ROOFING SHEET

Abstract: A roofing sheet comprises a projecting corrugation (11, 12) at each one of two opposite side edges. One corrugation (12) is adapted to be positioned over the opposite corrugation (11) of an adjacent sheet (10), so that several sheets (10) can be positioned adjacent each other with the corrugations (11, 12) overlapping and holding each other. One flange portion (13) of the lower corrugation (11) is provided with a groove (15) and the other flange portion (14) is provided with a support portion (16). One flange portion (20) of the upper corrugation (12) is provided with a rib (22) and the other flange portion (19) is provided with a portion (21) adapted to bear on the support portion (16). The rib (22) is adapted to engage in the groove (15), so that the rib and the groove form a hinge. In that way, a sheet having an upper corrugation can easily be turned around a lower corrugation, until a tight contact has been provided between the corrugations. The free edge of the upper corrugation can be bent outwards or inwards to form the hinge.

Description: Roofing sheet Technical Field The present invention relates to a roofing sheet comprising at least one projecting corrugation at each one of of two opposite side edges. One corrugation is adapted to be positioned over the opposite corugation of an adjacent sheet, so that several sheets can be positioned adjacent each other with the corrugations overlapping and holding each other. The lower corrugation is adapted to be attached at its free edge to a roof frame lying underneath and is provided with a groove running along the full length of the corrugation on the flange portion facing the opposite corrugation of the same sheet. The upper corrugation is provided with a rib projecting into the. corrugation on the flange portion turned away from the opposite corrugation of the same sheet. The rib is adapted to engage in the groove of the lower corrugation, so that rib and the groove form a hinge. Thus, a sheet having an upper corrugation can be turned around a lower corrugation. Background Art It is previously known to position corrugated roofing sheets adjacent each other with the outer corrugations overlapping each other, and to design the roofing sheets so that the free edge of the lower corrugation can be fastened to the roof frame underneath by means of screws, for example. By the overlap is achieved that the fastening means of the sheets can be covered and protected against moisture. However, even with overlapping corrugations there is a risk of water penetrating between the sheets in the gap between a lower and an upper corrugation due to the capillary force and the partial vacuum created under the sheets as the result of the action of the wind. Many attempts have been made to prevent this penetration of water, for example by securing the corrugations tightly against each other, providing spaces eliminating the capillary forces between the sheets and grooves draj.ning the water, as more clearly explained in the Swedish patent speci ication 8103543-8. Different methods of preventing water penetration have frequently been combined when designing the corrugations. In order to provide a tight contact between the lower and the upper corrugation it is known to design the corrugations in such a way that the upper corrugation can be snapped onto the lower corrugation. However, the work operation to be carried out when mounting the sheets in order to snap an upper corrugation onto a lower corrugation is difficult and time consuming, as the sheets have a length of several meters. It is also previously known, for example through the Swedish laid open publication 388 895, to design the corrugations in such a way that the overlapping corrugations form a hinge, so that the upper sheet can be turned around said hinge during the mounting. However, in this known design of the sheets the corrugations have not been designed to provide a space as tight as possible between the upper and the lower corrugation. Furthermore, the fastening means of the sheets have been positioned in the space formed between the sheets. Thus, said space has not been fully used to prevent, water penetration. Disclosure of Invention The main object of the invention is to provide a roofing sheet of the type set orth above having the corrugations so designed that their flange portions can bear on each other tightly, so that the space formed between the corrugations can be fully used to prevent water penetration without making the mounting of the sheets more difficult. According to the invention this object is achieved by giving the sheets the features set forth in the claims. Two embodiments of a roofing sheet according to the invention will now be further described below with reference to the accompanying drawings. Brief Description of Drawings Figure 1 shows a cross-section of a roofing sheet according to the invention with one projecting corrugation at each side edge. Figure 2 shows on an enlarged scale an overlap with a lower corrugation and an upper corrugation. Figure 3 shows a modified embodiment of the upper corrugation in an overlap according to Figure 2. Best Mode for Carrying Out the Invention The roofing sheet 10 illustrated in Figure 1 comprises a projecting corrugation 11 along one longitudinal edge and a projecting corrugation 12 along the opposite longitudinal edge. Two