A roofing sheet

Abstract: The invention relates to a roofing sheet which is built up of a rigid sheet (1) of insulating material and a covering layer (3) bonded to said sheet. On both sides of the sheet cuts (2) are provided in the sheet, said cuts extending from the surface along part of the height of the sheet. The cuts provided from the one side of the sheet are thereby staggered with respect to the cuts provided from the other side of the sheet.

Description: The invention relates to a roofing sheet built up of a rigid sheet of insulating material and a covering layer bonded to said rigid sheet, whereby on one face of the rigid sheet cuts are provided in the rigid sheet, said cuts extending from the surface to a depth of part of the thickness of the rigid sheet. Such roofing sheets, whereby the insulating material is usually made of polystyrene foam, are known per se, e.g. from DE-A-2746121. The purpose of the cuts is to avoid undesirable shrinkage in the roofing sheet as a result of the inherent properties of the material and/or as a result of outside influences. Such shrinkage has an adverse effect on the construction of the roof-covering, which is built up of said roofing sheets. The effect of providing cuts from one side of the rigid sheet along part of the thickness of the rigid sheet has appeared to be insufficient in many cases. Therefore DE-A-2746121 has proposed an alternative of providing said cuts along the entire thickness of the rigid sheet. With such an embodiment it is necessary to provide a covering layer on both faces of the rigid sheet, which by itself is already a drawback in many cases. A further disadvantage is that the cohesion of the rigid sheet is lost, which makes handling more difficult. In addition to that the slots extending along the entire thickness of the sheet form so-called thermal bridges The object of the invention is to obtain a roofing sheet of the above kind, wherein the above drawbacks can be overcome. According to the invention this can be achieved in that on the other face of the rigid sheet cuts are provided as well, said cuts extending from the respective surface to a depth of part of the thickness of the rigid sheet, whereby the cuts provided from the one face of the rigid sheet are staggered with respect to the cuts provided from the other face of the rigid sheet. Surprisingly it has appeared that by carrying out this simple measure the adverse effects of the above shringkage are avoided, whilst a solid cohesion of the roofing sheet is still ensured and thermal leakage through the roofing sheet is avoided. It is noted that from Patent Abstracts of Japan, Vol. 014, No. 509 (C-0776), 7 November 1990, a polystyrene sheet is known, whereby shallow, comparatively wide grooves are provided in both faces of the sheet. The grooves on either side are thereby located directly opposite each other. The invention will be further explained hereafter with reference to the accompanying figures. Figure 1 is a diagrammatic perspective view of a rigid sheet comprised of an insulating material, for use with a roofing sheet according to the invention. Figure 2 is a diagrammatic, perspective view of a roofing sheet according to the invention, which is built up of two rigid sheets of insulating material, which are interconnected by a covering layer bonded to said sheets. The parallelopiped rigid sheet 1 of insulating material, such as polystyrene foam, shown in figure 1 is provided with a plurality of cuts 2 extending parallel to each other and to the longitudinal direction of the rigid sheet, said cuts extending downwards from the upper face 3 of the sheet 1, when seen in figure 1, perpendicularly to said upper face 3, to a dpeth of approximately 2/3 of the thickness of the rigid sheet. With a rigid sheet having a thickness of approximately 8 cm the depth of a cut or slot 2 is e.g. approximately 5 cm. In a similar manner cuts or slots 5 extending parallel to each other and to the cuts or slots 2 are provided in the rigid sheet from the bottom face 4 of the sheet, when seen in figure 1, said cuts or slots 5 likewise extending to a depth of approximately 2/3 of the thickness of the sheet. As will be apparent from figure 1 said cuts 2 extending from the upper face 3 are staggered transversely to their longitudinal direction with respect to the cuts 5 extending from the bottom face 4. In the illustrated embodiment the cuts or slots 2 are located centrally between the cuts or slots 5, when seen in the plan view. In the embodiment shown in figure 1 cuts or slots 6 extending at least substantially perpendicularly to the cuts or slots 2 are provided as well, said cuts or slots 6 extending from the upper face 3 of the rigid sheet 1 to a depth substantially the same as the depth of the slots 2. In a similar manner cuts or slots 7 extending upwardly from the bottom face 4 of the sheet are provided, said cuts or slots 7 extending parallel to and spaced from the cuts 6. Preferably the parallel cuts or slots provided in the rigid sheet 1 from the upper face 3 or from the bottom face 4 are spaced approximately 20 cm apart. Dependent on the circumstances it may be sufficient to provide only longitudinal cuts or only cross cuts. As is indicated in figure 2 a conventional covering layer 8 is provided on the upper face of the rigid sheet comprised of an insulating material, so as to produce a roofing sheet, said covering layer being bonded to said rigid sheet of insulating material. In the embodiment illustrated in figure 2 a pair of rigid sheets 9 and 10 corresponding with the above-described rigid sheet 1 is bonded to the covering layer 8, whereby in the position shown in figure 2 said rigid sheets 9 and 10, which are interconnected by means of the covering layer 8, lie one on top of the other. This position of the rigid sheets 9 and 10, one lying on top of the other, is suitable for transport. When being placed on a roof the rigid sheet 10 will be pivoted with respect to the rigid sheet 9 in the direction according to the arrow A, so as to be placed in line with the rigid sheet 9 on the respective roof. As is furthermore indicated in figure 2, the covering layer projects from the rigid sheet 9, 10 on two adjoining sides. When the rigid sheets 9, 10 are placed one beside the other, said projecting parts will come to lie on the covering layers of adjacent roofing sheets. Preferably the projecting parts which come into contact with the covering layers of adjacent roofing sheets are self-adhesive thereby, so that a good sealing between the covering layers of adjacent rooding sheets is formed immediately upon said roofing sheets being placed, so that the roof becomes watertight immediately upon the roofing sheets being placed. Afterwards further roofing layers may be provided on the covering layers. For transport of the roofing sheets the self-adhesive, projecting parts are generally covered with easily removable protective strips.

