GB2212833A - Laminated panels for pitched roof - Google Patents

Abstract

A stressed skin pitched roof is formed by one or more panels (10) each panel (10) having outer sheets or skins (14) and an expanded plastics material bonded or self-bonded to the sheets so that the foam provides structural strength. In one embodiment the panels (10) provide substantially the only structural components. In a second embodiment a comparatively small frame is bonded to the inner surface of opposed sheets (14) with a view to preventing relative motion between the sheets under prolonged and variable loading.

Description

PITCHED ROOF STRUCTURES n r) 12 8,3 3 This invention relates to roof

structure assemblies and to buildings incorporating such assemblies.

It is conventional practice for especially for domestic purposes, to of roof trusses and purlins which, framework, serve to support battens slates are secured, generally with roofing felt. Of recent years the been pre-fabricated off site since enables the amount of site work to costs and also of roof structures, comprise a series as an assembled to which tiles or an underlayer of roof trusses have this arrangement be reduced, thus saving ensuring more consistent quality in the joints between the members of each truss.

Although there have been minor changes in the details of roof construction of recent years, basically there has been no change over many centuries. Conventional structures, even when incorporating roofing felt, have the disadvantage that the thermal insulating value is very low and because of this, it is essential to ventilate roof spaces since, otherwise, condensation under certain climatic conditions gives rise to dampness problems. The need for ventilation in turn gives rise to a requirement which is currently being met in many 2 - domestic dwellings and other buildings of providing insulating layers between the joists which support the uppermost ceiling of the building. As a consequence problems arise with pipes in the loft space which are more liable to freeze under winter conditions and, in high winds the risk of tiles or slates being displaced is materially increased because of the internal pressure increase and external pressure decrease on the leeward side of a pitched roof.

Where current designs of roof trusses are employed, the number of members which are required in each truss in order to give adequate strength means that the loft space becomes awkward for use of any kind and if there is a requirement for converting the loft space into a room, appreciable and costly modifications are necessary to the roof trusses. These prefabricated timber roof trusses also have the potential disadvantage that the joints are held together merely by pairs of galvanized plates which have doked spikes which are hammered or pressed into the timber. While the plates are galvanized, the doked spikes are formed after galvanizing so that there is no protection to the edge surfaces and the inevitably rather damp conditions in loft spaces will eventually lead to failure of the joints and ultimately failure of the whole roof.

- 3 With a view to overcoming the problems of conventional pitched roof construction, proposals have been made, for example to use a stressed skin construction in which conventional rafters are sandwiched between sheet material such as plywood and insulating material is infilled between the sheets on site. One such construction is disclosed in the journal "Building Today" pages 28-29 for November 5, 1987. The construction described does provide an advance over conventional roofs as no trusses are required, thus leaving a clear loft space. However, the amount of site work is little reduced in comparison with conventional roof assembly operations.

In the Netherlands stressed skin roofs with insulation between the skins have been in use for some years as indicated in EP-A-0 284 319 but problems have been encountered with condensation causing loss of strength as the skins become saturated especially if rot, whether dry or wet occurs. EP-A-0 284 319 proposes to overcome the condensation problem by spacing the skins by means of structural timber and providing a space between an insulating layer and the inner face of the outer skin. This arrangement may well overcome the condensation problem but as a result there is no possibility that the insulating layer will contribute to the structural strength of the opposed skins or sheets.

- 4 The structural timber disclosed in EP-A-0 284 319 presents the di. sadvantage that special panels have to be provided at roof hips or if the roof involves any complexity. In other words, if the roof has any form other than a conventional inverted V, problems will arise if only standard panels are available.

With the inherent disadvantages of conventional roof structure assemblies in mind, it is the general object of the present invention to provide an improved roof structure assembly.

According to the present invention there is provided a roof structure assembly comprising at least one composite panel the or each panel incorporating opposed outer sheets and an intermediate layer of rigid, expanded, material bonded to the inner face of each panel, and a frame intermediate the top and bottom of the or each panel secured to the inner faces of each sheet, the frame occupying only a comparatively small area of the panel, the or each panel being mounted substantially completely to define structurally a section of roof of selected pitch, at least one edge of the or each panel being arranged to be supported by wall structure of an associated building.

