GB2239031A

GB2239031A - Corrugated roofing panel

Info

Publication number: GB2239031A
Application number: GB8928401A
Authority: GB
Inventors: Risto Saivosalmi
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-12-15
Filing date: 1989-12-15
Publication date: 1991-06-19
Also published as: GB8928401D0

Abstract

A roof slab, which is manufactured preferably of plastic coated steel sheet by roll-forming a plane sheet web first to be corrugated and by pressing subsequently transverse steps in the corrugated sheet web, thus providing a tile-like structure in the roof slab. The roof slabs are laid on the roof so that the extreme ridges (2, 3) of two adjacent slabs overlap at least partly. According to the invention, the ridges (1, 2, 3) and grooves (4) of the corrugated roof slab are made asymmetrical so that one slope (6) of the groove is essentially steeper than the opposite slope (7) of the groove. At the joint (8) of the roof slabs, the edge (9) of the top slab joins smoothly the plane shape of the steeper slope (6) of the ridge (3) of the subjacent slab and at the joint a water drain (11) has been formed at the edge (10) of the subjacent slab.

Description

Roof slab The invention relates to a roof slab, which is preferably manufactured for instance from a plastic coated steel sheet by roll forming a plane sheet web first into a corrugated shape with ridges and grooves oriented in the direction of the sheet web, and by pressing subsequently transverse steps into the corrugated sheet web, thus achieving a tile-like structure on the roof slab, the ridges and grooves of the corrugated roof slab being asymmetrical, the one slope of the groove being essentially steeper than the opposite slope of the groove, and at the joint of the slabs, the edge of the top slab joins the shape of the steeper slope of the subjacent slab, and the slabs are laid on the roof so that the extreme ridges of two adjacent slabs overlap at least partly, and a water drain is formed at the edge of the subjacent slab at the joint.

The excellent advantage of roof slabs made of steel sheet consists in their light weight and easy laying. A good corrosion resistance has been obtained e.g. by means of plastic coating. Since the slab material used in the manufacture of roof slabs cannot be very thick due to lightness and forming requirements, the produced roof slabs are often too easily flexible and thus difficult to hoist onto the roof. Due to lacking stiffness, such roofs are also noisy during rain and stormy weather. Studies have proved that vibrations advancing in a metal sheet cause resonances, which increase the noisiness of the roof significantly.

The purpose of the present invention is to eliminate the above inconveniences and to provide an improved roof slab in a new manner. The invention is characterized by that the upper and lower ridges of the inclined plane forming the steeper slope of the asymmetrical ridge of the corrugated roof slab comprise clearly distinguishable creases and in that the ridge of the top slab essentially joins the top crease at the joint, and that the visible inclined plane of the subjacent slab at the joint of the slabs is formed by a plane, the angle of inclination of which preferably is 50-60 , and that in a top view of the roof slab, the shape of the transverse step corresponds to the asymmetrical corrugated shape of the cross-section of the slab.

When studying roof slabs, it has been observed that the asymmetrical construction according to the invention is clearly more rigid than known symmetrical shapes. Hence, such å roof is essentially less noisy and the laying operation is facilitated. It is, of course, easier to hoist a stiff slab, as there is no risk of bending of the slab.

The stiffness of the roof slab according to the invention is further increased by the fact that, in a top view of the roof slab, the shape of the transverse step corresponds to the asymmetrical, corrugated shape of the cross-section of the slab. In such a slab, the longitudinal ridges and the corrugated, transverse steps form together a construction assembly that provides a efficient stiffness.

Waterproofing is another problem involved with steel sheet roofs. Although the slabs overlap partly and the joint coincides with the ridge, a storm would press rain water even through a small opening. In the roof slab of the invention, the problem has been solved so that, at the joint, the ridge of the top slab joins the crease formed in the steep slope of the ridge of the subjacent slab. Thus, the joint between the slabs is made as tight as possible. At the edge of the subjacent slab, a steep wall and a connected water drain are formed. Owing to this steep wall inclined 60-70 the water having entered through an opening in the roof slabs is sure to flow into the water drain without passing into the substructures.

The invention is described below by means of an example with reference to the enclosed drawings, in which figure 1 shows a cross-section of the roof slab of the invention at the ridge, figure 2 corresponds to figure 1 and shows a cross-section at the groove, figure 3 shows a cross-section of the superposed slab edge, figure 4 shows a cross-section of the subjacent slab edge, figure 5 shows a cross-section of the joint between the roof slabs, figure 6 shows a top view of the roof slab of the invention, figure 7 shows a section of figure 6 along the line VII VII.

Figure 1 shows the cross-section of the roof slab of the invention at the ridge in the centre of the slab. The figure shows the asymmetrical shape of the ridge 1. On the other side the slope 7 is gentle and the opposite slope 6 is steep. The roof slab is supported by the substructure 16 at the bottom portion 13 of the groove 4. The figure does not show the transverse step.

