GB2391026A - A roofing system and roofing panel therefore - Google Patents

Abstract

A prefabricated, modular roofing system comprises main roof panels 10 which can span the distance between gable ends (54, fig 9) and can be supported thereby and intermediate panels 44 which do not span the whole roof and are supported by, and cooperate with, the main roof panels 10. One side of the roof system preferably comprises at least two main roof panels 10, one set of intermediate panels 44 arranged between the main roof panels 10 to provide window openings, an eave panel 40 and an apex panel 48 (see fig 3). The cooperating surfaces (20, 22, fig 4) may extend across the full length of the panels. The roof is preferably attached by a tongue (50, figs 5-6) and groove (52, figs 5-6) system, wherein the groove (52) is provided on the gables (54) and the tongues (50) are located on the ends of the roof panels 10. The invention is also for use in terraced buildings, where an intermediate gable may be provided. A method of assembling the roof using bracing means is also disclosed (see fig 10).

Description

- 1 - ROOFING SYSTEM, ROOF PANEL THEREFOR, AND METHOD OF

ASSEMBLING A ROOF

FIELD OF THE INVENTION

This invention relates to a roofing system, to a roof panel therefor, and to a method of assembling a roof. The invention is expected to find its greatest utility in relation to roofs for domestic dwellings, and the following 10 description therefore relates to such use. It may,

however, be that the invention also has utility in relation to commercial or industrial buildings and such applications are not excluded.

DESCRIPTION OF THE PRIOR ART

Domestic dwellings can have flat roofs or pitched roofs; the invention relates to the latter. A pitched roof is 20 traditionally created by a number of roof trusses comprising wooden frames (typically pre-fabricated) which are set upon the brick or timber-frame walls of the building. A layer of waterproofing material is laid over the trusses and battens are mounted thereupon which support the tiles or other 25 outermost roof covering.

The trusses are usually of general triangular shape, with a horizontal (in use) member (which members together define the ceiling of the topmost storey of the building) and two 30 angled members which define the pitched sides of the roof.

In order to support the weight of the tiles etc., most truss designs include intermediate members connecting between the horizontal member and the angled members. It is a recognized disadvantage of such truss designs that the 35 intermediate members cause obstructions within the loft space, and render the loft space substantially unusable as living accommodation.

- 2 It is becoming increasingly common for newly-built homes to utilise the loft space as additional living accommodation.

One factor driving this trend is that the price of building land is generally increasing, and a house in which the loft 5 space is utilised as an additional bedroom or bedrooms for example can usually be sold for more money than a house occupying the same ground area in which the loft- space is not utilized. Also, the planning authorities are increasingly demanding greater density of domestic dwellings 10 upon the available building land (in the U.K in particular the planning requirements have recently changed from 13 dwellings per acre to 16 dwellings per acre, for example).

To allow living accommodation in the loft space' so-called 15 "attic trusses" have been developed, in which the triangular shape of the roof truss is supported by intermediate members which define a living space, i e. the intermediate members span the areas close to the apices of the triangle but leave open a large central area of each truss, which central area 20 can be used as living space. However, attic trusses are heavier than traditional trusses and are difficult to handle on site.

Another significant factor for house builders is the cost of 25 materials and labour used in building domestic dwellings, particularly low-cost domestic dwellings. Whilst the attic trusses allow a home with a given number of bedrooms to be constructed on a smaller ground area, and therefore at greater density, the materials and labour costs of 30 construction are high. It has therefore been proposed to reduce the cost of building construction by employing "modular" construction techniques using pre-fabricated panels where possible. The desire for such improvements was set out for example in the consolation paper "Rethinking 35 Construction - The Report of the Construction Task Force", published by the U.K. Department of the Environment, Transport and the Regions in July 1998 (ISBN 1 85112 094 7).

The Report highlights the advantages of standardization and

3 - pre-assembly which modular construction techniques allow, and cites the ability to construct a fully-functioning fast-

food restaurant in 24 hours using a high degree of prefabrication and modularisation.

