BACKGROUND ART Concrete ground slabs which are laid directly on the ground surface can suffer from rising damp and moisture penetration. The moisture particularly penetrates between the slab and a fixture (for instance a pipe) which passes through the slab. This occurs because as a slab is poured and cures, shrinkage occurs which results in a small gap being present between the slab and the through slab fixture. This gap is a source of moisture penetration and termite penetration.

Moisture penetration is particularly troublesome as it can result in lifting of tiles attached to the slab and a host of other problems. The damage caused by termites is well-known.

In order to reduce moisture penetration through a slab, it is known to pour the slab onto a moisture barrier membrane which is typically in the form of black plastic sheets. The sheets come in lengths which are overlapped with each other and taped together to eliminate moisture penetration between adjacent sheets. Holes or slits are cut into the sheet to allow the various through slab fixtures to pass through the membrane. This in turn provides a gap through the barrier membrane through which termites and moisture can pass. Attempts are often made to close the gap by the use of copious amounts of tape, but there is often insufficient grip between the plastic sheet and the vertical fixture to ensure that gaps are not formed. It is also found that when the slab is poured, the weight of the poured concrete is often enough to tear the tape away.

It appears that attempts have been made to provide a barrier membrane formed with holes at predetermined positions with the holes having extending collars. However, such sheets are extremely limiting as the fixtures

must be exactly placed to align with the holes.

It is also noticed that when pouring concrete around the through slab fixtures, the membrane can often be torn or weakened as the membrane already has a slot or opening cut in it (usually roughly with a knife) to allow the fixture to pass through the membrane. Thus, this part of the membrane is particularly vulnerable to tearing and therefore opening up areas for moisture penetration and possibly termite activity.

It appears to be known to tape a flange around a through slab fixture with the specific purpose to reduce the passage of termites. These flanges are taped in such a manner that the remainder of the flange becomes embedded in the concrete. This type of flange is not fixed directly to the moisture barrier membrane, and provides no reinforcement to the membrane.

OBJECT OF THE INVENTION It is an object of the invention to provide a barrier collar which may overcome the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

In one form, the invention resides in a barrier collar to reduce moisture penetration from under a slab to inside a dwelling, the collar comprising a flexible moisture impermeable base sheet portion adapted to be taped to a moisture barrier membrane under a slab, the base sheet member having an opening which is spaced from edges of the sheet member and which is dimensioned to allow one or more fixtures to pass through the opening, and a flexible moisture impermeable tubular collar portion which is integral with the base portion and which extends about the opening and which is adapted to be taped or otherwise engaged with a said fixture.

In another form, the invention resides in a method for reducing moisture penetration from under a slab to inside a dwelling, the method comprising: placing a moisture barrier membrane on a ground surface, passing fittings through the membrane, fixing a barrier collar to the membrane and the fitting, the barrier collar comprising a flexible moisture impermeable base sheet portion which is

taped or otherwise fixed to the moisture barrier membrane, the base sheet member having an opening which is spaced from edges of the sheet member and which is dimensioned to allow one or more of the fixtures to pass through the opening, and a flexible moisture impermeable tubular collar portion which is integral with the base portion and which extends about the opening and which is taped or otherwise fixed to a said fixture, and pouring a slab over the membrane and the sheet portion.

The barrier collar has a flexible moisture impermeable base sheet portion. The base sheet portion may be formed from a woven or non- woven material. It is preferred that the sheet portion is formed of plastic material which is flexible. By being flexible, there is reduced chance of the base sheet portion being torn, stretched, or damaged by pouring concrete or by being walked on by tradespersons. The size of the base sheet portion can vary, as can the thickness. A typical base sheet portion is square or rectangular when viewed in plan and may have a edge length of between 25- 100cm and preferably 25-50cm, although larger and smaller edge lengths are also envisaged. The sheet member may be made of a plastic coated fabric which provides good flexibility and is tough and robust. The base sheet portion may have a thickness of up to 5 mm, and preferably between 0.2- 3mm. The base sheet member can have various shapes when viewed in plan including rectangular, but also circular, oval, polygonal, or other irregular shapes.