- 5 According to the present invention there is further provided a roof structure assembly comprising at least one pair of composite panels each panel incorporating opposed outer sheets, an intermediate layer of rigid, expanded, material bonded to the inner face of each panel, and a frame intermediate the top and bottom of each panel secured to the inner faces of the respective sheets, each frame occupying only a comparatively small area of the panel, the or each pair of panels being mounted substantially completely to define structurally a section of roof of selected pitch.

According to the present invention there is still further provided a roof structure assembly comprising at least one pair of composite panels, each panel incorporating opposed outer sheets, an intermediate layer of rigid, expanded, material bonded to the inner face of each panel, and a timber frame intermediate the top and bottom of each panel secured to the inner faces of the respective sheets, each frame occupying only a comaratively small area of the panel; the or each pair being mounted substantially completely to define structurally a section of roof of selected pitch, means at the ri dge or apex connecting the upper edge portions of each pair together and support framework means disposed at a lower edge portion of each composite panel, which framework means are arranged to be carried by structure of an associated building.

According to the present invention there is yet further provided a pitched roof structure assembly comprising at least one pair Io f composite panels each panel incorporating opposed outer sheets of relatively dense material, an intermediate layer of rigid, extruded, expanded, polymeric material, a timber framework secured to and lying between the outer sheets whereby to prevent relative movement of the sheets, the or each pair of panels being mounted substantially completely to define structurally a section of roof of selected pitch, means connecting the upper edge portions of each pair together and support framework means disposed at or adjacent a lower edge portion of each composite panel, which framework means are arranged to be carried by other structures of an associated building.

According to the present invention there is yet still further provided a roof structure assembly comprising pairs of composite panels, each panel incorporating opposed outer wooden sheets, an intermediate layer of rigid, 'extruded, expanded, polymeric material, adhesively bonded to the opposed inner faces of the sheets, a timber framework interposed between and bonded to the inner faces of the sheets whereby to prevent relative motion of the sheets, each pair being mounted substantially completely to define structurally a section of roof of selected pitch, means at the ridge or apex connecting the upper edge portions of each pair together and wooden support framework means disposed at a lower edge portion of each composite panel, which framework means are arranged to be carried by joists spanning the walls of the associated building.

A roof structure assembly embodying the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which:

Figure 1 is a cross-section through a building incorporating a roof structure assembly in accordance with the present invention; Figure 2 is an inverted plan view of a fragment of the apex or ridge portion of the roof assembly; Figure 3 is a fragmentary cross-section showing connecting means at the apex or ridge of the roof assembly; Figure 4 shows a bolt assembly as used in the ridge construction of Figure 3; - 8 Figure 5 is a fragmentary cross-section illustrating a lower edge portion of a roof assembly in accordance with the invention; Figure 6 is an alternative, cantilevered modification of an edge portion of the roof assembly in accordance with the invention; Figure 7 is an exploded, isometric view showing support framework structure at a lower edge portion of the roof assembly; Figure 8 is a section on the line 8-8 of Figure 1; Figure 9 illustrates in cross-section a connecting means between a composite sheet panel and a framework structure of the roofing assembly.

Figure 10 is an end elevation similar to Figure 1 but showing modifications; Figure 11 is a plan view of the structure of the roof of Figure 10; Figure 12 is an outline end view of the roof structure of Figures 10 and 11 indicating the locations of details fully shown in subsequent Figures; Figure 13 is a plan view showing structure within a single panel of the roof of Figures 10 to 12; Figure 14 is a section on the line 14-14 of Figure 13; Figure 15 is an end elevation of detail A in Figure 12; Figure 16 is a plan view of the detail of Figure 15; Figure 17 is an isometric view of one part of a hinge assembly shown in Figures 15 and 16; Figure 18 is an end elevation of an alternative of detail A of Figure 12; Figure 19 is a plan view of Figure 18; Figure 20 is an end elevation of a further alternative of detail A of Figure 12; Figure 21 is a plan view of Figure 20; Figure 22 is an end elevation of detail B of Figure 12; Figure 23 is a perspective view of detail B; - Figure 24 is an end elevation of detail C of Figure 12; and Figure 25 is a view in the direction X in Figure 24.

