field of structural wall ties for tying two or more structural skins, e.g. in the construction industry. More particularly, the invention relates to a wall tie, components for a wall tie and methods of manufacturing a wall tie.

BACKGROUND OF THE INVENTION

In building construction, a common practice is to construct building having two skins, especially in brick or concrete block cavity wall construction, but also in buildings having reinforced concrete or steel frame structures which may have an outer or inner skin.

It is typically necessary in order to produce structures with the desired structural integrity to tie the walls to one another, usually using wall ties.

The conventional solution is a wall tie, such as a steel wall tie. In the case of dual skin cavity wall brick or concrete block construction, a steel wall tie is typically adapted to be secured during building in the mortar between the bricks or blocks and extend beyond the cavity. If there is a skin, such as a wooden skin or steel skin tied to a brick/block skin, one end of the tie may be adapted for securing to the wooden or steel skin, whilst the other end is adapted for securing in the mortar between the bricks/blocks. Failure of wall ties can lead to loss of structural integrity in the building, bulging walls and failure of the building ultimately. Failure is most likely in the event of corrosion of the wall ties, poor fixing of the wall ties to one or other skin, failure of the wall tie due to weakness in its fabric or loss of integrity in the event of fire.

One problem associated with steel wall ties has been corrosion, which has led to a significantly shorter lifetime in wall ties than had been expected, although this has been partially addressed by the use of more expensive and energy demanding stainless steel. Another problem with conventional steel wall ties is their high thermal conductivity, which leads to loss of heat from the home and reduced benefit of insulation provided by the cavity wall arrangement. By virtue of their high thermal conductivity, such steel wall ties are a focus for condensation, which may increase the tendency to corrode and may lead to dampness at associated points in one or other skin. Where, cavity wall insulation is provided, condensation can lead to dampness in the insulation material close to the ties and associated problems, such as damp spots and/or cold spots on internal walls.

There have been some efforts to overcome the problems associated with conventional steel wall ties and to make them adaptable for use with multiple skin types.

Ancon Limited, for example in GB-A-2416356, describe a wall tie whereby stainless steel ties of sufficient integrity and strength that can be used to tie wooden frame skins to outer masonry skins and, in EP-B-0882164, to tie masonry skins to steel structures. There are also adapted steel wall ties that have drips, undulations in the tie that cause any condensate to drip at a central point of the tie away from the skins thus minimising any damp problems against the skins and to prevent water penetrating the outer skin from tracking across the cavity via the tie. However, these solutions still suffer from the thermal insulation problems associated with steel.

Several inventors have offered alternatives to steel, by using wall ties formed of plastics or fibre-reinforced plastics. US-B-6212841 describes a one-piece moulding in plastic having a horizontal arm with an undulating end portion for binding in mortar in a brick course and a horizontal arm at the opposing end comprising an aperture close to the junction of the arms to enable securing of the moulding to a stud frame structure. The moulding, e.g. of HDPE, should be of such a thickness to provide the desired rigidity than a conventional steel tie, whilst having the flexibilty to allow for structural movement. A problem for such ties is to meet the requirements for inherent strength and fire resistance that is often needed to meet building standards, which is often not met by such materials. WO-A-2006/074361 describes a one-piece synthetic wall tie for tying an outer brick skin to an inner structure such as a stud wall. The synthetic wall tie described is of lightweight composite material of sufficient structural strength to support or anchor brickwork whilst being non-corrosive, thus overcoming an inherent problem of steel ties. The wall tie of WO-A-2006/074361 is an L-shaped member formed of composite materials and which may be rigidified by using additional stiffening materials within a thermoplastic matrix. One embodiment shows a steel substrate (or, optionally carbon-reinforced plastic substrate) of L-shaped configuration in a thermoplastic coating in order to meet the strength and rigidity requirements whilst being protected from corrosion. US-A-2009/133357 describes a tie system for tying a masonry external wall to an insulation supporting internal timber skin, which system is designed to minimise thermal transfer through the insulation. The tie system comprises a composite fastener, such as a fibre reinforced polymer fastener (e g. fibreglass), with a tapered or threaded tip for hammering or screwing into an internal insulation-supporting timber stmcture and a threaded other end. A belly nut may be screwed onto the threaded other end of the composite fastener which belly nut itself is configured to receive a steel pintle shaped and configured to bind to mortar between bricks in an outer masonry wall. The pintle should be adjustable in position within the belly nut, to vary the relative height of the attachment to the brick course as compared with the attachment to the wooden frame whilst providing an insulating securing cavity wall tie. Such an arrangement is very specific as to its application and suffers from the disadvantage that multiple highly engineered parts are required for each tie and thus is a relatively expensive product. A particular problem is the provision of a wall tie in a cost-effective manner that provides sufficient structural strength to meet necessary building standards but is flexible enough to allow for settlement of a structure whilst being non-corrosive and ideally having low thermal conductivity. Optionally, a wall tie structure should be adaptable to be fixed between a range of inner and outer skins.

The present inventor has invented a new wall tie allows him to overcome many of the above problems.

PROBLEM TO BE SOLVED BY THE INVENTION

There remains a need for improvements in wall ties, to allow flexibility of use, adaptability by building contractors to new wall ties and energy efficiency in manufacture and performance.