The possibility of using roof panels in place of the traditional roof trusses has been recognized, and several companies are manufacturing prefabricated roofing panels. A major benefit of using roofing panels is that they may be 10 prefabricated to include insulting material, which is a necessary requirement if the loft space is to be used for living accommodation.

One company manufacturing roof panels is Unilin Systems of 15 Esselgem, Belgium. This method of construction is suitable for gable-ended roofs and employs a number of purling which are laid upon the gables to span the width of the roof.

Typically, there is a ridge purlin at the apex of the roof, an eaves purlin adjacent to each set of eaves (i.e. adjacent 20 to the top of the front and back walls of the building) and an intermediate purlin approximately mid-way between the ridge purlin and each of the eaves purling. The roof panels each run from top to bottom of one side of the roof, substantially supported by the three purling.

It is a recognized disadvantage of this type of construction that the intermediate purlins lie within the loft space.

Because of the considerable weight of the roof panels, and the snow load they must be designed to withstand, the 30 purlins are necessarily of large cross-section, and so present a significant obstruction within the loft space.

Also, the intermediate purlin restricts the positioning of windows within the roof, i.e. the windows must usually be located above the intermediate purlin, and are therefore 35 relatively high in the roof, and higher than would necessarily be desirable. Furthermore, because the purlins must span the width of the building they are necessarily

- 4 - heavy and difficult to transport and handle on site (whether of wood, steel or composite material).

It is another recognized disadvantage that the weight of the 5 panels is at least partly supported on the front and back walls, and tends to push those walls apart. It is therefore necessary to ensure that the front and back walls can withstand the lateral loading applied 10 The TRADA Technology Report 2/2000 entitled "Timber Frame: Re-Engineering for Affordable Housing" by TRADA Technology Limited of High Wycombe, England (ISBN 1 900510 25 1) also describes the use of roof panels, but mounted across the roof. In this way the weight of the panels is supported by 15 the gable ends (sometimes called the "spandrel panels") and not by the front and back walls. Also, no purlins are required to encroach into the loft space. This document therefore describes a solution to the problems with the Unilin type of construction technique described above.

to However, the TRADA document is an incomplete disclosure and

only sets out the principles of the construction techniques, and not the practical details thereof; accordingly, the TRADA document alone does not provide a disclosure which

would enable a skilled person to construct a roof.

It will be understood that reference has been made above to "gable-ended" buildings, and this term is usually used to describe roofs with the gables at each side. It is however known that some buildings are constructed with the gables at 30 the front and rear. For all practical purposes the roofs of these two types of building are equivalent, and no distinction between them is drawn in this application.

It will also be understood that modular building techniques 35 are most suited to low cost buildings; such buildings typically have simple roof constructions which are well suited to the use of modular panels. Accordingly, the present invention (and the applicable prior art) is

- 5 - especially well-suited to roofs which comprise two flat and continuous roof surfaces or sides between parallel gable ends, and may be less well suited to more complex roofs. In addition, the distance which each panel must be able to span 5 between the gable ends is limited by the strength of the panels, and it is desired that the maximum span be around 5.5 metres; such a span is suitable for the vast majority of low- cost domestic housing applications.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a roofing system, and roof panels therefor, which avoids or 15 reduces the above-stated problems with the Unilin type of construction technique. The present invention utilises roof panels which are configured to lie across the roof as in the TRADA disclosure, and seeks to avoid or reduce the practical

problems which lie in the way of a skilled person seeking to 20 put the teaching of that document into effect.

According to a first aspect of the invention, there is provided a roofing system for a building, the building having four walls, an opposed two of the walls including 25 gable means, the roofing system comprising a number of panels which can span the distance between the gable means and be supported thereby, characterized in that the gable means includes one of a tongue and groove, and in that the ends of the panels include a respective groove and tongue 30 for location with the gable means.

The provision of a tongue and groove connection between the gable means and the ends of the panels ensures a positive location for the panels (facilitating ease of construction) 35 and helps to maintain the separation of the gable means in the assembled structure.

