Cavity wall ties and methods of installing cavity wall ties

Abstract

A cavity wall tie includes an elongated tie member 12 to bridge a cavity in a cavity wall and a nail holder 14 attached to the elongated tie member. The nail holder 14 has an opening 16 through which,

Description

Field of the Invention The invention relates to cavity wall ties and methods of installing cavity wall ties. Background to the Invention Cavity wall ties are unseen components that tie the internal and external leaves of a cavity wall together. Cavity wall ties are added to a cavity wall during construction. The ends of the ties may be bedded into the mortar bed at regular intervals. Cavity wall ties span the cavity, tying the load-bearing inner leaf to the outer leaf. Cavity wall ties impart stability to the outer leaf, holding the wall in place. They are also designed to accommodate small movements from temperature fluctuations, and prevent outside water transfer. Summary of the Invention The invention provides a cavity wall tie as specified in claim 1. The invention also includes a cavity wall tie system as specified in claim 10. The invention also includes a cavity wall as specified in claim 11. The invention also includes a method of installing a cavity wall tie as specified in claim 12. Brief Description of the Drawings In order that the invention may be well understood, some examples thereof will now be described with reference to the drawings in which: Figure lisa schematic side view of a cavity wall tie; Figure 2 is schematic view from above of the cavity wall tie of Figure 1; Figure 3 is a schematic illustration of the cavity wall tie of Figures 1 and 2 installed in a partially completed cavity wall; Figure 4 is an enlarged schematic illustration of the cavity wall tie of Figures 1 and 2 installed in a partially completed cavity wall; Figure 5 is a schematic illustration of a method of installing the cavity wall tie of Figures 1 and 2 using a nail gun; Figure 6 is a perspective view of an example of a sleeve fitting for a cavity wall tie as shown in Figures 1 and 2; Figure 7 is a section on line VII-VII in Figure 6; and Figure 8 is a section on line VIII-VIII in Figure 7. Detailed Description Referring to Figures 1 and 2, a cavity wall tie 10 comprises an elongate tie member 12 to at least partially bridge a cavity in a cavity wall and a nail holder comprising a sleeve holder 14 attached to the elongate tie member. The sleeve holder 14 extends laterally of the elongate tie member 12 and has an opening 16 through which, in use, a nail is driven to secure the elongate tie member to a leaf of a cavity wall. The sleeve holder 14 may take the form of an annular member disposed at a first end region 18 of the elongate tie member 12. The sleeve holder 14 may be a separate member secured to the first end region of the elongate tie 12 member by, for example, welding. Alternatively, the elongate tie member 12 and sleeve holder 14 may be a one-piece construction with the sleeve holder formed by a deformation process. The nail holder further comprises a sleeve fitting 20 held by the sleeve holder 14. The sleeve fitting 20 comprises an elongate plastics sleeve 22 having a longitudinally extending cavity 24 through which, in use, the nail is driven to pass through the opening 16 in sleeve holder 14 to secure the elongate tie member 12 to a leaf of a cavity wall. The sleeve fitting 20 may further comprise a flange 26. The sleeve holder 14 is fitted to a first end region 28 of the elongate plastics sleeve 22 and the flange 26 is disposed at a second end region 30 of the elongate plastics sleeve. The first end region 28 of the elongate plastics sleeve 22 may extend through the opening 16 of the sleeve holder 14. A second end region 32 of the elongate tie member 12 extends through and beyond the flange 26. The second end region 32 includes a free end of the elongate tie member 12 that, in use, will overlie a brick or the like of a leaf of a cavity wall and in the finished wall will be embedded in the mortar that lies between that brick and the course of bricks above. The flange 26 may be provided with a slot 33 through which the elongate tie member 32 extends. The slot 33 may be configured to allow the elongate tie member 12 to flex, or deflect away from a nail gun when, in use, the cavity wall tie 10 is located on a nosepiece of the nail gun. The flange 26 has a through-hole 32 that is aligned with the longitudinally extending cavity 24. The longitudinally extending cavity 24 extends from the through-hole 32 to the first end region 28 of the elongate plastics sleeve 22. The longitudinally extending cavity 24 may be closed at the first end region 28 or open such that the longitudinally extending cavity and through-hole 32 define a continuous passage extending through