GB2166465A

GB2166465A - Bracket for securing timbers

Info

Publication number: GB2166465A
Application number: GB08523411A
Authority: GB
Inventors: Michael Douglas Hoyland; Graham Edward Haycox
Original assignee: PRESS BAT HOLDINGS Ltd
Current assignee: PRESS BAT HOLDINGS Ltd
Priority date: 1984-10-31
Filing date: 1985-09-23
Publication date: 1986-05-08
Also published as: GB8523411D0; GB8427569D0

Abstract

A bracket for hip (39, 40 Fig. 1) or valley (42, 43 Fig. 1) connections in a cut-and-nail roof construction is formed from a universal blank. For hip fastenings the blank, having an elongate body zone 37 with a pressed out end location strap 33 has first and second attachment flaps 28, 30 extending from the same longitudinal edge of the body zone 37 and bent in opposite senses relative to the general plane of the blank. The body zone 37 is also bent transversely and obliquely (36 Fig. 2) between the first and second attachment flaps 28, 30 at an angle determined by the roof geometry. The first attachment flap 28 is secured to a jack 16 or cripple-jack (25 Fig. 1) rafter and is presented to, and secured to a hip rafter 15. By alternative folding of the blank, it can form a valley bracket in which first and second attachment flaps 44, 46 folded oppositely from the other longitudinal edge of the body zone 37 are adapted to be secured respectively to jack 24 or cripple-jack (25 Fig. 1) rafters, and to a valley rafter (21). <IMAGE>

Description

SPECIFICATION Bracket for securing timbers method of making and using the bracket and timber assembly This invention relates to a bracket for securing timbers. It was devised particularly for use in the construction of roofs.

There are two main types of pitched roof construction. In the traditional "cut and nail" method each timber is separately cut to length and shaped on site and the timbers are then secured together by nailing.

In the so called "truss" constructional method, timber trusses of generally triangular shape are prefabricated and are then erected on site.

The variety of roof shapes and pitches which can be achieved with the traditional cut and nail method is difficult to achieve using trusses. Furthermore, trussed roofs have more internal obstructions in the roof space which makes it impossible to utilise the roof space as living accommodation for example.

Replacement and repair of existing roofs is also done by the traditional method.

However, a great deal of skill is required of a carpenter in constructing a traditional roof.

A pitched roof has a timber ridge board extending horizontally along the top and supported by pairs of oppositely sloping common rafters. Near their outer ends, the common rafters bear on the wall plates of a pair of opposite walls of the building and extend to form outwardly projecting rafter tails overhanging the walls.

At the ends of the roof, overhanging gables may be provided with an upright gable wall extending into an inverted V meeting the ridge. However, in another form, the pitched roof may end at a "hip", where a triangular, inwardly sloping roof surface meets the main ridge. An upwardly sloping "hip rafter" lies at each convex junction of the hip with the main roof.

Similarly, it is possible to provide two ridges, of the same or unequal heights, which intersect each other, usually at right angles.

The roof of the familiar "dormer" window is one example. A "valley" runs down the junction between the intersecting roofs, and an inclined "valley rafter" lies at each such concave valley junction.

Particular skill and precision is needed to calculate and cut the short "jack" rafters to meet hip and valley rafters because, both in plan and in elevational views, they meet at an oblique angle.

In some parts of a complex roof, rafters may run from a valley rafter to a hip rafter, which means that obliquely angled cuts need to be made at both ends, in addition to correctly cutting the so-called "hip-valley cripple jack rafter" to length.

It is an object of the present invention to provide a bracket for connecting a first timber such as a jack rafter and a second timber such as a hip rafter or a valley rafter, which is capable of providing a secure and easy fixing.

According to the invention, there is provided a bracket for connecting a first and a second timber, the bracket comprising integrally connected first and second attachment parts for attachment respectively to said first and second timbers, the first and second attachment parts being so disposed as to connect said timbers in use at a selected oblique angle as considered in any plane.

The first and second attachment parts may each comprise a seating adapted to abut at least two faces of the first and of the second timber respectively in use.

The second attachment part may include an abutment adapted to abut an end of the second timber in use.

Each of said attachment parts may be provided with fixing means such as nail holes for fixing the attachment parts to the associated timbers.

The invention also provides a blank for a bracket embodying the invention.

According to this aspect, the invention provides a sheet metal blank for a bracket, the blank being of elongate form and comprising an elongate body zone, a first attachment flap extending laterally from said body zone at one end portion thereof and a second attachment flap extending laterally from said body zone at the other end thereof, the first and second attachment flaps being provided on the same lateral edge of the elongate body zone.

