In the patent specification of WO-A-96/25632 and EP-A-0384787, there is disclosed a solar energy collector, a number of which can be incorporated into the south facing part of the roofofa house.

Each solar energy collector is incorporated into a roof panel having its own supports which act as rafters, when in position on a roof construction.

The construction of a roof of the kind referred to requires the use of a crane to lift each panel into position. The alignment and securing of the individual panels to construct the roof is difficult and time consuming.

One object of the present invention is to provide a method of constructing a roof, the method being more efficient than the conventional method and using novel roof panels.

The invention accordingly provides a pair of elongate roof panels hingedly connected together at one end and angularly movable about the hinged end from a collapsed position in which the panels lie in parallel spaced apart relationship to an operative position as part of a roof construction in which the panels are splayed apart so that the hinged ends connect to form part of the ridge of the roof construction.

Advantageously, the panels are hingedly connected together by a pair of hinges, each connected internally of each panel so that consecutive pairs of panels can be connected side by side without a gap between the pairs of panels and so that the hinges can be removed from the interior of the roof when constructed.

Each panel may consist of three rafters connected together in mutually parallel disposition by a plurality of bridging elements connected between the middle rafter and each outer rafter, the outer rafters being bevelled at the hinged end and also connected together at the hinged end thereof by a bridging element disposed at the same inclination as the bevelled edges and forming a T-junction with the contiguous end of the middle rafter.

Each hinge may comprise a pair of arms, each arm protruding from the rafter to which it is connected at a predetermined angle, the protruding arms being pivotally connected together at a point eccentric to and equidistant from the near corner of each of the bevelled edges.

The invention also provides a method of constructing a roof on a partially constructed dwelling which comprises the following steps a) lifting the pair of roof panels above the dwelling on which the roof is to be constructed so that the hinged ends are uppermost, b) lowering the pair of roof panels towards the dwelling, c) splaying apart the lower ends of the panels so that.the hinged ends connect to form part of the ridge, d) connecting the lower ends of the panels over the side walls of the dwelling, e) repeating operations a), b), c) and d), with a second pair of roof panels, f) joining the second pair to the first pair, and g) repeating operations a) to f) to form a complete roof construction.

The invention will hereinafter be described more particularly with reference to the accompanying drawings which illustrate, by way of example only, a preferred embodiment of the pair of roof panels and a preferred method of constructing the roof.

In the drawings Figure 1 is a perspective view of a roof panel.

Figure 2 is an end view of a pair of such panels hinged together at one end and disposed in the collapsed or transport position.

Figure 3 is an end view of the pair of panels in the fully open position in which the hinged ends meet to form part of the ridge of a roof construction.

Figure 4 is a diagrammatic view of the pair of panels being lifted by a crane from a transport vehicle and another pair in the collapsed or transport position on the vehicle.

Figure 5 is a diagrammatic view of the pair of panels being lowered by the crane onto the attic floor of a partially built.

Figure 6 shows a pair of panels connected to the floor and secured together.

Figure 7 shows two pairs of roof panels in juxtaposed position on the dwelling.

Figure 8 shows to an enlarged scale, a detail of Figure 6.

Figure 9 shows a detail of a construction upon a wooden, rather than a concrete, floor.

Referring to the drawings, and initially to Figure 1, the roof panel 8 comprises three elongate rafters 15, secured together by a transverse bridging element 22, which forms part of the ridge of the building, and by transverse bridging elements 23 intermediate the ends of the rafters 15.

In figure 2 is shown two such panels 8 and 8a, hinged together at one end thereof, the panels 8 and 8a being shown in a collapsed position.

In the collapsed position, the panels are held in mutually parallel spaced apart relationship by transverse battons 31 which prevent corresponding brackets 32a, 32b, 34a, 34b on

rafters 15 from abutting against each other in the collapsed position of the hinged pair of panels.