It is an object of this invention to provide a wall tie that demonstrates good thermal transfer performance, is relatively low cost to manufacture and is energy efficient to manufacture and is adaptable for use in a range of wall tie applications.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention, there is provided a wall tie for tying two structural skins and having a body portion adapted for affixing to a first structural skin and a first end portion adapted for affixing to a second structural skin, which body portion is formed of a first material and which first end portion is formed of a second material different to the first material, wherein the first material comprises a polymer-based material and has relatively low thermal conductivity relative to the second material and wherein the second material is a relatively ductile or malleable material relative to the first material, which wall tie further comprises a pre-formed permanent joint portion between the body portion and first end portion, at which joint portion the body portion and first end portion are joined, wherein the joint portion is a pre-formed permanent joint which comprises a body joint end of the body portion having adhered with an adhesive resin and/or mechanically immobilized thereon a first joint end of the first end portion and wherein at least half the length of the wall tie comprises the first material and wherein the first end portion comprises a fixing head portion adapted for securing in a cooperating channel element shaped to receive and secure the fixing head portion, which fixing head portion of planar sheet shape having two indents disposed in the side edges thereof for receiving two corresponding leaves of the cooperating channel element.

In a second aspect of the invention, there is provided a method for the manufacture of a wall tie as defined above, the method comprising forming a first body portion of a first material having a body joint end, providing and shaping a first end portion of a second material different to the first material, wherein the first end portion comprises a fixing head portion adapted for securing in a cooperating channel element shaped to receive and secure the fixing head portion, which fixing head portion of planar sheet shape having two indents disposed in the side edges thereof for receiving two corresponding leaves of the cooperating channel element, adapting the body joint end and the first end portion having a first joint end such that they are joinable and permanently joining said body joint end and first joint end , by adhering to the body joint end with an adhesive resin and/or mechanically immobilizing thereon a first joint end of the first end portion to provide a pre-formed joint portion between the body portion and first end portion to form the wall tie, characterized in that the first material comprises a polymer-based material and has relatively low thermal conductivity relative to the second material and the second material is a relatively ductile or malleable material relative to the first material.

ADVANTAGES OF THE INVENTION

The wall ties of the present invention provide the structural strength of and low thermal conductivity of polymer based materials such as basalt fibre reinforced polymer whilst being sufficiently ductile to compensate for any structural movement as a result of settlement or to compensate for inexact positioning during the building process. The wall ties of the present invention also offer the significant advantage of being adaptable and/or adapted for tying skins of various structural materials, e.g. wooden frame skins or steel frames, to masonry skins.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1A is a diagrammatic representation in perspective view of a wall tie;

Figure IB illustrates a wall tie of Figure 1A as it is fixed to a brick course;

Figure 2 shows in perspective view a wall tie having two end portions;

Figure 3 A shows in perspective view a wall tie which is bendable between stored and extended positions;

Figure 3B illustrates the wall tie of Figure 3 A in its two configurations when attached to a structural skin;

Figure 3C shows in longitudinal cross-section the wall tie of Figure 3A;

Figure 4 shows in perspective view a wall tie having an alternative end portion and fixing;

Figure 5A shows in perspective view a wall tie according to an embodiment of the invention in which the first end portion has a planar fixing head adapted for fitting to a fixing channel element;

Figure 5B illustrates a wall tie fixing system having a fixing channel element and a wall tie of Figure 5 A;

Figure 5C illustrates a variable wall tie fixing system to that of Figure 5B according to a further embodiment of the invention;

Figures 6A, 6B and 6C illustrate wall ties with variant screw thread end portions for affixing the ties to timber structural skins and other structural skins;

Figure 7 illustrates in perspective view a wall tie having a planar fixing element and screwthread separable body portion;

Figure 8 shows a wall tie in situ in which the joint portion comprises an insulation retaining element;

Figures 9A, 9B and 9C illustrate in perspective view wall ties in which a body portion and a first end portion are separably joinable at a joint portion; and

Figure 9D shows a wall tie according to Figure 9C in situ tying a first and second structural skin.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides for an improved wall tie for tying structural skins in buildings. The wall tie according to the invention has a body portion for affixing to a first structural skin and a first end portion for affixing to a second structural skin. The body portion is formed of a first material and the first end portion is formed of a second material which is different to the first material. In particular, the first material comprises a polymer-based material and has relatively low thermal conductivity relative to the second material whilst the second material is a relatively ductile or malleable material relative to the first material.

The body portion comprises at least 50 % of the length of the wall tie, more preferably, at least 60% and still more preferably at least 75%. In any case it is preferred that the first end portion comprises less than 50% of the length of the wall tie, more preferably less than 40% and still more preferably less than 25%. The length of the first end portion, which may be thermally conducting, is preferably minimized to minimize thermal bridging. Preferably, the body portion comprises in situ at least 50% of the separation of the first and second skins (i.e. in the horizontal plane across the cavity), more preferably at least 60%, still more preferably at least 75% and most preferably at least 90%.

The first end portion, which may optionally be a thermally conductive material such as steel, preferably extends no more than 50 mm (measured in a horizontal plane) across the cavity when in situ, preferably no more than 30 mm and still more preferably no more than 25 mm. Optionally, the first end portion may not extend into the cavity at all, i.e. 0 mm, or only slightly e.g. up to 2 mm, however, to benefit from ductility of the first material, it is preferred that the first end portion protrudes at least 5 mm into the cavity and optionally at least 10 mm. Ideally, the first end portion protrudes from 5 mm to 25 mm into the cavity from the skin to which it is secured.

Optionally, the first material, being a polymer-based material may be composite material or reinforced plastic material.