Preferably, the blank is provided with a pair of first attachment flaps and a pair of second attachment flaps for alternative use, the first attachment flaps extending laterally from opposed edges of the elongate body zone at one end portion thereof and the second attachment flaps extending laterally from opposed edges of the elongate body zone at the other end portion thereof.

The first and second flaps at one edge of the blank may be spaced apart.

The blank may also have a pair of longitudinally extending slits disposed in the body zone between the second attachment flaps.

According to a further aspect, the invention provides a bracket when formed from said blank.

The bracket may be formed by folding the blank along fold lines so that first and second attachment flaps on one edge of the blank alone are folded out of the general plane of the blank in opposite senses and the central zone of the blank is folded transversely and obliquely to its general longitudinal axis.

Where the first and second flaps at one lateral edge of the blank are spaced apart, the transverse fold of the central zone may terminate at the edge of the blank anywhere in the region between said first and second attachment flaps, thereby enabling the angle of the transverse fold relative to the general longitudinal axis of the blank to be selected.

The invention also provides a method of making a bracket for connecting a first and a second timber, the method comprising taking a blank as set out above and folding the first and second attachment flaps on one edge of the blank alone out of the general plane of the blank in opposite senses, and folding the central zone of the blank transversely and obliquely to its general longitudinal axis.

The invention further provides a method of forming an assembly of a first and a second timber, the method comprising taking a bracket according to the foregoing description, securing said first timber to the first attachment flap of the bracket, offering up the second attachment flap of the bracket to the second timber and securing the second attachment flap to the second timber.

In this method, the first timber may comprise a jack rafter or cripple-jack rafter and the second timber may be a hip or valley rafter of a roof.

Viewed from a further aspect, the invention provides an assembly of a first timber such as a jack rafter or cripple-jack rafter and a second timber such as a hip or valley rafter, when secured together by means of a bracket or a method according to the earlier aspects of the invention.

The invention also contemplates a roof including such an assembly.

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 a perspective view of the rafter assembly used to construct a complex roof.

FIGURE 2 shows a blank for making a bracket embodying the invention, FIGURE 3a shows a bracket formed from the blank and used for connecting a left hand hip jack with a hip rafter, FIGURE 3B shows the same bracket formed to provide a connection between a right hand valley jack and a valley rafter, FIGURE 4 shows, in plan view, the blank when formed into brackets for supporting left and right hand hip and valley junctions, FIGURE 5 is a scrap perspective view of a left hand hip junction, FIGURE 6 is a scrap perspective view of a right hand valley junction.

Referring firstly to Figure 1 of the drawings, this shows the timbers required to construct a portion of a complex roof. A first ridge roof generally indicated at 10 comprises a ridge board 11 and a plurality of common rafters 12 which are seated on a wall plate 13 at each side wall of the building.

The ridge roof 11 terminates in a hip generally indicated at 14 and comprising a pair of hip rafters 15 which are supported by pairs of hip jack rafters 16. The hip jack rafters 16 again rest on a wall plate 13 of the end wall of the building. As will be seen, the complete hip roof shown has two hip rafters 15 but, for example where the end of a building is rounded, a greater number of hip rafters may be provided. One hip rafter only will be provided where a pair of ridge roofs of equal height meet at a corner of a building.

Figure 1 also shows an intersecting ridge roof generally indicated at 17 which comprises a ridge board 18 and pairs of common rafters 19. Where the ridge roof 17 meets the main ridge roof 10, a valley generally indicated at 20 is formed between the two sloping roof surfaces. Naturally, a valley will exist at each side of the intersecting ridge roof 17.

Each valley is formed from a valley rafter 21, and 22, the valley rafter 22 being shortened where it meets the valley rafter 21 at the point of intersection 23 with the main roof 10.

Each valley rafter 21, 22 is supported by pairs of valley jack rafters 24.

As will be seen from the portions of Figure 1 which are encircled, the intersections between the hip and valley jack rafters and their associated hip rafter or valley rafter involve quite complex calculations to cut the timbers to meet at the correct angle. As viewed in plan, each jack rafter meets the associated hip or valley rafter at an acute angle. As seen in elevation, the hip and valley rafters are also inclined upwardly towards the ridge of the pitched roof.

