Failure in Waterproofing: Substrate Moisture

Believe it or not the Australian Standards for waterproofing (AS 3740 / AS 4654.1) has not defined or specified any methods for determining the substrate dryness or moisture content prior to installing waterproofing.

As we all know failures due to residual moisture in the substrate will cause adhesive failure or delaminating of the membrane system and in some extreme cases the membrane can re-emulsify.

From the research available the following Australian Standards all make provisions for moisture content for various materials over concrete and mortar screeds and specify the substrate dryness:

tiling (AS 3958.1)

painting (AS 2311)

textile floor coverings (AS/NZS 2455.1)

vinyl flooring (AS 1884)

timber (AS/NZS 1080.1, AS 2792.2)

plywood (AS/NZS 2269)

These standards above represent the materials or finishes around, over or under the waterproofing, so why can’t these same provisions or specifications be included as part of the most critical trade involved Domestic or Commercial waterproofing?  There are no Australian Standard specifically detailing moisture content testing in various substrates and materials for our industry.

As a professional waterproofing company, “Australian waterproofing company”.  we have taken the time to educate ourselves on this critical part of our trade, we have brought the best possible moisture meters available at a cost of around $1000.00 dollars each, but it’s not enough we as contractors need the specifiers and the builders to be educated as well, I urge the committee members of the Australian Standards for waterproofing (AS 3740 / AS 4654.1) to put a guideline, specification or make it apart of the core standard.  We need to put something in place so we can correct this part of our industry.

Can you believe residual moisture is the 3rd major cause of waterproofing failures and there is still no provision to stop it under our current Australian Standards for waterproofing (AS 3740 / AS 4654.1) it is unbelievable?

Every concrete area or screed substrate should be accurately tested for moisture content before the application of any waterproofing products or system. Thoroughly document all readings this should be made compulsory and form part of the Certificate of Compliance so everyone knows how and when it’s been tested.

As there is no provision for testing it’s critical for the architect, Builder and the Waterproofing Contractor to test the concrete or screed substrate before the application of any waterproofing membrane system, whether your using sheet or liquid membrane system testing first will reduce the current amount of failures in our industry.