It is important to note that just because a screed is touch dry, does not mean that it is ready for an application of waterproofing product over the top of it. A screed has to be fully cured, prior to membrane application, and curing times can vary dramatically due to a number of factors, including thickness of the screed, specific mixture of the screed, humidity, air flow and temperatures amongst other things. If you are unsure as to the curing status of a screed, it is highly recommended that an epoxy primer be used prior to applying a waterproofing membrane.

As a very general rule of thumb, you should wait a bare minimum of 24 hours for every 10mm of screed thickness or a minimum of 72 hours for screeds thinner than 30mm. This is a basic guideline only, and in reality screed curing times have varied wildly; in some extreme cases taking up to 30 days to fully cure. The Australian Standards state that screed can take up to 1 day per 1mm of screed thickness to fully cure.

If possible, use a moisture meter to check the moisture content of the screed – you’re looking for a value below 8% to ensure against membrane failure.

If in any doubt whatsoever as to the curing status of the screed, always use an epoxy primer or a product such as Gripset P10 as a vapor barrier prior to membrane application.