Roof tile for ventilation purposes

Abstract: Roof tile (1) of synthetic material, comprising a top plate (2) and a bottom plate (3), which are spaced at a distance from each other for defining therebetween a hollow space closed in lateral directions, with a lower opening (30), which is arranged in the lower head edge (6) of the tile, for the passage of air to and from the hollow space and the discharge of moisture from the hollow space, and with an upper opening (31), which is at least in part arranged in the bottom plate (3), for the passage of air to and from the hollow space from and to the spaces located below the roof tile in the situation in which the roof tile is used, respectively, wherein the bottom plate (3) is shaped such that an expansion tray (19) is formed in the hollow space for air entering through the lower opening (30).

Description: The invention relates to a roof tile for ventilation purposes, in particular a hollow roof tile made of synthetic material, with which spaces below the roof tile covering of a building and the outside air can be brought into communication with one another. Such a roof tile is known from the British patent application GB-A-2.262.295. The known roof tile formed by extrusion comprises a top plate and a bottom plate, which are spaced at a distance from one another in order to define therebetween a hollow space closed in lateral directions, in which the hollow space is continuous in a longitudinal direction of the roof tile and connects to the outside air at the lower head edge of the roof tile and is connected to the space between the roof tiles and the underlying roof structure at the top head edge of the roof tile. The known roof tile has the advantage that a ventilation means is provided which works bilaterally, which will, moreover, not or almost not be conspicuous in a tiled roof; only the open, lower head edge of the known roof deviates from the adjacent tiles. The known tile, of which the hollow space has a straight course the entire length of the tile, can, if so desired, be provided on the inside of the bottom plate with transverse ridges or suchlike sills to prevent moisture/water being blown through the hollow space to the top opening and the space below the tiles. Suchlike ridges, which reduce the flow cross section, can cause an undesired obstruction of the air flow in the hollow tile, whereas if they were to leave a sufficient flow area free, they would be insufficiently high for preventing precipitated water being dragged along by air to the top opening. It is an object of the invention to improve on this and for that purpose it provides a roof tile made of synthetic material comprising a top plate and a bottom plate, which are spaced at a distance from each other for defining therebetween a hollow space closed in lateral directions, with a lower opening, which is arranged in the lower head edge of the tile, for the passage of air to and from the hollow space and the discharge of moisture from the hollow space, and with an upper opening, which is at least in part defined by the bottom plate, for the passage of air to and from the hollow space from and to the spaces located below the roof tile in the situation in which the roof tile is used, respectively, wherein the bottom plate is shaped such that an expansion chamber is formed in the hollow space for air entering through the lower opening. By the expansion chamber, which forms a widening of the flow profile of, in any case, the air flowing in from the outside, a deceleration area is provided for the air carrying moisture and dirt, as a result of which the water and dirt particles, which when it rains come in the form of drops or as a stream flowing down from the roof tile in the vicinity of the bottom opening and are carried with the entering air into the hollow space, will be allowed to be deposited on the floor of the chamber. Preferably in the roof tile according to the invention precipitated moisture is received by the expansion chamber, for which purpose the bottom plate in a portion thereof located at a distance from the lower opening and the upper opening, forms a tray defined by a lowered floor, in which the top plate is straight in the longitudinal direction of the roof tile. The precipitated water is thus held outside the main air flow. Superfluous water can then run off out of the tray and leave the hollow space through the lower opening. Preferably the expansion chamber also forms an enlargement of the flow cross section compared to the upper opening. As a matter of fact with this the upper opening forms a narrowing compared to the expansion chamber, as a result of which an acceleration area for air flowed in, which is substantially freed of moisture, is realized, whilst moreover a sill is put up against water which may have accumulated in the expansion chamber. Preferably, the hollow space extends at least substantially over the full width of the tile. Owing to this air flows in the hollow space can equalize each other out in a transverse direction, so that a flow arises which is as uniform as possible and local, large water carrying accelerations are avoided. In addition, the ease with which the hollow tile is manufactured is enlarged by the absence of longitudinal partitions, such as can be found in the roof tile according to British patent application GB-A-2.262.295. If necessary, local projections can be formed integrally with the bottom plate, on the top side of which the top plate can find support. Preferably, the hollow space extends at least substantially in an uninterrupted way from the