GB2214944A

GB2214944A - Adjustable roof truss

Info

Publication number: GB2214944A
Application number: GB8802651A
Authority: GB
Inventors: William Maldwyn Rowlands
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-02-05
Filing date: 1988-02-05
Publication date: 1989-09-13
Anticipated expiration: 2008-02-05
Also published as: GB2214944B; GB8802651D0

Abstract

The truss 12 includes a beam 13, the ends of which are fastened by end plates to wall plates 15. The beam 13 is formed to two axially alignable lengths 21 joined together by axially adjustable fasteners, such that the overall length of the beam can be selected and fixed. The fasteners typically comprise metal plate 5, 23, 24 each secured to a respective length of the beam, the plates having parallel rows of holes 25 in two identical sets of three rows, and bolts passing through respective holes in each of the two sets. <IMAGE>

Description

ADJUSTABLE ROOF TRUSS This invention relates to an adjustable roof truss for incorporation into buildings.

According to the invention, there is provided an adjustable roof truss, including a beam, the opposite ends of which are to be supported by a building, the beam being formed of two axially aligned elongate elements joined together by axially adjustable fastening means, whereby the overall length of the beam may be selected and fixed.

Preferably, the axially adjustable fastening means is adjustable in finite steps and may comprise perforated plates affixed to one element, to fit against correspondingly perforated plates affixed to the other element, the elements being rigidly joined by bolts or the like passed through perforations in the plates of both elements. The perforations may be disposed in rows parallel to the beam axis, there being two sets of rows, each set having a plurality of rows, and the perforations in each row of one set being staggered relative to the other rows of that set, to provide a fine axial length adjustment.

Conveniently, the truss includes a rafter fastenable to the beam by adjustable inclination means, such as a pivot. The rafter may incorporate an axial length adjustment, which may be a screw means. Where two rafters of the truss are to abut at the truss apex, there may be provided an apex fastening of adjustable inclination.

Where a beam, rafter or other strut of the truss is of rectangular section the axial adjustment fastening means may include perforated plates affixed to both sides and the top and bottom of the beam, rafter or other strut. To obtain a finer axial length adjustment the aligned holes in the side plates may be staggered relative to the aligned holes in the top and bottom plates, whereby either the side plate holes or the top and bottom plate holes may be used, but not both at the same time.

The beam, rafter or other strut of the truss may be of metal lattice construction.

One embodiment of the invention is described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an elevation of an adjustable roof truss, according to the invention, installed in part of a building, Figure 2 is an enlarged view of part of a beam shown in Figure 1, Figure 3 shows. another part of the beam shown in Figure 1, Figure 4 is an enlarged view of part of a rafter shown in Figure 1, Figure 5 is a section along the line V - V in Figure 4, and Figure 6 shows an alternative to Figure 4.

In the drawings, a building having two cavity walls 10 is covered by proof 11 supported by a truss, indicated generally at 12.

The truss 12 includes a beam 13, the ends of which are fastened by end plates 14, seen in Figure 3, to wall plates 15. Rafters 16 are pivotted together at the truss apex, for example, by a pin joint 17.

The ends of the rafters 16 remote from the apex are fastened to the beam 13 with an adjustable elevation, such as a shoe 18, shown in Figure 3, comprising two parallel plates extending upwardly from the beam 13 and formed with arcuate slots 19.

The rafter 16 is fastened between the plates of the shoe 18 by a through bolt 20.

Figure 2 shows how the axial length of the beam 13 may be adjusted to suit the spacing between the walls 10. The beam 13 is typically of rectangular cross-section and of latice construction, having tubular or solid metal members 21 spaced apart by a latice 22 of strips or tubes welded thereto.

One end of one length of the beam 13 has a pair of parallel metal plates 23 affixed thereto, one plate 23 on each side of the beam end. The adjacent end of the other length of the beam 13 has a similar pair of parallel metal plates 24 affixed thereto. The plates 23 are spaced apart such than they can fit against the plates 24, either both plates 23 inside plates 24, or outside them or one plate 23 inside and one outside.

All the plates 23, 24 have six parallel rows of holes 25 in two indentical sets of three rows. The holes 25 in the lower rows of each set are disposed such that the plates 23, 24 ,may be moved in the direction of the beam axis until all the lower row holes are aligned. The holes 25 in the middle rows of the sets are at the same pitch as the lower row holes but are staggered relative to the lower row holes by one third of a pitch. Similarly, the upper row holes 25 are staggered relative to the lower row holes by two two thirds of a pitch. Thereby, the axial length of the beam 13 may be adjusted in steps of one third of the pitch of the holes 25.

A similar axial length adjustment is provided in the rafters 16 or in struts 26 which form part of the truss 12. Figure 5 shows a construction in which there are upper and lower plates 27 at the same locations as the side plates 23, 24. The holes in the plates 27 may be staggered relative to the holes 25 in the plates 23, 24 to give an even finer axial length adjustment to the beam 13, rafter 16 or strut 26.

Figure 6 shows the use of a screw means 28 as an alternative to the use of perforated plates 23, 24, 27 in the rafter 16 or strut 26.

The roof 11 is supported from the truss 12 by purl ins 29 which are fastened to the rafters 16 by brackets 30, which may be inclined to hold the purl in 29 normal to the rafter 16 or normal to the beam 13, as required.

Claims

CLAIMS:

1. An adjustable roof truss, including a beam, the opposite ends of which are to be supported by a building, the beam being formed of two axially aligned elongate elements joined together by axially adjustable fastening means, whereby the overall length of the beam may be selected and fixed.

2. An adjustable roof truss according to claim 1, wherein said fastening means is adjustable in finite steps.

3. An adjustable roof truss according to claim 2, wherein said fastening means comprises a perforated plate member affixed to one said element, to fit against a correspondingly perforated plate member affixed to the other said element; and connecting members arranged to pass through perforations in each of said plate members.

4. An adjustable roof truss according to claim 3, wherein the perforations in each of said plate members are disposed in rows parallel to the axis of said beam, there being two sets of said rows, each set comprising a plurality of rows, the perforations in each row of each set being staggered relative to the other rows of said set.

5. An adjustable roof truss according to any of claims 1 to 4, which includes a rafter fastenable to said beam by adjustable inclination means.

6. An adjustable roof truss according to claim 5, wherein said rafter is provided with means permitting axial length adjustment thereof.

7. An adjustable roof truss according to claim 6, wherein said axial length adjustment means comprises screw means.

8. An adjustable roof truss according to any of claims 1 to 7, in combination with apex fastening means of adjustable inclination.

9. An adjustable roof truss substantially as described herein with reference to Figures 1 to 5, or Figures 1 to 3, 5 and 6 of the accompanying drawings.