Referring now to the drawings, a roof structure assembly embodying the invention comprises, basically, two panels 10 connected together at the ridge or apex of the roof and supported at the lower edge portions by two opposed wooden frameworks 12 each in the form of an outline of a right prism. Each panel comprises two sheets 14 of plywood 'such as Finnish birch plywood to Finnish Standard SFS 2412, Finnish faced plywood to Finnish Standard SFS 2416, Finnish Conifer plywood to Finnish Standard SFS 4091 or marine plywood. Preferably the sheets are one piece, that is no laps or splices.

An intermediate layer 16 of extruded, expanded, polystyrene or other rigid, expanded polymeric material is provided. The intermediate layer is bonded to the inner surfaces of the outer sheets with an adhesive which does not permit an creep over an extended period. Such adhesives are defined in British Standard 6566: PT8, 1985. Examples of other possible material in extruded polystyrene polyisocyanurates, p.v.c., glass, Dlace of are polyurethane, phenol-formaldehyde, - 1 1 - and a.b.s. Polyurethane is a preferred foamed material. it can be preformed but preferably it is foamed in situ between the outer sheets so as to take advantage of self-bonding in relation to plywood. Self-bonding ensures that the panels are not subject t6 any substantial creep when subject to a permanent load. Under certain conditions, (span, location etc.) it is also possible that conventional expanded polystyrene (beadboard) will be suitable. Extruded, expanded polystyrene is manufactured by Dow Chemical Corporation and marketed under the Registered Trade Mark STYROFOAM. Expanded, foamed, glass, although expensive would provide an excellent intermediate layer. It is available from Corning Glass Works.

The outer sheets preferably have a thickness of at least 6 mm and the intermediate layer of expanded polymeric material has a thickness of at least 50 mm. This thickness is necessary to prevent condensation as a result of temperature changes in the atmosphere. With other materials of different insulating value the thickness will be varied according to properties. As an alternative to plywood, Sterling board is a possibility where requirements from a climatic standpoint are less onerous than in the United Kingdom. Other possible materials for the outer skins or sheets are tempered hardboard, sheet aluminium, wood chipboard, thin sheet steel or even some plastics sheeting.

A preferred modular width of each panel is 2438 mm (8 feet) and the length will depend upon the width of the building and the esired pitch. For some purposes composites of this character have adequate strength to withstand wind forces, snow loads and other stresses normally encountered by roofs in the United Kingdom in addition to self weight. In this embodiment the panels require no overall supporting structure, but as will be apparent from the drawings, supporting structure 12 is provided adjacent the eaves of the building and each supporting structure or framework comprises an outline right prism with triangular end frames 18 built up from three members, vertical 20, horizontal 22 and inclined 24 and these end frames are interconnected by horizontally extending members 26, 28, 30 at each corner. These frameworks can be made larger or smaller than as illustrated, depending upon the amount of space required for services. The proportion of the span of the panels which is supported will depend upon the thickness of the panels.