Preferably, the first material is a fibre-reinforced polymer (FRP). The FRP is preferably formed of a fibre dispersed in a cured polymer resin. Any suitable fibre or fibres may be used in the manufacture of the fibre-reinforced polymer. Examples of fibres that may be used in the FRP or polymer-based material in accordance with the present invention may be synthetic and/or natural fibres and may include any one or a combination of: glass fibres; carbon fibres; boron fibres; Kevlar™ fibres; mineral fibres; basalt fibre; metal strands such as aluminium, copper or steel; polymer fibres such as polyester, polyethylene or aramids; or natural fibres such as cotton, jute, hemp or flax. Preferably the fibres are selected from fibres having low thermal conductivity. Thus, preferably, the fibres are selected from glass fibres, polymer fibres and basalt fibres, more preferably glass fibres and basalt fibres and most preferably basalt fibres.

Optionally, more than one fibre material can be used in combination in the fibre-reinforced polymer in forming the wall-tie of the invention. Such constitution of combinations of fibre materials may vary longitudinally along the length of the wall-tie, for example, or radially from core to surface, or the combination may comprise a random distribution of constituent fibres. Suitable such combinations of fibre materials might be, for example, any two or more of glass fibres, polymer fibres, carbon fibres and basalt fibres in combination, such as glass and basalt fibres or basalt and carbon fibres in combination.

Particularly suitable fiber-reinforced polymers for the wall-tie of the invention include glass fiber-reinforced polymers or basalt fiber-reinforced polymer.

The fibres may be orientated in any suitable arrangement, e g. random, partially aligned or aligned. Preferably, at least a portion (e g. a core) of the body portion of the wall-tie of the invention is formed of fibre-reinforced polymer having partially aligned and preferably aligned fibres. Preferably, the body portion comprises a core fibre-reinforced polymer material having longitudinally aligned fibres, typically of basalt fibre, being fibres aligned longitudinally with the body portion of the wall tie.

The body portion may be formed of a core of fibre-reinforced polymer, preferably basalt fibre and preferably longitudinally aligned fibres. Optionally, the body portion may comprise more than one layer of fibre reinforced polymer material. For example, the body portion may comprise of a longitindal core of fibre-reinforced polymer and one or more layers of fibre-reinforced polymer formed thereon. Longitudinal alignment of fibres enables the body portion to have the tensile strength in the longitudinal direction that is the main requirement of a wall-tie. In one embodiment, the body portion comprises a core of FRP having randomly orientated fibres and an outer layer of FRP having longitudinally aligned fibres and, optionally further layers therebetween or thereon. In another embodiment, the body portion comprises a core of FRP having longitudinally aligned polymer and at least one layer of FRP thereon which may comprise a layer of randomly orientated fibre-reinforced polymer, a layer of FRP having lateral fibres and a layer of FRP having longitudinal fibres. An outer layer may be provided by providing a mat of randomly orientated fibres. A fibre-reinforced polymer may have lateral fibres or laterally orientated fibres provided by a helical wind of fibre rovings about a longitudinally aligned core. There may be multiple layers comprising successive layers of longitudinal and random and/or lateral fibres. Lateral and randomly orientated fibres provide additional strength in other dimensions (other than the key longitudinal direction). In a preferred embodiment of the present invention, the body portion comprises at least one layer (e.g. the core) of longitudinally aligned fibre-reinforced polymer and radially outward therefrom at least one layer of laterally aligned fibre-reinforced polymer, which preferably a helically wound layer of fibre rovings. A helical wind of fibres about a longitudinally aligned fibre-reinforced polymer provides significant longitudinal tensile strength combined with further enhanced fire-resistance and other dimensional strength (e.g. torsional and shear strength).

In these multi-layer embodiments, the fibre may be the same or different in each or any layer, but is preferably basalt fibre.

By longitudinal fibres, it is meant fibres which are tending to be orientated in the direction of pultrusion or co-axial with the mandrel. Any fibre which is at an angle of less than 45 degrees to the direction of pultrusion is a longitudinal fibre, although preferably they are less than 15 degrees and more preferably less than 10 degrees deviated from the direction of pultrusion and most preferably substantially in the direction of pultrusion, i.e. most preferably they are substantially axial in orientation.

By laterally orientated fibres, it is meant that the fibres are offset from the median or the direction of pultrusion (e.g. the axis of a mandrel) generally at an angle of 45 degrees or more. More preferably, the laterally orientated fibres are offset from the axial direction by at least 60 degrees and still more preferably at least 75 degrees. In preferred embodiments of the invention, the lateral orientated fibres are arranged as wound fibres having an angle offset from the transverse direction by up to 15 degrees, optionally up to 30 degrees and possibly up to 45 degrees. More preferably, the wound fibres are offset from the transverse by up to and including 10 degrees and most preferably at least fibre rovings on the relatively wide side of the profile are orientated in the range 1 to 5 degrees from the transverse direction.

The fibre-reinforced body portion of an embodiment of the invention may be manufactured by any suitable means, such as pultrusion, injection moulding, resin transfer moulding, vacuum bag and press moulding, press moulding, compression moulding, filament winding, but preferably, the body portion is manufactured by pultrusion and/or filament winding.

Any suitable resin may be used. Optionally the resins may be thermosetting or thermoplastic, but thermosetting resins are strongly preferred. Actinic-radiation curing resins may alternatively be used.

