GB2195678A

GB2195678A - Roofing bracket or hanger

Info

Publication number: GB2195678A
Application number: GB08722625A
Authority: GB
Inventors: Michael Douglas Hoyland; Graham Edward Haycox
Original assignee: EXPAMET U K Ltd
Current assignee: EXPAMET U K Ltd
Priority date: 1986-09-30
Filing date: 1987-09-25
Publication date: 1988-04-13
Also published as: GB8623503D0; GB8722625D0

Abstract

A roofing bracket 14 for securing a purlin (12 Fig. 1) to the inclined surface 11 of a gable wall 10 is made from a sheet metal blank and has integrally formed base 15, rear wall 16 and top flange 17, together with a side wall 18 to support the "downhill" side of the purlin (12 Fig. 1) and an extension 20 of the top flange 17 at the "uphill" side only of the bracket. The extension 20 may include a stiffened spine 22 and provides both increased bearing area and a means of support disposed directly above the centre of gravity of the purlin (12) which is firmly supported by the base 15 and "downhill" side wall 18. <IMAGE>

Description

SPECIFICATION Roofing bracket This invention relates to a bracket for use in roofing and more particularly to a bracket for supporting a generally horizontal timber such as a purlin at the gable end of a building or in any similar location where the timber is tilted about its longitudinal axis and supported from a non-horizontal surface.

Currently, a conventional joist hanger is usually used to secure such a timber, (which is referred to in the following description as a "purlin"), in these circumstances. A single bolt is arranged to pass through the back of the joist hanger into the supporting masonry.

However, this has disadvantages in that the conventional joist hanger has a relatively narrow top flange, similar in width to the purlin, bearing on the masonry. Because the purlin is tilted, and rests on the base of the joist hanger, the loading below the fixing bolt is laterally offset and may tend to rotate the joist hanger about the fixing bolt, causing the upper or uphill" edge of the top flange to dig into the masonry of the supporting wall.

The load acts downwardly at a position outside the bearing area of the top flange. This type of movement of the joist hanger could give rise to problems of the purlin and its supported load becoming insecure.

The use of joist hangers in such an application also does not afford adequate lateral restraint for the purlin and the associated roofing against wind loading.

It is an object of the invention to provide a new or improved bracket for use in roofing.

According to the invention there is provided a bracket for securing a timber generally horizontally to a support having an inclined surface (for example a purlin to a gable wall), the bracket comprising a base, a rear wall and a top flange extending from the rear wall, wherein the bracket also includes a side wall at one side thereof and wherein the top flange has an extension extending u substantial distance laterally from the rear wall at the other side only.

The side wall may be integral with or secured to, both the base and the rear wall.

An extreme upper portion of the rear wall may also be extended laterally with the extension of the top flange. This will provide a rigid laterally extending spine at said other side of the bracket.

The junction between the extension and the rear wall may have rigidifying formations such as pressed ribs or grooves.

Said other side of the bracket may also be provided with side location means for the timber, extending from the base and/or from the rear wall.

The rear wall may have a fastener receiving aperture.

The bracket may comprise a single sheet metal member having the top flange, base and side wall connected at fold lines to the rear wall.

The side wall may be provided with an extension flap, which may be bent to lie in face to face abutment with the base. The extension flap may be permanently secured to the base by welding or riveting for example.

The base may have an integral flap at said other side which may be folded upwardly to afford said side location means.

Additional or alternative side location means may be provided by a flap connected by a further fold line to the rear wall, immediately below said extreme upper portion thereof.

A bracket embodying 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 small scale end elevational view of part of a roof.

FIGURE 2 is a perspective view of a bracket embodying the invention.

FIGURE 3 is a detail sectional view on the line 3:3 of Figure 2.

FIGURE 4 is a plan view of a blank layout for the bracket.

Figure 1 illustrates the application of the bracket according to the invention. A gable end wall 10 of masonry provides inclined support surfaces 11 from which purlins 12 of timber are supported to carry the rafters and other constituent parts of a roof. It will be seen from Figure 1 that each purlin 12 is tilted over at an angle complementary with the angle of the inclined support 11 of the gable end.

Each purlin 12 is supported by a bracket which may be a right handed bracket 13 or a left handed bracket 14.

Figure 2 illustrates a left hand bracket 14 in more detail. The bracket is shown mounted upright but it will be understood that it is normally used in a tilted position as shown in Figure 1.

The bracket generally indicated at 14 is made out of single piece of sheet metal such as galvanised mild steel or stainless steel. It comprises a base 15, a rear wall 16, a top flange 17 and a single side wall 18. The base 15, rear wall 16 and side wall 18 define a location and support for the purlin 12 (not shown in Figure 2) which is therefore supported from underneath and from the lowermost or "downhill" side in use.

The bracket 14 rests on the supporting masonry surface 11 by means of the top flange 17 and is secured by a single bolt passing through a bolt aperture 19 in the rear wall of the bracket. The end of the purlin timber 12 may be notched to accommodate the bolt.

The flange 17 is wider than the purlin, having an extension 20 which extends laterally from the remainder of the bracket at the side opposite to the side wall 18. Thus, the extension 20 projects along the supporting surface 11 in an "uphili" direction.

