IE46715B1

IE46715B1 - Strengthening of roofs

Info

Publication number: IE46715B1
Application number: IE684/78A
Authority: IE
Original assignee: Pelmore James Robert
Priority date: 1977-04-07
Filing date: 1978-04-06
Publication date: 1983-09-07
Also published as: DE2814396A1; FR2386659A1; DE7809923U1; GB2000208A; GB2000208B; FR2386659B1; DE2814396C2; IE780684L

Abstract

In order to strengthen a slate or tile roof, for example where nails securing the individual slates or tiles 10 to the roof battens are corroded, a block 11 of fire-resistant, self-extinguishing foamed plastics material having a layer 13 of tensile reinforcing material bonded to its lower side face is positioned in the angle between and is bonded to an individual slate or tile and a side face of a batten. The reinforcement may be afforded by a layer of an adhesive, such as a thixotropic self-curing resin, used to secure the block to the batten and the slate or tile. Such a layer of adhesive may incorporate a layer of paper or wood or metal foil reinforcement.

Description

The present invention relates to strengthening of l roofs formed of slates or tiles hung on battens and is more I particularly concerned with the strengthening of such roofs formed from slates.

In British Patent No. 1,337,653 there is described a system for strengthening roofs in which, a strip or block of a foamed plastics is positioned in the angle between a roof batten and a slate and is adhesively secured to both the slate and the i batten. The foamed plastics then performs two functions (a) it prevents the slate from sliding longitudinally in the ( event of failure of the normal hold down nail and (b) it serves to prevent the slate from lifting as the result of wind suction. In order to perform the latter function I have found that the foamed plastic should have a relatively high tensile strength, for example 80 lbs. per square inch.

In practice this has meant employing particular grades of ί / ·· ? ' ί : foamed polyurethane which has given excellent results.

However, polyurethane foam is itself somewhat flammable;, and in the B.S. Test 476, part I (Surface Spread 20 of Flame Test) its rating is normally no better than class 4.

It has the added disadvantage of having an upper continuous working temperature limit which is normally no higher than 110 C and this factor tends to limit the performance of the system under Test B.S, 476, part III. - 2 ί ti ι' 1 5 It is an object of the present invention to provide a method which gives improved fire resistance without any material loss of resistance to wind suction.

I have found ss a result of inspecting many hundreds of roofs reinforced by use of the system of Patent No. l,337,t>53 that in many old slate roofs a substantial gap of up to fe mm or more may be found between some of the battens and their overlying slates. Since wind forces tend to lift the lower ends of slates it will readily be understood that the maximum stress encountered in the foamed plastic blocks is at the lower leading end. Where there is a gap between the battens and the slate there is a tendency for the block to split in a plane parallel to the slate, in this region. Whilst some particular grades of polyurethane foams have sufficient tensile strength to resist this tendency to split, weaker foamed plastics do not. I have found that just those foamed plastics materials which have more satisfactory fire-resistance characteristics than high-strength polyurethane are those which also have lower tensile . strength.

My present invention provides a method of strengthening a roof of the kind in which an assemblage of slates or tiles is hung on a series of spaced horizontal battens, comprising positioning in an angle between an individual slate or tile and a side face of a batten a block of fire-resistant or self-extinguishing foamed plastics - 3 & w '< 1 a ! * ’ I material having a layer of tensile reinforcing material bonded to its side face facing the batten in a manner to reinforce the plastics material against splitting in planes generally parallel to the plane of the slate or tile, the block being bonded to both the slate or tile and the batten.

My preferred’ foam materials are those which achieve a rating better than Class 4 under Fire Test B.S. 476, part I, and also have an upper continuous working temperature of the order of 150° C. In some arrangements according to the invention an adhesive by which the block is bonded to slate or tile and the batten constitutes also the said tensile reinforcing material. In one simple . example I achieve the desired result by dipping the top face and leading end face of the foamed plastics block in a thixotropic, self-curing resin. The block is then pressed manually into position against the undersurface of the slate and brought into contact with the batten.

