Improvements in or relating to formwork

Abstract

 The invention relates to formwork for supporting an arched head over a window or door opening. The formwork (8) includes a front horizontal portion (10), a front upright portion (11), an upper arched portion (12) and a rear vertical portion (13 or 23). At each end of the formwork the upper arched portion (12) merges into a horizontal extension (14). In one embodiment of the invention (Figures 1 and 2) the upper arched portion (12) interconnects the arcuate upper edges of the front vertical portion (11) and the rear vertical portion (13). In another embodiment of the invention (Figures 3 and 4) the rear vertical portion (23) has a straight upper edge (21), the height of which is greater than the maximum height of the front vertical portion.

Description

[0001] This invention relates to formwork for supporting an arched head over a window or door opening in a wall of a building.

[0002] It is sometimes required to provide an arched head over a window or door opening, but such provision may involve difficulties in view of the fact that modern lintels are normally designed to support a horizontal course of bricks, blocks, or the like. Accordingly, it is necessary for the builder to provide some means of filling in the space between the flat upper surface of the. lintel and the curved under surface of the arch, and it is an object of the present invention to provide a simple means of filling in this space.

[0003] The invention consists in a formwork for supporting an arched head over a window or door opening in a wall of a building, said formwork including a front horizontal portion spanning said opening; a front vertical portion upstanding from said front horizontal portion and having an arcuate upper edge., a rear vertical portion having a straight lower edge coplanar with said front horizontal portion; and an arched upper portion connecting the arcuate upper edge of the front vertical portion to the rear vertical portion and forming a support for a course of bricks, blocks, or the like, forming said arched head.

[0004] In one embodiment of the invention, the rear vertical portion of the formwork has an arcuate upper edge, the curvature of which corresponds to the curvature of the upper edge of the front horizontal portion. Thus, in this case, the arched upper portion interconnects the arcuate upper edges of the front vertical portion and the rear vertical portion.

[0005] In a second embodiment of the invention, the rear vertical portion has a straight upper edge, the height of which is greater than the maximum height of the front vertical portion. Thus, in this case, the rear edge of the arched upper portion is joined to the front face of the rear vertical portion.

[0006] The invention is particularly applicable to buildings having cavity walls. In such buildings, it is usual to support the weight of the walls above an opening by means of a lintel having a front horizontal portion spanning the opening in the front wall skin, and a rear horizontal portion spanning the opening in the rear wall skin. In particular, such lintels may be made of metal and one example of a lintel of this kind is shown in U.K.Patent Specification No 1 388 391. The present invention provides a formwork which is particularly suitable for use in connection with a lintel of the kind shown in Figures 1 and 2 of the said U.K. Patent Specification No 1 388 391, but it is to be understood that it may also be used with other types of lintel.

[0007] From another aspect the invention consists in a lintel and formwork extending across an opening in a cavity wall, said lintel being as claimed in any of the Claims of U.K. Patent Specification No 1 388 391, and said formwork being in accordance with the last paragraph but three.

[0008] It is preferred that a formwork in accordance with the present invention should be made of glass fibre reinforced synthetic resin material (hereinafter referred to as fibreglass). In this case, the whole formwork may be moulded in one piece. However, a weather-resistant thermoplastic synthetic resin material may be used instead of fibreglass and in this case the formwork is preferably produced from a sheet of the material by vacuum forming. Furthermore a formwork in accordance with the invention may also be made of metal and, in this case, it is preferably fabricated from a number of sheets welded together.

[0009] Preferably a formwork in accordance with the invention includes a horizontal extension at each end, the width of each of said extensions being equal to the total width of the arched upper portion and the front horizontal portion. Thus each extension constitutes an extension both of the arched upper portion and also of the front horizontal portion. Moreover the extensions will be coplanar with the front horizontal portion.

[0010] In either embodiment the front horizontal portion preferably includes a dependent lip along its outer edge and, in a modification of the invention, the front horizontal portion and the lip may be replaced by a doubly-curved portion.

[0011] If the formwork in accordance with the second embodiment of the invention is made of glass fibre reinforced synthetic resin material, it may be moulded in one piece in the form defined above, preferably with the front vertical portion upstanding from the rear of the front horizontal portion. If, however, the formwork is made of metal, the front horizontal portion and the rear vertical portion are preferably formed from a length of angle section metal, and the front vertical portion and the arched upper portion are formed from a further length of metal, the lower edge of the front vertical portion being welded to the front horizontal portion and the rear arcuate edge of the arched upper portion being welded to the front face of the rear vertical portion. In this case, it will be understood that the central portion of the formwork is in the form of a closed box section. If it is desired that the central portion should be open on the underside, the central portion of the angle section may be removed, for example, by shearing, before the two parts are welded together.