- 6 - Preferably, the groove is located on the gable means and the tongue is located on the ends of the panels.

The gable means may be a traditional gable constructed from 5 bricks or blocks, with the groove (or tongue) provided therein. Alternatively, the gable means may be a prefabricated panel which is fitted onto the top of the wall of the building. The latter has the considerable advantage that the brickwork or the like for all of the four walls can 10 terminate at the same height (i.e. the wall plate level).

In such embodiments, the prefabricated gable means can be fitted by the roof installer/assembler as part of the roof construction process.

15 Preferably, the tongue and groove have inclined sides and a flat bottom. The flat bottom provides a bearing surface supporting at least part of the weight of the panel in use.

The inclined sides facilitate ease of fitment, i.e. the width of the bottom wall of the tongue is less than the 20 width of the open end of the groove so that precise location of the panel above the gable means is not required to ensure cooperation of the tongue and groove.

Desirably, the groove or tongue is continuous across each of 25 the gable means. Desirably also the tongue or groove is continuous across the ends of the panel.

Preferably, the roofing system includes a set of intermediate panels which cannot span the distance between 30 the gable means. The intermediate panels have engagement means by which they may be supported by the adjacent panels.

The use of the intermediate panels allows window panels to be fitted therebetween, a set of intermediate panels and windows panels together spanning the width of the roof in 35 place of a continuous (standard) panel.

- 7 - The roofing system may be used on individual buildings having gable means on opposed walls. Also, it may be used on terraced buildings having two end gable means at the opposed ends of the building, and a series of intermediate 5 gable means located therebetween along the terrace.

Usually, the intermediate gable means will lie upon the intermediate walls separating adjacent dwellings in the terrace. In such embodiments, the system will include intermediate gable means which may include a groove which 10 could be identical to that of the end gable means, and panels adapted to span the distance between an end gable means and an intermediate gable means and between adjacent intermediate gable means. The ends of the panels can be adapted to abut at the intermediate gable means, and may 15 include a partial tongue, so that the two partial tongues of the abutting panels together engage the groove of the intermediate gable means.

According to a second aspect of the invention, there is 20 provided a roofing system for a building, the building having four walls, an opposed two of the walls including gable means, the roofing system comprising a number of panels which can span the distance between the gable means and be supported thereby, characterized by intermediate 25 panels which cannot span the distance between the gable means, and by cooperating surfaces on the panels and the intermediate panels whereby the intermediate panels can be supported by the adjacent panels.

30 Preferably, the cooperating surfaces are complementary step-

formations. Preferably also, the cooperating surfaces lie along substantially the full length of the longitudinal edges of the panels and intermediate panels.

35 The invention also provides a roof panel for use in a roofing system as defined herein.

- 8 - BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which: Fig.1 shows a crosssectional view through a roof panel according to the invention, and includes certain details of a roof in which the panel has been installed; Fig.2 shows a cross-section through the panels which make up a typical roof, and the roof made therefrom; 15 Fig.3 shows a plan view of the panels which make up one side of a typical roof; Fig.4 shows a crosssectional view of the cooperating surfaces of adjacent panels; Fig. 5 shows a perspective view of the tongue and groove connection between a panel and an end gable means; Fig.6 shows a cross-sectional view of the tongue and 25 groove connection of Fig.5; Fig.7 shows a cross-sectional view of the tongue and groove connection between two abutting panels and an intermediate gable means; Fig.8 shows an end view of an eaves panel; Fig.9 shows a perspective view of a building and two prefabricated gable panels for fitment thereto; 35 and, Fig.10 shows a support member for use in a method of constructing a roof according to the invention.

9 - DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Fig.1 shows a cross-sectional view of a roof panel 10. The panel comprises a first sheet 12 (which is the innermost 5 sheet in use), and a second sheet 14 (which is the outermost sheet in use), which are interconnected by four longitudinal beams 16. Insulating material 18 fills the volume between the sheets 12 and 14 which is not occupied by the beams 16.