This method results in the presence of an excess of self20 curing resin adhesive in the gap (if any) between the batten and the slate, serving to strengthen the leading ? end of the foamed plastics at precisely the position where it is most vulnerable to the commencement of a split.

In.'an-alternative,method I use composite blocks which have a main body portion composed of a fireresistant foamed plastics material, as mentioned above, and a thin reinforcing layer of a foamed plastics material of relatively high tensile strength bonded to the lower side face of the main body portion. Such high tensile strength foamed plastics material may be a foamed polyurethane which thus acts as a reinforcement to prevent splitting of - 4 -. the block from its lower side face. When this composite foamed plastics block is employed there is no need to use highly thixotropic resin adhesive and a normal selfmrinv oolyester resin adhesive may be substituted and used in - 5 ----- . , . ] . ; j In putting the invention into effect the main body . portion of the foamed plastics block may be constituted by foamed polyisocyanurate or a self-extinguishing grade of polyurethane or a foamed phenol-formaldehyde. All these materials have good fire-resistance but would have, in my experience, too little tensile strength to withstand wind suction in many instances without provision of reinforcement at the vulnerable area of the lower side face of the block.

In a further development of this alternative the thin 10 layer of foamed plastic of high tensile strength can be replaced by a thin layer of a fibrous absorbent material (which may be woven or non-woven), e.g. paper, bonded to the main body portion by a self-curing resin so that the reinforcing layer is of cured reinforced resin. The reinforcing layer may alternatively be a· thin layer of wood, or else a metal foil compatible with the resin adhesive. j The attached drawing showing a fragmentary sectional l view of a slate roof illustrates my invention. The slates 10 sre secured to battens 11, and I strengthen the roof by adhesively securing in the angle between the individual slates and the battens elongate blocks 12 of a fire-resistant foamed plastics material with a layer 13 of tensile reinforcing material secured by an adhesive to the lower side face of the block.

A gap 15 such as is referred to above is shown between the - 6 _ * & » χ ίί lower of the two battens and the slate extending across ft, and it is the part of the block 12 extending across the gap that is subjected to the greatest tensile stress by suction forces tending to lift the slate. The stress is greatest at the lower side face of the block and is resisted by the tensile reinforcing layer 13.

Claims

1. A method of strengthening a roof of the kind in which an assemblage of slates or tiles is hung on a series of spaced horizontal battens, comprising positioning in an angle between an individual slate 5 or tile and a side face of a batten a block of a fireresistant or self-extinguishing foamed plastics material having a layer of tensile reinforcing material bonded to its side face facing the batten in a manner to reinforce the plastics material against splitting in planes generally 10 parallel to the plane of the slate or tile, the block being bonded to both the slate or tile and the batten.

2. A method as claimed in claim 1, wherein an adhesive by which the block is bonded to slate or tile and the batten constitutes also the said tensile 15 reinforcing material.

3. A method as claimed in claim 2, wherein the adhesive is a thixotropic self-curing resin.

4. A method as claimed in claim I, wherein the reinforcing material comprises a ! thin layer of a 20 foamed plastics material having a high tensile strength.

5. A method as claimed in claim 4, wherein the said thin layer comprises a foamed polyurethane.

6. ' A method a’s claimed in claim 1, wherein the layer of tensile reinforcing material comprises a 25 thin layer of wood.

7. A method as claimed in claim 1, wherein the layer of tensile reinforcing material comprises a layer of metal foil. -

8. 8. A method as claimed in claim 1, wherein the layer of tensile reinforcing material comprises a thin layer of a fibrous absorbent material bonded to the main body portion of the block by a self-curing resin. 5

9. A method as claimed in claim 8, wherein che layer of tensLiG reinrcrcing material lon.prisGs a sheet o£ paper.

10. A method as claimed in claim 8 or claim 9, wherein the layer of tensile reinforcing material is incorporated in a thixotropic, self-curing resin adhesive by which the block 10 Is bonded to the slate or tile and the batten.

11. A method of strengthening a roof substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.

12. A roof formed of slates or tiles hung on a series of spaced horizontal battens whenever strengthened by a method as claimed in any of the preceding claims.