one longitudinal side to the other longitudinal side of the roof tile. In order to be able to keep the mutual distance between the bottom plate and the top plate as small as possible, that is as far as possible consistent with the thickness of the surrounding tiles, the lower opening extends at least substantially over the full width of the roof tile. According to a first further development of the roof tile according to the invention the upper opening is arranged in the upper head edge of the tile. Preferably, this upper opening extends at least substantially over the full width of the tile. Consequently the roof tile is extremely suited for the exchange of air between the surroundings and the space directly beneath the roof tiles. According to a second further development of the roof tile according to the invention the upper opening is arranged in the bottom plate, that is above the portion thereof that forms the floor of the expansion chamber. This upper opening is preferably defined by a short tubing extending downward. This embodiment of the roof tile according to the invention is particularly suited for being connected to a mechanical ventilation system or a sewage relief system, in which both cases the roof tile has to be connected to a roof passage or a pipe located directly below the roof covering. In the case of discharge of air from the spaces located below the roof of a building, the expansion chamber is advantageous, because a too large pressure build-up generated by wind is thereby counteracted and the discharging function can be maintained for longer. The expansion chamber works in the manner described above by reducing the transfer of moisture, to wit by preventing the passage of moisture from outside the roof to the mechanical ventilation system. The roof tile according to the invention is further preferably characterized, in that the bottom plate is step-shaped near the top edge of the roof tile to define bearing surfaces for support on a roof batten. The roof tile according to the invention can then be laid quickly, the roof batten coming to rest between the expansion chamber and the step-shaped portion of the bottom plate. The spaces between the roof battens can make room for the floor of the expansion chamber of the roof tile. It is advantageous if the upper head edge of the top plate is substantially straight. This is especially advantageous if the roof tile will have to have a undulating appearance, because the undulating top plate can then connect via a straight edge to the bottom plate, as a result of which the manufacture of the top plate is easier and the length of the connecting area of the top edges of the bottom plate and the top plate is kept to a minimum. In addition, one and the same top plate can be used for the two developed further types of the roof tile described above. In the embodiment of the roof tile with the step-shaped bottom plate area near the top edge and the straight upper head edge of the top plate it is advantageous if the upper head edge of the top plate is arranged in the same plane as the edge of the step, which plane is substantially parallel to the main plane of the roof tile. The flow of air through the hollow space is then offset downward and flows out of the roof tile into an area which is close to the roof covering, so that the incoming flow is slowed down less quickly by the projecting portions of other roof tiles in the direct vicinity. The invention will now be described on the basis of a number of preferred embodiments shown in the accompanying drawings; figure 1 shows a perspective view of a first preferred embodiment of the roof tile according to the invention; figure 2 is a side view of the roof tile of figure 1; figure 3 is a front view, on the lower head edge, of the roof tile of figure 1; figure 4 shows a perspective, schematic bottom view of the roof tile of figure 1, in which the length is, however, shortened; figure 5 shows a schematic representation of the roof tile of figure 1 in a position as placed in a tiled roof; figure 6 shows a perspective, schematic bottom view of a second preferred embodiment of the roof tile according to the invention, similarly not to scale as in figure 4; and figure 7 shows a schematic representation, corresponding to figure 5, of the roof tile of figure 6 in a position placed in a tiled roof. The hollow roof tile 1 shown in figure 1 consists of a top plate 2 of synthetic material and a bottom plate 3 of synthetic material, both manufactured from, for example, polycarbonate, by, for instance, vacuum forming or injection moulding. The circumference of the roof tile 1 corresponds to that of the tile which will be located adjacent thereto. The top plate 2 has a colour (not shown) which corresponds to the colour of the roof tiles which will be joined to it in the situation in which the tile is in use. The form of the top plate 2 also corresponds to the roof tiles which are joined to it in the situation in which the tiles are in use. The top plate 2 can therefore have a flat or undulating top surface 10. The top plate 2 has, moreover, an upper edge 5, a lower edge 6, a side edge area 7 and an opposite side edge area 8. The upper edge 5 is straight and forms the end of a portion 36 which extends horizontally and connects smoothly to head wall areas 4, which also merge smoothly into the undulating top surface 10 of the top plate 2. The lower edge 6 of the top plate 2 is undulated, corresponding to the form of the top surface 10 of the top plate 2 in cross section. The side edge area 8 has a dependant, longitudinal edge and has