For the construction of a pitched roof, the common rafters 12, 19, need to be cut off "plumb", that is so that their cut surfaces are truly upright in use. However, the upright faces of the ridge board 11 or 18 which they meet are disposed at right angles to the rafters as seen in plan. This is not the case where hip jack rafters 16 meet a hip rafter 15 or where valley jack rafters 24 meet a valley rafter 21. The timber must be cut at a complex angle determined by the individual characteristics of the roof.

It will be seen that some rafters 25 meet both a hip rafter 15 and a valley rafter 21.

These so called "hipvalley cripple jack rafters" need to be cut at an oblique angle at both ends.

In addition to providing the correctly angled cut, the traditional roof construction requires that the lengths of each timber are correct.

It will be seen that very considerable skill needs to be used in constructing a traditional "cut and nail" roof and the present invention provides a bracket which seeks to reduce the amount of skill required in the construction of such roofs.

Referring to Figure 2 of the drawings, a bracket generally indicated at 26 is made of sheet metal such as galvanised mild steel or stainless steel sheet and is of elongate form.

It comprises a central body zone 27 following the general axis of elongation of the blank 26, and pairs of laterally extending attachment flaps. A first attachment flap 28 is divided from the main body zone 27 by a fold line shown in dotted lines on the drawing at 29.

A second attachment flap 30 is provided at the other end of the blank, again extending laterally from the same side edge of the body zone 27. In this case, the flap 30 can be bent away from the main body zone at a fold line lying within a region whose extremities are indicated by the dotted lines 31.

The body zone 27 has a pair of parallel longitudinal slits 32 which define a strap 33 which can be folded out of the plane of the body zone 27 at a fold line 34 and which can then be folded again at a fold line such as those shown at 35 to form a channel together with the body zone 27. This channel will receive a square cut end of a first timber such as a jack rafter.

The central body zone 27 can itself be folded at a fold line lying within the region defined between the dotted lines 36 on the blank. The fold on the body zone will always be obliquely inclined relative to the general axis of the blank but the angle of this inclination can be varied within the limits of the dotted lines 36.

Folding the main body zone 27 on the fold 36 defines a first attachment part 37 which includes the first attachment flap 28 and will be secured to a first timber such as a jack rafter. A second attachment part 38 including the second attachment flap 30 will be secured to a second timber such as a hip or valley rafter.

The basic form of bracket so far described is suitable for use as a means of connecting timbers at a hip roof such as that shown in the drawings at 14. This bracket would be used for example at the positions encircled at 39 and 40 in the drawings. For use at the position 40, a left hand hip bracket would be used. This shown in Figure 3a of the drawings. The view shown in Figure 3a is taken on the arrow 3 of Figure 2, after the blank has been formed to shape by pressing.

The first attachment part 37 is seen end on in Figure 3a and the strap 33 will be seen to have been bent out into a channel shaped seating as previously described. The first attachment flap 28 has been bent to the left hand side as seen in Figure 3a of the general plane of the attachment part 37.

The second attachment part 38 is bent to the left hand side of the first attachment part 37 as seen in Figure 3a. However, the second attachment flap 30 is bent to the right hand side as viewed in Figure 3a so as it projects on the opposide side of the bracket from the first attachment flap 28.

The bracket so formed can be seen in use in Figure5 of the drawings. In Figure 5, the left hand side of the drawing represents a junction such as that encircled at 40 in Figure 1. This is a left hand hip junction between a hip rafter 15 and a hip jack rafter 16. The end of the hip jack rafter 16 (which cannot be seen in Figure 5) is cut off square, that is with no attempt made to match it in angle to the face of the hip rafter 15 to which it is intended to be secured.

The end of the jack rafter 16 abuts against the ortion 41 of the strap 33, which is bent round and nailed to the unseen upright face of the hip jack rafter 16. The first attachment flap 28 is secured against the upper face of the jack rafter and the first attachment part 37 is nailed to the upright face of the jack rafter.

Thus, the jack rafter 16 is securely located in a seating defined between two metal flanges at right angles, namely the attachment part 37 and the attachment flap 28, and the strap 33 engages both the end and the other face of the jack rafter.

It will be appreciated that the bracket is secured by nailing in this position to the jack rafter and the end of the jack rafter is then presented to the hip rafter 15. The second attachment flap 30 rests on the upper surface of the hip rafter 15 and can be nailed in place. Finally, the unseen second attachment part 38 is nailed to the face of the hip rafter 15 using the nail holes which can be seen in Figure 3a. Because of the angle of inclination of the hip jack rafter relative to the hip rafter, there is clear space for using a hammer to nail the second attachment part 38 to the hip rafter 15.