further corrugations having lower height than the corrugations 11 and 12 are provided between the corrugations 11 and 12. Said further corrugations run parallel to the corrugations 11 and 12 and are arranged to stabilize the sheet surface between the outer corrugations 11 and 12. The outer corrugaton 12 can be positioned on the outer corrugation 11 of an adjacent -sheet, so that several sheets can be positioned adjacent each other with the corrugations overlapping and holding each other, as will be further explained with reference to Figure 2. Figure 2 illustrates on an enlarged scale the edge portions of two sheets 10, one of which (the left one in the figure) being illustrated with its corrugation 11 and the other (the right one in the figure) being illustrated with its corrugation 12. The corrugation 12 of the right sheet is positioned over the corrugation 11 of the left sheet, so that the edges of the sheets overlap each other. The corrugation 11 has a flange portion 13 facing the other corrugation -12 (not shown) of the same sheet, and a flange portion 14 turned away from the corrugation 12 (not shown) of the same sheet. The flange portion 13 forms an angle a, slightly larger than 90°, with the plane of the sheet, and the flange portion 14 forms an angle b, which is 90° or slightly less than 90°, with the plane of the sheet. At its upper portion the flange portion 13 is provided with a groove 15, the bottom of which is procj.ecting into the space between the flange portions 13 and 14 of the corrugation. At its upper portion the flange portion 14 is provided with a support portion 16 at substantially the same height over the plane of the sheet as the groove 15. The top surface of the corrugation 11 is shaped as a rib 17 projecting over the groove 15 and the support portion 16. The groove 15, the support portion 16 and the rib 17 run along the full length of the corrugation 11. The free edge of the flange portion 14 lies in the plane of the sheet and is adapted to be attached to a roof frame underneath (not shown) by fastening means 18. The corrugation 12 of the right sheet has a flange portion 19 facing the other corrugation 11 (not shown) of the same sheet and a flange portion 20 turned away from the other corrugation 11 (not shown) of the same sheet. The flange portion 19 forms an angle c slightly larger than 90° with the plane of the sheet. The flange portion 20 is substantially narrower than the flange portion 19 and runs only about half- way towards the plane of the sheet. The flange portion 19 is provided with a portion 21 projecting into the space between the flange portions 19 and 20 'and adapted to bear on the support portion 16 of the lower corrugation 11, when the corrugations 11 and 12 of two adjacent sheets engage each other. The flange portion 20 is provided with a rib 22 projecting into the space between the flange portions 19 and 20 and. is adapted to engage in the groove 15 of the flange portion 13 of the lower corrugation. The groove 15 and the rib 22 are soft-rounded and have preferably substantially equal radii of curvature, so that the rib 22 and the groove 15 form a hinge. The top surface 23 of the corrugation 12 is substantially plane and is at its lower side provided with a sealing strip 24 adapted to bear on the rib 17 of the upper surface of the lower corrugation, so that the closed space between the corrugations is divided into two sub-spaces 25A and 25B. The free edge 26 of the flange portion 20 is adapted to form an air gap 27 with the flange portion 13 of the lower corrugation, for example in the way explained in the Swedish patent specification 8103543-8. The projecting portion 21, the rib 22, the top surface 23 and the sealing strip 24- run along the full length of the corrugation 12. The flange portion 13 of the lower corrugation at the groove lb and the portion above the groove, and the flange portion 20 of the upper corrugation at the rib 22 and the portion above the rib are S-shaped with substantially equal radii of curvature, so that a -broad contact surface is provided between the corrugations. The above described roofing sheets are mounted in the following way. A roofing sheet 10 is first positioned on the roof frame and attached with a convenient number of fastening means 18, as shown in Figure 2. The next sheet is then positioned with its corrugation 12 over the corrugation 11 of the already mounted sheet, the opposite side edge of the sheet with the corrugation 11 being lifted up from the roof frame, so that the rib 22 of the flange portion 20 of the corrugation 12 can be positioned in the groove 15 of the flange portion 13 of the lower corrugation 11. The sheet 10 is then turned towards the roof frame using the rib 22 and the groove 15 as a hinge, the projecting portion 21 of the flange portion 19 of the upper corrugation 12 being forced against the projecting portion 16 of the flange 14 of the lower corrugation, so that the rib 22 and the groove 15 and the portions 16 and 21 are forced to a tight contact with each other. Due to the fact that the sheet has a considerable width and this width can be used as a lever, a big contact pressure can easily be obtained between said portions, and said contact pressure is then maintained due to the fact that the flange portions of the corrugations, particularly the free flange portion 20 of the upper corrugation, are