AU700471B2

AU700471B2 - Roof framing system

Info

Publication number: AU700471B2
Application number: AU63486/96A
Authority: AU
Inventors: John Allan Trenerry
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-07-11
Filing date: 1996-07-11
Publication date: 1999-01-07
Anticipated expiration: 2016-07-11
Also published as: AU6348696A

Description

WO 97/03257 PCT/AU96/00437 ROOF FRAMING SYSTEM The present invention relates to roof construction and, in particr.dar, to a roof framing system having elongate structural members for use in load bearing frameworks and the application of these load bearing frameworks in roof construction. The roofing system of the present invention is primarily used in relation to domestic housing, but can be equally applicable to many different types of buildings.

BACKGROUND TO THE INVENTION Conventional roofing systems for domestic housing generally include a number of parallel trusses or rafters which are perpendicular to the roof s ridge, in the case of gable or skillion roof construction. In the case of a hip roof, the number of parallel trusses are augmented by perpendicular rafters for that section of roof. Battens are then arranged perpendicular to the trusses or rafters, ie perpendicular to the pitch of the roof, to enable the roofing material to be attached thereto. In the case where metal decking or sheets is/are used as the roofing material, the metal decking is generally secured to the battens by fasten-.rs such as screws or nails.

The trusses and battens are thus the basic arrangement for conventional roofing systems where metal decking or like roof covering material is used as well as when other types of roofing material, such as tiles etc, are used.

However it is believed that a more efficient roofing system, in relation to the costs of the components of the roof, can be achieved. Such a roofing system would provide a building with a roof having comparable load capabilities and which is able to withstand similar stresses when forces are applied thereto, when compared with convention roofing systems.

OBJECT OF THE INVENTION The present invention has been conceived out of the need to provide a roofing system, and components thereof, which lowers the cost of construction of the roof of a building due to the elimination of some of the roof components. At the very least, the invention provides an alternative to known roofing systems.

mN PAu 9 6 0 0 4 3 7 RECEIVED 0 6 JUN 1997 2 DISCLOSURE OF THE INVENTION According to the present invention there is provided a roofing system for a building having a roof supported by load bearing walls, said roof having a building ridge or being a top elevation of a skillion, said roofing system comprising a plurality of elongate load bearing framework members which are supported by the walls of the building, said plurality of elongate load bearing framework members supporting roof decking material, each said elongate load bearing framework member including at least two parallel elongate structural members and at least one structural web member therebetween, wherein said plurality of elongate load bearing framework members are aligned substantially parallel to the line of the building ridge and perpendicular to the slope of the roof with the roof decking material being fastened directly to said plurality of elongate load bearing framework members.

Preferably, each pair of two parallel elongate structural members and the structural web members therebetween form a parallel chord truss, thereby a plurality of the parallel chord trusses are positioned parallel to the building ridge, with the plane of the upper chords defining the pitch of the roof and the plane of the lower chords defining the ceiling line.

The roof can be a gable, a skillion, hip or any other type construction and the ceiling line can be flat, raked or cathedral construction independent of a particular roof line.

In one form of the invention, the plurality of parallel chord trusses are spaced evenly apart on the load bearing walls of the building, however, in other forms of the invention, the spacing can be varied. This can be the case if the parallel chord trusses are made in standardised shapes and sizes, and therefore, standard heights relate to standard roof pitches. If a non-standard roof pitch or roof alignment is used, the spacing can be changed if the standard sizes of parallel chord trusses are used.

In a preferred form of the invention, the upper surface of the upper chord is partially substantially co-planar to the pitch of the roof, while in another preferred form, the upper surface of the upper chord is partially curved.

",AMENDED SHEET

IPFAAU

PC/A U 600 437 In the preferred form the elongate structural members are substantially Z-shaped in transverse cross-section and the structural web members form is zig-zag like. The height of the structural web members varies according to the position of that particular parallel chord truss within the roof.

BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the present invention will now be described with reference to the drawings in which; Fig. 1 is a plan view of a roof framing system of a preferred embodiment; Fig. 2 is a transverse cross-sectional view along the lines A-A of Fig. I showing the outline of the roof framing system; Fig. 3 is a partial side view of a roof truss of the roof framing system of Fig. 1 showing one end thereof; Fig, 4 is a transverse cross-sectional along the lines B-B of Fig, 3; and Fig. 5 is a partial detailed view C of Fig. 4 showing a prelerredi fastening arrangement of roof sheeting to the truss with a preferred arrangement of the elongate structural member; and Fig. 6 is a partial detailed view C, of Fig. 4 showing an alternative fastening arrangement of roof sheeting to the truss with an alternativc- arrangement of the elongate structural member; BEST MODE OF CARRYING OUT THE INVENTION A roof framing system of a preferred embodiment as illustrated in Figs. 1 and 2 includes a roof 10 having, a number of roof trusses (or load bearing framework members) 11I supported by the end walls 12 of a building 13. The roof 10 as illustrated has gables 14 at each end ~\and a roof ridge 15 positioned along the longitudinal central axis of the roof QANEo&,lcSEET WO 97/03257 PCT/AU96/00437 4 In the particular embodiment illustrated, there are five trusses 11 including trusses of three different heights. Trusses 1 la having the smallest height are positioned towards the outer side walls 16 of the building 13, trusses 1 lb with the medium height are the intermediate trusses while truss 1 lc with the greatest height is the ridge truss. The heights of all the trusses 11 are selected so that the trusses 11 can be evenly spaced apart across the width of the building 13 with the pitch of the roof 10 being predetermined at a particular angle. In the embodiment illustrated the two portions of the roof 10 are planar. In other preferred forms the roof can have a different pitch or can be curved if so desired. In such instances the spacing between the trusses 11 which have predetermined heights, can be adjusted to provide the desired pitch or curvature of the roof.