The frameworks 12 are themselves supported on joists 32 which span the upper edges 34 of the inner leaves of the walls 36 of the building. These joists 32 preferably take the form of plywood box beams (see especially, Fig. 8). Each member of the framework 12 is of wood and the joints are made by any convenient conventional means (not shown). The frameworks are secured by bolts or screws (not shown) to the plywood box beams 32 and are secured to the roof panels either by metal angle section members 38 and bolts 40 or self-tapping screws or, preferably, by a hinge-like arrangement 42 (see especially Fig. 2) conventionally known as a piano hinge which comprises two plates 44, 46, one attached to each horizontal member 30 spanning the upper apices of end frames 12 and the undersurface of the triangular the panel 10. The plate abutting the panel is secured by an adhesive and by self-tapping screws. This alternative, but preferred, connection means is illustrated at the ridge or apex of the roof, but will be of similar construction when used in conjunction with frameworks 122. Each plate 44, 46 has several annular section portions 48, 50 (Figure 4) so that when assembled, the annular section portions of one plate alternate with the annular section portions of the other plate. A pin, bolt or other elongate member 52 which fits into the aligned annular portions secures the parts together. If desired a protruding end portion of a pin can be bent slightly out of alignment to prevent inadvertent 14 withdrawal although the friction forces will normally be adequate to retain the elongate member within the annular section members 48, 50 of the two co-operating plates.

At the ridge or apex 54, the two composite panels 10 are similarly interconnected by members generally in the form of a piano hinge and it is therefore not necessary to further describe these members. It is, however, to be noted that at the upper edge portions of each composite panel 10, solid pieces 56, preferably of wood, are inserted in place of the expanded foamed polymeric material to ensure that the securing pins, bolts or nails of the connecting means are adequately held in position. The pins or bolts should be a reasonably tight fit in the annular section members of the plates, with a view to avoiding relative movement which could cause wear in the long term. If bolts and nuts are used in order to ensure tightness, care must be taken to take into account differential expansion of the bolt and the panels.

As illustrated in Figure 1, the outside of the roof structure assembly is provided with conventional tiles 61 and ridge tiles 60 at the apex. Battens 62 and counter-battens 63 will be provided, again as is Y conventional, in order to provide mountings for the tiles. Both battens and counter-battens are necessary because otherwise any water which penetrates the tiles or slates will not be able to drain away as battens mounted directly on the panels will bar drainage. Other conventional roofing forms such as slates can be used or, alternatively the outer face of each panel may be provided with an impervious layer capable of resisting all weather conditions. The impervious layer can also be used additionally, when tiles or slates are employed as the external cladding.

As illustrated in Figure 1 the loft space can be used as a room so that the inner faces of the composite panels are clad with plasterboard 64 and plastered in the normal manner. Alternatively, the composite panels can be coated internally with intumescent paint, which provides both a finish and fire resistance to an acceptable standard. The apex or ridge portion can be blanked off with plasterboard 66.

Figures 2 and 3 illustrate the piano hinge connecting means at the ridge 54 and as will be apparent the plates of the hinge portions will be screwed to the wooden pieces 56 mounted between edge portions of the outer sheets 14 of the composite panel. The connecting means associated with the lower frameworks are generally the same.

Figure 4 illustrates a securing bolt 52 and two annular-section numbers 48, 50 associated each with one plate 44, 46 (not shown in this Figure). A nut 58 holds these parts firmly together. A pin or wire can be used alternatively.

Figures 5 and 6 illustrate eaves in two alternative versions. In Figure 5 gutter brackets 65 (only one shown) are mounted substantially directly on the vertical outer leaf 67 of the wall of the building and the lower edge 69 of the composite panel terminates only a short distance beyond the vertical outer face of the brickwork. A deflector 68 may be provided to ensure that all water running off the roof is collected in the gutter (not shown). It will be noted that the upper edge 70 of the wall 67 is chamfered at an angle precisely matching the pitch of the roof. Since many wall structures have a rough texture it may be desirable to provide a sealing member between the chamfered edge and the inner face of the composite panel. Such a sealing member may be conventional mortar or a special seal of mastic.

In Figure 6 the lower edge 69 of the composite panel 10 extends appreciably beyond the upper edge 70 of the associated wall, the gutter brackets 65 are supported t 17 - (at spaced intervals) along its length by frames 72.

Once again, the upper edge 70 of the wall is chamfered as in Figure 5.

Figures 7 and 8 illustrate the right prism outline framework structure 12 which supports one of the composite panels 10 adjacent the eaves and also shows the alternative fixing in the form of an angle plate 38 effective between the support framework and the composite panel. Figure 9 further illustrates the angle plate connecting means 38 effective between a panel 10 and one of the frameworks 12.