somewhat resilient. When the sheet is turned towards the roof frame, also the sealing strip 24 of the upper corrugation is brought into contact with the rib 17 of the top surface of the lower corrugation. The sheet 10 can then be attached to the roof frame by means of fastening means 18 in the same way as the first sheet. The next sheet can then be mounted. Thus, the sheets can be mounted on a roof easily and rapidly. Due to the fact that the fastening means 18 will be covered by the flange portion 19 of the corrugation 12 of the next sheet to be mounted, the fastening means will be protected against moisture. Due to the fact that the upper corrugation is brought to tight contact with the lower corrugation at the hinge 22-15 between the flanges 20 and 13 as well as at the portions 16-21 between the flanges 14 and 19, particularly the contact surface at the hinge 22-15 being very efficient because of its width, water and moisture is prevented from penetrating between the corrugations. Should water or moisture nevertheless penetrate through the hinge, the water or the moisture is drained through the space 25A, the sealing strip preventing water and moisture from penetration into the space 25B, from which it more easily could penetrate between the flanges 14 and 19 of the corrugations to the fastening means 18. Due to the fact that the corrugations are designed to fulfill several sealing functions, a satisfactory sealing is provided also under severe conditions. Due to the fact that the flange portion 14 of the lower corrugation forms an angle b that is 90° or slightly less than 90° with the plane of the sheet, and the flange portion 19 of the upper corrugation forms an angle c that is slightly larger than 90° with the plane of the sheet, the flange portions 14 and 19 will lean towards each other. In this way the corrugations 11 and 12 will stabilize each.other, so that the corrugations become very load resistent, when the sheets have been mounted. The risk of deformation of the corrugations, for example due to a person working on the roof treading on the corrugations, is thus substantially reduced. Deformation of the corrugations or portions of the corrugations could cause a large risk of leakage. Furthermore, due to this stabilization of the corrugations separate fastening and supporting elements in the corrugations can be dispensed with. The design of the corrugations illustrated in Figure 3 is substantially in agreement with the design illustrated in Figure 2. Therefore, the same reference numerals have been used for corresponding parts. The only difference is that the free edge of the upper corrugation 12 has been given a different shape. The free edge of the upper corrugation is bent to form a substantially cylindrical portion 28 adapted to engage in the hinge-forming groove 15 of the lower corrugation. The outer radius of the cylindrical portion 28 is substantially equal with the inner radius of the groove 15, so that a tight contact is obtained between the lower and upper corrugation along a large portion of the circumference of the cylindrical portion. Furthermore, the upper corrugation is so designed that it bears on the lower corrugation at a distance above the cylindrically bent edge portion 28, so that the closed space 25A,25B is formed between this bearing and the bearing at the support portion 16 of the lower corrugation. In the embodiment illustrated in Figure 3, the top portion of the upper corrugation is slightly rib-shaped. However, said top portion could alternatively be absolutely plane, as illustrated in Figure 2. Furthermore, the sealing strip 24 shown in Figure 2 is missing in Figure 3, but such a sealing strip can of course be inserted also in the embodiment according to Figure 3, when suitable. The advantages of the embodiment illustrated in Figure 3 are that it is much more difficult to break up mounted roof sheets, so that the embodiment thus provides a good housebreaking protection; that the finished roof has a nicer look from an aesthetic point of view, and that there is no risk of a person working on the roof hurting himself on a projecting edge of a roof sheet. Furthermore, the consumption of material is slightly less. Whilst only two embodiments of the roof sheet according to the invention have been described above and illustrated on the drawings, it is clear that many modifications and variations are possible within the scope of the invention. The design of the flange portions of the corrugations and their inclination can for example be varied within wide limits, provided that a hinge is formed, so that a sheet can be turned around the corrugation of an already mounted sheet to force the flange portions of an upper and a lower corrugation towardds each other, when the sheet is being mounted. The top surfaces of the corrugations and the spaces between said corrugations can also be designed in many different ways. The sealing strip may be dispensed with. The bent edge of the upper corrugation need not necessarily be cylindrical, but can be only partly bent towards the inside of the corrugation. However, it is convenient to bend it at least 180° in order to obtain a satisfactory operation of the hinge . The design of the sheets between the outer corrugations has no significance for the invention. The roof sheets may be made of metal or plastics or any other suitable material.

