GB2148146A

GB2148146A - A waterproofing material for use as an underslating felt

Info

Publication number: GB2148146A
Application number: GB08328298A
Authority: GB
Inventors: Bryan Holton
Original assignee: BPB Industries PLC
Current assignee: BPB Ltd
Priority date: 1983-10-22
Filing date: 1983-10-22
Publication date: 1985-05-30
Also published as: GB8328298D0

Abstract

An underslating felt designed to inhibit condensation is formed from an open structure base material formed by fusing together fibres of a nylon-coated polyester. This is then coated with bitumen. Only some of the spaces between the fibres are filled with bitumen, leaving other spaces which are sufficiently big to give ventilation but which are too small to allow leakage of water.

Description

SPECIFICATION A Waterproofing Material for Use as an Underslating Felt This invention relates to a so called "underslating felt" for use beneath slates or tiles.

Over the past three or four decades it has become conventional to place over open rafters a form of bituminised roofing felt manufactured by using a sheet of paper (grey fibre or kraft brown paper) as a carrying vehicle which is saturated and coated with bitumen so as to improve its resistance to rot and to render it waterproof. A hessian cloth is embedded into the bitumen coating on one side of the carrying vehicle whilst the bitumen coating is in a hot fluid state. This renders the finished product more burst and tear resistant which is important during its installation and prior to the placing of the slates or tiles.It can be readily understood that the primary weatherproofing of a slate or tile pitched roof is provided by the slates or tiles and that the underslating felt serves as a secondary line of defence to prevent the ingress of rain, snow or hail into a space beneath the roof e.g. in the event of slate(s) or tiles becoming dislodged, broken or removed. in that event the elemental ingredients are directed into the eaves gutters and prevented from entering the space beneath the roof in the same way as would be the case if the slate(s) or tile(s) were to remain in their correct position.

There are two types of traditional bituminised hessian reinforced underslating felt both of which are essentially identical with the exception that one, made to conform to BS747 type 1 F, is possessed of a hessian cloth having a more closely woven structure than its non BS counterpartwhich has a hessian cloth with approximately half the substance i.e. 2 oz linear yard instead of 4 oz linear yard and in consequence is recognisable by its more open weave when viewed alongside the BS747 type 1 F.

Both of the aforementioned types as manufactured as continuous waterproofing sheets free from holes and other perforations. They are supplied in rolls 15mx1m.

A disadvantage of traditional underslating felt, particularly when placed over open rafters, is that condensation forms on its underside. The invention arose with a view of reducing this problem.

The invention provides a waterproofing material for use beneath slates or tiles and comprising a sheet perforated with pores of a size such as to allow ventilation but to prevent passage of water droplets.

By encouraging ventilation in this way, the problem of condensation on the underside of the felt can be greatly reduced or even eliminated.

The sheet is preferably formed from a web of fibres coated in waterproof material, so that the coated fibres define the pores between them. In such a structure the fibres serve as a carrier and as reinforcing for the waterproof material. Individual fibres of the web are preferably secured together at the points where they cross. This prevents relative displacement of the fibres, prior to application of the coating, which displacement could result in a nonconsistent porosity over the finished product. One suitable commercially available material for use as the web is a fabric known a Colback manufactured by Enka/Colbond b.v., of Velperweg 76, Arnhem, Holland. This is made from filaments of polyester carrying a polyamide coating (the latter being nylon).These coated filaments are not woven but are fused together to form a highly porous web structure having in this particular product, a nominal weight of about 7580 grams/sq.m..

Different nominal weights anywhere within the range of 60 to 150 grams/sq.m. have however been found to be satisfactory.

The waterproof material preferably consists of or includes bitumen or a mixture of bitumen and some other material such as a synthetic rubber. Tar can also be used. Other possibilities include flexible synthetic plastics material. Fiexibility of the finished product is desirable so that it can be formed into a roll.

One way in which the invention may be performed will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 shows a schematic magnified view of part of a fibre web used in making a felt in accordance with the invention; and Fig. 2 shows, on the same magnified scale as Fig.

1 part of the felt manufactured from the part of the fibre web shown in Fig. 1.