Preferably the resin is selected from one or more of epoxy resins, vinyl ester resins, polyester resins, polyurethane resins or phenolic resins. More preferably, especially for use in pultrusion manufacture, the resin is vinyl ester, epoxy or polyester resin, more preferably vinyl ester or epoxy and still more preferably epoxy resin.

Certain additives may optionally be included in the resin formulation to enhance performance, such as Intumescent™ to improve fire resistance (which is incorporated by dissolving or dispersing in the resin) and/or nano clay particles (to enhance fire resistance and increase strength).

The fibre-reinforced polymer used comprising the body portion, which is preferably a pultruded profile, preferably has a fibre content of greater than or equal to 50% by weight of the fibre-reinforced polymer body portion, for example in the range 50 to 75%, more preferably in the range 55 to 70%, e g. in the range 60 to 65%.

Optionally, the body portion may be provided with an outer coat for enhancing the fire resistance of the wall tie. The outer coat may be any suitable material, such as a Kevlar™ coating or other heat resistant material. Preferably, the outer coat comprises a granular, preferably of variable size grains, material such as a silica-based material, e.g. sand, preferably adhered to the outer surface with a suitable heat-resistant resin.

The second material may be any material that is relatively ductile as compared with the first material. Typically, the second material may be selected from injection moulded plastic (e.g. polypropylene), especially for Type 4 ties, plastic coated metals or metal, especially steel, the second material preferably being corrosion resistant. Examples of second material which may be suitable, depending upon the particular application, include galvanized low carbon steel (e.g. in accordance with 3.2 or 3.3 of BS 1243:1978), plastic-coated zinc coated mild steel (e.g. in accordance with 3.3 and 5.3 of BS 1243:1978), austenitic stainless steel wire (e.g. in accordance with 3.6 of BS 1243:1978), austenitic stainless steel strip (e.g. in accordance with 3.7 of BS 1243:1978), copper (e.g. in accordance with 3.4 of BS 1243:1978) or copper alloys (e.g. in accordance with 3.5 of BS 1243:1978).

Preferably the second material is steel, more preferably stainless steel.

The first end portion comprises a fixing head portion adapted for engaging with a fixing channel element itself affixed to the second skin. A fixing head portion of a wall tie and a fixing channel element may together provide a wall-tie fixing system.

The ductility of the first end portion provides a particular advantage in combination with the thermally insulating body portion in that the body portion provides a tie which minimizes tie-mediated thermal loss through the cavity wall whilst the ductility of the first end portion (and optional second end portion) allows for movement in the structure over time, especially where one or other of the skins comprises wood (which are expected to shrink and settle by as much as 24 mm). It is a particular advantage of the wall ties of the present invention that these two objectives can be met.

The body portion and first end portion may have the same or different profiles. The body portion may have a profile that is of a cross section of any suitable shape, such as circular, oval, quadrangular (e.g. square or rectangular), triangular, pentagonal, hexagonal or other regular or irregular shape. Optionally, the body portion may be flattened, or flattened at its end adapted for fixing to a first skin. Preferably, the body portion has a circular or oval profile and is in the form of a rod or bar.

The body portion may be any suitable size. Preferably, the body portion has a maximum transverse dimension (e.g. diameter) of up to 20 mm, more preferably up to 10 mm, preferably at least 4 mm, and most preferably from 4 to 8 mm, e.g. about 6 mm.

The wall tie of the present invention comprises a joint portion between the body portion and the first end portion, at which the body portion and first end portion are joined to form the wall tie. The joint portion is a pre-formed permanent joint portion.

According to the invention, in which the joint portion is a preformed permanent joint, any suitable method for joining the body portion and first end portion may be adopted. The part of the body portion which forms or is connected with the joint portion may be defined as a body joint end and the part of the first end portion which forms or is connected with the joint portion may be defined as a first joint end. Thus, for example, the body portion and first end portion may be joined by alignment or overlapping of the body joint end with the first joint end and by bolting through both the respective joint ends, by gluing together of the respective joint ends (e.g. when overlapping, for example tapered overlapping joint ends), by mechanical locking of the joint ends (eg. clipping together tension locked joint ends), by clamping (e.g. the respective joint ends may be pressed together whereby the first end portion of more ductile material may be mechanically locked onto the body portion, which may be provided with undulations or deformations suitable for clamping to), by a screw thread arrangement whereby the body end portion may comprise a threaded screw element, whilst the first end portion may comprise a corresponding receiving screw thread or vice versa, or by any other suitable means.

In a preferred embodiment of the pre-formed joint embodiment, the joint portion is formed by adhering the body joint end to the first joint end with an adhesive resin. Preferably, the body joint end, which may be a fibre-reinforced polymer, optionally in the shape of a rod, is received in a receiving element of the first joint end shaped to receive the body joint end, which receiving element is preferably tubular and secured therein with an adhesive resin. More preferably, the receiving element is or maybe shaped to form a cavity with a relatively small aperture, whereby cured adhesive on the body joint end may form a dovetail-type joint thereby additionally providing a mechanically locked joint as whereas resin-adhered joint, thus providing particular strength. Optionally, the relatively narrow aperture of the receiving element is formed by crimping the end of the first joint end about the body portion. The joint portion manufactured in this manner does not represent a weak point in the wall-tie and preferably performs in a manner similar and ideally no worse than the body or other portions of the wall-tie, for example it should be suitable heat resistant and corrosion resistant/durable.