a profile 9 in cross section, which is comparable to that of regular roof tiles, for providing support and resistance to sideward movement for the regular roof tile located adjacent thereto. The other side edge area 7 also has a dependant longitudinal edge and is intended for being supported on the profiled side edge area of the regular roof tile located adjacent thereto and to be checked against sideward movement. At the lower edge 6, adjacent the side edge areas 7 and 8, the top plate 2 has more dependant portions 11 and 12, which serve to define a downward open receiving channel for the side edge strips 15, 16 of the bottom plate 3, yet to be described, in conjunction with the dependant longitudinal edges of the edge areas 7 and 8. The bottom plate 3 has a shape which deviates from the shape of the bottom sides of regular roof tiles. As can also be seen in figure 2, a striking characteristic of the bottom plate is the presence of a tray-shaped portion 19, which is bounded in longitudinal cross section by a highly sloping wall 22, slightly sloping walls 20 and 21, and again a highly sloping wall 23. As can be see in figure 1 the tray 19 extends over almost the full width of the roof tile 1 and is bounded in a lateral direction by substantially upright side walls 32 and 33, which at their upper edges merge into sidewardly projecting side edge strips 15 and 16, respectively, which extend from the lower head edge to the upper head edge of the bottom plate 3. The wall portion 22 connects to the lower portion 35, which, seen in transverse cross section, is shaped substantially consistent with the transverse cross section of the top plate 2, because this portion is intended to come to rest in a tiled roof on a regular roof tile located therebelow. The wall portion 22 will then come to rest directly above the upper head edge of that regular roof tile, such as is also shown in figure 5. On the upper side the wall 23 merges via a sharp bend into a transverse strip area 24, which, together with the edge 26 and the transverse strip area 25 connected to it, forms a step. The space determined by wall portion 23 and transverse strip areas 24 and 25 is suited for receiving a roof batten, as is shown with roof battens 42 in figure 5. Via a sharp bend the transverse strip area 25 merges into transverse strip area 27, the top edge 13 of which forms the head edge of the bottom plate 3. This edge 13 extends in such a way from the one side edge of the bottom plate to the other side edge thereof, that it extends horizontally over a small area connecting to the side edge strip 15 of the roof tile, extends subsequently downward and then over almost the full width of the roof tile to the other side thereof, parallel to the edge 5 of the top plate 2, then again vertically upward, to finally end in a substantially horizontal portion connecting to the other side edge strip 16. A wide rectangular air passage opening 31 is defined by the straight edge 5 of the top plate 2 and the edge 13 of the bottom plate 3, which is actually located adjacent the top plate 2, that is to say only unilaterally defined by the top plate 2. At the lower end of the roof tile 1 the lower edge 14 of the bottom plate 3 and the lower edge 6 of the top plate 2 define an undulated slot 30 extending over at least almost the full width of the roof tile 1, through which air can flow into and out of the space defined between the top plate 2 and the bottom plate 3. The hollow space between the top plate 2 and the bottom plate 3 is only interrupted by an elevation 17 formed integrally with the bottom plate 3, the top surface 18 of which (see also figure 3) can provide a suppport for the top plate 2. In conjunction with the strength properties as a result of the undulated profile of the top plate 2, the maintenance of the hollow space between the top plate 2 and the bottom plate 3 is herewith ensured, whilst the flow profile, which is preferably at least as large as 70 cm 2 ,is not notably reduced. Moreover, interexchange of (part) air flows is possible over the greater portion of the length of the roof tile in a lateral direction. The flow profile in the lower opening 30 is at least 70 cm 2 , is enlarged at the site of the tray 19 to, for example approximately 150 cm 2 , then again amount to at least 70 cm 2 at the transverse strip 24 and the transverse strip 27, as well as opening 31. The turned and substantially horizontally extending strips 15 and 16, respectively, can be accomodated in the previously mentioned downwardly open channels in the side edge areas of the top plate 2. At the top end of the bottom plate 3 these edge strips 15 and 16 are turned downward by means of areas 28, to then again be turned back into a substantially horizontal direction in areas 37 directly connecting to the head edge 13 of the bottom plate 3. On a level with the side areas 15 and 16, the areas 28, 37 extend similar to the areas 4, 36 of the top plate 2. After the top plate 2 and the bottom plate 3 have been formed, they can easily be attached to each other by means of adhesive, in which the adhesive will be applied at the site of the areas 28, 37 and 15, 16. Another possibility is connecting those areas of both plates 2 and 3 to one another by heat welding or fusing. Yet another possibility is forming the roof tile by means of blow moulding, the roof tile then being formed in one piece. A further possibility is forming the top plate and the bottom plate by means of the "twin-sheet" method, in which both plates are formed at the same time and as opposites by vacuum forming and are fused together