The base sheet portion is adapted to be taped to the moisture barrier membrane under a slab. The moisture barrier membrane is known in the art and typically consists of a black plastic sheet. The sheet is quite prone to tearing and it is found that addition of the barrier collar, and particularly the base sheet portion, to overlie the barrier membrane around the fixture penetration point provides an enhancement of the strength and a reduction in tearing or damage of the barrier membrane. The base sheet portion can be taped or otherwise fixed to the barrier membrane. Typically, plumbers tape or duct tape is used, but it is envisaged that other type of fixtures could be used including adhesive, pressure stick adhesive, adhesive strips having a peel off

layer and the like. It is preferred that the attachment is such to minimise or eliminate moisture or termites passing between the base sheet portion and the barrier membrane.

The base sheet portion has an opening extending therethrough which is spaced from the edges of the sheet. The opening is typically circular as the fixtures are typically circular, but other shapes are envisaged to suit.

The size of the opening is also typically complimentary to the size of the fixture. For instance, if the fixture is a 100mm pipe, the opening is typically slightly larger than 100mm. However, it is envisaged that the opening may be larger than the fixture or a different shape to the shape of the fixture.

The barrier collar additionally has a flexible moisture impermeable tubular collar portion. It is preferred that the collar portion is made of a material identical or similar to that of the base sheet portion. The collar portion is tubular and is typically open at both ends. One end is integrally attached or is integral with the base portion. This can reduce any moisture or termite penetration between the collar portion and the base sheet portion. The collar portion has a height sufficient to allow it to extend sufficiently along the fixture to allow it to be properly fixed to the fixture. This can be achieved by tape or by other means which are suitable. Some of these are as described with respect to the attachment of the base sheet portion to the barrier membrane. In an embodiment, the collar portion may have a height or length of up to 100 cm, but typically has a height or length of between 3-20cm with a typical height being between 5-15cm. The collar portion is flexible which can allow it to be tightly taped to the fixture.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will be described with reference to the following drawings in which Figure 1 is a perspective view of a barrier collar according to an embodiment of the invention.

Figure 2 shows the barrier collar in place.

BEST MODE Referring to the figures, the barrier collar in the embodiment has

a base sheet portion 11 which is substantially square when viewed in plan and has an edge length of about 50cm. The base sheet portion is formed of a plastic coated fabric which is tough and water impermeable The base sheet portion and/or the collar portion may be impregnated or otherwise treated with a termiticide or similar material. The base sheet member is flexible in two dimensions which allows it to properly overlie and be attached to the moisture barrier membrane. The base sheet member has a circular central opening about which is fitted a tubular collar portion 12. Tubular collar portion 12 is formed of the same material as base sheet portion 11 and is integrally fixed to base sheet portion, for instance by stitching and/or adhesive to form a strong moisture impermeable bond. In the particular embodiment, the collar has a height of 8cm and a diameter of approximately 10cm. The thickness of the collar material and the base sheet material is less than a millimetre.

Referring to Figure 2, there is shown how the barrier collar 10 is attached. In Figure 2, there is shown a through slab fixture in the form of a 90 or 100mm pipe 13. Pipe 13 extends under the ground surface 14 and through a poured slab 15. This arrangement is standard.

On top of ground 14 is a known moisture barrier membrane 16 which can be in the form of a black plastic sheet. Sheet 16 has an opening cut through it to allow fixture 13 to pass through the sheet. A barrier collar 10 is attached in this vicinity. The base sheet portion 11 overlies sheet 16 and the edges of sheet portion 15 are taped to sheet 16 by tape 17. It can be seen that the base sheet portion provides reinforcement around this area to the weaker membrane sheet 16. Also, sheet portion 11 provides a good degree of overlap with membrane 16 and tape 17 reduces or eliminates any passage of moisture or termites between the underside of sheet portion 11 and the top of barrier sheet 16. Collar 12 extends vertically about the vertical portion of fixture 13 and is taped to fixture 13 through tape 18 thereby again preventing moisture penetration.

The concrete slab 15 can then be poured and there is a reduced likelihood of the membrane sheet tearing of pulling away from fixture 13.

Once the concrete has set, there is very little possibility of moisture of termites

being able to pass between the concrete and fixture 13 due to the barrier formed by the barrier collar.

It should be appreciated that various other changes and modifications can be made to the embodiment described without departing from the spirit and scope of the invention.