[0012] If formwork in accordance with the first embodiment of the invention is used in combination with a lintel of the kind shown in U.K. Patent Specification No. 1 388 391, an independent damp-proof course is provided to bridge the inner and outer skins of the wall in order to deflect moisture from within the cavity to the outside of the building. This damp-proof course extends down the front face of the lintel and stretches to the front of the building between the base of the formwork and the front horizontal portion of the lintel. In some circumstances, this arrangement provides some difficulty in construction and, if the formwork is modified in accordance with the second embodiment of the invention, it is unnecessary to continue the damp-proof course between the formwork and the lintel. Instead, the lower edge of the damp-proof course merely overlaps the front upper edge of the formwork and terminates substantially along a horizontal line tangential to the arched upper portion of the formwork.

[0013] In the drawings:-

Figure 1 is a perspective view of an opening in the cavity wall of a building having a lintel in accordance with U. K. Patent Specification No 1 388 391 extending across the opening, together with a formwork in accordance with a first embodiment of the invention ;

Figure 2 is a cross-sectional view of the lintel and formwork of Figure 1 taken at the centre of the arch with a slightly modified arched head;

Figure 3 is a perspective view of an opening in the cavity wall of a building having a lintel in accordance with U.K. Patent Specification No 1 388 391 extending across the opening, together with a formwork in accordance with a second embodiment of the invention; and

Figure 4 is a cross-sectional view of the lintel and formwork of Figure 3 taken at the centre of the arch with a slightly modified arched head.

[0014] Figures 1 and 2 of the drawings show a wall of a building including a front skin 1 consisting of bricks, and a rear skin 2 consisting of blocks. A window opening defined by a frame 3 including a horizontal top member 17 is provided in the wall. The window opening is spanned by a lintel 4 as illustrated in Figures 1 & 2 of UK Specification No 1 388 391. An independent damp proof course 5 is also provided across the opening, and this bridges the inner and outer skins to deflect moisture from within the cavity to the outside of the building. The lintel 4 includes a front horizontal portion 6, and a part 7 of the damp proof course 5 is located above this front horizontal portion of the lintel. Resting on the portion 7 and supported by the portion 6 of the lintel is a fibreglass formwork 8.

[0015] The formwork is moulded in one piece and includes a front lip 9, a generally horizontal front portion 10, a front upright portion 11, an upper arched portion 12, and a rear vertical portion 13. At each end of the formwork, the upper arched portion 12 merges into a horizontal extension 14. It will be understood that the undersides of the front horizontal portion 10 and the two extensions 14 are coplanar with the bottom edge of the rear horizontal portion 13 so that, when the formwork is supported by the lintel 4, the front portion 10 and the two extensions 14 are horizontal.

[0016] Preferably the arched upper portion 12 is provided with a central channel 15. This channel provides a mortar key to assist in retaining a course of bricks or blocks 16 in position. These bricks or blocks may be laid either flat or soldier-fashion.

[0017] Figures 3 and 4 of the drawings again show a wall of a building including a front skin 1 consisting of bricks, and a rear skin 2 consisting of blocks. A window opening defined by a frame 3 including a horizontal top member 17 is provided in the wall. The window opening is spanned by a lintel 4 as illustrated in Figures 1 & 2 of UK Specification No 1 388 391. An independent damp-proof course 25 is also provided across the opening, and this bridges the inner and outer skins to deflect moisture from within the cavity to the outside of the building. The lintel 4 includes a front horizontal portion 6, and a fibreglass formwork 8 is supported by this portion.

[0018] The formwork is moulded in one piece and includes a front lip 9, a generally horizontal front portion 10, a front upright portion 11, an upper arched portion 12, and a rear vertical portion 23. At each end of the formwork, the upper arched portion 12 merges into a horizontal extension 14. It will be understood that the undersides of the front horizontal portion 10 and the two extensions 14 are coplanar with the bottom edge of the rear horizontal portion 23 so that, when the formwork is supported by the lintel 4, the front portion 10 and the two extensions 14 are horizontal.

