GB2454709A

GB2454709A - Roof slates

Info

Publication number: GB2454709A
Application number: GB0722487A
Authority: GB
Inventors: John Alfred Fifield
Original assignee: Forticrete Ltd
Current assignee: Forticrete Ltd
Priority date: 2007-11-15
Filing date: 2007-11-15
Publication date: 2009-05-20
Anticipated expiration: 2027-11-15
Also published as: GB0722487D0; GB2454709B

Abstract

The invention relates to a roof slate 1 comprising upper and lower edges 7 and 8, oppositely facing side edges 9 and 10, an upper surface 3 and an under surface 5 which has a lower edge region 24 provided with one or more longitudinal weather checks 30 extending along the said oppositely facing side edges 9 and 19 and one or more transverse weather checks 32 extending along the said lower edge 8. By providing such longitudinal and transverse weather checks 30 and 32, slates can be laid to roof pitches below 35{ and down to 17.5{. Moreover, the ingress of wind-driven water through the gaps between the double lapped slates of the low pitch roof into the roof space is prevented. The slates are preferably made from concrete or clay and the weather checks 30 and 32 are preferably in the form of bars. A later embodiment relates to a tiled roof formed of a multiplicity of said roof slates.

Description

ROOF SLATES

This invention relates to roof tiles made of a cementitious material, such as concrete or clay, and more particularly to plain tiles and slates.

Plain tiles and slates are of generally rectangular configuration, have a smooth, embossed or riven upper surface and plain tiles optionally have hanging nibs on their under surface for engaging over roof battens when the plain tiles or slates are laid in double- lapped (side-to-side and upper edge-to-lower edge overlapping) relationship to form a roof. Traditionally, plain tiles may be of flat or cambered geometry whereas slates are of flat geometry.

Plain tiles are normally laid to form roofs at pitches of no less than 35°: otherwise wind-driven water can more easily pass through the gaps between the overlapping edges of the double-lapped tiles and into the roof space. Indeed, the minimum pitch for plain tiles of both flat and cambered geometry is 35°. Thus, it has hitherto not been possible to provide a wind-driven water-proof low-pitch roof laid from plain tiles at pitches of <35° and down to at least 25°.

Hereinafter, for convenience of description, plain tiles and slates of flat geometry will be referred to generically as roof slates.

Accordingly, the main object of the present invention is to provide a slate that is capable of being laid at pitches of <35° to form a wind-driven rain-proof low-pitch roof.

To this end, and from one aspect, the present invention resides in a roof slate having upper and lower edges, oppositely facing side edges and an upper surface and an under surface, characterised in that the under surface has a lower edge region provided with one or more longitudinal weather checks extending along the said oppositely facing side edges and one or more transverse weather checks extending along the said lower edge.

By providing such longitudinal and transverse weather checks, slates can be laid to roof pitches down to at least 25° and the ingress of wind-driven water through the gaps between the double lapped slates of the low pitch roof into the roof space is prevented. Furthermore, the weather checks by Spacing the main underside of the overlying slate from the upper surface of the underlying slate prevent water from creeping on the top surface of the underlying slate.

Conveniently the weather checks are in the form of one or more bars.

For large format slates, e.g. with imperial dimensions of 15 x 9 inches or greater, it is possible to lay the slates in accordance with the invention down to a pitch of 17.50.

The length of the longitudinal weather checks is such that they stop at the overlap when the slates are laid to form the roof, thereby avoiding water ingress by capillarity.

Additionally, the weather checks act as supports for the laid double-lapped roof slates on the roof slates beneath and serve as reinforcements against breakage, thereby increasing their strength in situ.

The transverse weather check or checks extends laterally beyond the lower ends of the longitudinal weather checks such that their ends align with the longitudinal sides of the longitudinal weather checks leaving anti-capillarity gaps between the lower ends of the longitudinal weather checks and the transverse weather checks.

In order to increase such support and yet avoid risks of wind-driven water ingress by capillarity, separate, short longitudinal supports can optionally be provided on the said under surface spaced from, and preferably in alignment with, the upper ends of the longitudinal weather checks.

In the laid roof, the lower edges of the adjacent upper double-lapped tiles are located directly above the spaces between the short longitudinal supports and longitudinal weather checks. Thus, the longitudinal weather checks are located downwardly beyond the overlapping lower edges of the adjacent slates whereas the separate supports are located upwardly beyond the lower edges of the adjacent slates.

With a view to avoiding any rocking motion when the weather checks engage with the upper surfaces of adjacent roof slates when laid to form a roof, the under surfaces of the weather checks, as well as the under surfaces of any separate, short longitudinal supports, preferably lie in the same plane.

From another aspect, the present invention resides in a tiled roof formed of a multiplicity of any of the roof slates as defined above in double-lapped relationship.

