Roof structure

Abstract: A roof structure comprises a roof-supporting framework 1 over which a layer of corrugated waterproof sheeting 12 is placed to cover the entire roof structure in a waterproof manner. Tiles or slates are placed over the corrugated sheeting. The sheeting is formed from fibres impregnated with bitumen

Description: The invention relates to roofing, and is particularly suitable for the construction of tiled or slated roofs. In a conventional roof, sheets of underlay, such as roofing felt, are laid over a timber framework formed by the rafters, and tiles or slates are laid on top of the underlay. The underlay thus forms a secondary barrier to water penetration. Low-pitch roofs of this type are particularly prone to problems, a major one being that of water ingress. As the roof is relatively flat, water or snow may collect on the tiles or slates and then seep between the tiles or slates. The low pitch of the roof also means that wind can blow water underneath the tiles or slates. Pantiles are particularly likely to allow water to creep beneath them, due to their shape. Once water has entered under the tiles or slates, the roofing felt underlay is the only barrier to prevent water from entering the building. Often it does not prove to be an effective barrier, as the roofing felt tends to sag between the rafters on which it is laid, creating gaps between adjacent overlapping sheets. Another disadvantage of known tiled or slated roofs is that there is little ventilation between the tiles and the underlay. This can cause problems in cold weather, as warm humid air inside the building condenses on the cold surface of the underlay, and the moisture cannot escape due to the lack of ventilation. Therefore, the moisture re-enters the building. A further drawback of known tiled or slated roof structure is that they provide very little thermal insulation. CH-A-219877 describes roof comprising a roof-supporting structure, corrugated waterproof sheeting supported by the structure and covering substantially the entire roof in a waterproof manner, and tiles overlying the corrugated waterproof sheeting. The waterproof sheeting has its corrugations running down the slope of the roof and is supported from below across its entire width by boarding or the like. DE-A-1784371 describes a roof structure in which a corrugated sheeting is laid under the battens which are fixed by nailing into rafters. In one embodiment ceiling boards are placed below the corrugated sheeting. According to the present invention there is provided a roof according to Claim 1. Preferred features are set out in the subclaims. An embodiment of the invention will further be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a partly cut-away schematic diagram of a building, showing a roof structure according to the present invention at an intermediate stage of construction; Figure 2 is a partly cut-away schematic diagram of the roof struction of figure 1 at a later stage of construction; Figure 3 is a fragmentary section along the line III-III of figure 2, on an enlarged scale; Figure 4 is a partly cut-away fragmentary view of a modified roof structure according to the present invention; Figure 5 is a fragmentary section along the line V-V of Figure 4; Figure 6 is a partly cut-away fragmentary view of a further modified roof structure according to the present invention; and Figure 7 is a fragmentary section along the line VII-VII of Figure 6. The roof shown in the drawings comprises a timber framework on which sheets of corrugated waterproof material 12 are laid. Slates or tiles 20 of stone, clay, or concrete are then laid on top of the corrugated sheeting. To provide the framework, as shown in figure 1, roof trusses 1 are fixed in position extending from a ridgeboard 2 to a wall 3 of the building in the conventional manner. An undercloak 4 is fitted flush to the top of each gable wall 5 of the building at this stage. Purlins 6 are fixed across the roof trusses 1 at regular intervals, perpendicular to the trusses. An apron of waterproof material 7 may be fitted at the eaves of the roof structure, supported by plywood 8 and an inclined chamfered board 9 secured to a fascia board 10. The outer edge of the apron overhangs the fascia board. The arrangement causes the lower margin of the corrugated sheeting 12 adjacent the eaves to slope at a lesser angle to the horizontal than the remainder of the sheeting, as can be seen in Figure 7. Supporting battens 11 are laid on top of the purlins, parallel to the roof trusses. The supporting battens 11 are spaced apart at regular intervals, to coincide with whole numbers of corrugations of corrugated waterproof sheets 12 (figs. 2 and 3) and are fixed in place by nails or analogous means to the purlins. The corrugated sheets 12 are laid on top of the framework of roof trusses 1, purlins 6 and supporting battens 11, so that the corrugations run parallel to the roof trusses and supporting battens. Each supporting batten runs underneath a crest 13 (fig. 3) of a corrugation of the corrugated sheets. The corrugated sheets are preferably about 3mm thick and made into a monolayer from organic fibres impregnated with bitumen under high pressure and at high temperature. Such a corrugated material is sold under the Trade Mark "Onduline" by Onduline Building Products Ltd., London. Several sheets of corrugated material may be used in the construction of a roof, and each sheet overlaps its neighbours. Where the overlap is between adjacent sheets at different heights on the roof, the sheets are arranged so that the lower edge of the higher sheet overlays the upper edge of the lowe