along portions of their edges intended for that purpose. The roof tile may also be formed by means of an injection moulding method. The synthetic roof tile 1 according to the invention is then ready to be included into a tiled roof structure, as is shown schematically in figure 5. It can be seen that the roof tile 1 rests with the area 35 on a following regular roof tile 43a located therebelow and with the upper area located near the top edge of the top surface provides support to the bottom side of the connecting regular roof tile 43b located thereabove. In addition, due to the engagement of batten 42 with the step which is formed in the lower plate of the hollow roof tile 1, the hollow roof tile 1 is held against sliding along the roof, of which rafter 40 and covering 41 are shown, and also held with its top surface at the correct height, so that the planes in which the tops of the waves of the roof tiles 1 and 43a, b are located are parallel with each other and the appearance of the tiled roof is as regular as possible. It is, however, also possible to make the tray 19 so deep that the vertical distance from the top surface of the roof tile 1 to the covering 41 corresponds to the required distance, to let the highly sloping wall 22 to keep the roof tile 1 in position in the sloping direction by bearing against the head top edge of the regular roof tile 43a. In figure 5 it can be seen that through the hollow roof tile according to the invention a flow of air from outside to the space between the roof tiles and the roof covering 41 can occur, the flow of air entering the lower opening 30 in the direction A1, subsequently arriving in a space which is formed by the tray 19 and suddenly widened by wall 22, and there allowing water and dirt particles to be deposited on the floor of the tray 19 as a result of decelaration phenomena of the flow of air. The flow of air continues in the direction A3 to exit via a buckle-shaped path in the direction A2 via the upper opening 31. As a result of the buckled shape, which shape is achieved because, as can be seen in figure 2, the top edge 5 of the top plate 2 is located in one plane parallel to the top plate 2, with the edge 26 of the step, this upper opening 31 is located near the covering 41, so that the flow A2 can be more effective. The effectiveness of the inflowing air is further enhanced by the lowered outflow of air in the direction A2 which is a result of the neck which is realized by the opening 31 being lowered relative to the edge 26 of the step. Reverse flow is also possible, according to the directions B1, B3 and B2, from the space under the roof tiles to the space outside the roof. In the figures 6 and 7 a roof tile 101 is shown, which corresponds substantially to the roof tile 1 shown in the figures 1-5, but is provided with a roof passage for connecting to a sewage relief system or a mechanical ventilation system. Corresponding portions are indicated with corresponding reference numbers, multiplied by 100. The difference with the roof tile 1 is that the upper opening 31 is no longer present: there there is an end wall 152 formed integrally with the bottom plate 3. As a result the top edge 113 is entirely straight and the connecting area which corresponds to the area 37 of roof tile 1 can possibly be one continuous straight transverse strip for forming a continuous bearing surface for the edge area of the top plate 102 corresponding to the edge area 36 of the roof tile 1. Note that the top plate 102 can be identical to the top plate 2, and thus that for a modified embodiment of the roof tile 101 viz-a-viz roof tile 1 only the bottom plate has to be changed. The bottom surface of the bottom plate 103 is interrupted by the formation of a circle-shaped opening 150, which is bounded by a short tubing 151 which is formed integrally with the bottom plate 103. The short tubing 151 is designed for forming a roof passage for, for example, a mechanical ventilation system. In figure 7 the situation is shown in which the roof tile 101 can be included in a tiled roof, in which the roof batten 142' is interrupted at the site of the short tubing 151. In the adjacent areas the step 124, 125, also formed in the bottom plate 103, forms a bearing means for the roof tile 1 on the adjacent parts of the roof batten 142', so that a stable position of roof tile 101 is guaranteed. If the roof tile 101 is used for ventilation in connection with sewage relief, air can enter in the direction C1, can release its water and dirt in the tray 119 and then continue to flow in the direction C3, to then flow further in the direction C2 to the pipe connected to the short tubing 151. In a mechanical discharge system air can flow in the direction D1 through the short tubing 151 from the mechanical ventilation system, flow further in the direction D3 to finally be discharged outwards in the direction D1. The chamber 119 sees to it that the flow of air entering through the short tubing 151 will only be influenced to a small extent by gusts of wind in which air can be pushed up in the direction C1. It will be seen that the roof tile according to the invention can easily be fitted into a roof tile system and, at least in the embodiments of the figures 1-5, can be treated as the other, regular roof tiles, without special provisions being necessary. Besides, the roof tile according to the invention takes up little space. The versatility of the roof tile according to the invention is guaranteed in that the structure can be tuned to the desired, ventilating effect by means of just adapting the bottom plate.