the sleeve fitting 20. The elongate tie member 12 may extend alongside the elongate plastics sleeve 22, spaced apart from the elongate plastics sleeve. The elongate tie member 12 may be disposed parallel to the outer surface of the elongate plastics sleeve 22. As shown in Figure 1, the elongate plastics sleeve 22 tapers outwardly from the first end region 28 to the second end region 30. The flange 26 has a major surface 34 that faces away from the first end region 28 of the elongate plastics sleeve 22 and at least one resilient gripper 36 is provided on the major surface radially outwardly of the through-hole 32. The at least one resilient gripper may comprise a continuous annular member or, as shown in Figures 1 and 2, a plurality of spaced apart proj ections that proj ect from the maj or surface 34. The resilient grippers may comprise a plurality of generally triangular projections 36. The triangular projections 36 each have a base attached to the major surface 34 and an apex that is disposed radially inwardly of the base so that the triangular projections 36 are inclined towards the centre of the through-hole 32 and partially overlie the through-hole. Referring to Figure 3, a cavity wall 50 comprises an inner leaf 52 and an outer leaf 54. The outer leaf 54 is spaced from the inner leaf to define a cavity 56 therebetween. The width of the cavity 56 may be between 50 and 75mm. Each leaf 52, 54 is made up of a plurality of bricks, breeze or cinder blocks or the like. In the illustrated example, the leaves 52, 54 each comprise a plurality of bricks 58 with the bricks of each course separated from the bricks of adjacent courses by layers of mortar 60. Although not essential, an insulating or isolation layer 62 may be disposed in the cavity, typically against the inner leaf 52. The isolation layer 62 may be any known form of isolation material used in cavity walls, such as insulation board or a coated rockwool slab. A cavity wall tie 10 is secured to the inner leaf 52 by a masonry nail 64 and the elongate tie member 12 extends across the cavity 56 so that its free end lies over a brick 58A of the outer leaf ready to be embedded in a layer of mortar that will be applied to the upper surface of the brick 58A ahead of building up the next course of bricks. As shown in more detail in Figure 4, the cavity wall tie 10 is secured to the inner leaf 52 by a masonry nail 64 that has been driven through the sleeve fitting 20 so that its leading end is fixed in the motor 60 between two courses of bricks 58 of the inner leaf. The masonry nail 64 extends through the opening 16 in the sleeve holder 14. The head 66 of the masonry nail 64 is pressed against an opposing surface (not shown) defined within the longitudinally extending cavity 24 of the elongate plastics sleeve 22. The elongate plastics sleeve 22 extends through the isolation layer 62 towards the inner leaf 52 and the flange 26 presses against the major surface 62S of the isolation layer that faces away from the inner leaf towards the outer leaf 54. The elongate tie member 12 extends from the sleeve holder 14, which is disposed adjacent the inner leaf 52, and has its free end disposed above an uppermost brick 58A of the unfinished outer leaf 54 ready to be embedded in a layer of mortar 70 (shown in dashed lines) that will be applied when the next course of the outer leaf is laid. It can be seen that the elongate tie member 12 substantially bridges the cavity 56 and that when the cavity wall 50 is complete, the combination of the masonry nail 64 and the elongate tie member 12 provides a physical connection between the inner and outer leaves 52, 54 that bridges the cavity. The relatively large diameter flange 26 assists in spreading the force applied by the masonry nail 64 over a relatively large area of the major surface 62S of the isolation layer 62. As shown in schematically in Figure 5, the cavity wall tie 10 may be installed using a nail gun 100. Nail guns are tools that will be well known to those skilled in the art and so will not be described in detail herein. As shown in Figure 5, the nail gun 100 comprises a nosepiece 102. In use, the nosepiece 102 is pressed against a substrate into which a fastener is to be fired to position the fastener relative to the substrate and ready the nail gun for firing. A blade 104 is disposed within the nosepiece. The nail gun includes a force provider 106 configured to drive the blade 104 against a fastener to apply a blow to the fastener in similar fashion to a hammer. The force provider 106 may, for example, be powered by compressed air or a combustion engine disposed within the body of the nail gun 100. To install the cavity wall tie 10, the free end of the nosepiece 102 is inserted into the longitudinally extending cavity 24 of the plastics sleeve 22 via