Referring to Fig. 1 there is shown a small part of a web, of 7580 gramslsq.m. Colbackcomprising individual fibres e.g. as shown at 1 of nylon coated polyester. These fibres are not woven but are fused together at the points where they cross and define between them, spaces of varying size e.g. as shown at 2 and 3.

The fibre web is coated with filled blown oxidised bitumen so as to give a finished product weighing nominally between 500 grams/sq.m. and 1000 grams/sq.m. (about 700 grams/sq.m. being considered best). The bitumen adheres to the fibres and fills some of the smaller spaces (e.g. space 3) but not the larger spaces such as space 2. Thus a plurality of pores, such as shown at 2A, are formed.

These pores allow passage of air, and indeed light, but are too small to allow seepage of water, this being resisted by the effect of surface tension.

The finished membrane is flexible and is formed into a roll of preferably 1 m nominal width. It will be understood that it is very different from the conventional hessian reinforced underslating felt in that its polyester polyamide base serves both as the bitumen carrier and as the structural reinforcement.

Also the finished product is physically and visually micro-perforate whereas the conventional product is produced in a manner to ensure non-perforation.

1. A waterproofing material for use beneath slates or tiles and comprising a sheet perforated with pores of a size such as to allow ventilation but to prevent leakage of water.

2. A waterproofing membrane according to Claim 1 in which the sheet comprises a web of fibres

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A Waterproofing Material for Use as an Underslating Felt This invention relates to a so called "underslating felt" for use beneath slates or tiles. Over the past three or four decades it has become conventional to place over open rafters a form of bituminised roofing felt manufactured by using a sheet of paper (grey fibre or kraft brown paper) as a carrying vehicle which is saturated and coated with bitumen so as to improve its resistance to rot and to render it waterproof. A hessian cloth is embedded into the bitumen coating on one side of the carrying vehicle whilst the bitumen coating is in a hot fluid state. This renders the finished product more burst and tear resistant which is important during its installation and prior to the placing of the slates or tiles.It can be readily understood that the primary weatherproofing of a slate or tile pitched roof is provided by the slates or tiles and that the underslating felt serves as a secondary line of defence to prevent the ingress of rain, snow or hail into a space beneath the roof e.g. in the event of slate(s) or tiles becoming dislodged, broken or removed. in that event the elemental ingredients are directed into the eaves gutters and prevented from entering the space beneath the roof in the same way as would be the case if the slate(s) or tile(s) were to remain in their correct position. There are two types of traditional bituminised hessian reinforced underslating felt both of which are essentially identical with the exception that one, made to conform to BS747 type 1 F, is possessed of a hessian cloth having a more closely woven structure than its non BS counterpartwhich has a hessian cloth with approximately half the substance i.e. 2 oz linear yard instead of 4 oz linear yard and in consequence is recognisable by its more open weave when viewed alongside the BS747 type 1 F. Both of the aforementioned types as manufactured as continuous waterproofing sheets free from holes and other perforations. They are supplied in rolls 15mx1m. A disadvantage of traditional underslating felt, particularly when placed over open rafters, is that condensation forms on its underside. The invention arose with a view of reducing this problem. The invention provides a waterproofing material for use beneath slates or tiles and comprising a sheet perforated with pores of a size such as to allow ventilation but to prevent passage of water droplets. By encouraging ventilation in this way, the problem of condensation on the underside of the felt can be greatly reduced or even eliminated. The sheet is preferably formed from a web of fibres coated in waterproof material, so that the coated fibres define the pores between them. In such a structure the fibres serve as a carrier and as reinforcing for the waterproof material. Individual fibres of the web are preferably secured together at the points where they cross. This prevents relative displacement of the fibres, prior to application of the coating, which displacement could result in a nonconsistent porosity over the finished product. One suitable commercially available material for use as the web is a fabric known a Colback manufactured by Enka/Colbond b.v., of Velperweg 76, Arnhem, Holland. This is made from filaments of polyester carrying a polyamide coating (the latter being nylon).These coated filaments are not woven but are fused together to form a highly porous web structure having in this particular product, a nominal weight of about 7580 grams/sq.m.. Different nominal weights anywhere within the range of 60 to 150 grams/sq.m. have however been found to be satisfactory. The waterproof material preferably consists of or includes bitumen or a mixture of bitumen and some other material such as a synthetic rubber. Tar can also be used. Other possibilities include flexible synthetic plastics material. Fiexibility of the finished product is desirable so that it can be formed into a roll. One way in which the invention may be performed will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 shows a schematic magnified view of part of a fibre web used in making a felt in accordance with the invention; and Fig. 2 shows, on the same magnified scale as Fig. 1 part of the felt manufactured from the part of the fibre web shown in Fig. 1. Referring to Fig. 1 there is shown a small part of a web, of 7580 gramslsq.m. Colbackcomprising individual fibres e.g. as shown at 1 of nylon coated polyester. These fibres are not woven but are fused together at the points where they cross and define between them, spaces of varying size e.g. as shown at 2 and 3. The fibre web is coated with filled blown oxidised bitumen so as to give a finished product weighing nominally between 500 grams/sq.m. and 1000 grams/sq.m. (about 700 grams/sq.m. being considered best). The bitumen adheres to the fibres and fills some of the smaller spaces (e.g. space 3) but not the larger spaces such as space 2. Thus a plurality of pores, such as shown at 2A, are formed. These pores allow passage of air, and indeed light, but are too small to allow seepage of water, this being resisted by the effect of surface tension. The finished membrane is flexible and is formed into a roll of preferably 1 m nominal width. It will be understood that it is very different from the conventional hessian reinforced underslating felt in that its polyester polyamide base serves both as the bitumen carrier and as the structural reinforcement. Also the finished product is physically and visually micro-perforate whereas the conventional product is produced in a manner to ensure non-perforation. CLAIMS 1. A waterproofing material for use beneath slates or tiles and comprising a sheet perforated with pores of a size such as to allow ventilation but to prevent leakage of water. 2. A waterproofing membrane according to Claim