In such a low-pitch roof, the slates are preferably laid with a slight spacing between the oppositely facing side edges of adjacent slates thereby to avoid water ingress by capillarity that is more likely to happen if the side edges were touching.

In order that the invention may be more readily understood, an embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which:-Figure 1 is a top plan view of a slate made in accordance with the invention; Figure 2 is a perspective view from above of the roof slate of Figure 1; Figure 3 is an underneath perspective view of the roof slate of Figures 1 and 2; Figure 4 is a side view of the roof slate of Figure 1; Figure 5 is plan view of a part of a tiled roof including a multiplicity of the roof slates of Figures 1 to4; and Figure 6 is a side view of the roof of Figure 5.

Referring to Figures 1 to 4 of the drawings there is a shown a roof slate indicated at 1 that is of flat geometry, of generally rectangular configuration and has a flat smooth upper surface 3 and a shaped under surface 5. The roof slate 1 has upper and lower (leading) edges 7 and 8 respectively and oppositely facing side edges 9 and 10.

The roof slate 1 is made from a cementjtjous material, in this case concrete, by extrusion that is well-known and will therefore not be further described save for the following brief account.

Briefly, therefore, the shaped under surface 5 of the slate 1 is formed by a pallet, a succession of which are conveyed beneath an extrusion head where a charge of wet concrete is delivered onto the pallets. An extrusion roller compresses the wet concrete on the paHets and forms the flat, smooth, upper surface 3 of each roof slate 1. Nail holes 12 are formed after each pallet with a charge of wet concrete has passed through the extrusion head to form a continuous ribbon of wet concrete on the succession of pallets, the ribbon being cut into slate-forming lengths to provide the roof slates. If it is desired that the upper surface of the slate has a riven or textured surface then this can be achieved by the use of an embossing roller positioned preferably before cutting into slate-forming lengths.

Referring more particularly to Figures 3 and 4, the shaped under surface 5 of the slate 1 has hanging nibs 14 incorporated into a head bar 16 extending transversely along, and merging with, the upper edge 7 and with the side edges 9 and 10, as indicated 20. The under surface 5 has a non-overlapping upper edge region 22 and an overlapping lower edge region 24. By non-overlapping and overlapping is meant those regions 22 and 24 of the slate 1 that do not overlap and overlap respectively the upper surfaces of adjacent underlying slates 1 when laid to form a roof. The non-overlapping upper end region 22 includes a part 21 of a relatively flat central portion 23 that extends into the overlapping lower edge region 24 as a flat part 25 and an inclined portion 26. The inclined portion 26 is inclined with respect to the part 21 into the body of the slate 1 and in the direction of the head bar 16 and upper edge 7 and terminates in a transversely extending recess 28 for accommodating a roof batten.

The inclined portion 26 is also hollowed out as indicated at 27 in Figure 3 to reduce the overall weight of the slate 1.

In the lower edge region 24 including the flat part 25, there are longitudinal weather checks constituted by Iwo bars 30 extending along, and adjacent to yet spaced from, the oppositely facing side edges 9 and 10 and a transverse weather check constituted by a bar 32 extending along, and adjacent to yet spaced from, the lower edge 8. The transverse weather bar 32 extends laterally beyond the lower ends 34 of the longitudinal weather bars 32 such that its ends 36 align with the outer longitudinal sides of the longitudinal weather bars 30 leaving anti-capillarity gaps 37 between the lower ends 34 of the longitudinal weather bars 30 and the transverse weather bar 32.

As shown in Figure 3, the lower edge region 24 also has a hollowed-out weight-reducing portion 38 extending from the flat part 25 of the central portion 24 at a location 41 which is approximately one third of the length of the longitudinal weather bars from their upper ends 39. This results in the lower two thirds approximately of the longitudinal weather bars 30 increasing gradually in thickness in the direction of the lower edge 8 of the slate 1, as indicated at 40 on the left-hand as illustrated weather bar 30. This increase in thickness improves the strength of, and support for, the lower edge region 24 of the slate 1.

Further support in the overlapping lower edge region 24 of the slate 1 is obtained by the provision of two short longitudinal support bars 42 that are aligned respectively with the two longitudinal weather bars 30. The support bars 42 are spaced from the upper ends 39 of the longitudinal weather bars 30, leaving anti-capillary gaps 44.

As will be appreciated from Figure 4, the under surfaces of the longitudinal and transverse weather bars 30 and 32 and separate support bars 42 lie in the same plane so that their under surfaces all engage fully (i.e. without any rocking motion) with the upper surfaces of adjacent roof slates I when the slates I are laid to form a roof.

Referring now to Figures 5 and 6, there is shown a part of a roof 46 that is formed from a multiplicity of roof slates 1 laid in double-lapped (side-to-side and upper edge-to-lower edge overlapping) relationship. The slates 1 are supported on roof battens 48 that are nailed to roof rafters (not shown) through the nail holes 12 (not visible).