10 It is desirable but not essential that the panels be made from renewable and recyclable materials, and natural materials such as wood are preferred. In this (preferred) embodiment the beams 16 are of wood, the sheet 12 is of plywood, and the sheet 14 is of fibreboard. The beams 16 in 15 this embodiment have cross-sectional dimensions of approximately 50 mm by 197 mm, and the sheets 12, 14 are approximately 12 mm thick.

To ensure the required weatherproofing, the outermost sheet 20 14 includes a weatherproof material, and preferably a "breathable" material; in this embodiment, therefore, the sheet 14 comprises a sheet of Kronotex (RTM) fibreboard, this material being a one-way "breathable" material adapted for use in roofing applications. Though not shown in the 25 drawings, part of the weatherproof material projects beyond the edge of the panel and so can lap over the edge of the adjacent panel in use, to prevent water ingress between the respective panels.

30 It is also desirable but not essential that the insulating material 18 is of natural material, and wool or other natural fibre is preferred.

The panel 10 also includes cooperating surfaces in the form 35 of stepformations 20 and 22 along its longitudinal side edges, part of the step formation 20 being provided by a wooden beam having approximate crosssectional dimensions of 36 by 72 mm, part of the step formation 22 being provided by

- 10 a wooden beam having approximate cross-sectional dimensions of 36 by 122 mm. It will be understood that the step-

formations 20 and 22 can interengage, i.e. it is possible to lie two panels 10 alongside each other with the step 5 formation 22 of one panel engaging the step-formation 20 of the adjacent panel.

The panel 10 is manufactured in a standard width (the width being the distance between the step-formations 20 and 22) of 10 approximately 1200 mm (though other widths, or sets of widths, may be utilized if desired). The panel 10 will be made in a length to suit the particular application, the maximum practical length for a panel having the dimensions and materials referred to being around 5.5 metres (which is 15 believed to encompass the majority of the low-cost domestic housing market). Clearly, if other materials are used in place of the wooden beams 16, such as purling of rolled steel or composite material, the maximum practical length may be greater than 5.5 metros. Accordingly, if a panel 20 length greater than 5.5 metres is desired this can be accomplished with the present invention by an appropriate choice of materials from which the panel is constructed (and it may also be desired to use different materials than those specified above for other reasons).

To provide the structural strength required it is necessary that the beams 16 be continuous for the length of the panel, and it is preferable that the sheets 12, 14 are also continuous or effectively continuous. In that regard, it is 30 presently only possible in the U.K. to procure plywood sheets up to 2 metres long, but it is possible chemically to bond highly chamferred ends of adjacent panels to produce longer panels. If, for example, the ends are chamferred and bonded over a length of around 50 mm the bonded joint can be 35 at least as strong as the basic material.

When assembled into a roof, a series of panels will be used to cover the roof, and then a set of counterbattens 24

- 11 -

(running from top to bottom of the side of the roof) will be fitted thereto. Sheets of underalate paper (not shown) are laid thereover, and the roof is finished with the tiling battens 26 and tiles (not shown) in conventional fashion.

5 It will be understood that since the plywood sheet 12 faces the interior of the loft space, no surface finishing may be required in some applications. However, the joints between adjacent panels would be visible, and if finishing is required a set of counterbattens 30 may be added, to which 10 plasterboard 32 can be fitted. Such finishing would have the additional benefit of creating a hidden space for the location of services, and services could be incorporated into the space without needing to cut into the panels (which cutting may weaken the panels and/or reduce the thermal 15 insulation provided thereby.

The panels which will make up a typical roof are shown in Figs. 2 and 3. Adjacent the opposed walls which do not have the gable means are located eaves panels 40. The eaves 20 panels 40 are shown in Fig.8, and will be described in more detail later on. The uppermost longitudinal edge of each eaves panel has a step-formation 22.

Above each eaves panel is a standard panel 10, the step 25 formation 20 of the panel 10 engaging with the step-

formation 22 of the eaves panel 40.