sheet. Therefore, any water running down the corrugations does not enter the building at these overlaps. The layer of corrugated material covers the entire roof structure in a watertight manner. The corrugated sheets 12 are fixed in position with nails 14 (fig. 3). The nails are positioned at regular intervals, and each nail passes through a crest 13 (fig. 3) of a corrugation and into a purlin 6. Thus, the corrugated sheets 12 are supported by a framework of purlins 6 and roof trusses. A gas-permeable filler 15 made of polyethylene foam is positioned on the lowest purlin 6a, and the corrugated sheets 12 fit flush onto the filler. The filler 15 prevents the entry into the roof structure of dust, birds and other foreign material, whilst still permitting the passage of air. Tiling battens 16 (figs. 2 and 3) are laid on top of corrugated sheets 12, parallel to the purlins 6 and spaced at regular intervals at a pitch appropriate to the size and type of tile or slate. The tiling battens 16 are fixed in position with nails 17 (fig. 3). Each nail passes through a crest 13 of a corrugation of the corrugated sheets, and into one of the supporting battens 11 which lies beneath the crest of the corrugation (fig. 3). Thus, the tiling battens 16 are supported by the corrugated sheets 12 and the supporting battens 11. A bird comb 18 may be positioned at the eaves of the roof structure to prevent the entry of birds. A bargeboard 19 is fixed at the junction of the roof with the side walls 5. Tiles or slates 20 are hung on the tiling battens 16 in the normal manner, and guttering 21 may be fitted to the fascia board 10 at the eaves in the usual way. Figures 4 and 5 show a modification of the roof structure of Figures 1 to 3. In the embodiment of Figures 4 and 5, the purlins 6 are set at regular intervals corresponding to the gauge of the tiles or slates eventually to be used. The supporting battens 11 are omitted, the corrugated sheeting 12 being placed directly over the purlins 6. The tiling battens 16 are placed directly over the purlins and secured in place by nailing to the purlins 6 Rigid steel bridge members 40 are placed at intervals over the ridges in the corrugated sheet and underneath the tiling battens at the points where the tiling battens are nailed to the purlins to support the tiling battens and prevent them crushing the corrugations in the sheeting. As can be seen in Figure 5 the bridge members are in the shape of an inverted U with a cross piece 43 and two diverging legs 44. The bottoms of the legs are curved to form smooth feet 41 which rest on the sheeting and do not damage it. The height H of the bridge member 40 corresponds to the depth of the corrugations and the spacing W of the feet 41 of the bridge member corresponds to the width of the corrugations. Each nail which secures the tiling batten to the purlin also passes through a hole 42 in the bridge member and through the crest of the corrugation in the sheeting and thus serves to hold the corrugated sheeting and bridging member in place. The bridging members do not prevent air flowing up the spaces formed by the corrugations from the eaves to the ridge of the roof on both sides of the sheeting. In other respects the embodiment of Figures 4 and 5 is the same as that of Figures 1 to 3. Figures 6 and 7 show a modification of the embodiment of Figures 4 and 5 which is identical in every respect except that the bridge members 40 are omitted. The tiling battens 16 are nailed to the purlins 6 through the crests of the corrugations, care being taken when driving in the nails not to drive them in too far and thus distort the corrugations of the sheeting. The invention, therefore, provides a highly waterproof roof structure, as protection is provided both by the tiles or slates and by the underlaying sheet of corrugated material. The invention is particularly useful for low-pitch roofs or roofs with badly fitting tiles or slates, as even when water does seep between the tiles, it is prevented from entering the building by the corrugated waterproof underlay. Any water entering the roof simply runs down the troughs of the corrugations and leaves the building. Good waterproof sealing is possible between adjacent sheets of the waterproof material, so that water does not enter the building through gaps between the underlay sheets as can happen with conventional roofs. This effective sealing is partly due to the overlap of corrugations between adjacent sheets, which provides an interlocking junction between sheets, and partly due to the high bitumen content of the material used, so that one sheet adheres to the other. The positioning of nails through the crests of the corrugated sheets further prevents water seeping into the building. Any water present within the roof structure will collect in the troughs of the corrugated sheets, and as nails only perforate the crests, the likelihood of water entering building through these perforations is reduced. The invention also enables air-flow through the roof, due to the corrugated nature of the waterproof sheets, allowing evaporation of moisture present within the roof structure. A roof structure according to the invention is also thermally insulating. This results partly from the thickness of the corrugated sheets and partly from holding air within the structure due to the corrugations. By using a single corrugated, waterproof sheet of material such as is sold under the Trade Mark "Onduline", as described in the embodiment above, beneath the tiles or slates on a roof, improved waterproofing, ventilation and thermal insulation can be achieved with a single material; an advantage not found in the prior art.