As will be understood, several pairs of panels 10 will be necessary to form most domestic roofs and even larger numbers will be required for buildings on a more substantial scale. Where site cranes are available it will even be possible to preassemble the composite pairs and the supporting framework together with the connecting means. Even less work will then be required on site. The inclined edges of the panels may be interconnected by blocks of wood let into edge portions in place of the expanded polymeric material and, if desired, the outer surface and indeed the inner surface (which surfaces may themselves be waterproofed) also may be provided with waterproof tape at the join line.

Appropriate adhesives can also be used to secure the panels together either alone or additionally to the blocks. It is important that the adhesive selected shall be capable of withstanding extreme weather conditions without loosing its adhesive properties and without allowing creep to occur between the opposed sheets even over a lengthy time period. As a further choice, timber or metal tongues in one edge can co-operate with grooves in the adjacent edge of the adjacent panel.

Alternatively, or even additionally, the composite sheets can be held together by the same connecting means which serve to connect pairs of opposed sheets. if bolts are used as the elongate member then it is readily possible to tighten these to the required degree and thus ensure very high rigidity between pairs of adjacent panels. Here, it will be necessary to take into account the effects of differential thermal expansion. Flooring can be mounted on the beams 32, possibly with intermediate joists, as necessary.

The embodiment hereinbefore described is very simple both because of the roof shape and of the materials used. Evenif a more complex roof shape is required the panels selected can be cut on site so that hips and joints can readily be formed. This does not apply where the panels incorporate a substantial internal framework.

While the construction hereinbefore described with reference to Figures I to 9 will, it is believed, be adequate for many purposes, roofs of larger span or roofs where arduous conditions may be encountered such as exposed sites will need a stronger construction and such a construction is illustrated with reference to Figures 10 to 25. Similar parts will be given the same reference numerals as in the first embodiments and these parts will not be further described.

In Figure 10 the two differences are the addition of ties 100 adjacent the apex 54, two such ties being used between pairs of panels 10, and the incorporation of a rectangular frame 102 having dimensions to accommodate a rooflight assembly, if and when required. If required, for even greater strength and wind resistance diagonals (not shown) are connected between the ties 100. The ends of the ties are secured at preformed holes in the opposed roof-light frames 102. One frame 102 is shown in Figure 10, the primary purpose being to prevent relative movement between the sheets 14 as a result of creep in the bonding layers over an extended period. The frames 102 are, in fact sandwiched between sheets 14 and will be firmly secured to the inner faces of both sheets. The frames have the secondary purpose of r endering the fitting of a rooflight assembly particularly straightforward as it is merely necessary to cut out the plywood and foamed material within the frame 102 and substitute the rooflight assembly.

As an alternative to ties 100, the same effect can be achieved by securing a sheet of plywood between the upper horizontal members of the frames 102. Again the opposed edges of the horizontal plywood sheets can be secured with the aid of pre-drilled holes in the upper horizontal members of the frames 102.

Figure 11 shows the roof of Figure 10 in plan view, the rooflight frames being shown in each panel 10. It will be assumed that one plywood sheet 14 has been omitted. The panels are further reinforced by diagonal timber members 104 which are bonded to the inner faces of each sheet. For additional rigidity lighter diagonals 106 may be provided within each frame 102. For identification purposes the apex or ridge has been indicated by line 54, the location of the ties by line 100, the location of the cill of a rooflight frame by line 108 and the location of the eaves by line 110.

- 21 Turning now to the details of the second embodiment, as shown in Figure 12 detail A relates to the hinge assembly at the ridge or apex, detail B relates to a first internal joint corresponding to the apex of the frameworks 12 and detail C relates to the connection between the ties 100 and the panels 110.

Figures 13 and 14 show a single panel 10 with an internal frame 102 and external counter battens 63 fixed to the outer face of the outer plywood sheet 14 by a bonding adhesive applied under factory conditions. By the use of an adhesive damage to any external waterproof coating or film will be avoided. Preferably some of the counter battens are secured opposite to a longitudinal member 103 of the frame 102.