The trusses 11 as shown in Figs. 3 and 4 are formed as parallel chord trusses. The parallel chord trusses 11 are formed by a pair of parallel elongate structural members 17 which are preferably Z-section cold rolled steel, with a web structure 18 therebetween. The parallel elongate structural members 17 form an upper chord 19a and a lower chord 19b with the web structure 18 of the preferred embodiment having a zig-zag arrangement therebetween as shown in Fig. 3, but which can have any suitable alternative arrangement. As seen In Fig.

3, the upper chord 19a is longer than the lower chord 19b as it is attached to the load bearing end walls 12 of a gable arrangement of the preferred embodiment.

As illustrated in Figs. 4 and 5, roof decking material 20 is fastened to the upper surface 21 of the upper chord 19a by means of a screw 22. In this preferred embodiment the upper surface 21 is formed so that it provides a substantially flat surface to the roof decking material 20. This ensures that the decking material 20 is securely fastened. In this arrangement the upper surface 21 of the upper chord 19a is formed by part of a flange 23 of the Z-section elongate structural member 17, the flange 23 also having a perpendicular portion 24 and a parallel portion 26 for the required strength. The ceiling 26 as illustrated in Fig. 2 is supported by the lower chord 19b along the perpendicular portion 24 of the flange 23. It is noted that in the preferred embodiment the elongate structural member 17 as used as the upper chord 19a and the lower chord 19b are the same, however, this is only the preferred arrangement as any suitable chord could be used.

I WO 97/03257 PCT/AU96/00437 In an alternate arrangement as illustrated in Fig. 6, the upper surface 21 of the upper chord 19a is convex in shape. Such a shape can also provide the required support for the roof decking material 20 and/or ceiling 26.

The roof framing system of the preferred embodiment and alternative arrangements, provides a series of parallel chord trusses 11 which are positioned parallel to the building ridge 15 so that the roof decking material 20 can be fastened directly to the trusses 11 as if they were battens in conventional formed roofs. The trusses 11 have uniform varying heights and therefore can be used to provide roofs with standard and non-standard pitches depending on the spacing therebetween. Thus the amount of components used in the construction of the roof can be significantly reduced thereby allowing the construction costs to also be significantly reduced.

The foregoing describes the basic structure of a roof 10, but obviously the use of overhangs, dormers and the like with the basic structure are within the scope of the present invention The foregoing describes only some embodiments of the invention and modifications obvious to those skilled in the art can be made thereto without departing from the scope of the present invention.

For example, the preferred embodiment is described with respect to a building having gable ends. If the roof is constructed in the hip form, the trusses can be formed with the ends forming the pitch of the roof. Similarly, if the roof has a skillion construction, the trusses of the present invention can also be used.

Even though the preferred embodiment has referred only to flat ceilings, the present invention can be used in a modified form for ceilings which are raked or cathedral.

Claims

1. A roofing system for a building having a roof supported by load bearing walls, said roof having a building ridge or being a top elevation of a skillion, said roofing system comprising a plurality of elongate load bearing framework members which are supported by the walls of the building, said plurality of elongate load bearing framework members supporting roof decking material, each said elongate load bearing framework member including at least two parallel elongate structural members and at least one structural web member therebetween, wherein said plurality of elongate load bearing framework members are aligned substantially parallel to the line of the building ridge and perpendicular to the slope of the roof with the roof decking material being fastened directly to said plurality of elongate load bearing framework members.

2. The roofing system according to claim 1, wherein each pair of two parallel said elongate structural members and the structural web members therebetween form a parallel chord, truss, thereby a plurality of the parallel chord trusses are positioned parallel to the building ridge, with the plane of the upper chords defining the pitch of the roof and the plane of the lower chords defining the ceiling line.

3. The roofing system according to claim 2, wherein the roof is one of a group including a gable, a skillion, hip or other type construction and the ceiling line can be flat, raked or cathedral construction independent of a particular roof line.

4. The roofing system according to claim 1, wherein the plurality of parallel chord trusses are spaced evenly apart on the load bearing walls of the building.

The roofing system according to claim 1, wherein the plurality of parallel chord trusses are spaced apart on the load bearing walls of the building with the spaces between adjacent parallel chord trusses being different.

6. The roofing system according to claim 1, wherein the upper surface of the upper chord is partially substantially co-planar to the pitch of the roof. AMENDED SHEET SIDOA/Ali 1 1 7

7. The roofing system according to claim 1, the elongate structural members are substantially Z-shaped in transverse cross-section and the structural web members form is substantially zig-zag in shape.

8. The roofing system according to claim 1, wherein the height of the structural web members varies according to the position of that particular parallel chord truss within the roof.

9. The roofing system according to claim 2, wherein the ceiling line supports a ceiling.