Claims: A roof comprising a roof-supporting structure (1), corrugated waterproof sheeting (12) supported by the structure and covering substantially the entire roof in a watertight manner, and tiles or slates (20) overlying the corrugated waterproof sheeting (12) and resting thereon, the waterproof sheeting (12) comprising fibres impregnated with bitumen and having its corrugations running down the slope of the roof, the roof-supporting structure including rafters, the roof-supporting structure also including means (6) structurally supporting the corrugated waterproof sheeting (12) from below across its entire width, the said supporting means (6) being secured by securing means to the rafters (1), the corrugated waterproof sheeting (12) being secured to the said supporting means (6) by nails or other fixing means (14) which pass through crests (13) of the corrugations in the sheeting (12) into the supporting means at points between the rafters, and the corrugated sheeting (12) along the lower margin of the roof adjacent the eaves sloping at a lesser angle to the horizontal than the remainder. A roof according to claim 1 in which the corrugated waterproof sheeting is at least 3mm thick and has been formed by impregnating the fibres with bitumen under pressure. A roof according to claim 1 or 2 in which the tiles (20) are supported directly on the corrugated sheeting (12). A roof according to claim 1 or 2 in which tiling battens (16) are supported over the sheeting and the tiles or slates (20) are supported by the tiling battens. A roof according to claim 4 in which the tiling battens are attached to the supporting means by nails or other fixing means (17) extending into the roof supporting structure through crests (13) of the corrugations in the sheeting. A roof according to claim 4 or 5 in which spacer means (11, 40) are provided between the roof supporting structure and the tiling battens (16) for supporting the tiling batten (16) at the points where the tiling battens are secured to the roof-supporting structure. A roof according to claim 4 or 5 in which the roof supporting structure includes supporting battens (11) positioned so that each lies under a different crest (13) in the corrugations of the sheeting, the tiling battens (16) being attached to the supporting battens (11) by nails or other fixing means (17). A roof according to claim 4 or 5 in which the roof supporting structure includes purlins (6) spaced at intervals corresponding to the gauge of the tiles or slates and the tiling battens (16) lie over and parallel to the purlins and are attached to the purlins by nails or other fixing means (17). A roof according to any of the preceding claim in which the roof supporting structure comprises purlins (6) perpendicular to roof trusses or rafters and supporting battens (11) extending parallel to the roof trusses or rafters (1) and supported by the purlins (6). A roof according to claim 9 in which the corrugations of the sheeting (12) are parallel to the roof trusses (1), and each supporting batten (11) lies under the crest (13) of a corrugation in the sheeting. A roof according to claim 8 or 9 in which the corrugated waterproof sheeting (12) is attached to the purlins by nails or other fixing means (14) passing through crests (13) of the corrugations in the sheeting. A roof according to any of claims 9, 10, or 11 in which the tiling battens (16) are attached to the supporting battens (11) by nails (17) through crests of the corrugations in the sheeting (12), the tiling battens (16) being perpendicular to the roof trusses or rafters (1). A roof according to any of claims 4 to 12 a rigid bridge member (40) is placed over the crest of the corrugation at each point where the tiling batten (16)is nailed to the roof-supporting structure to support the tiling batten. A roof according to any of claims 1 to 7 which the roof-supporting structure comprises roof trusses or rafters (1) covered by weatherboarding (51). A roof according to any of the preceding claims in which the fibres of the corrugated waterproof sheeting (12) are organic. A roof according to any of the preceding claims in which the fibres of the corrugated waterproof sheeting (12) are impregnated with bitumen at high temperatures. A roof according to any preceding claim in which an air-permeable filling material (15) fills the space between the corrugated waterproof sheeting (12) and the roof supporting structure (6) at a position near to the eaves of the roof. A roof structure according to claim 17 in which the air-permeable filling material (15) is polyethylene foam. A roof according to any of the preceding claims in which a comb structure (18) is positioned over the lower ends of the corrugations at the eaves to prevent entry of birds whilst allowing air to enter the roof space and between the tiles and the corrugated sheeting through the lower end of the corrugation. A roof according to any of the preceding claims in which the supporting structure includes an inclined chamfered board (9) adjacent the eaves to support the lower margin of the corrugated sheeting (12) at the lesser angle of the slope. A roof according to any of the preceding claims in which the roof-supporting structure includes purlins (6) and in which an apron of waterproof material (7) extends from the lowest purlin (6a) of the roof to the lowest edge of the roof, supported by an inclined board (8).

Inventors: EICHENAUER HEINZ MICHAEL, LUPARINI LEONE, EICHENAUER, HEINZ MICHAEL, LUPARINI, LEONE
Applicants: ONDULINE BUILDING PROD LTD, ONDULINE BUILDING PRODUCTS LIMITED
Application year: 1990
Main classification: E04D12
IPC codes: E04D13, E04D1, E04D12, E04D3