GB2166173A - Bracket for securing timbers - Google Patents

Abstract

A bracket for securing first and second timbers such as a ridge board 13 and a common rafter 14 in a roof comprises integral first and second attachment parts 23, 21, typically a plate 23 and a shoe 21, to which the respective timbers are nailed. The plate 23 lies in a plane at right angles to the longitudinal axial plane of the shoe 21 but at an acute angle to its axis. In use, the bracket perm its common rafters to be more securely fixed to the ridge board without taper cuts being needed, with increased lateral restraint and with a reduction in time and timber usage. <IMAGE>

Description

SPECIFICATION Bracket for securing timbers 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 utilisethe 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 slotting common rafters. Neartheirouterends,the common rafters bear on the wall plates of a pair of opposite walls ofthe building and extend to form outwardly projecting raftertails overhanging the wall.

In even a simple roof, many pairs of common rafters are used, typically positioned at 400 mm spacing along the whole length, or most ofthe length of the building.

It requires great skill and practice to calculate and cutthe common rafters to the correct length and with correctly angled ends to meetthe ridge board. Any wastage of rafter timber is very expensive, and the work involved is time-consuming.

To assemblethe roof it is necessarytoskew nail each common rafter individually to the ridge board.

Since the rafters are cut obliquely attheir ends,the nails pass through a tapering part ofthe timber and may split the common rafter, making the connection insecure. Considering the length ofthe common rafters, little lateral restraint is provided by these nailed connections.

It is an object ofthe present invention to provide a bracketforconnecting a timber such as a common rafterto anothertimbersuch as a ridge board,which is capable of providing a secure and easy fixing.

According to the invention there is provided a bracketfor 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, thefirstand second attachment parts being so disposed as to connect said timbers in use in mutually perpendicular planes and with onetimber meeting the other atan acute angle.

The second attachment part may comprise a seating abutting at least two faces of said second timber in use.

The seating may be in the form of a shoe abutting three adjacent faces of the second timber, or an angle section abutting two adjacent faces, or a yoke abutting two opposed faces in use.

The first attachment part may comprise a plate.

The seating and/orthe plate may be provided with nail holes forfixing into said timber.

A bridge portion may be provided between the first and second attachment parts.

In one form, the bracket may comprise a first attachment plate, a bridge portion carrying a pair of side plates generally perpendicularto the bridge portion, an abutment portion generally perpendicular to both the side plates and the bridge portion, and a base generally parallel to the bridge portion, the base, side plates and abutment portion together defining a shoe.

Preferably, the attachment plate is widerthan the shoe.

The invention also provides a blankforforming a bracket as set out above.

The blank may be truncated triangular shape having a pair of slits perpendicularto and extending in parallel from the base edge of the truncated triangle to definethe base andthe abutment portion of the brackettherebetween, and to define a pair of side plates; the blankfurther having a pair of aligned slits extending parallel to said base edge into the truncated sides of the triangle whereby the truncated apex portion ofthe triangle defines said attachment plate and the region between said slits defines said bridge portion.

The invention also provides an assembly comprising a pair oftimbers secured together by a bracket as set out above.

Thefirsttimber may be a ridge board and the second timber may be a common rafter of a pitched roof.

The invention also provides a method ofsecuring a second timber in a perpendicular plane and at an acute angle to a first timber, the method comprising the steps of; securing the second attachment parts a bracket according to the invention to a square cut end of said second timber by nailing through said second attachment part into said timber; presenting the first attachment part ofthe bracket to the first timber; and nailing the first attachment part to the first timber.

Asan alternative, the method maycomprisesecur- ing the first attachment part of a bracket according to the inventiontothefirsttimber by nailing; presenting a square cut end of a second timber to the second attachment part ofthe bracket; and nailing the second timberto the second attachment part.

The invention also provides a method of constructing a roof comprising taking a plurality of pairs of common rafters as said second timbers and securing them by either version of the foregoing method to a ridge board as said firsttimber.

The invention also contemplates a roof so constructed.

Abracket embodying the invention will nowbe described in more detail by way of example onlywith reference to the accompanying drawings in which: FIGURE lisa scrap perspective view of part of a complex roof, FIGURE2 is a plan view of a blank for making a bracket embodying the invention, FIGURE3 3 is a side elevational view ofthe bracket showingatimbersuchasacommon rafter in position, FIGURE4 is an end elevational view on a reduced scale ofthe bracket of figures 2 and 3, FIGURE 5 is a perspective view ofthe bracket and common rafter FIGURE 6 is a side elevational view of the common raftersecured to a ridge board using the bracket.

Referring firstly to figure 1 ofthe drawings, a roof comprises a main pitched section generally indicated at 10, and terminating in a hip generally indicated at 11. Figure 1 also shows an intersecting ridge roof 12.