Claims: Roof tile (1;101) of synthetic material, comprising a top plate (2;102) and a bottom plate, (3;103) which are spaced at a distance from each other for defining therebetween a hollow space closed in lateral directions, with a lower opening (30), which is arranged in the lower head edge of the tile, for the passage of air to and from the hollow space and the discharge of moisture from the hollow space, and with an upper opening, (31;150), which is at least in part defined by the bottom plate, (3;103) for the passage of air to and from the hollow space from and to the spaces located below the roof tile in the situation in which the roof tile is used, respectively, characterized in that the bottom plate (3;103) is shaped such that an expansion chamber (19;119)is formed in the hollow space for air entering through the lower opening (30). Roof tile according to claim 1, wherein the bottom plate (3;103) in a portion thereof that is located at a distance from the lower opening (30) and the upper opening (31;150) forms a tray(19;119) defined by a lowered floor (20,21;120;121) and the upper plate (2;102) is straight in the longitudinal direction of the roof tile (1;101). Roof tile according to claim 1 or 2, wherein the expansion chamber (19;119) also forms an enlargement of the flow cross section with regard to the upper opening (31;150). Roof tile according to any one of the preceding claims, wherein the hollow space extends at least substantially over the full width of the tile (1;101). Roof tile according to any one of the preceding claims, wherein the hollow space extends at least substantially in an uninterrupted way from the one longitudinal side (32,132) to the other logitudinal side (33;133) of the roof tile. Roof tile according to any one of the preceding claims, wherein the lower opening (30) extends at least substantially over the full width of the roof tile (1;101). Roof tile according to any one of the preceding claims, wherein the upper opening (31) is arranged in the upper head edge of the tile. Roof tile according to claim 7, wherein the upper opening (31) extends at least substantially over the full width of the tile (1;101). Roof tile according to any one of the preceding claims, wherein the upper opening (150) is arranged in the bottom plate (103), above the portion thereof that forms the floor of the expansion chamber (119). Roof tile according to claim 9, wherein the upper opening (150) is defined by a short tubing (151) extending downwards. Roof tile according to any one of the preceding claims, wherein near the upper edge of the roof tile (1;101) the bottom plate is step-shaped (25;125) to define bearing surfaces for support on a roof batten. Roof tile according to one of the claims, wherein the upper head edge of the top plat (2;102) extends in a substantially straight manner and preferably the top plate (2;102) is undulated in a transverse direction. Roof tile according to claim 11 and 12, wherein the upper head edge (5;105) of the top plate (2;102) is arranged in the same plane as the edge (26;126) of the step (25;125), which plane is substantially parallel to the main plane of the roof tile. Roof tile according to anyone of the preceding claims, formed by blow moulding. Roof tile according to any one of the claims 1-14, formed by "twin sheeting", wherein the top plate (2) and bottom plate (3) are simultaneously formed opposite each other by vacuum forming and their edges (7,8;15,16) are then fused together.

Inventors: VAN SCHELLEBEEK DIRK JOHANNES, VAN SCHELLEBEEK, DIRK JOHANNES
Applicants: UBBINK NEDERLAND BV, UBBINK NEDERLAND B.V.
Application year: 1995
Main classification: E04D1
IPC codes: E04D1, F24F7