GB2026644A - Bracket for Timber Joints - Google Patents

Abstract

A bracket for securing a roof truss to a wall includes first, second and third planar portions 21, 22, 23, which are all mutually perpendicular. The bracket is formed from a rectangular metal blank 10 having a cut 11 parallel with its longer sides 12 and 13 and terminating in an angled further cut 14. The second portion 22 is bent along a fold-line 17 which forms an extension of the further cut 14. <IMAGE>

Description

SPECIFICATION Securing Means for Timbers This invention relates to a securing means for securing timbers in building structures. Such a securing means is typefied by a roof-truss securing means which is generally referred to in the trade as a truss clip. For convenience, the following description will also follow this practice, and it will be appreciated that although truss clips are specifically referred to below the invention applies to the securing of timbers in general.

Roofing of dwelling houses and other pitched roof buildings is done by assembling a plurality of generally triangular frames, usually of timber, which are known as trusses, the trusses being secured to the top of the standing wall structure by truss clips. Truss clips are required to prevent loss of the roof during exceptionally windy weather. Under normal circumstances, the weight of the roof would hold it in place but, when a strong wind meets a building, much of the flow is directed up the wall and over the roof, exerting a suction on the roof on the side of the prevailing wind. This is termed "wind uplift". The truss clips secure down the roof trusses against possible wind uplift.A prior design of truss clip has comprised a single metal sheet having a generally rectangular opening provided to receive the truss, the opening being formed by parting the metal centrally and bending two generally rectangular flaps out of the plane of the sheet to leave the opening. The flaps were then in parallel facing relationship to each other and were secured, usually by nailing, to opposed faces of the truss near its outer end. The remaining portion of the sheet below the rectangular aperture was secured to the top of the wall structure as an attachment plate.

However, wind uplift occurs only when the wall beneath a portion of roof is also being strongiy urged inwardly by the prevailing wind. The top portion of the wall structure would be secured to the attachment plate of the previously proposed truss clip and, if the wall bows inwardly at the top, the truss clip would tend to bend at its weakest part, namely at the base of the rectangular opening. This could lead to permanent distortion of the clip or failure or to pulling outoffastenings, especially over a prolonged period of usage. This in turn could lead to loss of security for the roof and/or the wall.

It is an object of the present invention to provide a securing means for timbers which overcomes or reduces this disadvantage.

According to the invention there is provided a securing means for timbers comprising a sheet metal member having mutually perpendicular first, second and third planar portions, integral with each other and formed from a sheet metal blank by forming a cut and folding from said cut a pair of flaps about mutually perpendicular fold lines, these flaps forming the second and third planar portions.

The second and third planar portions are adapted to be secured, in use, to two mutually perpendicular surfaces of the wall structure. The first portion is adapted to be secured in use to a side face- of a truss. Preferably, each roof truss is secured by two such securing means at each end of the truss.

Each of the planar portions may have a plurality of holes to receive fastening means.

The first planar portion may have a substantially greater area than the second and third planar portions respectively and may be provided with a greater number of securing holes.

In a particular preferred form, the sheet metal blank is elongate and rectangular in form and said cut extends parallel to and approximately midway between the longer sides for less than half the length thereof. The fold lines may be obliquely angled with respect to the cut and one or more further cuts may be provided extending from the inner end of the cut to provide appropriately sized second and third planar portions.

The invention will now be described in more detail by way of example only with reference to the accompanying drawings in which Figure 1 is a plan view of a blank for making a truss clip, Figure 2 is a perspective view of the clip secured to a portion of a wall, Figure 3 is a perspective view of an assembly of two truss clips and a truss.

Referring firstly to Figure 1 of the drawings, the truss clip is formed from a rectangular sheet metal blank generally indicated at 10, a plurality of similar blanks being cut from a large sheet of metal without wastage.