Preferably, the adhesive resin may be strengthened by dispersing fibres or particles therein, such as fibres the same or different as in a fibre-reinforced polymer body portion or nano clay particles, for example.

The adhesive resin may be selected from any suitable adhesive, which is capable of adhering to both the first and second materials. Optionally, the adhesive is the same as the resin in a fibre-reinforced polymer body portion.

Preferably, the joint portion comprises a stainless steel socket receiving a fibre-reinforced polymer rod-shaped body portion in-filled with a fire-resistant resin which socket is then crimped about the joint end to form a dovetail joint, thereby providing additional tensile strength.

Optionally, the body portion may be provided with a second end portion by way of adaptation to secure the body portion to the first skin. The second end portion may be the same or different to the first end portion and may optionally be of relatively malleable and ductile material or not relative to the body portion and/or the first end portion The second end portion may be formed of a third material, which may be any suitable material such as those from which the body portion and/or the first end portion may be formed. Preferably, the second end portion is formed of a similar or the same material to the first end portion. The second end portion and the body portion may be joined, either preformed or in situ, via a second joint portion, which second joint portion may be formed by any suitable means, such as those of the first joint portion.

Thereby, a wall-tie within the scope of the present invention may comprise a body portion, e.g. a fibre-reinforced polymer rod, having on each end thereof end portions (first and second end portions) which may be the same or different, which first and second end portions are adapted for fixing to respectively second and first skins.

The wall-tie of the invention may be adapted to tie a variety of cavity wall arrangements having various possible first and second skins.

Typically, the first skin is the exterior skin (where the skins reflect an interior and exterior of a construction).

The skins may be, for example, any combination of brick and mortar, concrete block, stone and mortar, wood, steel frame, aircrete, thin joint blocks, cellular clay blocks, masonry walls with no aligned bedjoint coursings, concrete with in situ channels, and any other skin The body portion and first end portion, and optional second end portion, may be adapted for securing to the respective skin.

The first end portion may therefore be adapted and shaped for securing to the second skin as appropriate. The first end portion comprises a fixing head portion adapted for engaging with a fixing channel element itself affixed to the second skin. A fixing head portion of a wall tie and a fixing channel element may together provide a wall-tie fixing system.

Optionally, the first end portion comprises a bending portion, whereby the first end portion may be bent so that the wall tie may be secured to the second skin by the first end portion or by the fixing portion of the first end portion and then bent at the bending portion such that the remainder of the wall tie (including the body portion) may be stored parallel to the second skin and bent back to its substantially horizontal position when required during construction of the first skin.

According to preferred embodiments of the wall-tie of the present invention are a wall-tie having a body portion adapted for securing to a first structural skin and a first end portion for securing to a second structural skin, wherein the body portion comprises a fibre-reinforced polymer rod (preferably of pultruded basalt fibres in cured resin) and the first end portion comprises a stainless steel fixing head adapted for receiving in a stainless steel receiving channel secured to a structural skin, whereby the fixing head and receiving channel provide a wall-tie securing system.

As discussed above, in a second aspect of the invention, there is provided a method for the manufacture of a wall tie as defined above, the method comprising forming a first body portion of a first material having a body joint end, providing and shaping a first end portion of a second material different to the first material, wherein the first end portion comprises a fixing head portion adapted for securing in a cooperating channel element shaped to receive and secure the fixing head, which fixing head portion is of planar sheet shape having two indents disposed in the side edges thereof for receiving two corresponding leaves of the cooperating channel element, adapting the body joint end and the first end portion having a first joint end such that they are joinable and permanently joining said body joint end and first joint end, by adhering to the body joint end with an adhesive resin and/or mechanically forming a joint portion between the body portion and the first end portion to form the wall tie, characterized in that the first material comprises a polymer-based material and has relatively low thermal conductivity relative to the second material and the second material is a relatively ductile or malleable material relative to the first material.

The nature, material and shape of the body and first portions may be as described above. Optionally, the method further comprises providing and shaping a of a third material, the same or different to either of the first or second materials, but preferably the same as the second material, adapting at least one end of the second end portion and an end of the body portion such that they are joinable and joining said body portion and second end portion to form the wall tie.

In one preferred embodiment, a wall-tie of the present invention is manufactured by providing a fibre-reinforced polymer rod as body portion, a metal tubular element as first end portion, inserting a joint end of the body portion into an end of the metal tubular element, in-filling with adhesive resin, crimping the end of the metal tubular element about the body portion and flattening and shaping the remainder of the first end portion according to the requirements for fixing to a second skin.

The invention will now be described in more detail, without limitation, with reference to the accompanying Figures.

In Figure 1 A, a wall tie 101 has a body portion 103 of basalt fibre reinforced polymer in the form of a rod which may affix or be adapted to affix to a first structural skin (not shown, but for example a brick course or concrete block course) and a first end portion 105 of stainless steel, in a flattened form and provided with two mortar-binding apertures 107, the end portion 105 being adapted for securing in a brick course 109 of a second structural skin as is shown in Figure IB. The body portion 103 and first end portion 105 are joined together at a joint portion 111 at which the first end portion 105 adjoins via its first joint end 113 with a body joint end (not shown) of the body portion 103. The first joint end 113 in this example is provided as a hollow tubing section for receiving the rod shaped body joint end of the basalt fibre reinforced polymer rod body portion 105. The body joint end is secured within the first joint end 113 using a suitable resin (not shown), selected for bonding to both stainless steel and basalt fibre reinforced polymer rod material. The hollow tube section first joint end 113 may have a greater internal diameter at its base 115 than at its opening 117 thereby creating a dovetail joint of the body joint end (not shown) when bonding resin is cured thereon within the joint portion 111 and thus substantial axial tensile strength may be achieved at the joint.