Above the standard panel 10 is a set of intermediate panels 44. As better seen in Fig.3, the intermediate panels 44 are 30 shorter than the (standard) panels 10, and in particular are not long enough to engage both gable means. Accordingly, the intermediate panels 44 must be supported by the panels 10 to either side, and cannot rely solely upon being supported by the gable means. The intermediate panels 44 35 therefore include a step-formation 20 along each of the longitudinal edges, which step-formation 20 can engage (and be supported by) the step formation 22 on the adjacent panels 10. The inclusion of intermediate panels 44 leaves

- 12 openings 46 (Fig 3) therebetween, which openings can accommodate window panels (not shown). The window panels are ideally constructed with top and bottom edges having step-formations such as 20, or edge formations which can 5 cooperate with and be supported by the step- formations 22 of the adjacent panels 10. Alternatively or additionally, the intermediate panels 44 can include step-formations or the like to support the side edges of the window panels.

10 Above the intermediate panels is another standard panel 10, and above that an apex panel 48 and a set of ridge blocks 38. The dimensions of the apex panel 48 are suited to the angle and width of the particular roof, it being expected that different-width apex panels 48 will need to be provided 15 to suit differently-angled and -sized roofs.

The roof shown in Fig.2 has a set of intermediate panels 44 on either side of the roof, so that windows can be installed in both sides of the roof. In other roofs, windows may be 20 desired only in one side, and in such embodiments one set of intermediate panels 44 would be replaced by a standard panel 10. Because a standard panel 10 has a step-formation 20 and a step-formation 22, it will be understood that replacing the intermediate panels 44 (which have two step-formations 25 20) with a standard panel 10 will require the step-

formations of the panels higher up the roof to be altered.

The step-formations of a standard panel 10 can be altered (reversed) by rotating the panel through 180 about an axis perpendicular to the plane of the panel. The step 30 formations of the apex panels cannot be reversed, however, and apex panels with step-formations 20 would need to be provided. It will therefore be understood that roofs of any width, and 35 with the sides at substantially any angle, with or without windows in both sides, can be constructed from standard panels 10, 22 and 44, with only the apex panels needing to be configured for the particular application. Despite the

- 13 different apex panels which will be required, however, a considerable amount of standardization can be incorporated into the roofing system of the invention. If more standardization is required of the apex panels, it can of 5 course be decided that both sides of all roofs will have windows and a set of intermediate panels 44, so that all apex panels have a step-formation 22 and it is not necessary to manufacture apex panels with a step-formation 20.

10 The large degree of standardization available with the invention can facilitate concurrence with the building regulations. Thus, in the U.K. for example bulding regulations stipulate that the stresses on each load bearing member in a structure be calculated; using standard panels 15 simplifies those calculations, and means that any re-

calculation due to a change in specification may be more

easily undertaken.

Figs. 5 and 6 show the tongue 50 and groove 52 connection 20 between the end of the panels 10 (and also the panels 40, 44 and 48 if desired) and the gable means 54. In this embodiment the panel 10 carries the tongue 50 and the gable means 54 carries the groove 52, but this could be reversed if desired. Also, in this embodiment the tongue 50 is a 25 discrete tongue located adjacent the corner of the panel (there being one tongue adjacent each of the four corners); in other embodiments the tongue is continuous across the width of the panel. The groove 52 is continuous across the gable means 54 to ensure that the tongues of all of the 30 panels can locate thereinto, whatever their configuration.

The tongue 50 has inclined walls 56 and a flat bottom 60, and the groove 52 is correspondingly-shaped. The flat bottom 60 defines the bearing surface upon which a part of 35 the weight of the panel 10 can be supported. The inclined walls 56 facilitate ease of insertion of the tongue 50 into the groove 52. When the roof is assembled, the weight of the panels 10, 40, 44, 48 rests upon the gable means 54, and

- 14 the fixed location of the tongue 50 upon the panels, help to ensure that the spacing between the gable means 54 is maintained, i.e. the roof panels 10 (and also perhaps the eaves panels 40 and the apex panels 48) ensure that the 5 gable means 54 cannot move together or apart. The structure is therefore made more secure against applied loads such as wind loads.