Comparing the left hand hip junction with a traditional right hand hip junction shown in the same figure, it will be seen that not only is there no need to cut the end of the hip jack rafter 16 to shape to suit the hip rafter 15, but there is a saving in timber. The position where the hip jack rafter would be cut off square is shown in chain dotted lines at the right hand side of Figure 5.

So far, this description has centred on the use of the bracket for hip junctions. However, the same bracket can be used for valley junctions such as those encircled at 42 and 43 in Figure 1.

Returning firstly to the drawing of the bracket blank in Figure 2, it will be seen that there are further flaps provided on the lower edge of the body zone 27. Again, a first attachment flap 44 is provided at one end, divided from the main body zone by a fold line 45. A second attachment flap46 isprovided at the other end of the blank, divided from the second attachment part 38 by a fold lying in the region defined between the dotted lines 47. However, in this case, a gap generally indicated at 48 is provided between the first and second attachment flaps 44 and 46.

Within this gap, the bracket body zone 27 can be folded at a dotted line within the region limited by the lines 36.

In order to form the blank into a bracket for use at a valley junction, these lower attachment flaps 44 and 46 are folded out of the plane of the blank and the body zone 27 is also folded. The previously described attachment flaps 28 and 30 remain in the general plane of the adjacent part of the body zone 27, in contrast to the foregoing description of the hip bracket shown in Figure 3a.

Referring specifically to Figure 3b of the drawings, the first attachment flap 44 is bent to the right hand side, the second attachment flap 46 is bent to the left hand side and the second attachment part 38, shown broken away, is bent to the right hand side. The strap 33 is also bent to the right hand side of the main body zone 27 of the attachment part 37.

Referring to Figure 6 of the drawings, this illustrates a valley junction similar to those encircled at 42 and 43 in the drawings.

As with Figure 5, one of the valley junctions is shown made by the traditional method and this left hand junction would correspond to the junction 42. However, at the right hand side of the drawing, corresponding to the encircled portion 43, is a valley junction made using the bracket of Figure 3b.

A valley jack rafter 24 is secured to a valley rafter 21 by means of the bracket. The first attachment part 37 is concealed, in the view shown, at the back of the valley jack rafter 24 but the strap 33 bent from the metal of the body zone 27 can be seen at the front face and end of the jack rafter, the end being supported by an abutment 41 of the strap 33.

At the upper edge of the valley jack rafter 24, the first attachment flap 44 is secured by nailing. It will be seen that the bracket has been inverted from the position shown in Figure 3b, which was intended to relate the folds to the blank shown in Figure 2.

The end of the valley jack rafter 24 is cut off square as shown at 49 and it will be seen that a certain amount of timber has been saved by using the bracket, comparing the left and right hand valley jack rafters in Figure 6.

The bracket having been secured to the valley jack rafter 24, it is then presented to the valley rafter 21 with the second attachment flap 46 lying on top of the valley rafter. Both the second attachment flap 46 and the second attachment part 38 are secured by nailing to respect adjacent faces of the valley rafter 21.

Using the blank shown in Figure 2, valley and hip junctions in a traditional roof can be constructed with the minimum of skill and using a somewhat reduced amount of timber.

Additionally, the fixing will be stronger and more secure than a traditional fixing. This is because a traditional fixing only has a small area of timber to timber contact, between two timbers, one of which is obliquely cut. To fix the jack rafter to the hip or valley rafter, it is therefore necessary to skew nail through a tapered end portion of the timber which may result in splitting of the timber. Because of the small fixing area, only a limited number of fastenings can be used.

With the bracket described and illustrated, all nailing takes place straight through the respective timber and a large number of nails can be used to secure each attachment part of the bracket to the associated timber.

The timbers are also supported by the attachment flaps and, in the case of the jack rafters, by the straps 33. Thus, each timber has a seating defined by at least two flanges of the bracket, secured to respective faces of the timber. The strength of the junction is dependent on the strength of the metal when adequate fixings are used and the timber is not weakened by being cut off on a taper.

Figure 4 of the drawings is a view of the various different types of bracket formed from the blank of Figure 2 and taken on the arrow 4, by way of comparison.

The upper part of Figure 4 shows a left hand hip bracket in plan view at50 and, in dotted lines shows the comparable right hand hip bracket.

In the lower part of the figure, a right hand valley bracket is shown at 52 and the comparable left hand valley bracket at 53.

