COMPOSITE ROOF COVERING PLATE COMPRISING AN INSULATING SUPPORT LAYER AND A COVERING LAYER SUITABLE FOR WALKING ON, AND A ROOF COVERING FORMED BY MEANS OF SUCH A COMPOSITE PLATE

Abstract: Composite sheet 1, particularly a tile consisting of a sup­ porting layer 3 made of foam plastic, and a top layer 2 joined thereto, made of rubber or concrete. The supporting layer 3 is provided with a layer 3a which is staggered relative to the periphery of the top layer 3. The projecting parts 4, 4′ formed by layer 3a match opposite re­ cess 5, 5′. The layer 3a is integral with the layer 3b of the supporting layer 3 extending under the top layer. The composite sheet 1 can also be designed with a sup­ porting layer 3 with upright walls which form the extension of the upright walls of the top layer, while the top layer 2 is provided with peripheral edge parts 16 which extend under the top face 14 of the supporting layer 3 and which are prov­ ided in a matching edge recess which is designed as an un­ dercut groove.

Description: The invention relates to a composite sheet comprising a lower insulating supporting layer of foam plastic material, and a top layer for walking upon disposed thereon and joined thereto made of rubber and/or concrete, said supporting layer having on at least one upright face a part projecting beyond the periphery of the top layer and on an opposite upright face having a recess extending within the periphery of the top layer and matching the projecting part, said supporting foam plastic layer comprising free upstanding sides capable of engaging a supporting foam plastic layer of another composite sheet over a substantial height of the supporting layer. Such a composite sheet in the form of a tile is known from EP-A-0 088 198. This sheet comprises a lower insulating support layer of polystyrene foam and a top layer made of concrete disposed thereon and adhered thereto by means of an adhesive. This known composite sheet which is used for forming a roof covering suitable for walking on presents the disadvantage that due to the different expansion properties of the supporting layer of foam plastic material and of the top layer and the fact that the foam plastic material is integral with the top layer, the foam plastic material is rather rapidly damaged due to the formation of cracks in the foam plastic. The object of the invention is now to provide a composite sheet of the abovementioned type which does not or substantially does not present this disadvantage. This object is achieved according to the invention in that the top layer is provided with edge parts extending under the top face of insulating supporting layer and being anchored in matching edge recesses of the supporting layer and the top face and the supporting layer of the opposite underside of the top layer are free from an adhesive binding these surfaces. In particular, such a composite sheet provides the great advantage that differences in expansion which occur between the insulating supporting layer and the top layer which can be effected by direct sunlight do not lead to cracks in the insulating supporting layer. It should be noted that DE-A-24 05 949 discloses a steel reinforced concrete element having a top layer provided with edge parts extending under the top face of an insulating foam plastic layer, said edge parts being anchored in matching edge recesses of the insulating foam plastic layer. However, the free upstanding sides of the insulating foam plastic layer are substantially over their complete height enclosed by downwardly extending concrete walls, except a bottom layer of a very small thickness extending outside the downwardly extending walls at two subsequent sides and on the other hand ending before the downwardly extending walls at the two other sides. It will be clear that the foam plastic layer is in in this case not a supporting layer as the concrete element is supported by concrete parts of the building. Thus, by walking on the concrete element the foam plastic is not subjected to compression forces in contrast to the foam plastic support layer of the invention. For this last reason cracks in the foam plastic layer of the invention are very disadvantageous is comparison with cracks in the foam plastic steel reinforced concrete element. Moreover, the document does not explicitly stipulate the absence of an adhesive connection between the plastic foam and the concrete. At last the upper side of these concrete elements are often covered with another layer so that sunlight provokes less expansion of the concrete. FR-A-2.538.430 discloses an element of polystyrene connected with a top layer of plaster, the top layer being provided with edge parts extending under the top face of an insulating foam plastic layer, said edge parts being anchored in matching edge recesses of the foam plastic layer. However, these elements are not suitable as walking on elements in outside roof coverings. It is particularly advantageous for a lower layer part of the supporting layer to be staggered relative to the face determined by the periphery of the top layer. This gives the great advantage that the projecting part of a composite sheet which is used for a roof covering extends completely over the surface of the