In Figure 2, a wall tie 201 with a body portion 203 of a basalt fibre-reinforced polymer rod having a first end portion 205 at one end and a second end portion 206 at the other end, each end portion 205, 206 being stainless steel with a morter binding aperture 207 formed therein for securing between brick courses. As with the first end portion 105 in Figure 1, the end portions 205, 206 have respectively first and second joint ends 213, 214 of tubular form for receiving body joint ends (not shown) of the body portion 203 which may be secured therein using a suitable polymer resin for binding with the body portion 203. By providing a joint end 213, 214 with a hollow tube section base 215 that is of greater diameter than the opening 217 (e.g. by forming in that shape or subsequently crimping the openings 217), a dovetail-type joint can be formed which is of substantial axial tensile strength.

Figure 3 A shows another embodiment of the invention, similar to Figure 1 A, which comprises a wall tie 301 having a body portion 303 which may be adapted to be secured (e g. in a brick or block course) in a first structural skin (not shown) and adjoined thereto a first end portion 305 joined to the body portion 303 in a similar manner to those of Figures 1 and 2 described above. The tie 301 of Figure 3 has a first end portion 305 consisting of a first joint end 313 for joining the end portion 305 to the body portion 303 and a skin securing portion 319 having mortar binding apertures 307 formed therein for securing to mortar within a brick course (not shown). Between the skin securing portion 319 (which will be embedded within a brick course and not visible in situ) and the first joint end 313 of the first end portion 305 a bending portion 321 is provided of typically the same material as the joint end 313 and skin securing portion 319, e.g. steel, and in thinner profile sheet material such that is sufficiently malleable yet sufficiently self supporting (and resistant to movement) that it may be readily bent to define a desired angle between the end portion 305 and the body portion 303 and stay at that relative position. Accordingly, the wall tie 301, when affixed in situ in a structural skin 323 via the skin securing portion 319 of its first end portion 305 can, as can be seen from Figure 3 A, be moved from a first bent configuration 325 to its second straightened configuration 327 ready for affixing to corresponding structural skin (not shown). By this arrangement, whilst a structural skin is constructed (typically an internal structural skin, but referred to herein as a second structural skin irrespective of the order of construction), wall ties 301 can be added in bent form 323 so as not to protrude and thereby not represent a safety hazard to workers. Then when the other skin is being constructed, they may be straightened 325 to as to be affixed within the second course to perform the function of a wall tie.

Figure 3C shows a longitudinal cross section 329 of the wall tie 301 of Figure 3 A. As can be seen, the body joint end 331 of the body portion 303 is received in the tube-shaped first joint portion 311 and can be secured therein with a suitable adhesive resin. The first end portion 305 is shown with the bending portion 321 in bent configuration and mortar binding apertures are shown in the skin securing portion 319.

Figure 4, shows a variant wall tie 401 of the wall tie 301 of Figure 3A in which the end portion 405 comprises a shortened skin securing portion 419 with only a single mortar binding aperture 407.

Figure 5 A shows a wall tie 501 of the invention in which the end portion 505 comprises a fixing head portion 533, which is typically of stainless steel and is joined to the basalt fibre-reinforced polymer rod body portion 503 via the joint portion 535 formed of a first joint end 513 of end portion 505 and body joint end 531 of body portion 503. The fixing head portion 533 is adapted for securing in a fixing channel element 537, as can be seen in Figure 5B. The fixing channel element 537 may be secured or securable to a structural skin and provide a means of fixing the wall tie 501 to the structural skin (not shown). Typically the fixing channel element 537 comprises a channel 539 for receiving a distal end 541 of the fixing head portion 533 which is of planar sheet shape and the channel 539 is punctuated by two intruding leaves 543 configured to slot into corresponding indents 545 of the fixing head portion 533. Thereby the wall tie 501 may be fixed to the fixing channel element 537 by orientating the planar fixing head portion 533 to substantially in the plane of the longitudinal axis of the channel 539 and the distal end 541 inserted into the channel 539 before twisting the wall tie 501 about its longitudinal axis until the intruding leaves 543 engage with the indents 545 and secure the fixing head 533 in place. Such fixing head portions 533 and fixing channel elements 537 as are known in the art may be adopted in this embodiment of the invention. Together the wall tie 501 (or wall ties 501) and the fixing channel element 537 may be described as a wall tie fixing system 547. The fixing head and fixing channel element may, in practice, take numerous different forms to fit together and is thus not limited to the shapes illustrated in and described with reference to Figure 5 A and 5B. The tie should hold in the channel without rotating out or sliding down. Optionally, there is a snap-fit configuration for securing the fixing head to the fixing channel element.

Figure 5C illustrates an alternative embodiment of the wall tie fixing system 547 of Figure 5C. According to Figure 5C, the first end portion 505 comprises a kink or undulation 549 which provides a drip function to the end portion 505. Whilst the joint portion 535 may in effect act as a drip function, it is useful to provide a kink 549 with that function in the stainless steel part of the tie 501 since condensation onto that portion is more likely and thereby can be collected and dripped into the cavity instead of flowing to the structural skin.