Although the blank shown in Figure 2 can be used to form hip and valley brackets of either hand, it will be appreciated that a simpler blank could be provided having only one first and second attachment flap at either the top or lower edge, for forming either hip (only) or valley (only) junctions. Furthermore, although the blank shown can be formed along different fold lines to provide different angles between the first and second attachment parts 37 and 38 for example, or between the second attachment part 38 and the second attachment flap 30 or 46, it will be appreciated that this is only to provide versatility and is not an essential feature of the invention. Each fold will be made in an appropriate position for the particular angles involved in constructing the roof. The brackets can be pre-formed on the basis of calculations made on the building plans before being supplied to the site and the only calculations which need to be done by a carpenter on site are with regard to the line length of the jack rafters concerned. Some tolerances can be permitted because the strap 33 can be bent on site to wrap round the extreme end of the jack rafter and it is therefore of little importance if the rafter is slightly short because of the substantial nailing area still available in the first attachment part and first attachment flap.

Although the invention has been described in relation to hip and valley junctions in a traditional view it will be appreciated that the bracket may have more general application to other cases where timbers are required to meet at oblique angles considered in all planes.

Claims

1. A bracket for connecting a first and a second timber, the bracket comprising integrally connected first and second attachment parts for attachment respectively to said first and second timbers, the first and second attachment parts being so disposed as to connect said timbers in use at a selected oblique angle as considered in any plane.

2. A bracket according to Claim 1 wherein the first and second attachment parts each comprise a seating adapted to abut at least two faces of the first and of the second timber respectively in use.

3. A bracket according to Claim 1 or Claim 2 wherein the second attachment part includes an abutment adapted to abut an end of the second timber in use.

4. A bracket according to any preceding claim wherein each of each attachment parts is provided with fixing means such as nail holes for fixing the attachment parts to the associated timbers.

5. A sheet metal blank for a bracket, the blank being of elongate form and comprising an elongate body zone, a first attachment flap extending laterally from said body zone at one end portion thereof and a second attachment flap extending laterally from said body zone at the other end thereof, the first and second attachment flaps being provided on the same lateral edge of the elongate body zone.

6. A blank according to Claim 5 and provided with a pair of first attachment flaps and a pair of second attachment flaps for alternative use, the first attachment flaps extending laterally from opposed edges of the elongate body zone at one end portion thereof and the second attachment flaps extending laterally from opposed edges of the elongate body zone at the other end portion thereof.

7. A sheet metal blank according to Claim 5 or Claim 6 wherein the first and second flaps at one edge of the blank are spaced apart.

8. A blank according to any one of Claims 5 to 7 wherein a pair of longitudinally extending slits are disposed in the body zone between the second attachment flaps.

9. A bracket when formed from a blank according to any one of Claims 5 to 8 by folding the blank along fold lines so that first and second attachment flaps on one edge of the blank alone are folded out of the general plane of the blank in opposite senses and so that the central zone of the blank is folded transversely and obliquely to its general longitudinal axis.

10. A bracket according to Claim 9 when appendent to Claim 7 wherein the transverse fold of the central zone terminates at the edge of the blank in the region between said spaced apart first and second attachment flaps, to enable the angle of the transverse fold relative to the general longitudinal axis of the blank to be selected.

11. A method of making a bracket for connecting a first and a second timber, the method comprising taking a blank according to any one of Claims 5 to 8 and folding the first and second attachment flaps on one edge of the blank alone out of the general plane of the blank in opposite senses, and folding the central zone of the blank transversely and obliquely to its general longitudinal axis.

12. A method of forming an assembly of a first and second timber comprising taking a bracket according to any one of Claims 1 to 4 or 9 to 10, securing said first timber to the first attachment flap of the bracket, offering up the second attachment flap of the bracket to the second timber and securing the second attachment flap to the second timber.

13. A method according to Claim 12 wherein the first timber is a jack rafter or cripple-jack rafter and the second timber is a hip or valley rafter of a roof.

14. An assembly of a first timber such as a jack rafter or cripple-jack rafter and a second timber such as a hip or valley rafter, when secured together by means of a bracket according to any one of Claims 1 to 4 or 9 to 10 or by a method according to Claim 12 or Claim 13.

15. A roof including an assembly according to Claim 15.

16. A blank for a bracket for securing timbers, the blank being substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

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

18. An assembly of first and second timbers according to Claim 16 and substantially as hereinbefore described with reference to and as illustrated inFigure 5 of the accompanying drawings.

19. An assembly of first and second timbers according to Claim 16 and substantially as hereinbefore described with reference to and as illustrated inFigure 6 of the accompanying drawings.