1 in which the sheet comprises a web of fibres coated in a waterproof composition, the coated fibres defining the said pores between them.

3. A waterproofing material according to Claim 2 in which individual fibres of the web are secured together at points where they cross.

4. A waterproofing material according to Claim 3 in which the individual fibres are fused together.

5. A waterproofing material according to Claim 4 in which the individual fibres have at least a surface layer of a polyamide.

6. A waterproofing material according to Claim 5 in which the polyamide is nylon.

7. A waterproofing material according to Claim 5 or 6 in which the fibres are formed from a polyester having a surface layer of a polyamide.

8. A waterproofing material according to any one of Claims 2 to 7 in which the waterproof composition includes bitumen or a modified bitumen.

9. A roof structure comprising a waterproofing material, constructed in accordance with any preceding Claim, positioned over open rafters beneath slates or tiles.

New Claims or Amendments to Claims Filed on Sept 24th 1984 Superseded Claims All New or Amended Claims 1. A roof structure comprising waterproofing material located beneath slates or tiles and comprising a sheet perforated with pores of a size such as to allow ventilation but to prevent leakage of water.

2. A roof structure according to Claim 1 in which the sheet comprises a web of fibres coated in a waterproof composition, the coated fibres defining the said pores between them.

3. A roof structure according to Claim 2 in which individual fibres of the web are secured together at points where they cross.

4. A roof structure according to Claim 3 in which the individual fibres are fused together.

5. A roof structure according to Claim 4 in which the individual fibres have at least a surface layer of a polyamide.

6. A roof structure according to Claim 5 in which the polyamide is nylon.

7. A roof structure according to Claim 5 or 6 in which the fibres are formed from a polyester having a surface layer of a polyamide.

8. A roof structure according to any one of Claims 2 to 7 in which the waterproof composition includes bitumen ora modified bitumen.

9. A roof structure according to Claim 1 in which the waterproofing material is positioned over open rafters.

10. A waterproofing material suitable for use beneath slates or tiles comprising a sheet perforated with pores of a size such as to allowventilation but to prevent leakage of water, the sheet comprising a web of fibres coated in waterproof composition comprising bitumen or a modified bitumen.