Figures 15, 16 and 17 illustrate one hinge assembly 110 at the ridge or apex 54. Each hinge portion includes a pair of plates 112, 114 of 8mm thick galvanized or stainless steel interconnected by a transverse plate 116. Screws 118 secure each of these plates to the timber member 56. The plate 116 has upstanding members 120 and each member 120 has an aperture receiving a bolt 122. For additional security the opposed plates 112, 114 can be interconnected adjacent the edges remote from the respective plate 116 by a bolt and nut assembly 124. These hinge assemblies 110 will be spaced at intervals with three for each pair of panels.

In Figures 18 and 19 a simpler hinge assembly at the apex 54 is illustrated. A piano hinge 130 runs the length of each pair of panels and differs from the arrangement of Figure 3 only in as far as the securing screws 118 pass into the end edges of the timber members 56.

Figures 20 and 21 show a slightly modified hinge in comparison with Figures 18 and 19 in as far as each hinge leaf has an additional flange 132 enabling additional security.

Detail B will now be described with reference to Figures 22 and 23. For maximum reinforcement effect it is necessary that the frameworks 12 shall be adequately integrated with the panels 10.

The vertical member 20 of the frame is provided at its upper end with a Vsection groove 134 which receives the upper horizontal member 30 of the framework 12, the cross section being complementary to the V groove 134. A bolt and nut assembly 136 secures the member 30 to the panel 10 and an appropriate recess is provided in the upright 20 to enable access to the nut of the assembly. The members 20 and 30 are secured together by a plywood sheet 138 and woodscrews 118. The elongate sheet 138 may extend the whole length of a roof space and any joins will be at one of the uprights 20. The sheet may extend to floor level as indicated at 140 in Figure 10. Similarly the member 30 may extend the whole length of the roof space.

The joint at the level of the ties 100 is shown in detail in Figures 24 and 25. An elongate timber member 142, which may span several panels 10 or even extend the whole length of the roof is of the same section as the member 30 but is oppositely orientated. It is secured by nut and bolt assemblies 136 and as will be seen large lopd-spreading washers are used. Toothed plate connectors 144 are also included in the nut and bolt assembly at the locations indicated. Again a birdsmouth joint is formed by means of a V groove 146 in the end of the tie 100 and the end of the nut and bolt assembly is accommodated in a recess of the tie member 100. The joint is fully secured by a plywood sheet 148 and screws 118, the sheet being elongate and extending the length of a panel or possibly the length of the roof space.

Various advantages arise from use of the embodiments hereinbefore described. Although the components are likely to be rather more expensive than conventional roof constructions, the amount of site work is reduced so that the overall cost is reduced and, moreover, the requirement for thick layers of insulation above the uppermost ceiling of the building is reduced, or possibly eliminated, whether or not the roof space is used as a room.

The useable roof space is substantially increased in relation to roofs employing conventional trusses and because of the high insulating value of the composite sheets coupled with the fact that a vapour barrier can readily be provided, a loft can be totally enclosed and there is therefore no requirement for roof ventilators at the ridge or at the eaves. The prism-outline frameworks 12 which provide support for the panels 10

can be boxed in to form trunking or services and to accommodate water tanks which therefore leave the remaining space with greater headroom free for occupation or storage.

If it is desired to provide roof-lights or dormers, the required holes can be made very readily in either embodiment, but more especially in the second embodiment p k where frames suitable for insertion of a roof-light assembly are incorporated. The problems of sealing are appreciably reduced in comparison with conventional roof structures.

The thermally- insulating layer 16 of expanded polymeric material provides s ome sound insulation which i S certainly superior to conventional roofing tiles and felt alone. If roofing tiles are incorporated in the structure the overall sound reduction effect coupled with the absence of need for ventilation to the roof space will provide a useful noise reduction in areas adjacent to airports.