The two panels 8 and 8a are hinged together at one end by a pair of special hinges 10, only one of which is shown in Figure 2. Each hinge 10 consists of two brackets 16, 17 connected together at one end by a pivot pin 18. Bracket 16 is secured by screws 25 to the inner face of the outer rafter 15 of panel 8 and bracket 17 is secured by screws 26 to the inner face of the outer rafter 15 of panel 8a. The end of the rafters adjacent the hinge 10 have bevelled edges 20, 21. Each bracket 16, 17 is aligned in its correct orientation relative to the bevelled edges 20, 21 of the rafters 15 so that when the panels are opened about the hinge 10, the bevelled edges 20, 21 make contact with one another to form part of the ridge as shown in Figure 3.

The panels according to the invention can most conveniently be used to construct a roof on a partially built dwelling between the gable ends of the dwelling and over a floor supported upon the side walls of the dwelling, as shown in Figure 6.

In the construction of the roof, the prefabricated panels 8 are transported to the site of the partially constructed dwelling 61 and are lifted by a crane 62 from the transporting vehicle 63 to a position above the dwelling 61 and then lowered into position. The flexible link 65 on the crane passes under the bridging elements 22.

The pair of panels 8 are lifted at the hinged ends so that on being lowered into position on the dwelling 61 operators 66 on scaffolding 67 on the upper or attic floor 43 simply open the hinged panels, and connect the wall plate brackets 34a, 34b on the splayed ends of the panels 8 to the co-operating wall plates 45 on the floor 43, the disposition of the wall plate brackets 34a, 34b on the panels 8 being predetermined so that the free ends of the panels 8 depend below the floor 43 and overlap the upper ends of the side walls 47 of the dwelling 61.

The panels 8 are then further secured in position, with the bevelled edges 20, 21 contacting one another, by bolts 51 passing through the transverse bridging elements 22 which then form the ridge of the roof structure as shown in Figures 7 and 8. The transverse bridging elements are further secured in position between the outer rafters 15 by brackets 78 (see Figure 8).

Additionally, the collar tie brackets 32a, 32b on the panels adjacent the hinged ends are connected together by a collar tie 52. Finally, the panels are further supported in position by purlins 53 or structural studs connected between the floor 43 and a position intermediate the ends of the panels 8.

When the panels are fully connected as described, the hinges 10 are no longer required and may be removed if desired.

A further pair of hinged panels is then lifted into and secured in position as described and is then secured to the adjacent previously installed pair of panels by nails 55, as shown in Figure 7.

The roof construction according to the invention can be used to support solar energy collectors 75 and in particular solar energy collectors of the kind described in WO-A-96/25632 and EP-A-0384787. The solar energy collectors 75 are connected to one of the panels in the pair of panels and are installed so that the solar energy collectors face south in the construction of the roof. The roof can then be finished in a conventional manner, for example, by the addition of insulation, water proofing materials and battens to support tiles.

Not only is the hinge 10 connected internally to the pair of panels 8, but because the pivot point is eccentric relative to the contiguous corners of the bevelled edges 20, 21 of the rafters 15 to which the hinges 10 are connected, the collar tie brackets 32a, 32b and wall plate brackets 34a, 34b can all be secured to the inner face of the outer rafters 15. Batton type spacers 31 are used between the panels 8 so that when the hinged pair of panels 8 is

being stored and transported, the mutually opposite brackets 32a, 32b, and 34a, 34b are separated one from the other and are not damaged.

Additionally, because the brackets 32a, 32b, 34a and 34b are secured internally of the outer rafters 15, pairs of panels can be bolted securely together as shown in Figure 7 by nails 55 without leaving a gap between the panels.

In Figure 6, a pair of panels is shown in position on a concrete floor.

A roof using pairs of panels 8 according to the invention can equally be constructed on a wooden attic floor over conventional rafters supported on concrete walls as shown in Figure 9.

The wooden attic floor can conveniently be constructed using plywood decking 75 on which are supported wooden wall plates 76 secured to the edges of the decking 75 and bevelled on the inside to present a right angle to the angle at which the roof panels 8 are disposed relative to the attic floor. In this construction, the lower ends of the panels 8 do not overlap the side walls 77 so that (1) the spacing of the roof rafters is independent of the spacing of the floor joists and (2) the floor area is independent of the width between the side walls 77. Thus the construction shown in Figure 9 can provide an attic floor area larger than the area defined between the side walls 77.