GB2356206A

GB2356206A - Damp proof course

Info

Publication number: GB2356206A
Application number: GB0025825A
Authority: GB
Inventors: Colin James Michael Knox
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-10-20
Filing date: 2000-10-20
Publication date: 2001-05-16
Anticipated expiration: 2020-10-20
Also published as: GB2356206B; GB0025825D0

Abstract

Damp proof course material comprises a flexible sheet 11 of water - impermeable plastics having a series of elongate grooves 14 in at least one surface. The sheet may be extruded in direction A, from granules of thermoplastic material such as polypropylene or polycarbonate, and in use is laid as shown across inner 22 and outer 23 leaves of a cavity wall, with the grooves 11 orthogonal to the plane of the wall to assist water drainage. Sheets of the form shown may be joined by bridging using an inverted sheet of the same material such that the "dovetail grooves" interlock.

Description

2356206 D=-Proof Course Material The present invention relates to a damp

proof course material (DPC). DPC's are impermeable membranes which are located in building constructions, particularly walls, to provide a moisture barrier. Traditionally, these have comprised a felt or fabric-base coated in bitumen or asphalt.

However, these materials are expensive to produce and are difficult to locate in position on site between brick crosses. In addition, they tend to crack with age.

Smooth polyurethane sheets have also been tried as an alternative. However, these sheets suffer from a low bond strength in the mortar joints where they are installed and they are difficult to join together in a waterproof fashion.

It is an object of the present invention to provide a DPC material which is inexpensive and easy to install, but which also offers a high bond strength in mortar. Adjacent elements should also be easily and reliably joined.

According to the present invention, there is provided a damp proof course (DPC) material which comprises a sheet of water-impermeable plastics material having a series of elongate grooves in at least one surface.

The material is preferably a thermoplastic material and is preferably extruded eg. from granules as a continuous sheet. In addition, or alternatively, the sheets may be rolled or callendered. Preferred materials include polypropylene and polycarbonate. The grooves are preferably continuous, preferably straight and preferably parallel. They are preferably formed in one surface only, and the under surface may be textured, scuffed or roughened. Alternatively, grooves may be formed in both surfaces.

A DPC sheet in accordance with the invention can therefore be easily installed and 2 offers a more secure bond to the worker in which it is located. It is also far less costly than conventional bitumen/felt DPC's.

The sheets may be formed in any suitable width, though conveniently, the width is between 200 and 500nim, preferably 300 to 400mm. Preferably, the grooves run across the width and since the direction of extrusion or rolling is most conveniently along the length of the sheet, the grooves preferably extend in a direction transverse to the extrusion/rolling direction.

The sheets may have an overall thickness of from I to 3mrn and the grooves may have a depth of 25 to 75% of the thickness. Preferably the thickness is from 1. 75 to 2.25min and the grooves have a depth of 40 to 60% and preferably 50% of the thickness. In a preferred embodiment, the sheet is 2mm thick and the grooves I mm deep. Preferably the width of the grooves is greater than or equal to the spacing between them. Typically the width of the grooves might be from 2 to 4mm, preferably about 3nim.

In use, a sheet in accordance with the invention is installed with the grooves running towards the outside of the wall or structure and facing upwards. The invention therefore extends to a wall or structure incorporating such a DPC in this orientation.

This arrangement has the advantage that moisture/water is directed to the outside by the grooves. This is particularly beneficial when the DPC sheet is used in a stepped orientation in a cavity wall. The preferred width of the grooves means that it is a relatively simple matter to join together adjacent sheets. This can be achieved by taking a short length of the sheet, preferably at least 100mm, eg. up to 150mm, and inverting it so that the grooves are on the under surface. This is then lapped over two adjacent sheets, with the ridges between the grooves in the inverted length being located in the grooves of the adjacent sheets and vice versa. Preferably, the overlapping sheet is fixed in position eg. with adhesive, preferably in the form of double-sided adhesive tape located either at the base of the grooves or more preferably 3 on the ridges between the grooves of the overlapping sheet.

The invention may be carried into practice in various ways and some embodiments will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a perspective sketch of a DPC sheet in accordance with the invention; Figure 2 is a schematic sketch showing the sheet of Figure I in position in a cavity wall; and Figure 3 is a perspective sketch of a joint formed between two adjacent sheets.

As shown in Figure 1 a damp proof course (DPQ sheet 11 comprises a base 12 with a series of straight, parallel ridges 13 which are undercut. Between them, the ridges 13 define grooves or channels 14 which are slightly wider than the channels 13.