Although, internally, the structure is radically different to conventional roofing structures, externally it is possible to make it appear entirely conventional with any form of tiles or slates currently in use.

In the hereinbefore described embodiments the roof structure is built up from pairs of panels, but it must be emphasized that the construction is equally applicable to mono-pitch roofs. Single panels then span two walls of unequal height. The means connecting the panels to the upper edges of the walls may be similar to the connecting means used at the ridge of the double-pitched roof as hereinbefore described.

- 26 The fact that there is no substantial air entry means that under high velocity wind conditions, the risk of a roof being blown off a house or other building is appreciably reduced.

It must be emphasized that the composite panels and the connecting means provide the sole overall structure of the roof. The frameworks at the eaves are not essential, but are useful in ensuring that the panels are adequately secured and also the frameworks provide ducting for services. In other W ords, the panels substantially, completely define the roof structurally. Cladding, of whatever form, cannot be considered as structural. Probably the most important advantage is the potential reduction in size of a domestic or other dwelling because the roof space becomes acceptably habitable so that, for example, a two bedroomed house readily becomes a four bedroomed house.

The second embodiment has the advantage over the first embodiment that it is very strong and will be able successfully to resist winds of exceptional velocity. Although more complex than the first embodiment, the second embodiment ensures that even under prolonged heavy loads and many changes in climatic conditions there will be no relative motion between the outer skins 1 of the panels as the internal structure between the skins inhibits creep in the adhesive and in the foam of the panels.

The materials have been indicated in the description of the two embodiments, but it is worth mentioning that bearing in mind the long term use of roofs, all metal components should either be galvanized or made of stainless steel. When manufacturing the panels it is important that the plywood should be fully bonded to the polystyrene or other foamed, rigid, high-strength plastics and to this end the polystyrene should be hot wire cut on both faces. If foamed polyurethane is used the self-bonding provided by expanding in situ will ensure that there can be little or no relative movement between the sheets.

The use of panels with no internal structural members or at most the rectangular frames intended, when required, to accommodate a roof-light assembly overcomes the problem of use in roofs of more complex shape than those illustrated. Obviously any interruption of an internal structural member will materially weaken the panel.

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Claims (21)

1. A roof structure assembly comprising at least one composite panel, the or- each panel incorporating opposed outer sheets and an intermediate layer of rigid, expanded, material, bonded to the inner face of each panel, and a frame intermediate the top and bottom of the or each panel secured to the inner faces of each sheet, the frame occupying only a comparatively small area of the panel, the or each panel being mounted substantially completely to define structurally a section of roof of selected pitch, at least one edge of the or each panel being arranged to be supported by wall structure of an associated building.

2. A roof structure assembly comprising at least one pair of composite panels each panel incorporating opposed outer sheets, an intermediate layer of rigid, expanded, material, bonded to the inner face of each panel, and a frame intermediate the top and bottom of each panel secured to the inner faces of the respective sheets, each frame occupying only a comparatively small area of the panel, the or each pair of panels being mounted substantially completely to define structurally a section of roof of selected pitch.

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3. A roof structure assembly comprising at least one pair of composite panels each panel incorporating opposed outer sheets, an intermediate layer of rigid, expanded, material bonded to the inner face of each panel, and a timber frame intermediate the top and bottom of each panel secured to the inner faces of the respective sheets, each frame occupying only a comparatively small area of the panel, the or each pair of panels being mounted substantially completely to define structurally a section of roof of selected pitch, means at the apex connecting the upper edge portions of each pair together and support framework means disposed at a lower edge portion of each composite panel, which framework means are arranged to be carried by structure of an associated building.

4. A roof structure assembly comprising at least one pair of composite panels each panel incorporating opposed outer sheets of relatively dense material, an intermediate layer of rigid, extruded, expanded, polymeric material bonded to the inner face of each panel, and a timber frame intermediate the top and bottom of each panel secured to the inner faces of the respective sheets, each frame occupying only a comparatively small area of the panelthe or each pair of panels being mounted substantially completely to - define structurally a section of roof of selected pitch, means connecting the upper edge portions of each pair together and support framework means disposed at and adjacent a lower edge portion of each composite panel, which framework means are arranged to be carried by other structures of an associated building.