Claims: A roofing sheet built up of a rigid sheet (1, 9, 10) of insulating material and a covering layer (8) bonded to said rigid sheet (1, 9, 10), whereby on one face (3) of the rigid sheet (1, 9, 10) cuts (2) are provided in the rigid sheet, said cuts (2) extending from the surface to a depth of part of the thickness of the rigid sheet (1, 9, 10), characterized in that on the other face (4) of the rigid sheet (1, 9, 10) cuts (5) are provided as well, said cuts (5) extending from the respective surface to a depth of part of the thickness of the rigid sheet (1, 9, 10), whereby the cuts (2) provided from the one face (3) of the rigid sheet are staggered with respect to the cuts (5) provided from the other face (4) of the rigid sheet. A roofing sheet according to claim 1, characterized in that a cut (2, 5) extends to a depth of approximately 2/3 of the height of the rigid sheet (1, 9, 10) of insulating material. A roofing sheet according to claim 1 or 2, characterized in that the cuts (2) provided from the one face (3) of the rigid sheet (1, 9, 10) are located approximately centrally between the cuts (5) provided from the other face (4) of the rigid sheet. A roofing sheet according to any one of the preceding claims, characterized in that said cuts (2, 5) extend at least substantially parallel to one edged of the rigid sheet (1, 9, 10). A roofing sheet according to any one of the preceding claims, characterized in that intersecting cuts (2, 6, 5, 7) are provided in the rigid sheet (1, 9, 10). A roofing sheet according to any one of the preceding claims, characterized in that the mutual spacing of the cuts (2, 5) provided from one face (3, 4) of the rigid sheet (1, 9, 10) is approximately 20 cm.

Inventors: HOMPUS RUUD, MEUWISSEN EDMAR GERARD JOZEF, HOMPUS, RUUD, MEUWISSEN, EDMAR GERARD JOZEF
Applicants: ISOBOUW BV, ISOBOUW B.V.
Application year: 1992
Main classification: E04D3
IPC codes: E04D3