If desired, the inclination on the walls 56 of the tongue 50 10 can be identical to the inclination of the side walls 58 of the groove 52; alternatively, the inclinations can differ, which might be necessary if it is desired that the walls 56, 58 will not foul one another as a result of manufacturing tolerances. When the panels have been assembled onto the gable means 54, they may be secured there by way of screws passing through the panel and into the gable means, ensuring that the screw passes through and into the structural timber of the panel 20 and gable means.

The gable means 54 of Figs. 5 and 6 is an end gable means, i.e. it is one of the two gable means of an individual building, or it is an end gable means of a terraced 25 building. Because the length of a terraced building (between its end gable means) will usually exceed the maximum practical length of the panels 10 (etc.), a terraced building will be provided with intermediate gable means between the end gable means. Since the gable means must 30 support the weight of the roof, it must itself be strongly supported, and it will typically be arranged that the intermediate gable means are supported upon the intermediate walls separating the homes within the terrace (i.e. a terrace of four homes will have two end walls and three 35 intermediate walls, and a similar number of gable means).

So that the maximum length of the panels can be maintained at around 5.5 metres it is desired to abut two adjacent panels at an intermediate gable means.

- 15 Since it is desired to maintain the tongue and groove arrangement between the gable means and panel", an exploded cross-sectional view of a suitable structure is shown in Fig.7. In this embodiment, each panel 110 has a "half 5 tongue" 150 at its end, which can engage in a groove 152 of the intermediate gable means 154. If desired, the groove 152 can be identical to the groove 52, and the "half-

tongues" 150 suitably configured to locate therein. In this embodiment, one function of the inclined walls 156 and 158 10 is to urge together the abutting ends of the panels 110, and to ensure that the panels remain in abutment.

The eaves panel 40 is shown in Fig. 8 (and also in Figs 2 and 3). The eaves panel 40 comprises a structure of wood, 15 plywood, fibreboard and insulating material as are the other panels 10 etc. The eaves panel 40 carries lateral beams 62 which are designed to overlie the side walls of the building, in known fashion. It is arranged that the eaves panel 40, including the lateral beams 62, is the same 20 thickness as the other panels 10 etc., so that together they present a flat surface for the addition of the counterbeams 24 (see Fig.1).

The gable means 54, 154 are constructed as prefabricated 25 panels, and are designed to be assembled together with the roof panels 10 etc. by the roof installer/assembler. Such prefabricated gable panels have the considerable advantage that the brickwork for the building 100 (Fig.9) can stop at the same level (i.e. the wall plate level) for each of the 30 four walls.

Alternatively, the gable means may be constructed out of brickwork or Clockwork, the bricks or blocks being continued beyond the wall plate level for the gables. This 35 alternative arrangement has a known disadvantage in that the bricklayer must stop laying bricks at the wall plate level in any event whilst other construction work in undertaken, and must then continue the brickwork or Clockwork for the

- 16 gables at a later time; it is not always convenient or efficient for the bricklayer to do this, and a system which allows all of the brickwork to be undertaken as an uninterrupted operation is highly desirable.

The gable means 54, 154 is a panel of triangular shape (the shape of the gable means determining the shape of the roof), and may if desired be constructed of wood beams and plywood and fibreboard sheets as are the panels 10 etc. Fig.10 shows a part of the building 100 with the roof beingconstructed in accordance with the invention, the roof being mounted upon spandrel panels 54 (only one of which is shown) which are themselves mounted upon the brickwork of the 15 building 100 as in the embodiment of Fig.9. Despite being secured to the brickwork in known fashion, it will be understood that prior to location of the panels 10 etc. the spandrel panels 54 are liable to sideways movement caused by winds for example. In a method according to the invention a 20 support member 70 is used to secure the spandrel panel 54 in position until the spandrel panel has been secured by one or more fitted panels 10 etc. It is a particular feature of the support member 70 that it 25 can be fitted from around the height of the top of the brickwork of the building 100, and the fitter does not need to access the top of the spandrel panels themselves.