The extreme top portion 21 of the rear wall is extended laterally and, with the top flange extension 20 provides a rigid spine 22 extending along the front edge of the supporting masonry. The structure is further rigidified by stiffening formations 23 in the form of Vshaped ribs raised from the metal of the bracket along and across the spine 22.

Figure 3 shows one of these stiffening ribs in enlarged section. Although a generally Vshaped formation is preferred, alternative stiffening formations such as inverted U-shape or square section ribs or depressions could be provided at the spine 22.

The objective of both the spine 22 and the stiffening formations 23 is to ensure that load applied to the bracket is transmitted to a large area of the supporting gable wall surface 11.

Due to the stiffening along the length of the spine 22, the top flange 17 and its extension 20 do not flex relative to the backplate 16 of the bracket, which might concentrate loading at the forward edge of the masonry.

In use, the weight of the purlin 12 will act on a line 24 passing through the centre of gravity. It will be seen from Figure 1 that this line will tend to be within the area of the top flange extension 20 rather than the area of the main part 17 of the top flange. Thus, the rigid top plate and extension share the load of the purlin and spread it along the supporting masonry surface 11. The tendency for unbalanced forces to twist the bracket is thereby greatly reduced.

It will also be seen that the side wall 18 on the "downhill" side of the bracket can assist in supporting the purlin with the base 15.

Where a conventional joist hanger is used, the downhill side of the hanger is not adapted for or strengthened to carry load and undue reliance is placed on the fastenings attaching the purlin to the hanger.

The uphill side of the hanger is provided with location means for the timber puriin but, because the uphill side is not loaded in use, these do not need to be particularly strong. In the example illustrated, the base 15 has an integral flap 25 bent upwardly more or less coplanar with the side edge 26 of the backplate at the side opposite the side wall 18.

Additionally, a small flap 27 is integrally formed by bending a portion attached to the side edge 26 of the backplate, immediately below the extreme upper portion 21 and the projection 20 of the top plate.

The use of small flaps permits economy of use of metal, by enabling the efficient cropping layout of Figure 4 to be used. The flaps 25 and 27 can be bent to suit various widths of timber and nailed in position for security.

In order to strengthen the junction between the side wall 18 and the base 15, a side wall extension flap 28 is bent into face to face relationship with the base 15, either overlying or, as illustrated, abutting the underside of the base. The extension flap 28 is secured to the base 15 for example by a pair of spot welds at the positions shown at 29. The extension 28 reinforces the heavily loaded corner of the bracket.

Suitable nailing holes are provided on the bracket as illustrated, for securing the purlin.

The bracket is made from a sheet metal blank by a series of cropping and bending operations. The shape of the blank can be seen from Figure 4 which illustrates the layout of a number of blanks which are successively cropped from a strip of sheet metal. Reference numerals indicate the parts which are formed from different areas of the blank. It will be seen that very little metal is removed during cropping of the blanks, giving economy of production.

The bracket described in relation to Figure 2 is a left handed bracket. Right handed brackets are formed from the same blank but by folding in the opposite sense at each of the fold lines.

Although the invention has been described in relation to supporting purlins from a gable wall, it may be used for supporting other timbers in a tilted condition, from a non horizontal surface.

Claims

1. A bracket for securing a timber generally horizontally to a support having an inclined surface, the bracket comprising a base, a rear wall and a top flange extending from the rear wall, wherein the bracket also includes a side wall at one side thereof and wherein the top flange has an extension extending a substantial distance laterally from the rear wall at the other side only.

2. A bracket according to Claim 1 wherein the extreme upper portion of the rear wall is also extended laterally with the extension of the top flange to provide a laterally extending spine at said other side of the bracket.

3. A bracket according to Claim 1 or Claim 2 wherein the junction between the extension of the top flange and the rear wall has rigidifying formations such as ribs or grooves.

4. A bracket according to any preceding claim wherein the side wall is integral with or secured to both the base and the rear wall.

5. A bracket according to Claim 4 wherein the side wall is provided with an extension flap, bent to lie in face to face abutment with the base.

6. A bracket according to Claim 5 wherein the extension flap is permanently secured to the base by welding or riveting.

7. A bracket according to any preceding claim wherein said other side of the bracket is also provided with side location means for the timber.

8. A bracket according to Claim 7 wherein said side location means extend from the base.

9. A bracket according to Claim 7 or Claim 8 wherein said side location means extend from the rear wall.

10. A bracket according to Claim 8 wherein the base has an integral flap at said other side which is folded upwardly to afford said side location means.

11. A bracket according to Claim 9 wherein said side location means are provided by a flap connected by a further fold line to the rear wall, immediately below said extreme upper portion thereof.

12. A bracket according to any preceding claim wherein the rear wall has a fastener receiving aperture.

13. A bracket according to any preceding claim comprising a single sheet metal number having the top flange, base and side wall connected at fold lines to the rear wall.

14. A bracket substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

15. A blank for forming a bracket according to any preceding claim and substantially as hereinbefore described with reference to and as illustrated in Figure 4 of the accompanying drawings.