roof on which the composite sheet has been places. In this way, optimum insulation of the roof is obtained with the use of a composite sheet of the type mentioned above as any direct vertical connection between the environment and the roof on which the composite sheet is placed, which means a so-called "cold bridge effect" has been practically eliminated. The composite sheet comprises particularly preformed rigid foam plastic layer on which the top layer is disposed. If the top layer is made of concrete, a foam plastic supporting layer is placed in a mould and a mixture of a setting binder and fillers, such as granules, is then placed on the plastic layer, following which the desired top layer suitable for walking on is obtained once the binder has set. The binder can be a hydraulic binder such as cement, but can also be a thermosetting synthetic resin binder. If concrete is used, a heavier top layer is obtained, which means that it is possible to use a thinner top layer in order to obtain the desired aggravation The composite sheet of the invention in particularly suitable to suppress the phenomenon of concrete resonance when walking over a roof of composite sheets of the invention. Providing the top layer with edge parts which are anchored in matching edge recesses of the insulating supporting layer being located under the top face of the insulating supporting layer means that a good attachment is ensured, while the edge parts also ensure that good cohesion of the insulating supporting layer is retained. It is particularly advantageous for the edge parts to extend along the entire periphery of the top layer, which ensures optimum protection of the join between top layer and insulating supporting layer and also holds the insulating supporting layer clamped between the continuous edge parts. The matching edge recess in the insulating supporting layer is very advantageously designed as an undercut groove which ensures very good anchoring between top layer and insulating supporting layer and, on the other hand the production of such a composite sheet is simple, since the mortar used for forming a top layer can penetrate well into said undercut groove. The invention also relates to a roof covering formed from composite sheets according to the invention. The invention will now be explained with reference to an example of an embodiment shown in the drawing, in which: Fig.1 shows a composite sheet according to the invention in the form of a tile; Fig.2 shows a top view of such a tile; Fig.3 shows a cross section of a tile of the type shown in Fig. 2, along the line III - III; Fig.1 shows a tile, for example with the dimensions 30 by 30 cm, comprising a top layer 2 and disposed thereunder an insulating supporting layer 3. The top layer is made of concrete and is applied by placing the insulating supporting layer 3 in a mould and then placing a fluid mortar made of a hydraulic binder 19 and gravel particles 17 on top of the insulating supporting layer 3. The insulating supporting layer 3 comprises a top layer part 3b which is directly joined to the top layer 2. The upright wall parts 27 of this layer part 3b form the extension of the upright faces 9, 10, 11 and 12 of the top layer. On the other hand, the insulating supporting layer 3 of rigid expanded plastic material has a lower layer part 3a which is staggered relative to the top layer 2. The bottom side of the composite sheet therefore exhibits projecting parts 4 and 4' and on the opposite side matching recesses 5, 5'. In the embodiment shown in Fig.2 the lower layer part 3a of the supporting layer 3 is bounded by two successive upright walls 6, 7 which extend outwards and at a distance from the extension of the wall faces 10, 11 of the top layer which are situated above, thereby forming projecting parts 4, 4', and the opposite upright walls 8, 9 of the lower layer part extend inwards and at a distance from the extension of the wall faces 12, 13 of the top layer which are situated above, thereby forming recesses 5, 5' which match the projecting parts 4, 4' It can be seen from Fig.3 that at the transition between two successive tiles there is a slit 20 which in the absence of projecting parts 4, 4' would extend from the outside to the roof surface on which such composite sheets in the form of tiles are placed. This "cold bridge effect", which adversely affects the insulation of the roof, is eliminated by the top face 21 of a projecting part 4 of a first tile being covered by the bottom face 22 of the recess 5 of another tile. For a good union of the insulating supporting layer 3 and the covering layer 2 for walking on with a walking-on surface 23, the top layer 2 is provided with edge parts 16 which extend along the entire periphery of the top layer and which are anchored in edge recesses 15 of the insulating supporting layer which are designed as undercut grooves. The undercut groove or edge recess 15 comprises a groove bottom part 15a and a slanting groove part 15b which intersect each other in edge 15'. If at the point of transition from the insulating supporting layer 3 in the form of a foam plastic sheet to groove bottom part 15a damage occurs to the foam plastic sheet 3, this does not lead to the ultimate breaking of the