[0019] It will be seen that the upper edge 21 of the rear vertical portion 23 is parallel to the lower edge so that, in use, it also is horizontal. The upper arched portion 12 merges into the rear vertical portion 23 along a curved line on its front face. The height of the rear vertical portion is such that it extends a short distance above the highest part of the arched portion as shown most clearly in Figure 4. The width of the damp-proof course 25, which will normally consist of waterproof felt or the like, is such that its lower edge reaches approximately to the highest part of the arched upper portion. It will be understood that this arrangement represents a saving in the amount of damp-proof material required as compared to the arrangement of Figure 1 and 2, as well as making construction of the arch easier for the builder.

[0020] The hereinbefore described embodiments of the invention were moulded from fibreglass. However, as previously mentioned, it is possible to use a thermoplastic weather-resistant material in place of fibreglass. One particularly suitable material is sold under the name Bexel XS and is made from Hostyren XS developed by Hoechst. In manufacturing a formwork in accordance with the invention from this material a sheet of the material is heated and then vacuum formed to the required shape.

Claims

1. A formwork for supporting an arched head over a window or door opening in a wall of a building, said formwork including a front horizontal portion spanning said opening; a front vertical portion upstanding from said front horizontal portion and having an arcuate upper edge; a rear vertical portion having a straight lower edge coplanar with said front horizontal portion; and an arched upper portion connecting the arcuate upper edge of the front vertical portion to the rear vertical portion and forming a support for a course of bricks, blocks, or the like, forming said arched head.

2. A formwork as claimed in Claim 1, wherein the rear vertical portion has an arcuate upper edge, the curvature of which corresponds to the curvature of the upper edge of the front horizontal portion so that the arched upper portion interconnects the arcuate upper edges of the front vertical portion and the rear vertical portion.

3. A formwork as claimed in Claim 1, wherein the rear vertical portion has a straight upper edge and wherein the rear edge of the arched upper portion is joined to the front face of the rear vertical portion.

4. A formwork as claimed in Claim 3, wherein the height of the rear vertical portion is greater than the maximum height of the front vertical portion.

5. A formwork as claimed in any of the preceding Claims, made of fibreglass.

6. A formwork as claimed in Claim 5, wherein the whole formwork is moulded in one piece.

7. A formwork as claimed in any of Claims 1-4, made of metal.

8. A formwork as claimed in Claim 7, fabricated from a number of sheets welded together.

9. A formwork as claimed in any of the preceding Claims, including a horizontal extension at each end, the width of each of said extensions being equal to the total width of the arched upper portion and the front horizontal portion, and said extensions being coplanar with the front horizontal portion.

10. A formwork as claimed in any of the preceding Claims, wherein the front horizontal portion includes a dependent lip along its outer edge.

11. A formwork as claimed in Claim 3 and Claim 8, wherein the the front horizontal portion and the rear vertical portion are formed from a length of angle section metal, and wherein the front vertical portion and the arched upper portion are formed from a further length of angle section metal, the lower edge of the front vertical portion being welded to the front horizontal portion and the rear arcuate edge of the arched upper portion being welded to the front face of the rear vertical portion.

12. A lintel and formwork extending across an opening in a cavity wall, said lintel being as claimed in any of the Claims in UK Patent Specification No. 1 388 391 and the formwork being as claimed in Claim 2 or any of Claims 5-10 when dependent on Claim 2.

13. A lintel or formwork as claimed in Claim 12, including a damp-proof course bridging the inner and outer skins of the wall in order to deflect moisture from within the cavity to the outside of the building, said damp-proof course extending down the front face of the lintel and stretching to the front of the building between the base of the formwork and the front horizontal portion of the lintel.

14. A lintel and formwork extending across an opening in a cavity wall, said lintel being as claimed in any of the Claims UK Patent Specification No. 1 388 391 and the formwork being as claimed in Claim 3, Claim 4, Claim 11 or any of Claims 5-10 when dependent on Claim 3.

15. A lintel and formwork as claimed in Claim 14, where a damp-proof course bridges the inner and outer skins of the wall in order to deflect moisture from within the cavity to the outside of the building, said damp-proof course extending down the front face of the lintel and terminating substantially along a horizontal line tangential to the arched upper portion of the formwork.

16. A formwork as claimed in any of Claims 1-4 made of a weather-resistant thermoplastic synthetic resin material.

17. A formwork as claimed in Claim 16, wherein the formwork is vacuum formed from a sheet of said material.

Drawing