Considering the main pitched roof section 10, a ridge board 13 oftimberruns horizontally along the top ofthe roof. It is met by pairs of oppositely disposed common rafters 14,typically spaced about400 mm apart along mostofthe length ofthe building. The intersecting ridge roof 12 comprises a ridge board 15 and pairs of common rafters 16.

In each case,thecommon rafters 14,16meetthe associated ridge board 13,15 atan angle which depends on the pitch angle ofthe roof. Each pair of common rafters lies in a plane at right angles to that of the ridge board, as seen in plan. However, as seen in side elevation the common rafters are inclined at an acute angleto the vertical plane of the ridge board.

The joint between the common rafters 14 and the ridge board 13 can be seen encircled at 17 in figure 1.

In conventional practice, the common rafter must be cut plumb, that is in a plane which will lie truly vertical againstthefaceofthe ridge board in use.Thisplane must be calculated before the rafter is lifted in place.

Atthe lower end, each common rafter is supported on awall plate 18 ofthe associated wall of the building, and a projecting part 19, known asthe raftertail, extends beyond the wall plateto overlap the wall. A fascia board will be added to join the raftertails and supportthe guttering (notshown).

It will be apparent from this description that each common rafter must be cut to the correct length to extend from the fascia to the ridge board, with the correctly positioned and shaped notch or"birdsmouth"to meetthewall plate and with the correctly angled upper end to meetthe ridge board.

Calculating the cuts required is skilled work and any mistakes are expensive, since a whole rafter may be wasted if a cut is badly positioned.

It is also difficult to ensure that the cut rafters are securelyfixed to the ridge board, since skew nailing through the tapering upper end of the common rafter may result in splitting ofthe timber.

Figures2to6showa bracketwhich enables a common rafterto be used with a square cut end, as distinctfrom a plumb cut end, where it is secured to the ridge board. In addition to avoiding the need to cut the timber at an angle, itwill be seen that less line length of timber is used than with the traditional method, becausethetop or crown edge ofthe common rafter is spaced from the ridge board.

Referring firstly to Figure 6, the ridge board 13 is shown in vertical section and itwill be seen that a bracket 20 is secured to the square-cut end ofthe common rafter 14.The bracket20 defines a seating or shoe 21 in which the rafter is secured by nails, which extend straight into the timber ofthe rafter at its full thickness. The nail holes 24 can be seen in Figures 3 and 5. As alternatives (not show) to a shoe abutting three faces of the rafters, an angle-section seating could be provided abutting two adjacent faces or a yoke-like seating abutting two opposed faces.

The end ofthe rafter meets an abutment 22 ofthe shoe 21, which also abuts the ridge board 13. The bracket 20 is secured to the ridge board 13 by an integral attachment plate or part 23. This is nailed to the ridge board through nail holes 28, shown in Figures 3 and 5. The plate 23 projects above the level ofthe raftertop byan amount sufficient to enable the builderto use a hammer.

The angle ofthe plate 23 relative to the base ofthe shoe 21 is equal to the desired ridge angle ofthe roof.

This can betaken from the building plans and the brackets preformed to the desired angle. Alternatively, the bracket can be fixed to the common rafter end with the latter seated firmly in the shoe and the plate 23 can be bent to the correct angle on being presented to the ridge plate, by hammering itflatagainstthe ridge plate before nailing in place.

In either case, the bracket will be secured both to the common rafter and to the ridge board by straight nailingintothefulllthicknessoftimberwith greatly reduced risk of splitting.

In some circumstances, forcertain timbersizes and angles, it may be necessary to reverse the order of fixing.The plate 23 will then be secured to the ridge boards 13 by nailing, either before or after the ridge board is lifted into place.Acommon rafter with a square cut end is then located into the shoe 21 ofthe bracket 20 and secured by nailing at the sides and undersideoftheshoe21 through the holes 24.

The details of the bracket can be seen in more detail in the remaining Figures 2to 5 of the drawings.

Figures 3 and 5 showthe bracket secured to the common rafter 14 and illustrate the nail holes 24 used forfixing.

The shoe 21 is ofthe same width as the raftertimber 14 and has a base 25 integrally connected with the abutment 22. The abutment 22 is connected by a bridging portion 26 to the attachment plate 23. The shoe is further defined by a pair of side plates 27 integrally connected to the bridge portion 26. The side plates are apertured at 28 forfixing nails to secure the brackettothe ridge board. Itwill be seen that the height of the common raftercanvarysomewhat without needing a differently-sized bracket The whole bracket is made as a pressing from a single sheet metal blank, shown in Figure 2, of galvanised or stainless steel for example. The shape of the blanks enables them to be cutfrom sheet metal with minimum wastage. Referring to Figure 2, the blank 30 is of generallytruncated triangularform with the truncated apex forming the attachment portion 23 and the rest of the triangle forming the shoe 21. The shoe is divided into the base 25and the side plates 27 by longitudinal slots 31. There are also a pair of oppositely disposed transverse slots 32 separating the attachment portion 23 ofthe bracketfrom the shoe 21.