the through-hole 32 in the flange 26. The triangular projections 36 engage the outer surface of the nosepiece 102 to locate and centre the cavity wall tie 10 on the nosepiece. Typically, there is a clearance between the internal wall of the elongate plastics sleeve 22 that defines the longitudinally extending cavity 24 and the outer surface of the nosepiece 102. The leading end of the plastics sleeve 22 is then pressed against the major surface 62S of the isolation layer 62 to locate the cavity wall tie 10 in a desired position relative to the inner leaf 52 and push the nosepiece 102 backwards towards the main body of the nail gun 100 to ready the nail gun for firing. On the operation of a trigger or firing button 108, the force provider 106 is activated to cause a heavy impact force to be applied to the head 66 of a masonry nail 64 by the blade 104, thereby driving the nail into the longitudinally extending cavity 24 of the elongate plastics sleeve 22 and forcing the leading end of the nail through the isolation layer 62 into the inner leaf 52 of the cavity wall 50. The cavity wall tie 10 is driven into the isolation layer 62 by the masonry nail 64 so that the elongate plastics sleeve 22 is disposed within the isolation layer 62, the flange 26 engages the major surface 62S of the isolation layer and the cavity wall tie 10 is secured to the inner leaf 52 by the masonry nail. Figures 6 to 8 illustrate an example of a sleeve fitting 200 that may form a part of various embodiments of a cavity wall tie 10. The sleeve fitting 200 comprises an elongate plastics sleeve 202, which has a relatively large diameter flange 204 at one end. The plastics sleeve 202 has a longitudinally extending cavity, which in this example is a through-passage 206 that extends from a first, or free, end 208 of the plastics sleeve 202 to a second end 210 that adjoins the flange 204. The flange 204 is provided with a through-hole 212, which is aligned and contiguous with the through- passage 206 so that there is a continuous passage running through the sleeve fitting 200. The flange 204 is provided with a plurality of resilient grippers, which in the illustrated example take the form of triangular projections 214. The triangular projections 214 each have a base attached to or near the major surface 216 of the flange 204 that faces away from the first end 208 of the plastics sleeve 202 and are configured to overlie the through-hole 212. The triangular projections 214 are configured to grip the outer surface of the nosepiece of a nail gun in similar fashion to the triangular projections 36 shown in Figure 5 in order to align the sleeve fitting 200 with and hold it on the nosepiece. The through-passage 206 may be a multi-diameter feature comprising a first, relatively smaller diameter, portion 206F at a first end region 202F of the elongate plastics sleeve 202 that extends from the first end 208 of the plastics sleeve 202 towards the flange 204 and a second, relatively larger diameter, portion 206S at a second end region 202S of the elongate plastics sleeve that extends from the smaller diameter portion 206F to the end 210 of the plastics sleeve. In the illustrated example, the relatively larger diameter 206S is stepped so that it comprises different diameter portions that are larger in diameter than the smaller diameter portion 206F. The portion of the larger diameter portion 206F closest to the flange 204 is sized to allow it to receive the nosepiece of a nail gun, preferably with clearance so that the engagement of the sleeve fitting 200 with the nosepiece is at least substantially only via the triangular projections 214. In examples in which the larger diameter portion 206F has only one diameter, it is similarly sized to receive the nosepiece of a nail gun, preferably with clearance. The smaller diameter portion 206F of the through-passage 206 is typically sized to receive the shank of a nail the cavity wall tie is designed to be used with, allowing a small clearance for the nail shank so that the internal wall defining the smaller diameter portion 206F can act as a guide for the nail as it enters the surface of the substrate it is driven into. As best seen in Figure 7, the first end region 202F of the elongate plastics sleeve 202 may be smaller in diameter than second end region 202S. This facilitates driving of the sleeve fitting 200 into a substrate such as the isolation layer 62 and reduces the amount of material needed to form the sleeve fitting. One of both of the first and second end regions 202F, 202S may be provided with external ribs 220 that extend in the lengthways direction of the elongate plastics sleeve 202. Optionally, these ribs 220 may have a generally triangular cross-section as shown in Figure 8. The ribs 220 may strengthen the walls of the elongate