Installation of Gas, Moisture & Vapour Barrier/ DPC

Site preparation:

On approved consolidated basecourse apply an even layer of sand (5 mm) to blind all sharp aggregate basecourse materials. Alternatively apply continuous woven or nonwoven separation fabric over prepared consolidated basecourse, with panels overlapped a minimum 150mm.

As a waterproofing membrane and concrete underlay: Loose lay (colour side up where applicable) over the required area in sheet sizes that require minimum site joining. Allow 1 mm surplus each way per 1 degree C temperature drop per 10m of membrane. Turn up all edges at walls to the level of the top of the finished concrete slab. Extend above exterior wall weep holes and under flashings. Extend a minimum 150mm past form bulkheads to provide overlap to subsequent adjacent membrane sections.

As a moisture and vapour barrier in walls and ceilings: The membrane may be fastened to the warm side of walls and ceilings by clouts or staples to timber battens. Overlaps are as per following methods using Vulcanseal adhesive, polyethylene or PVC adhesive tape.

Ground cover in crawl spaces and sub floor cavities: Loose lay the membrane over the entire area to be covered. Overlaps and joining methods including sealing to piles and other protrusions are as per below. The membrane should extend above foundation walls to finished floor level.


When joining films with 48mm polyethylene or PVC tape overlap panels a minimum 150mm. Alternatively 48mm (min.) wide Vulcanseal tape sealant or other approved non-stretch polyisobutylene tape can be used allowing for a 75mm overlap. All surfaces must be clean, dry and free from oil and grease. Fold back overlap and apply Vulcanseal adhesive to the entire edge of the bottom sheet of each adjacent membrane section. Peel off the backing paper approximately 1m at a time, bringing the folded edge over the taped surface. Pressure seal the joint using a 50mm - 100mm wide rubber hand roller with firm support under the membrane (wooden board) shifted progressively as jointing proceeds. Avoid tape and membrane wrinkles to achieve a smooth and moisture proof seal. Full strength is achieved after 72 hours curing. In critical conditions a 48mm polyethylene or PVC adhesive tape may be applied over sealed joint as extra protection.


Secure screeds and form bulkheads by an approved means to avoid penetration or any form of damage to the integrity of the membrane. Penetration of the membrane shall not be allowed except for protrusion of structural elements and permanent utilities. Coat all utilities with an approved wet applied sealant, allow to cure and apply 48 mm wide Vulcanseal around protrusion at membrane edge and seal with press roller. Care shall be taken that the membrane not be damaged by any other means and that the membrane shall be damp proof at the time concrete placement is completed. For more critical installations, see also Moldable Sealant.

Approved products for use as superior waterproofing membranes include Dampstop Reinforced, Permaliner, HDPE, LLDPE, Polypropylene, Liquid Boot.

In the use of gas proofing membrane panels are to be sealed by fusion welding or other approved means. All extrusion welds including seals around protrusions and boots require copper wire for leak detection. All welds to be tested in accordance with Permathene QA/ QC Manual, including pressure and tensile tests for polypropylene geomembranes.