Figure 3 shows the border ridge 2 of the roof slab, which is laid on top at the joint. The edge portion of the slab is bent downwards with a slightly smaller radius of curvature than the rest of the ridge 2. The radius of curvature is determined so that at the free edge 9 the tangent of the free surface is in the direction of the inclined plane 6 of the subjacent slab. This ensures a smooth shape of the joint and an optimal tightness.

Figure 4 shows the edge portion of the subjacent slab at the joint. The top portion of the ridge 3 at the edge is partly equally shaped as the other ridges of the slab, but in the vicinity of the highest point of the ridge it turns into a steep wall 17, comprising a water drain 11 at its bottom part. The bottom 12 of the water drain 11 is supported by the substructure 16, likewise as the bottom of the groove 4.

Figure 5 shows a cross-section of the joint of the roof slabs. The superposed ridges 2 and 3 lock the slabs laterally. Thus, the edge 9 of the top slab coincides with the crease 14 of the subjacent slab. The reduced radius of curvature of the edge portion is determined-so that at the edge 9, the tangent of the curved surface is in the direction of the plane 6 of the subjacent slab. Thus, in a top view of the slabs, at the joint 8, the curvature of the ridge 2 seems to go on smoothly as the plane 6 of the following slab. The water having possibly entered through the joint 8 flows along the wall 17 of the subjacent slab into the water drain 11 formed in the edge and is discharged at the eaves. In this manner, the substructure stays dry.

Figure 6 shows a top view of the roof slab of the invention.

The manufacture of the roof slab is carried out from the left to the right in the figure so as to roll-form the plane sheet to be corrugated first. The shape of the waves is asymmetrical, as it is shown in the cross-section views of figures 1 and 2. The plane 6 of the steeper slope of the ridge 1 is limited by the creases 14 and 15. At the edge 9 in the top portion of figure 6, the border ridge 2 of figure 3 has been formed and at the bottom edge 10, the water groove 11 of figure 4 has been formed.

After roll-forming, equally spaced transverse steps 5 are pressed in the slab. In a top view, the shape of the steps 5 corresponds to the asymmetrical undulating shape of the cross-section, so that the ridge point 18 of the step line coincides with the ridge 1 of the cross-section profile.

The wave pattern of the step line and the cross-sectional pattern of the roof slab correspond also in that the height of both the waves is equal. By means of such a construction, an extremely rigid and strong roof slab is provided.

Figure 7 shows a section of figure 6 along the line VII-VII.

The section line passes along the ridge of the ridge 1.

The figure shows a bottom view of the plane 6 of the steeper slope as well as the limiting creases 14 and 15.

In the example of the drawings the wave length of the crosssection as well as of the step line is 200 mm. The height of both the waves is 44 mm. Thus, the ratio of the wave height to the wave length is 0.22. The height of the step is 18 mm, so that the ratio between the step height and the wave height is 0.41. The angle of inclination of the plane steep slope is 55 . The height and radius of curvature of'the water groove are 10 mm and the inclination of the steep slope adjacent to the water groove is 650.

It is obvious to a person skilled in the art that the different embodiments of the invention may vary within the range of the following claims.

Claims

1. A roof slab, which is preferably manufactured of a plastic coated steel sheet by roll-forming a plane sheet web to be corrugated first, so that the ridges (1, 2, 3) and the grooves (4) are in the direction of the sheet web, and by pressing subsequently transverse steps in the corrugated sheet web, thus forming a tile-like structure in the roof slab, the ridges (1, 2, 3) and grooves (4) of the corrugated roof slab being asymmetrical, the one slope (6) of the groove being essentially steeper than the opposite slope (7) of the groove, and that at the joint (8) of the roof slabs, the edge (9) of the top slab joins the shape of the steeper slope (6) of the ridge (3) of the subjacent slab, and the roof slabs being laid on the roof so that the extreme ridges (2, 3) of two adjacent slabs overlap at least partly, and that at the joint, a water drain (11) has been formed at the edge (10) of the subjacent slab, characteri zed in that the upper and lower edge of the inclined plane forming the steeper slope (6) of the asymmetrical ridge (1, 2, 3) of the corrugated roof slab comprise distinct creases (14, 15), in that at the joint (8) of the roof slabs, the edge (8) of the top slab joins essentially the upper crease (14), in that at the joint (8) of the roof slabs, the visible inclined plane (6) of the bottom slab is formed by a plane, the angle of inclination of which is preferably 50-600, and in that in a top view of the roof slab, the shape of the transverse step corresponds to the asymmetrical, undulating shape of the cross-section of the slab.

2. A roof slab according to claim 1, characterized in that the height of the asymmetrical wave of the transverse step (5) and the height of the asymmetrical wave of the crosssection are essentially equal.

3. A roof slab according to claim 1 or 2, characterized in that the ratio between the height of the asymmetrical wave of the corrugated roof slab and the height of the wave is preferably 0.2-0.3.