Clearly, there is a considerable advantage in terms of health and safety if the fitter only need access to this 30 lower height on the building site.

The support member 70 includes a cup-shaped bracket 72, a mounting plate 74, and a bracing member 76 joining the bracket 72 to the mounting plate The cup-shaped bracket 72 35 is adapted to be placed over the top of the spandrel panel, one side wall 80 of the bracket engaging one side of the spandrel panel 54 and the other side wall 82 engaging the other side of the spandrel panel. It is not necessary that

- 17 the side walls 80,82 are a tight fit upon the spandrel panel, and indeed the support member 70 is easier to fit if there is some freedom therebetween; it is expected that a few millimetres of clearance is all that is required to 5 facilitate fitment and yet restrict the spandrel panel to movements within the tolerance allowed by the cooperating tongue 50 and groove 52. If desired, to increase ease of fitment further, the extreme ends of the side walls 80,82 can be internally chamferred if desired.

The mounting plate 74 has a number of apertures (not shown) to receive fixing means such as screws or nails by which it may be fixed to a joist 84.

15 The mounting plate 74 is connected to the brace member 76 by a pivot 86, and the brace member is connected to the bracket 72 by another pivot 88. The pivots 86, 88 allow limited articulation between the bracket and brace member and the mounting member and brace member, respectively.

20 Accordingly, it is possible to fit the bracket 72 at any position of the spandrel, the higher up the spandrel 54 the bracket 72 is fitted (i.e. the nearer the apex of the spandrel panel 54) the greater the angle of the brace member 76. The hinges 86, 88 are adapted to allow sufficient 25 articulation for fitment to the highest and lowest parts of the spandrel panel 54.

In practice, it is expected that two or more support members 70 would be fitted to each spandrel panel to provide the 30 support required. Clearly, a greater number of support members 70 can be used when conditions require, such as when the roof is being constructed in a high wind, for example.

Whilst the pivot 88 in particular allows a considerable 35 degree of articulation between the brace member 76 and the bracket 72, it is desired that the pivot have sufficient friction that the fitter can place the bracket 72 in a chosen position relative to the brace member 76, and the

bracket 72 will retain this position, i.e. the weight of the bracket tending to force the bracket to pivot downardly is less than the frictional force maintaining it in position.

This allows the fitter to hold the support member 70 5 adjacent the mounting member 74 and manipulate the bracket 72 over the spandrel at the chosen height. It is not necessary that the fitter choose the angle of articulation exactly since by manipulating the bracket when this engages the spandrel panel 54 the fitter can ensure that the 10 articulation is correct to allow the side walls 80, 82 to engage respective sides of the spandrel panel.

When the bracket 72 has been placed over the chosen part of the spandrel panel 54 the mounting member can be secured to 15 a joist 84 of the building. To allow fine adjustment, in case the spandrel panel 54 is not held precisely vertical during fitment, the brace member 76 is in two parts which are held together by a collar 90, the two parts of the brace member 76 having opposite threads and the collar 90 being 20 correspondingly threaded whereby rotation of the collar in one direction reduces the length of the brace member (and moves the bracket 72 towards the mounting member 74) and rotation of the collar in the other director increases the length of the brace member (and moves the bracket 72 away 25 from the mounting member 74).

It will be understood that one or more support members 70 can be fitted to the spandrel panel whilst this is still supported by the crane which lifted the spandrel panel into 30 place, so that the spandrel panel 54 is only released from the crane when it is adequately supported.

A major advantage of the roof system according to the invention is that substantially all of the weight of the 35 roof is supported by the end walls (and intermediate walls if present) of the building. Accordingly, each dwelling requires no internal walls to provide support for the roof.