Claims: Claims 1. Roofing sheet, comprising at least one projecting corrugation (11,12) at each one of two opposite side edges, one corrugation being adapted to be positioned over the opposite corrugation (11) of an adjacent sheet (10), so that several sheets (10) can be positioned adjacent each other with the corrugations (11,12) overlapping and holding each other, the lower corrugation (11) at its free edge being adapted to be attached to a roof frame lying underneath and on the flange portion (13) facing the opposite corrugation of the same sheet being provided with a groove (15) running along the full length of the corrugation, and the upper corrugation (12) on the flange portion (20) turned away from the opposite corrugation of the same sheet being provided with a rib (22) projecting into the corrugation and arranged to engage in the groove (15) of the lower corrugation, so that the rib (22) and the groove (15) form a hinge and a sheet having an upper corrugation can be turned around a lower corrugation, characterized in that the flange portion (14) of the lower corrugation (11) turned away from the opposite corrugation of the same sheet is provided with a support portion (16) running along the full length of the corrugation, and the flange portion (19) of the upper corrugation (12) facing the opposite corrugation of the same sheet is provided with a portion (21) adapted to bear on the support portion (16) of the lower corrugation (11), so that when the sheet is turned around the hinge the bearing portion (21) of the upper corrugation is forced to bear on the lower corrugation and a closed space (25A,25B) is formed between the uppper and lower corrugation between the hinge and the points of attachement at the free edge of the lower corrugation. 2. Roofing sheet according to claim 1, characterized in that the bearing portion of the upper corrugation (12) is designed as a support rib (21) projecting into the corrugation. 3. Roofing sheet according to claim 2, characterized in that the support rib (21) of the upper corrugation (12) is provided at substantially the same height on the corrugation as the rib (22) of the hinge. 4. Roofing sheet according to any of the preceding claims, characterized in that the top surface (23) of the upper corrugation (12) at its lower side is provided with a sealing strip (24) adapted to bear on the upper surface (17) of the lower corrugation (11), so that the closed space between the corrugations is divided into two separate sub-spaces (25A,25B) . 5. Roofing sheet according to claim 4, characterized in that the top surface of the lower corrugation is designed as a rib (17) adapted to penetrate into the sealing rib (24) of the upper corrugation (12). 6. Roofing sheet according to any of the preceding claims, characterized in that the flange portion (14) of the lower corrugation (11) which is provided with a support portion (16) and the flange portion (19) of the upper corrugation (12) which is provided with a bearing portion (21) are inclined towards each other, so that the corrugations stabilize each other. 7. Roofing sheet according to claim 1, characterized in that the rib (22) of the upper corrugation (12) forming the hinge (15,22) consists of the free edge of the upper corrugation that is bent towards the interior of the corrugation. 8.- Roofing sheet according to claim 7, characterized in that the free edge of the upper corrugation (12) is bent at least 180°. 9. Roofing sheet according to "claim 8, characterized in that the free edge of the upper corrugation (12) is bent to a substantially cylindrical portion (28) adapted to engage in the groove (15) forming the hinge in the lower corrugation (11). 10. Roofing sheet according to claim 9, characterized in that the outer radius of the cylindrical portion (28) is substantially equal with the inner radius of the groove (15), so that a tight contact is provided between the corrugations (11,12) along a large portion of the circumference of the cylindrical portion. 11. Roofing sheet according to any of claims 7-10, characterized in that the upper corrugation (12) bears on the lower corrugation (11) above the bent edge portion, so that the closed space (25A,25B) is formed between said bearing and the bearing at the support portion (16) of the lower corrugation.

Inventors: VINBERG HANS, VINBERG, HANS
Applicants: GRAENGES ALUMINIUM AB, GRAENGES ALUMINIUM AKTIEBOLAG
Application year: 1989
Main classification: E04D3
IPC codes: E04D3