5. A roof structure assembly comprising pairs of composite panels each panel incorporating opposed outer wooden panels, an intermediate layer of rigid, extruded, expanded, polymeric material adhesively bonded to the opposed inner faces of the sheets, a timber framework interposed between and bonded to the inner faces of the sheets whereby to prevent relative motion of the sheets,each pair of panels being mounted substantially completely to define structurally a section of roof of selected pitch, means at the apex or ridge connecting the upper edge portions of each pair together and wooden support framework means disposed at a lower edge portion of each composite panel, which framework means are arranged to be carried by joists spanning the walls of the associated building.

6. A roof structure assembly comprising at least one composite panel, the or each panel incorporating opposed outer timber-based sheets and an intermediate -1 31 - 1 layer bonded or self-bonded to the inner faces of the opposed sheets, the intermediate layer being of an expanded plastics material selected in conjunction with the bonding such that under load substantially no relative motion occurs between the sheets over a lengthy period of use.

7. A roof structure assembly comprising a pair of opposed composite panels connected to form a roof structure at their apex, each panel comprising two skin sheets and an intermediate layer of expanded polyurethane self-bonded to the inner surface of each sheet, the panels providing substantially the sole structural components of the roof.

8. An assembly according to any one of claims 1 to 6, wherein the sheets of each composite panel are of plywood and the intermediate layer is of extruded, expanded polystyrene bonded to the inner surfaces of the sheets.

9. An assembly according to any one of claims 1 to 6, wherein the sheets of each composite panel are of Sterling board and the intermediate layer is of extruded, expanded polystyrene bonded by an adhesive in accordance with British Standard 6566: PT8: 1985 to the inner surfaces of the sheets.

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10. An assembly according to any one of claims 3 to 5, wherein the connecting means comprises means secured to edge portions of said opposed panels defining at least part-annular section members and an elongate member which fits into the annular section members when aligned to provide the connection.

11. An assembly according to claim 10, wherein the means secured to the edge portions include plates held to the material of the composite panels by screws.

12. An assembly according to any one of claims 3 to 9, wherein each framework means includes horizontal members secured to horizontal structure of an associated building, vertical members and members inclined at an angle matched to the pitch of the roof and joined to the horizontal and vertical members to define a structure in the form of an outline of a right prism.

13. An assembly according to claim 12, wherein each right prism structure is 'secured to an associated composite panel by means defining at least part annular section member secured to the underside of the panel and to a horizontal member of the framework interconnecting two ends of the framework and by an elongate member passing through aligned annular section members.

1 W 33 -

14. An assembly according to any one of the preceding claims wherein the outer face of each composite panel is clad with an impervious layer.

15. An assembly according to claim 14, wherein in the impervious layer comprises slates or tiles.

16. An assembly according to any one of claims 2 to 15 comprising tie members secured to opposed said panels adjacent the ridge or apex whereby to reinforce the assembly.

17. An assembly according to claim 16 wherein the tie members include members extending transversely between the opposed panels and also diagonally between the points at which the transverse members are secured to the panels.

18. An assembly according to any one of claims 2 to 5 wherein the connecting means is a piano type of hinge.

19. A building comprising an assembly in accordance with any one of the preceding claims comprising walls the upper edges of which walls are fitted to lower edge portion surfaces of a said composite panel without any clearance.

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20. A roof structure hereinbefore described accompanying drawings.

assembly substantially as with reference to the

21. A building comprising an assembly according to any one of claims 1 to 15 or 17.

1 0069e z Pilbliahed 1989 atThePatentOfftee. State House,88.171 High Ho1born. IondonWC1R4TP, Further copies maybe obtained from The PatantOMoe. Wes Branch, St Mary Cray, Orpington. Kent BR5 3RD. Printed by Multiplex techniques Rd, St Mary Cray. Kent, Con. 1187