The sheet 11 is extruded from granules of polypropylene or polycarbonate in the direction of arrow A in Figure 1. The thickness of the base 12 is I mm, the height of the ridges 13 and therefore the depth of the channels 14 is also Imm, and so the overall thickness of the sheet 11 is 2mrn. The width of the ridges 13 at the crown is somewhat less than 3mm and the width of the channels at their bases is about 3mm.

The width of the sheet 11 (in the direction of the channels 14) is 300mm. The under surface of the base 12 is textured.

As shown in Figure 2, in one particular use, the sheet I I is used to form a damp proof course in a cavity wall 21, consisting of an inner leaf 22 and an outer leaf 23. The sheet I I is bedded into a mortar course 24 in the inner leaf and also in a lower mortar course 25 in the outer leaf 23. The channels 14 run across the cavity 26, and so direct water ftorn the inner leaf 22 to the outer leaf 24. The textured under surface provides 4 a sound bond with the mortar beneath and the channels 14 provide a sound bond with the mortar above.

Figure 3 shows how two lengths of sheet I I can be joined together. The two sheets 11 a and I I b are laid side by side. A section of similar sheet 3 1 is inverted and positioned so that the ridges 33 of the inverted sheet 31 fit into the channels 14a and 14b of the respective sheets I I a and 1 1b. At the same time, the ridges 13a and 13b fit into the channels 34 in the inverted sheet 3 1, strips of double sided adhesive tape 35 (only one of which is shown) are located on the ridges 33. This forms a secure bond at the base of the channels 14a, 14b. In this way, the two sheets I I a and I I b are j oined together and the gap 35 between them is sealed. Typically, the sheet 31 would be about 100 to 150mm long.

I

Claims

1. A damp proof course (DPQ material which comprises a flexible sheet of water-impermeable plastics material having a series of elongate grooves in at least one surface.

2. A material as claimed in Claim 1, the material being a thermoplastic material.

3. A material as claimed in Claim 1 or Claim 2 in which the material is extruded as a continuous sheet.

4. A material as claimed in Claim 3 in which the material is extruded from granules.

5. A material as claimed in any preceding claim in which the grooves are continuous, straight and parallel.

6. A material as claimed in any preceding claim in which the grooves are formed in one surface only. 20

7. A material as claimed in Claim 6 in which the other surface is textured, scuffed orroughened.

8. A material as claimed in any preceding claim in which the material. comprises 25 polypropylene or polycarbonate.

9. A material as claimed in any preceding claim in which the sheet has a width between 200 and 500 mm.

10.A material as claimed in any preceding claim in which the grooves run across the width of the material.

11. A material as claimed in any of Claims 3 to 10 in which the grooves extend in a direction transverse to the extrusion direction.

12. A material as claimed in any preceding claim in which the sheet has an overall thickness of from I to 3 mm and the grooves have a depth of from 25 to 75% of the thickness.

13. A material as claimed in Claim 12 in which the thickness is from 1.75 to 2.25 mm and the grooves have a depth of 40 to 60% of the thickness.

14. A material as claimed in any preceding claim in which the width of the grooves is greater than or equal to the spacing between them.

15 15. A material as claimed in any preceding claim in which the width of the grooves is from 2 to 4 mm.

16. A wall or structure incorporating a DPC material as claimed in any preceding 20 claim. The sheet being arranged so that the grooves run towards the outside of the wall or structure and face upwards.

17. The use of a material as claimed in any of Claims I to 15 to form a damp proof course in a wall or structure. 25

18. A method of joining together adjacent sheets as defined in any of Claims 1 to 15, the method comprising: arranging the two sheets to be joined adjacent one another; inverting a relatively short length of similar material and lapping this over the two adjacent sheets; and locating the ridges between the grooves in the inverted sheet in 30 the grooves of the adjacent sheets and vice versa.

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19. A method as claimed in Claim 18 in which the overlapping sheet is fixed in position by means of an adhesive.

20. A method as claimed in Claim 19 in which the adhesive takes the form of double sided adhesive tape located either at the base of the grooves or on the ridges between the grooves of the overlapping sheet.

21. A damp proof course material constructed and arranged as herein specifically 10 described with reference to Figure 1 of the accompanying drawings.

22. A wall or structure incorporating a damp proof course, constructed and arranged substantially as herein specifically described with reference to and as shown in Figure 2 of the accompanying drawings. 15

23. A method of adjoining adjacent DPC sheets substantially as herein specifically described with reference to Figure 3 of the accompanying drawings.