The Figure also shows the transverse fold lines used to form the bridge portion 26 and the abutment portion 22, and the longitudinal fold lines used to form the side plates 27.

In use, the attachment portion 23 is secured by nails passing straight into the ridge board 13. The pattern of nail holes 28 is shown in Figure 2. Itwill be seen that the nailing area is much broaderthan the width ofthe shoe base 25, equivalent to the width ofthe common rafter. This meansthatthe common rafter is braced laterally to a greater extentthan would be possible if the rafterwere nailed directly to the ridge board.

Similarly, the large side plates ofthe shoe have widely spread nail holes 24,to give a much more secure fixing than is conventionally possible using skew nailing. Additionally,there are nail holes in the base 25 ofthe shoe, to assist in securing the rafter 14.

Although the invention has been described with reference to securing the common rafters 14to the main ridge board 13, it could also be used to secure the common rafters 1 6to the ridge board 15 ofthe intersecting roof 12. It may also find more general application in other building structures in which timbers meet at appropriate angles.

Claims (21)

1. A bracketfor connecting a first and a second timber,the bracket comprising integrally connected first and second attachment partsforattachment respectively to said first and secondtimbers,thefirst and second attachment parts being so disposed asto connect said timbers in use in mutually perpendicular planes and with onetimber meeting the other at an acute angle.

2. A bracket according to Claim 1 wherein the second attachment part comprises a seating abutting at leasttwofaces of said second timber in use.

3. A bracket according to Claim 2 wherein the seating comprises an angle section abutting two adjacentfaces ofthe second timbers.

4. A bracket according to Claim 2whereinthe seating comprises a yoke abutting two opposed faces ofthe second timber.

5. A bracket according to Claim 2 wherein the seating comprises a shoe abutting three adjacent faces ofthe second timber.

6. A bracket according to any preceding claim wherein the first attachment part comprises a plate.

7. A bracket according to any preceding claim wherein a bridge portion is provided between the first and second attachment parts.

8. A bracket according to Claim 7 and comprising a first attachment plate, a bridge portion carrying a pair of side plates generally perpendiculartothe bridge portion, an abutment portion generally perpendicular to both the side plates and the bridge portion, and a base generally parallel to the bridge portion, the base, side plates and abutmentportiontogetherdefining a shoe.

9. A bracket according to Claim 8wherein the attachment plate iswiderthantheshoe.

10. Ablankforforming a bracket according to any one of Claims 1 to9.

11. A blank according to Claim 10 and oftruncated triangular shape having a pair slits perpendicularto and extending in parallel from the base edge ofthe truncated triangle to define the base and the abutment portion ofthe brackettherebetween and to define a pair of side plates; the blankfurther having a pairof aligned slits extending parallel to said base edge into thetruncated sides of the trianglewherebythe truncated apex portion ofthe triangle defines said attachment plate and the region between said slits defines said bridge portion.

12. An assembly comprising a pairoftimbers secured together by a bracket according to any one of Claims 1 to 9.

13. An assembly according to Claim 12wherein the firsttimber comprises a ridge board and the second timber comprises a common rafter of a pitched roof.

14. Amethodofsecuring asecondtimberin a perpendicular plane and at an acute angleto a first timber,themethodcomprisingthesteps of: securing the second attachment part of a bracket according to any one of Claims 1 to 9 to a square cut end of said second timber by nailing through said second attachment part into said timber; presenting the first attachment part ofthe bracket to the firsttimber; and nailing thefirst attachment parttothefirst timber.

15. A method of securing a second timber in a perpendicular plane and at an acute angleto afirst timber,the method comprising the steps of: securing the first attachment part of a bracket according to any one of Claims 1 to 9tothefirsttimber by nailing; presenting a square cut end ofthe second timberto the second attachment part ofthe bracket; and nailing the second timbertothe second attachment part.

16. Amethodofconstructing a roof comprising taking a plurality of pairs of common rafters as second timbers and securing them to a ridge board of the roof as a first timber, the method comprising the steps of Claim l4orClaim 15.

17. Aroofwhenconstructed bythemethod of Claim 16.

18. A bracketfor securing timbers substantially as hereinbefore described with referenceto and as illustrated in the accompanying drawings.

19. A blankfora bracket substantially as hereinbefore described with reference to and as illustrated in Figure 2 ofthe accompanying drawings.

20. An assembly oftimbers according to Claim 12 and substantially as hereinbefore described with reference to and as illustrated in Figures 3,5 and 6 of the accompanying drawings.

21. A method according to Claim 12 or Claim 13 and substantially as hereinbefore described.