The blank 10 is cut along a line 11 parallel to and midway between the longer side edges 12 and 13 of the rectangular blank. A further short cut 14 extends from the inner end 1 5 of the cut 11, at an oblique angle. The blank is also formed with a plurality of holes 16.

The blank is then formed by pressing into a three dimensional shape. Two mutually perpendicular fold lines 1 7 and 18 are chosen.

The line 1 7 is an extension of the further cut 14 to the side edge 12. The line 18 is perpendicular to the line 1 7 and extends from the inner end 19 of the further cut 14 to a corner of the blank 20.

It will be seen that the fold lines divide the blank into three irregularly shaped parts, a first part 21, a second part 22 and a third part 23.

The bending operation is carried out so that the second and third parts 22 and 23 are each bent at right angles to the first part 21, both the second and third parts extending in the same direction away from the first part and being also perpendicular to each other because of the orientation of the fold lines 1 7 and 18.

Some of the holes 1 6 are provided on each of the first, second and third parts.

Figure 2 shows the clip in perspective, secured to the top of a wall structure 24. The expression "wali structure" is used to indicate that it need not necessarily comprise part of the masonry of the wall but could be a timber or other attachment provided at the top of the wall of a building.

The second part 22 of the clip lies on the top of the wall structure 24 and the third part 23 lies against an upright face of the wall structure. Each of these parts is secured to the wall structure by nails or other fixings passing through the holes 16.

The first part of the clip extends upwardly and outwardly of the wall structure 24, in a vertical plane perpendicular to the general plane of the wall. In this position, it can be secured to a face of a truss which is presented in generally known manner to the top of the wall structure. Again, nails are used passing through the fixing holes 1 6.

Figure 3 shows a pair of truss clips as shown in Figure 2 secured to opposed faces of a truss which is generally indicated at 25. The clips 26 and 27 are identical except that they are of opposite hand. The clip 26 is as shown in Figure 2.

In windy conditions, one wall of the building may be subjected to a strong inward thrust and the roof portion supported thereby may be under uplift conditions whilst, at the opposite side of the building, a suction may be exerted which tends to bow the top of the opposed wall outwardly.

Irrespective of whether the wall is being pushed inwardly or outwardly at the top, the truss clips shown in the drawings will have the second part 22 aligned with the general direction of the wind load on the wall so that there is a direct transmission of force through the fastenings which are in shear. Similarly, if the roof trusses are subjected to wind uplift, this will tend to be in the general plane of the third part 23 of the clip so that again there will be a direct transmission of the forces acting.It will be seen that, whatever type of loading is acting on the top portion of the wall structure or on the truss, there will not be any significant tendency for the truss clip to bend and distort because of the fact that the three parts 21, 22 and 23 are in planes which are mutually perpendicular to each other and hence forces are transmitted in the plane of one or other of the parts or as face loads on one or other of the parts.

The strength and durability of the clip is substantially greater than the previously proposed type of clip.

Modifications are of course possible within the scope of the invention, particularly with regard to the precise layout of the fold lines and the shape of the blank from which the clip is formed. If desired, integral fixing means can be provided the form of fixing teeth pressed out of the metal of one or more of the parts, either in addition to or alternatively to the fixing holes.

Claims filed on 24 July 1979.

Superseded Claims-None.

New or Amended Claims: 1. A securing means for securing timbers in building structures, comprising a sheet metal member having mutually perpendicular first, second and third planar portions, integral with each other and formed from a sheet metal blank by forming a cut and folding from said cut a pair of flaps about mutually perpendicular fold lines, these flaps forming the second and third planar portions.

2. A securing means according to Claim 1 wherein each planar portion has a plurality of holes for fastening means.

3. A securing means according to Claim 1 or Claim 2 wherein the first planar portion has a substantially greater area than the second and third planar portions respectively.

4. A securing means according to Claim 2 and Claim 3 wherein the first planar portion is provided with a greater number of securing holes than are the second and third planar portions respectively.

5. A securing means according to any preceding claim comprising a sheet metal blank of elongate rectangular form, said cut extending parallel to and approximately midway between the longer sides for less than half the length of the rectangle.

