Surprisingly, even after all these years of discussion and legal finger pointing regarding membrane decks, there are still a number of issues that are not specifically addressed in the building code.
Ultimately this means your design solution has to be rock solid, and not an improvised design solution created by you or the builder based on interpretations of 3604 E2/AS1.
Broad guidelines in 3604 E2/AS1 cover some of the basic points, however it's most important you have an understanding of the typical deck over waterproof membrane issues and that you can confidently specify a solution that addresses these.
A membrane decking surface needs the following attributes in order to significantly reduce the risk of potential headaches:
- sufficient airflow underneath the tiles or decking boards
- on demand access to gutters and downpipes for removal or debris
- stable, durable low height dimensionally stable structural materials that are unaffected by moisture
- the ability for the decking boards or tile surface to be uplifted and reinstated without damage or costly re-installation when inspection of the membrane is required
- a lightweight solution that requires no re-engineering to carry potential heavy materials such as structural tiles.