WO1997003257A1

WO1997003257A1 - Roof framing system

Info

Publication number: WO1997003257A1
Application number: PCT/AU1996/000437
Authority: WO
Inventors: John Allan Trenerry
Original assignee: John Allan Trenerry
Priority date: 1995-07-11
Filing date: 1996-07-11
Publication date: 1997-01-30
Also published as: AUPN411295A0

Abstract

A roofing system for a building (13) having a building ridge or top elevation of a skillion roof (10) is disclosed. The roofing system comprises a plurality of elongate load bearing framework members (11) which are supported by the building (13) and which support roof decking material (20), each of the elongate load bearing framework members (11) including at least two parallel elongate structural members (17) and at least one structural web member (18) therebetween. The plurality of elongate load bearing framework members (11) are aligned substantially parallel to the line of the building ridge and perpendicular to the slope of the roof (10) with the roof decking material (20) fastened directly to the plurality of elongate load bearing framework members (11).

Description

ROOF FRAMING SYSTEM

The present invention relates to roof construction and, in particular, to a roof framing system having elongate structural members for use in load bearing frameworks and the application ofthese load bearing frameworks in roof construction. The roofing system ofthe 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 roofs 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 peφendicular to the pitch ofthe 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 fasteners 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 ofthe components ofthe 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 ofthe need to provide a roofing system, and components thereof, which lowers the cost of construction ofthe roof of a building due to the elimination of some ofthe roof components. At the very least, the invention provides an alternative to known roofing systems. DISCLOSURE OF THE INVENTION

According to the present invention there is provided a roofing system for a building having a building ridge or top elevation of a skillion, said roofing system comprising a plurality of elongate load bearing framework members which are supported by the building and which support 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 ofthe building ridge and perpendicular to the slope ofthe 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 ofthe parallel chord trusses are positioned parallel to the building ridge, with the plane ofthe upper chords defining the pitch ofthe roof and the plane ofthe 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 ofthe invention, the plurality of parallel chord trusses are spaced evenly apart on the load bearing walls ofthe building, however, in other forms ofthe 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 ofthe invention, the upper surface ofthe upper chord is partially substantially co-planar to the pitch ofthe roof, while in another preferred form, the upper surface ofthe upper chord is partially curved.

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 ofthe 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. 1 showing the outline ofthe roof framing system;

Fig. 3 is a partial side view of a roof truss ofthe 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 preferred fastening arrangement of roof sheeting to the truss with a preferred arrangement ofthe elongate structural member; and

Fig. 6 is a partial detailed view C of Fig. 4 showing an altemative fastening arrangement of roof sheeting to the truss with an altemative arrangement ofthe 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) 11 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 ofthe roof 10. In the particular embodiment illustrated, there are five trusses 11 including trusses of three different heights. Trusses lla having the smallest height are positioned towards the outer side walls 16 ofthe building 13, trusses 1 lb with the medium height are the intermediate trusses while truss l ie 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 ofthe roof 10 being predetermined at a particular angle. In the embodiment illustrated the two portions ofthe 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 ofthe 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 ofthe preferred embodiment having a zig-zag arrangement therebetween as shown in Fig. 3, but which can have any suitable altemative 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 ofthe 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 ofthe 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 ofthe 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. In an alternate arrangement as illustrated in Fig. 6, the upper surface 21 ofthe 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 ofthe preferred embodiment and altemative 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 tmsses 11 as if they were battens in conventional formed roofs. The tmsses 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 constmction ofthe roof can be significantly reduced thereby allowing the constmction costs to also be significantly reduced.

The foregoing describes the basic stmcture of a roof 10, but obviously the use of overhangs, dormers and the like with the basic stmcture are within the scope ofthe present invention

The foregoing describes only some embodiments ofthe invention and modifications obvious to those skilled in the art can be made thereto without departing from the scope ofthe present invention.

For example, the preferred embodiment is described with respect to a building having gable ends. If the roof is constmcted in the hip form, the tmsses can be formed with the ends forming the pitch ofthe roof. Similarly, if the roof has a skillion constmction, the tmsses 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

CLATMS

1. A roofing system for a building having a roof with a building ridge or top elevation of a skillion, said roofing system comprising a plurality of elongate load bearing framework members which are supported by the building and which support roof decking material, each said elongate load bearing framework member including at least two parallel elongate stmctural members and at least one stmctural web member therebetween, wherein said plurality of elongate load bearing framework members are aligned substantially parallel to the line ofthe building ridge and perpendicular to the slope ofthe 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 stmctural members and the stmctural web members therebetween form a parallel chord truss, thereby a plurality ofthe parallel chord tmsses are positioned parallel to the building ridge, with the plane ofthe upper chords defining the pitch ofthe roof and the plane ofthe 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 constmction and the ceiling line can be flat, raked or cathedral constmction independent of a particular roof line.

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

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

6. The roofing system according to claim 1, wherein the upper surface ofthe upper chord is partially substantially co-planar to the pitch ofthe roof

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

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