GB2143874A

GB2143874A - Cavity wall damp-proof course

Info

Publication number: GB2143874A
Application number: GB08320071A
Authority: GB
Inventors: Colin James Michael Knox
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-07-26
Filing date: 1983-07-26
Publication date: 1985-02-20
Also published as: GB2143874B; GB8320071D0

Abstract

A method of forming a damp- proof course in a cavity wall, comprising an inner leaf (11) and an outer leaf (12), which comprises locating a support member (17) so that it spans the cavity wall, placing a first sheet (14) of a waterproof material so that it spans the cavity wall and overlies the support member (17) and placing a second sheet (15) so that it overlies the first sheet (14). The two sheets are then glued together in the region of the support member using the support member as a backing. <IMAGE>

Description

SPECIFICATION Cavity wall damp proof course The present invention relates to damp proof courses (DPC's) in cavity walls.

Cavity walls are generally provided with a DPC near the top and the bottom to prevent moisture seeping through the brickwork and into the cavity. Such DPC's usually take the form of a sheet of plastics material or a sheet treated with a waterproof material such as bitumen or pitch polymer which runs the length of the wall and spans the inner and outer leaves. Frequently the DPC is located between two courses of bricks at a higher level in the inner lead so that it descends about two or three courses within the cavity before being located between two courses in the outer leaf.

The DPC is generally laid in lengths of up to 1 5 feed which means that in the case of a long wall, it is necessary to join two lengths together. In order to maintain a waterproof seal this is achieved by using a mastic or impact adhesive between two adjacent overlapping sheets. An overlap of some 1 00mm is common.

This arrangement suffers the disadvantage that it is difficult to achieve a good bond between the two sheets in the region of the cavity since the sheets have no support in this region and hence it is difficult to apply a relative pressure between the sheets. This frequently results in non-waterproof joints.

Furthermore, when an impact adhesive is used there is no opportunity for adjustment once contact has been made; this often results in kinks at the joint.

It is therefore an object of the invention to provide a method of laying a DPC in a cavity wall which does not suffer these disadvantages and which results in a waterproof seal between adjoining sheets.

According to the present invention a method of forming a damp proof course in a cavity wall comprises: locating a support member spanning the cavity wall; placing a first sheet of waterproof material spanning the cavity wall and overlying the support member; placing a second sheet of waterproof material spanning the cavity wall and overlying both the support member and the first sheet in the region of the support member; and joining the two sheets in the region of the support member.

Thus, two adjoining sheets can be glued together using the support member as a backing to press against.

The support member preferably has a profile corresponding to that ultimately taken up by the DPC. Conveniently, the support member may begin as a flat strip which can be bent to the desired shape in situ. Preferably, the strip is composed of a material which when folded, snaps, but does not break completely, thus effectively forming a hinge. Suitable materials may be wood, fibreboard, or more preferably a plastics material.

The support member may degrade and disappear with the passage of time after the DPC has been laid.

The invention may be carried into practice in various ways and one embodiment will now be described by way of example with reference to the accompanying drawings in which the single figure is a schematic, isometric, part-cutaway sketch of a cavity wall having a damp proof course (DPC).

The cavity wall comprises an inner leaf 11 and an outer leaf 1 2 with a cavity 1 3 therebetween. The DPC comprises a number of sheets of a waterproof material of which two 14, 1 5 are shown. These sheets 14, 1 5 are joined together by an adhesive to form a waterproof joint.

At the position where the two sheets 14, 1 5 are to overlap, a support 1 6 is located, spanning the two leaves 11, 1 2 and the cavity 1 3. The support 1 6 is initially a flat plastics strip measuring about 250mm long and about 1 00mm wide by about 2mm thick.

It is first placed with one end 1 7 on the course of bricks 21 of the inner leaf 11 on which the DPC is to be located. It is then folded at the edge of the course 21 and led down to the course of bricks 22 of the outer leaf 1 2 on which the DPC is to be located, three courses below the course 21, where it is folded again so that its other end 1 9 lies on the course 22 leaving a middle portion 1 8 straddling the cavity 1 3.

The first sheet 14 is placed in position spanning the two courses 21, 22 and overlying the support 1 6 as indicated by the chain line arrows A and B. The second sheet 1 5 is then located similarly as shown by the chain line arrows C and D so that the two sheets 14, 1 5 overlap at the support. The two sheets 14, 1 5 can be glued and pressed together at this position using the support 1 6 as a backing. The sheets can then be glued to the support but it is preferred simply to glue them together. Any suitable adhesive can be used, e.g. mastic or an impact adhesive.

The cavity wall is then completed in the normal way.

Whilst the support may constitute a single.

initially planar, sheet of material, in an alternative embodiment which is not illustrated the support comprises two spaced sheets of plastics material connected by a plurality of spaced parallel webs and formed as an integral moulding. This material readily forms an integral hinge with the webs extending parallel to the direction in which, in use, the two folds extend. However, the support is preferably made of a material which will disintegrate within a few weeks of its being placed in position.

Claims

1. A method of forming a damp-proof course in a cavity wall which comprises: locating a support member spanning the cavity wall; placing a first sheet of waterproof material spanning the cavity wall and overlying the support member; placing a second sheet of waterproof material spanning the cavity wall and overlying both the supportd member and the first sheet in the region of the support member; and joining the two sheets in the region of the support member.

2. A method as claimed in Claim 1 in which the two adjoining sheets are glued together using the support member as a backing.

3. A method as claimed in Clim 1 or Claim 2 in which the support member has a profile corresponding to that ultimately taken up by the damp-proof course.

4. A method as claimed in Claim 3 in which the support member is initially a flat strip which is bent to the desired shape in situ.

5. A method as claimed in any preceding claim in which the support member is composed of a material which when folded, snaps, but does not break completely, thus effectively forming a hinge.

6. A method as claimed in Claim 5 in which the support member is made of wood, fibreboard, or a plastics material.

7. A method as claimed in any of Claims 1 to 5 in which the support material comprises two spaced sheets of plastics material connected by a plurality of spaced parallel webs.

8. A method as claimed in any preceding claim in which the support member is made of a material which will degrade with the passage of time after the damp-proof course has been laid.

9. A method of forming a damp-proof course in a cavity wall substantially as herein specifically described with reference to and as shown in the accompanying drawing.