GB2331923A

GB2331923A - Roof cover for thatching

Info

Publication number: GB2331923A
Application number: GB9901322A
Authority: GB
Inventors: Derek Alfred Ward
Original assignee: Environmental Seals Ltd
Current assignee: Environmental Seals Ltd
Priority date: 1996-05-09
Filing date: 1996-05-09
Publication date: 1999-06-09
Anticipated expiration: 2016-05-09
Also published as: GB9901322D0; GB2331923B

Abstract

Roof coverings comprise a plurality of layers of thatching separated by a sheet or sheets of a permeable material which extends or extend over the entire length and width of the overlaid thatching layers and which is or are coated with a fluid in which is mixed a quantity of between 8% and 12% by weight of intumescent material, the or each sheet retaining its permeability after coating. Sheets may be a metallic mesh, perforated metallic sheet or an open weave glass fibre sheet. Fluid is e.g. water, oil based paint or varnish. Intumescent material maybe exfoliating graphite or an alkaline metal silicate.

Description

2331923 1 THATCHED ROOF COVERINGS This invention relates to covers for

thatched roofing including fire barriers.

Fire barriers are known which are either coated with or include intumescent materials which expand rapidly in the presence of fire to seal off protected areas and to prevent a fire hazard passing from one area to another.

In some cases, there is a requirement for a fire barrier. to allow air to flow from one side of the barrier to the other. Such need arises, for example, in thatched roofs of buildings in which a continuous flow of air through the sheaths of straw thatching is essential.

Thatched roofing is, of course, readily combustible and is particularly vulnerable to chimney embers, fireworks and indeed ail manner of fire hazards. Fire proofed sheets which are intended to overlie a thatched roof are unsightly and detract from the aesthetic qualities of a Properly thatched building. Fire barriers in accordance with the present invention are permeable until subjected to fire and are intended to lie below the upper layer of thatching thereby not detracting in any way from the appearance of the thatching. In the event of a fire, it is only the exposed thatch layer which is destroyed, thereby reducing significantly the cost of renovation.

1 2 According to the present invention in one aspect there is provided roof coverings which comprise a plurality of layers of thatching separated by a sheet or sheets of a permeable material which extends or extend over the entire length and width of the overlaid thatching layers and which is or are coated with a fluid in which is mixed a quantity of between 8% and 12% by weight of intumescent material, the or each sheet retaining its permeability after coating.

The sheet may comprise an open weave sheet woven from glass fibres. Alternatively, the sheet may comprise a metallic mesh or perforated metallic sheet.

The fluid may take the form of a water or oil based paint or varnish and the granulated intumescent material may comprise powdered exfoliating graphite and/or an alkaline metal silicate such as sodium silicate.

One or both sides of the sheet may be coated. If both sides are coated, one coating may act as an adhesive for securing the sheet to a surface to be protected. Alternatively an adhesive may be provided for this purpose. The adhesive may be mixed with a quantity of particulate intumescent material, this quantity being typically between 5% and 20% by weight. The intumescent material may comprise powdered exfoliating graphite and/or an alkaline metal silicate such as sodium silicate.

By "open weave" is meant a woven sheet in which discrete openings are provided between neighbouring fibres. The discrete openings are typically from 1 to 3 mm in width. For metallic meshes or perforated sheets, the mesh openings or perforations are again typically from 1 to 3 mm in width or diameter.

The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings in which Figures 1 1 3 and 2 are plan and sectional views of a fire barrier of a roof covering in accordance with the invention.

As will be seen from Figure 1 of the drawings, the fire barrier comprise an open weave sheet 1 woven from glass fibres in which the individual fibres essentially define an irregular mesh which is coated with a fluid mixed with a quantity of powdered exfoliating graphite andlor sodium silicate. The coating is indicated by reference numeral 2. The openings of the woven sheet defined between neighbouring glass fibres remain open after coating. The fluid may comprise a water or oil based paint mixed with a required quantity of powdered exfoliating graphite and/or sodium silicate to define a substantially homogenous mix. Typically, the amount of powdered intumescent represents 10% by weight of the mix. A range of quantities of powdered intumescent is from 5% to 20% by weight. A preferred range of powdered intumescent is between 8% and 12% by weight.

As will be seen more clearly from Figure 2, the fluid is coated onto the surface of the woven sheet 1 with a layer of adhesive 3 provided on the undersurface of the sheet. The adhesive may also be mixed with a quantity of intumescent material, e.g. powdered exfoliating graphite and/or sodium silicate. This quantity is typically of 10% by weight.

In a unillustrated embodiment, the fibrous sheet is replaced by a metallic mesh or perforated sheet.

As mentioned previously, thatched cottages are vulnerable to being set on fire by for example embers leaving a chimney, fireworks or other hazards. Once a fire starts then normally the entire thatching of the cottage is destroyed.

As also mentioned previously, it is a requirement of thatch roofing that 1 1 4 it can breath. When using a fire barrier in accordance with the invention, the permeable barrier is sited immediately below the upper layer of straw thatching and in the event of fire will immediately intumesce to provide secure protection to the majority of the thatching which lies below the barrier. In this event only the surface layer of thatching need be replaced.

With the fire barrier in place therefore the appearance of the thatching is unchanged. Also the barrier enables the thatching to breath in a required manner and as mentioned above in the event of fire provides secure protection for all but the surface layer of thatch.

It will be appreciated that the foregoing is merely exemplary of fire barriers in accordance with the invention and that various modifications can readily be made thereto without departing from the true scope of the invention as set out in the appended claims.

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Claims

1 Roof coverings which comprise a plurality of layers of thatching separated by a sheet or sheets of a permeable material which extends or extend over the entire length and width of the overlaid thatching layers and which is or are coated with a fluid in which is mixed a quantity of between 8% and 12% by weight of intumescent material, the or each sheet retaining its permeability after coating.

2.

A roof covering as claimed in Claim 1 wherein the or each sheet comprises an open weave sheet woven from glass fibres.

3.

A roof covering as claimed in Claim 1 wherein the or each sheet comprises a metallic mesh.

4.

A roof covering as claimed in Claim 1 wherein the or each sheet comprises a perforated metallic sheet.

5.

A roof covering as claimed in any one of the preceding Claims wherein the fluid is a water or oil based paint or varnish.

6.

A roof covering as claimed in any one of the preceding Claims wherein the intumescent material comprises powdered exfoliating graphite.

A roof covering as claimed in any one of the preceding Claims wherein the particulate intumescent material comprises an alkaline metal silicate.

8. A roof covering as claimed in any one of the preceding Claims t 6 wherein one side of the open weave sheet is coated with an adhesive.

9. A roof covering as claimed in Claim 8 wherein the adhesive is mixed with a quantity of particulate intumescent material.

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