If in due course it is required to renovate the dwelling the

- 19 entire interior (including any non-supporting internal walls) may be removed and replaced without the roof needing also to be removed.

S As above indicated, it is preferable that the roof panels be made of renewable and recyclable materials, but this is not essential. Parts or the panels can for example be made of metals such as steel or aluminium, or composite materials such as reinforced plastics and fibreglass. It would for 10 example be possible to use a timber, metallic or composite skin over a framework of any suitable timber, metal or composite material. Also, whilst only certain timber materials have been described herein, it will be apparent that other timber materials could be used, such as any of 15 the many available proprietary laminated timber materials for example. Also, structural I-beams are known to be made of a material called "OSB", and beams of this material may be utilized in the roof panels. Furthermore, whilst in the foregoing disclosure the structural strength of the panel

20 comes from the timber framework with the insulating infill providing little or no stuctural strength, foam materials are available which provide insulation and also rigidity, and such materials may be used to provide structural strength for the panel.

Claims (18)

1. A roofing system for a building, the building having four walls, an opposed two of the walls including gable means, the roofing system comprising a number of roof panels which can span the distance between the gable means and be supported thereby and a number of intermediate panels which cannot span the distance between the gable means, the roof panels and the intermediate panels having cooperating surfaces whereby the intermediate panels can be supported by the roof panels.

2. A roofing system according to claim 1 in which the cooperating surfaces are complementary step-formations.

3. A roofing system according to claim 1 or claim 2 in which the cooperating surfaces lie along substantially the full length of the longitudinal edges of the roof panels and the intermediate panels.

4. A roofing system according to any one of claims 1-3 in which the roofing system includes at least two roof panels and at least one set of intermediate panels, the set of intermediate panels being arranged between two roof panels.

5. A roofing system according to any one of claims 1-4 including two eaves panels, the eaves panels each having complementary cooperating surfaces for engagement with one of the roof panels.

6. A roofing system according to any one of claims 1-5 including two apex panels, the apex panels each having complementary cooperating surfaces for engagement with one of the roof panels.

- 21 A roofing system according to any one of claims 1-6 in which the gable means includes one of a tongue and groove, and in which the ends of the roof panels include a respective groove and tongue for location with the gable means.

8. A roofing system according to claim 7 in which the groove is located on the gable means and the tongue is located on the ends of the panels.

9. A roofing system according to claim 7 or claim 8 in which the tongue and groove have inclined sides and a flat bottom.

10. A roofing system according to any one of claims 7-9 in which the groove is continuous across the gable means or roof panel.

11. A roofing system according to claim 10 in which the tongue is continuous across the ends of the roof panel or gable means.

12. A roofing system according to any one of claims 7-11 for use on a terraced building having two end gable means at the opposed ends of the building and a series of intermediate gable means located therebetween along the terrace, the intermediate gable means including a groove, the roof panels being adapted to span the distance between an end gable means and an intermediate gable means and between adjacent intermediate gable means, the roof panels including a partial tongue, the two partial tongues of abutting roof panels together engaging the groove of an intermediate gable means.

13. A roof panel for use in a roofing system as defined in any one of claims 1-12.

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14. A method of assembling a roof of a building, the building having four walls, an opposed two of the walls including gable means, the method including the use of a roofing system according to any one of claims 1-12.

15. A method according to claim 14 in which the gable means comprise spandrel panels mounted upon the brickwork of the building, the method including the step of supporting the spandrel panels with at least one support member, the support member having bracket means adapted to locate upon a part of the spandrel panel, mounting means adapted for mounting upon a joist of the building, and bracing means connecting the bracket means to the mounting means.

16. A method according to claim 15 in which the support means has a first pivot means between the bracket means and the bracing means and a second pivot means between the mounting means and the bracing means.

17. A method according to claim 15 or claim 16 in which the bracing means is adjustable in length.

18. A roofing system constructed and arranged substantially as described in relation to Figs. 1-6, 8 and 9, or Fig.7, of the accompanying drawings.