Figures 6A, 6B and 6C illustrate three different first end portions 605 of a wall tie 601, each attached to a body portion 605 via a joint portion 635. They show respectively a thick core shallow pitch helical screwthread, a tapered core shallow pitch screw thread and a narrow core, deep pitch helical screwthread, in each case providing wall ties 601 that may be used to link a first masonry structural skin (for example) to a second timber structural skin which can receive a screwthread fixing or for connecting in to aircrete. The end portion can be polymer may optionally be polymer or stainless steel and the fixing can be drilled directly into the structural skin material or secured within a pre-drilled pilot hole.

Figure 7 illustrates a wall tie 701 with a further variant first end portion 705 and variant joint portion 735 linking the end portion 705 and body portion 703. In this embodiment, the first end portion 705 comprises a planar sheet skin securing portion 719 and formed perpendicularly thereon a tubular first joint end 713. The tubular joint end 713 is provided on the interior surface with a receiving screw thread for receiving a screw thread formed on a threaded bit (not shown) which forms the body joint end of the body portion 705. The threaded bit is formed on a metal (e.g. steel) end 751 of the body portion which is joined to the basalt fibre-reinforced polymer rod by suitable means, such as by the metal end having a tubular receiving portion for receiving the rod 703 which may be secured in place by a suitable adhesive resin. According to this embodiment fixing plate 719 may be secured to a second structural skin (not shown), e.g. a timber skin, and be left with an exposed receiving thread. The body portion 703 may be inserted in due course when a second skin is being constructed.

In Figure 8, a wall tie 801 is shown in situ affixed to one structural skin 823 via first end portion 805 with basalt fibre-reinforced polymer body portion 803 protruding into the cavity and joined to first end portion 805 by joint portion 811 which comprises a retaining disc 853 to secure insulation sheet 851 to the structural skin 823.

Figures 9A-D show examples of wall-ties 901 according to another embodiment of the invention which comprise a joint portion 911 formable (and separable) in situ. Each wall-tie 901 has a first end portion 905 of various configuration which can be affixed to a second structural skin 953, which first end portion 905 protrudes from the structural skin 953 with first joint end 913 suspended in mid air. When first structural skin 955 is formed, body portion 903 may be connected to first end portion 905 and then secured to first structural skin 955 to form a wall tie 901 across the cavity formed between the structural skins.

As long as the joint portion may not be separated in an axial direction, it may have the required tensile strength.

EXAMPLE

Example 1 A wall tie comprising a body portion of basalt fibre reinforced bar and a stainless steel L-shaped end portion for affixing to a wooden inner skin was manufactured as follows: A core of basalt fibre with a transverse wrap was pultruded through a 6 mm pultrusion die in epoxy resin to produce a cured basalt fibre circular section bar of 6 mm diameter, which is then cut to 250 mm lengths. The basalt fibre was a 13 pm diameter fibre. The volumetric ratio of basalt fibre to resin used was in the range 60:40 to 65:35.

To one end of the pultruded fibre reinforced polymer bar, a coating of 2-3 ml of the same epoxy resin was applied along a 25 mm length and a length of steel tube is passed over the end of the bar on top of the resin. The inner end of the steel tube is crimped over the fibre reinforced polymer bar and the outer end is flattened and bent to produce an L-shaped end.

The wall tie was subjected to preliminary testing for tensile strength (by tension and compression). The test comprises securing the wall tie (by nailing) to a standard OSB board and clamping the free end to a testing rig and testing for compression (pushing the tie toward the board) and tension (pulling the tie away from the board). 5 mm of movement is the point of failure according to this test. The declared strength of a wall tie (as used in UK construction) is the load required to cause a failure (i.e. 5 mm of movement). A third test (compression at 24 mm movement) to allow for humidity changes in timber is also provided. The above wall tie was tested with a 200 mm cavity and the results of the test are as follows:

The standard requirement in the UK for tension is 630 N and 440 N in compression (including with 24 mm movement). As can be seen from the above results, a wall-tie of the present invention readily meets the UK standard for wall-tie tension and compression for cavity walls with one timber skin.

The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention.

Further aspects and/or embodiments of the invention are described in the following clauses:

Clause 1. A wall tie for tying two structural skins and having a body portion adapted for affixing to a first structural skin and a first end portion adapted for affixing to a second structural skin, which body portion is formed of a first material and which first end portion is formed of a second material different to the first material, wherein the first material comprises a polymer-based material and has relatively low thermal conductivity relative to the second material and wherein the second material is a relatively ductile or malleable material relative to the first material

Clause 2. A wall tie of clause 1, wherein at least half the length of the wall tie comprises the first material.

Clause 3. A wall tie of clause 1 or clause 2, wherein the first material is a fibre-reinforced polymer (FRP).

Clause 4. A wall tie of clause 3, wherein the fibre-reinforced polymer comprises a basalt fibre and/or glass fibre in an epoxy, vinyl ester or polyurethane resin.

Clause 5. A wall tie of any one of the preceding clauses, wherein the second material is steel.

Clause 6. A wall tie of clause 5, wherein the second material is stainless steel.

Clause 7. A wall tie of any of the preceding clauses, which further comprises a joint portion between the body portion and first end portions, at which joint portion the body portion and first end portions are joined or may be joined.

Clause 8. A wall tie of clause 7, wherein the joint portion is a permanent preformed joint portion.

Clause 9. A wall tie of clause 8, wherein the joint portion comprises a body joint end of the body portion having adhered with an adhesive resin and mechanically immobilized thereon a first joint end of the first end portion.