6. According to any preceding claim wherein the fold lines are obliquiely angled with respect to said cut.

7. A securing means according to any preceding claim wherein one or more further cuts are provided extending from the inner end of said cut.

8. A roof truss for a building structure and including at least one securing means according to any one of Claims 1 to 7 and having its first portion secured to one side face of the truss.

9. A securing means substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

1 0. A roof truss for a building structure including securing means substantially as hereinbefore described with reverence to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. attachment provided at the top of the wall of a building. The second part 22 of the clip lies on the top of the wall structure 24 and the third part 23 lies against an upright face of the wall structure. Each of these parts is secured to the wall structure by nails or other fixings passing through the holes 16. The first part of the clip extends upwardly and outwardly of the wall structure 24, in a vertical plane perpendicular to the general plane of the wall. In this position, it can be secured to a face of a truss which is presented in generally known manner to the top of the wall structure. Again, nails are used passing through the fixing holes 1 6. Figure 3 shows a pair of truss clips as shown in Figure 2 secured to opposed faces of a truss which is generally indicated at 25. The clips 26 and 27 are identical except that they are of opposite hand. The clip 26 is as shown in Figure 2. In windy conditions, one wall of the building may be subjected to a strong inward thrust and the roof portion supported thereby may be under uplift conditions whilst, at the opposite side of the building, a suction may be exerted which tends to bow the top of the opposed wall outwardly. Irrespective of whether the wall is being pushed inwardly or outwardly at the top, the truss clips shown in the drawings will have the second part 22 aligned with the general direction of the wind load on the wall so that there is a direct transmission of force through the fastenings which are in shear. Similarly, if the roof trusses are subjected to wind uplift, this will tend to be in the general plane of the third part 23 of the clip so that again there will be a direct transmission of the forces acting.It will be seen that, whatever type of loading is acting on the top portion of the wall structure or on the truss, there will not be any significant tendency for the truss clip to bend and distort because of the fact that the three parts 21, 22 and 23 are in planes which are mutually perpendicular to each other and hence forces are transmitted in the plane of one or other of the parts or as face loads on one or other of the parts. The strength and durability of the clip is substantially greater than the previously proposed type of clip. Modifications are of course possible within the scope of the invention, particularly with regard to the precise layout of the fold lines and the shape of the blank from which the clip is formed. If desired, integral fixing means can be provided the form of fixing teeth pressed out of the metal of one or more of the parts, either in addition to or alternatively to the fixing holes. Claims filed on 24 July 1979. Superseded Claims-None. New or Amended Claims:

1. A securing means for securing timbers in building structures, comprising a sheet metal member having mutually perpendicular first, second and third planar portions, integral with each other and formed from a sheet metal blank by forming a cut and folding from said cut a pair of flaps about mutually perpendicular fold lines, these flaps forming the second and third planar portions.

2. A securing means according to Claim 1 wherein each planar portion has a plurality of holes for fastening means.

3. A securing means according to Claim 1 or Claim 2 wherein the first planar portion has a substantially greater area than the second and third planar portions respectively.

4. A securing means according to Claim 2 and Claim 3 wherein the first planar portion is provided with a greater number of securing holes than are the second and third planar portions respectively.

5. A securing means according to any preceding claim comprising a sheet metal blank of elongate rectangular form, said cut extending parallel to and approximately midway between the longer sides for less than half the length of the rectangle.

6. According to any preceding claim wherein the fold lines are obliquiely angled with respect to said cut.

7. A securing means according to any preceding claim wherein one or more further cuts are provided extending from the inner end of said cut.

8. A roof truss for a building structure and including at least one securing means according to any one of Claims 1 to 7 and having its first portion secured to one side face of the truss.

9. A securing means substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

1 0. A roof truss for a building structure including securing means substantially as hereinbefore described with reverence to and as illustrated in the accompanying drawings.