The positions of the transverse and longitudinal weather bars 30 and 32 and the separate supports 42 in the overlapping lower edge region 24 of the slates 1 and the non-overlapping upper edge regions 22 can be seen in full lines in Figure 6.

As shown in Figure 5, the upper edges 7 of two overlapping slates 1 (designated la and lb for ease of explanation) are shown in dashed lines and the positions of the transverse and longitudinal weather bars 30 and 32 and the supports 42 of the slate la are shown in dashed lines. It will be seen that the longitudinal weather bars 30 are located below the overlapping lower edges 8 of the slates 1 whereas the separate supports 42 are located above the lower edges 8 of the slates 1. The slates 1, la, lb are disposed with the side edges 9 and 10 of adjacent tiles slightly spaced apart to provide anti-capillarity gaps 50.

Whilst the invention has been described with reference to a roof slate, the invention is equally applicable to cladding slates. Moreover, various modifications may be made to the described embodiment without departing from the scope of the invention as defined in the appended claims. For example, the central region 23 of the slate 1 may be bellied instead of being flat in order to increase the strength of the slate.

Claims

Claims 1. A roof slate having upper and lower edges, oppositely facing side edges, an upper surface and an under surface, characterised in that the under surface has a lower edge region provided with one or more longitudinal weather checks extending along the said oppositely facing side edges and one or more transverse weather checks extending along the said lower edge.
2. A roof slate as claimed in claim 1, wherein the longitudinal and transverse weather checks are in the form of bars.
3. A roof slate as claimed in claim 1 or claim 2, wherein the longitudinal and transverse weather checks act as supports for laid double-lapped roof slates on roof slates therebeneath and serve as reinforcements against breakage.
4. A roof slate as claimed in any one of claims 1 to 3, wherein the transverse weather checks extend laterally beyond the lower ends of the longitudinal weather checks such that its ends align with the longitudinal sides of the longitudinal weather checks leaving anti-capillarity gaps between the lower ends of the longitudinal weather checks and the transverse weather checks.
5. A roof slate as claimed in any one of claims 1 to 4, wherein the under surfaces of the longitudinal and transverse weather checks lie in the same plane.
6. A roof slate as claimed in any one of claims 1 to 5, wherein the under surface has separate, short longitudinal supports spaced from the longitudinal weather checks, the spacing between the upper ends of the longitudinal weather checks and the lower ends of the separate supports forming anti-capillarity gaps.
7. A roof slate as claimed in claim 6, wherein the short longitudinal supports are spaced from, and are in alignment with, the longitudinal weather checks.
8. A roof slate as claimed in any one of claims 6 and 7 as appendent to claim 5, wherein the under surfaces of the separate supports lie in the same plane as that of the under surfaces of the longitudinal and transverse weather checks.
9. A roof slate as claimed in any one of claims 6 to 8, wherein the arrangement of the longitudinal weather checks and separate supports is such that, in the laid roof, the longitudinal weather checks are located downwardly beyond the overlapping lower edges of the adjacent slates and the separate supports are located upwardly beyond the lower edges of the adjacent slates so that the anti-capillary gaps lie directly beneath above the lower edges of the adjacent upper double-lapped tiles.
10. A roof slate as claimed in any one of claims 1 to 9, wherein the under surface has a front edge region having a portion that is inclined into the slate body in the direction of the upper edge and terminates in a transversely extending recess for accommodating a roof batten.
11. A roof slate as claimed in claim 10, wherein the inclined portion is hollowed-out to reduce the over-all weight of the slate.
12. A roof slate as claimed in claim 11, wherein the lower edge region also has a hollowed-out weight-reducing portion extending between the longitudinal weather checks and terminating at the transverse weather check.
13. A roof slate as claimed in claims 10 and 11 or claim 12, wherein the under surface has a substantially flat central region extending between the hollowed-out portions in the upper and lower edge regions respectively.
14. A roof slate as claimed in claim 12 or claim 13, wherein the longitudinal weather checks increase in thickness in the hollowed-out portion in the lower end region in the direction of the lower edge of the slate.
15. A roof slate as claimed in any one of claims 1 to 14 and capable of being laid to a pitch of <350
16. A roof slate as claimed in claim 15 and of large format having dimensions of 15 x 9 inches or greater and capable of being lafd down to a pitch of 17.50.
17. A roof slate substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.
18. A tiled roof formed of a multiplicity roof slates as claimed in any one claims 1 to 17, the roof slates being laid on roof battens in double-lapped relationship.
19. A tiled roof as claimed in claim 18, wherein the slates are laid with a slight spacing between the oppositely facing side edges of adjacent slates to provide anti-capiflarity gaps between the oppositely facing side edges.
20. A tiled roof substantially as hereinbefore described with reference to Figures 5 and 6 of the accompanying drawings.