plastics sleeve 202 allowing it to be kept relatively thin and so reducing the amount of material needed to manufacture the sleeve fitting 200. The ribs 220 may also assist in anchoring the sleeve fitting 200 in the substrate by reducing the likelihood of the sleeve fitting rotating, or twisting relative to the nail. The smaller diameter portion 206F of the through-passage 206 may be extended into the larger diameter portion 206S by a tubular extension member 222. The tubular extension member 222 extends from the inner end of the smaller diameter portion 206F into the larger diameter portion 206S of the through-passage 206. One or more ties 224 may extend from the outer wall of the tubular member 222 to the inner wall of the second end region 202S of the elongate plastics sleeve 202. The free end surface 228 of the tubular member 222 defines a seat against which the securing nail head presses when the cavity wall tie is installed. The provision of the one or more ties 224 strengthens the tubular member 222 to allow it to absorb the impact of the nail head when fired from the nail gun and provide a stable seat for the nail head. The one or ties 224 may comprise one or more radially extending spokes extending outwardly from the tubular member 222. In similar fashion to the sleeve fitting 20, the sleeve fitting 200 may be provided with a slot through which the elongate tie member extends to pass through the flange 204. The slot may be configured to enable the elongate tie member to deflect, or flex, away from a nail gun when the cavity wall tie is loaded onto the nosepiece of the nail gun. In the illustrated examples, the at least one resilient gripper comprises a plurality of triangular projections. It is to be understood that this is not essential. In principle the at least one resilient gripper may comprise a part that has a base attached to the flange and an end that overlies the through-hole in the flange so that when the sleeve fitting is pushed onto the nosepiece of a nail gun the at least one resilient gripper is deflected away from the centre of the through-hole by the nosepiece to centre the sleeve fitting on the nosepiece and retain the cavity wall tie on the nosepiece while it is offered up to the surface of a cavity wall against which it is to be secured by a nail fired from the nail gun. In the illustrated example, the nail holder comprises a sleeve fitting that is attached to the elongate tie member by a sleeve holder. This is not essential. A sleeve fitting with a relatively large flange may be advantageous when fitting the cavity wall tie to a relatively softer substrate abutting the inner leaf of the cavity wall, for example a layer of thermal insulation. However, in principle, the sleeve fitting may be omitted, particularly if it is intended that that the cavity wall tie is to be secured directly to the inner leaf of the cavity wall. In examples intended for this usage, the nail holder may be a metallic component attached to or integral with the elongate time member that defines an opening through which a nail is driven to secure the elongate time member to a leaf of a cavity wall and a seat for the head of the nail. The nail holder may take the form of a cup-like member that defines a recess configured to receive the nosepiece of a nail gun. Alternatively, the nail holder may comprise a laterally extending member or members that define a seat for a nail head and are provided with a series of projections defining a recess to receive the nosepiece of the nail gun. It is to be understood that while typically the cavity wall tie will be secured to the inner leaf of a cavity wall by a masonry nail fired into mortar of the inner leaf, this is not essential. In some installations, the cavity wall tie may be secured to timber framing and so it is not essential the nail is a masonry nail. Typically, the elongate tie member is a metallic component and when the nail holder comprises a sleeve fitting, the sleeve holder is a metallic component. In embodiments in which there is no sleeve fitting, the nail holder is typically a metallic component. However, embodiments are envisaged in which the nail holder comprises a simple plastics cup-like component attached to the elongate tie member. In the illustrated examples, the elongate tie member and sleeve holder are made of a suitable metal, typically a steel, and the sleeve fitting is made of a suitable plastics material. This is not to be taken as limiting and any suitable materials known to the skilled person may be used. It is to be understood that it is not essential that the courses of the cavity wall are bonded to one another using mortar. Any suitable bonding material known to the skilled person, for example cement, may be used.

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