join between top layer 2 and insulating foam plastic sheet 3, since the actual join is ensured by the edge parts 16 and matching recesses 15 in the form of an undercut groove. Where there are differences in expansion between the material of the insulating supporting layer 3, in the form of a foam plastic sheet, and the top layer 2, the edge parts 16 and recesses 15 also ensure good retention of cohesion of the foam plastic sheet 3. As can be seen from Fig.3, the edge parts 16 extend under the top face 14 of the insulating sheet 3. In order to improve the join between top layer 2 and insulating supporting layer 3, it may be advisable to form in the foam plastic sheet 3 at least one swallow-tailed longitudinal groove, bounded by longitudinal groove bottom part and from this bottom part converging to upward-running walls which end in edges on the top face 23 of the insulating foam plastic sheet. Of course, the insulating foam plastic sheet 3 can be provided with at least one other longitudinal groove which extends perpendicular to the first longitudinal groove This longitudinal groove will end on the top face of the insulating foam plastic sheet in the edges. The longitudinal groove is bounded by longitudinal groove bottom and longitudinal groove walls converging upwards. In the longitudinal grooves are raised parts of the top layer which match said grooves. The top layer 2 as used is preferably a vapour-permeable layer. As already stated, the layer can consist of concrete, but can also be made from fillers and a thermosetting resin, and it must, of course, be ensured that the material of the insulating sheet is not attacked by the synthetic resin. The top layer can also be formed from rubber granules. The surface bounded by the middle of a longitudinal groove and the opposite outside of the top layer 2 is expediently smaller than 625 cm² and preferably smaller than 400 cm². In the case of a square tile measuring 40 x 40cm, the longitudinal grooves running perpendicularly to each other are therefore provided in the centre and this means that there can certainly be no damage due to expansion. Through the absence of a glue or adhesive between top face 14 of supporting layer 3 and bottom side 18 of top layer 2, these surfaces can move freely relative to each other, so that expansion does not lead to cracks in one of the two layers.

Claims: Composite sheet (1) comprising a lower insulating supporting layer (3) of foam plastic material, and a top layer (2) for walking upon disposed thereon and joined thereto made of rubber and/or concrete, said supporting layer (3) having on at least one upright face a part (4) projecting beyond the periphery of the top layer (2) and on an opposite upright face having a recess (5) extending within the periphery of the top layer (2) and matching the projecting part (4), said supporting foam plastic layer (3) comprising free upstanding sides (27, 6) capable of engaging a supporting foam plastic layer (3) of another composite sheet over a substantial height of the supporting layer (3), characterized in that the top layer (2) is provided with edge parts (16) extending under the top face (14) of the insulating supporting layer (3) and being anchored in matching edge recesses (15) of the supporting layer (3) and the top face (14) of the supporting layer (3) and the opposite underside (18) of the top layer (2) are free from an adhesive binding these surfaces. Composite sheet according to claim 1, characterized in that a lower part (3a) of the supporting layer (3) is staggered relative to the face determined by the periphery of the top layer (2). Composite sheet according to claim 1, characterized in that a lower layer part (3a) of the supporting layer (3) is bounded by two successive upright walls (6, 7) which extend outwards and at a distance from the wall faces (10, 11) of the top layer which are situated above them and the opposite upright walls (8, 9) of the lower layer part (3a) extend inwards and at a distance from the extension of the wall faces (12, 13) of the top layer (2) which are situated above them. Composite sheet according to anyone of the claims 1 to 3, characterized in that between the bottom side (18) of the top layer (2) and the lower layer part (3a) there is a layer part (3b) integral therewith and bounded by walls (27) which form the extension of the upright walls (10, 11, 12, 13) of the top layer (2). Composite sheet according to any one of the preceding claims, characterized in that the edge parts (16) extend along the entire top layer (2). Composite sheet according to any one of the preceding claims, characterized in that the matching recess (15) is designed as an undercut groove. Composite sheet according to one or more of the preceding claims, characterized in that the top layer (2) which may be vapour-permeable or not, is made of fillers (17) and a hydraulic binder agent or a thermosetting synthetic resin binder (19). Roof covering formed from composite sheets according to one or more of claims 1 to 7.

Inventors: RENDERS, JOHANNES THEODORUS MARIA, ZOONTJENS, ALBERTUS NICOLAAS PETRUS MARIA, ZOONTJENS, NICOLAAS ANTONIUS PETRUS MARIA
Applicants: ANJAP N.V.
Application year: 1986
Main classification: E04D11
IPC codes: E04D3, E04D11