Clause 10. A wall tie of clause 7, wherein the joint portion is formable in situ between a first joint-end and a second joint end when at least one end portion is fixed to a structural skin.

Clause 11. A wall tie of clause 10, wherein the joint portion comprises a releasably secureable mechanical fixing, optionally selected from a screw and screw-thread arrangement, a nut and boltable aligned plurality of apertures or a mechanically interlocking arrangement.

Clause 12. A wall tie of any one of the preceding clauses, wherein the first end portion comprises a fixing portion adapted for fixing the wall tie to wood.

Clause 13. A wall tie of clause 12, wherein the first end portion comprises an L-shaped stainless steel fixing portion for fixing the wall tie to wood

Clause 14. A wall tie as claimed in any one of clauses 1 to 11, wherein the first end portion comprises a fixing portion adapted for fixing to thin mortar joint walls.

Clause 15. A wall tie of any one of the preceding clauses, wherein the body portion is adapted for fixing to the first structural skin by providing a second end portion thereon, which second end portion is formed of a third material which may be the same or different to the first material and may be the same or different to the second material.

Clause 16. A wall tie of claim 15, wherein the second end portion comprises a stainless steel end adapted for fixing to the first structural skin.

Clause 17. A wall tie of clause 15 or clause 16, which further comprises a second joint portion between the body portion and second end portion, at which second joint portion the body portion and second end portions are joined or may be joined.

Clause 18. A method for the manufacture of a wall tie as defined in any one of the above clauses, the method comprising forming a first body portion of a first material, providing and shaping a first end portion of a second material different to the first material, adapting at least one end of each of the body portion and the first end portion such that they arejoinable and joining said body portion and end portion to form the wall tie, characterized in that the first material comprises a polymer-based material and has relatively low thermal conductivity relative to the second material and the second material is a relatively ductile or malleable material relative to the first material.

Claims

CLAIMS:

1. A wall tie for tying two structural skins and having a body portion adapted for affixing to a first structural skin and a first end portion adapted for affixing to a second structural skin, which body portion is formed of a first material and which first end portion is formed of a second material different to the first material, wherein the first material comprises a polymer-based material and has relatively low thermal conductivity relative to the second material and wherein the second material is a relatively ductile or malleable material relative to the first material, which wall tie further comprises a pre-formed permanent joint portion between the body portion and first end portion, at which joint portion the body portion and first end portion are joined, wherein the joint portion is a pre-formed permanent joint which comprises a body joint end of the body portion having adhered with an adhesive resin and/or mechanically immobilized thereon a first joint end of the first end portion and wherein at least half the length of the wall tie comprises the first material and wherein the first end portion comprises a fixing head portion adapted for securing in a cooperating channel element shaped to receive and secure the fixing head portion, which fixing head portion of planar sheet shape having two indents disposed in the side edges thereof for receiving two corresponding leaves of the cooperating channel element.

2. A wall tie as claimed in claim 1, wherein the joint portion comprises a body joint end of the body portion having adhered with an adhesive resin and mechanically immobilized thereon a first joint end of the first end portion.

3. A wall-tie as claimed in claim 1, wherein the body joint end is in the shape of a rod and is received in a tubular receiving element of the first joint end shaped to receive the body joint end and secured therein with an adhesive resin and mechanically locked by crimping the tubular receiving element over the body joint end.

4. A wall tie as claimed in any one of claims 1 to 3, wherein at least 75% of the length of the wall tie comprises the first material

5. A wall tie as claimed in any one of the preceding claims, wherein the first material is a fibre-reinforced polymer (FRP).

6. A wall tie as claimed in claim 5, wherein the fibre-reinforced polymer comprises a basalt fibre and/or glass fibre in an epoxy, vinyl ester or polyurethane resin.

7. A wall tie as claimed in any one of the preceding claims, wherein the second material is steel.

8. A wall tie as claimed in claim 7, wherein the second material is stainless steel.

9. A wall tie as claimed in any one of the preceding claims, wherein the body portion is adapted for fixing to the first structural skin by providing a second end portion thereon, which second end portion is formed of a third material which may be the same or different to the first material and may be the same or different to the second material.

10. A wall tie as claimed in claim 9, wherein the second end portion comprises a stainless steel end adapted for fixing to the first structural skin.

11. A wall tie as claimed in claim 9 or claim 10, which further comprises a second joint portion between the body portion and second end portion, at which second joint portion the body portion and second end portions are joined or may be joined.

12. A method for the manufacture of a wall tie as defined in any one of claims 1 to 11, the method comprising forming a first body portion of a first material having a body joint end, providing and shaping a first end portion of a second material different to the first material, wherein the first end portion comprises a fixing head portion adapted for securing in a cooperating channel element shaped to receive and secure the fixing head portion, which fixing head portion of planar sheet shape having two indents disposed in the side edges thereof for receiving two corresponding leaves of the cooperating channel element, adapting the body joint end and the first end portion having a first joint end such that they are joinable and permanently joining said body joint end and first joint end , by adhering to the body joint end with an adhesive resin and/or mechanically immobilizing thereon a first joint end of the first end portion to provide a preformed joint portion between the body portion and first end portion to form the wall tie, characterized in that the first material comprises a polymer-based material and has relatively low thermal conductivity relative to the second material and the second material is a relatively ductile or malleable material relative to the first material.

13. A wall tie as hereinbefore described with reference to Figures 5A, 5B and 5C of the drawings.