GB2278858A

GB2278858A - Damp course membranes

Info

Publication number: GB2278858A
Application number: GB9312153A
Authority: GB
Inventors: Fletcher Mathew Strickland
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-06-12
Filing date: 1993-06-12
Publication date: 1994-12-14
Anticipated expiration: 2013-06-12
Also published as: GB9312153D0; GB2278858B

Abstract

A damp course membrane 10, made of a water/moisture-proof material, is formed with a plurality of hollow protrusions 12 on one side surface. The protrusions 12 are configured such that, in use, a fluid mortar or cement layer 16b applied to one side of the membrane enters the interiors of the hollow protrusions 12 and the fluid mortar or cement layer 16a on the other side of the membrane flows around the outside of the hollow protrusions 12 so that, when set, the mortar or cement layers 16a, 16b on the two sides of the membrane are firmly keyed together whilst being mutually isolated by the membrane to maintain the damp course integrity. <IMAGE>

Description

DESCRIPTION IMPROVEMENTS IN DAMP COURSES AND DAMP COURSE MEMBRANES The present invention relates to damp courses in masonry walls and to damp course membranes for use in forming same.

It is a conventional practice, when forming masonry walls and buildings, to include a so-called damp-proof course just above ground level, which acts as a physical barrier to prevent water/moisture rising above this level into the main structure of the wall or building.

The traditional manner of achieving a damp-proof course is to incorporate between two adjacent layers of brickwork a continuous, elongate membrane made of a water/moisture-proof material, such as plastics sheet or bituminised felt. This conventional membrane, which is essentially flat and smooth on both sides, is placed on a layer of mortar laid on a row of bricks disposed just above ground level. A second layer of mortar is laid over the membrane and further rows of bricks then built up over this mortar layer. The membrane thus provides a physical barrier to water/moisture between the first mentioned row of bricks immediately below the membrane and the structure established above the membrane.However, t is also the case that this membrane effectively mechanically decouples the two rows of bricks on either side of it since it prevents integration of the mortar layers on its two sides. This results in a location of mechanical weakness in the region of the damp-proof course. Normally, once a structure such as the shell of a house has been completed, this line of weakness presents no problems since the overall closed peripheral shape of the structure counteracts any such weakness. However, during the course of the construction, and particularly in the case of straight wall runs, this weakness can be a problem in that these structures can, for example, be pushed over relatively easily as a result of the lack of tensile strength of the join between the membrane and the adjacent mortar layers.

It is an object of the present invention to provide a damp proof membrane which enables this problem to be avoided or at least to be considerably mitigated.

In accordance with the present invention, there is provided a damp course membrane made of a water/moisture-proof material and formed with a plurality of hollow protrusions on at least one of its two side surfaces, the protrusions being configured such that, in use, the fluid mortar/cement layer applied to one side of the membrane enters the interiors of the hollow protrusions and the fluid mortar/cement layer on the other side of the membrane flows around the outside of the hollow protrusions so that, when set, the mortar/cement layers on the two sides of the membrane are effectively keyed together whilst being mutually isolated by the membrane to maintain the damp course integrity.

Advantageously, the hollow protrusions are of frusto-conical configuration.

In some embodiments, the hollow protrusions can be of circular section. In other embodiments, the hollow protrusions can be elongate and extend across the whole width of the membrane.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic perspective view illustrating the use of one embodiment of a dampcourse membrane in accordance with the present invention; Fig. 2 is a diagrammatic sectional view through the wall of Fig. 1 on the line I-I; Fig. 3 is a side view of the damp-course membrane used in the structure of Figs. 1 and 2; and Fig. 4 is a perspective view of a further embodiment of a damp-course membrane in accordance with the present invention.

The damp-course membrane illustrated in Figs. 1-3 comprises an elongate strip 10 of liquid/moistureproof material which is formed with a plurality of hollow protrusions 12 which project from one otherwise flat face 14 (in this case, the lower face as viewed in Figs. 1-3) of the strip. As shown in Figs. 2 and 3, the protrusions 12 have external and internal sectional profiles which are of frusto-conical form.

As a result, when the membrane 10 is laid over the fist mortar layer 16a, which has been applied to the layer of bricks 18a, the mortar 16a flows around the protrusions 12 into the interstices defined between the protrusions and the surface 14 whereby, when set, the membrane is effectively "keyed" to the mortar layer 16a.

When the mortar layer 16b is applied over the membrane 10, the mortar flows into the interiors of the hollow protrusions whereby the membrane 10 also becomes effectively "keyed" to the mortar layer 16 when set. As is evident from Fig. 2, in the resulting structure, the mortar layers on the two sides of the membrane 10 are then effectively keyed together, with the membrane disposed therebetween to isolate the two mortar layers from each other and thereby maintain the integrity of the damp-course. In practice, the flow of fluid mortar into the interstices formed above and below the membrane is aided by the weight of the next, and subsequent layers of bricks 18b.

By virtue of the arrangement, the upper and lower brick layers 18b, 18a, are themselves mechanically coupled together much more positively than hitherto and the resulting structure is much more able to resist lateral destabilizing forces.

The embodiment of Figs. 1-3 uses a plurality of discrete protrusions 12 of convenient transverse section e.g., round, square, rectangular, oval etc.

However, the particular shape of these protrusions is capable of wide variation provided only that the facility for at least some "keying" of the mortar to the member on both sides thereof.

The use of protrusions of frusto-conical section provides a very positive "keying" of the mortar layers 16a, 16b, one with the other. However, it is probably not essential for the protrusions to be of frustoconical section and in other embodiments, sufficient "keying" can be obtained even if the protrusions are of cylindrical or approximately cylindrical form.

Fig. 4 illustrates a different embodiment in which the protrusions 12' extend in the form of continuous channels across the whole width of the membrane web 10'. The protrusions 12' are again shown in Fig. 4 to be of frusto-conical section. However, this is not essential and the channels could equally well be substantially parallel-sided. In a still further embodiment, the channels forming the protrusions 12' need not extend fully across the whole width of the membrane web.

The material of the membrane web 10, 10' is not limited to any particular material, provided only that it is water/moisture proof and is capable of being formed into the required shape, for example by moulding. Suitable materials include various plastics, rubbers and bituminised products.

Claims

1. A damp course membrane made of a water/moisture-proof material and formed with a plurality of hollow protrusions on at least one of its two side surfaces, the protrusions being configured such that, in use, the fluid mortar/cement layer applied to one side of the membrane enters the interiors of the hollow protrusions and the fluidmortar/cement layer on the other side of the membrane flows around the outside of the hollow protrusions so that, when set, the mortar/cement layers on the two sides of the membrane are effectively keyed together whilst being mutually isolated by the membrane to maintain the damp course integrity.

2. A damp course membrane as claimed in claim 1, wherein the hollow protrusions are of frusto-conical configuration.

3. A damp course membrane as claimed in claim 2, wherein the hollow protrusions are of circular section.

4. A damp course membrane as claimed in claim 1, wherein the hollow protrusions are elongate and extend across the whole width of the membrane.

5. A damp course membrane as claimed in claim 1, in which the hollow protrusions are of cylindrical configuration, being closed at their distal ends.

6. A damp course membrane as claimed in claim 1, having a plurality of said hollow protrusions on both side surfaces.

7. A damp course membrane substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.