Waterproofing membranes for external above-ground use
External waterproofing — balconies, decks, planter boxes, roof terraces.
Overview
AS 4654 covers external waterproofing where the membrane is exposed to weather and UV. Part 1 is materials; Part 2 is design and installation. Different from AS 3740 (which is for indoor wet areas) — external membranes face thermal cycling, UV and pooling.
Key Requirements
- Membrane rated for external/UV exposure.
- Falls to drainage outlets — min 1:100 generally.
- Upstands and terminations sealed to walls and through-roof penetrations.
- Compatible with adjoining materials.
How it's used in the NCC
Called up where roof terraces, planter boxes or balcony floors are part of the building envelope.
Practical Notes
- Planter-box waterproofing is the most common source of leaks into rooms below.
- Don't confuse with AS 3740 — internal-only membranes degrade fast outdoors.
Where to obtain
The full text of AS 4654 is published by Standards Australia and must be purchased — typical price A$150–400 per part. Always work from the current edition referenced in the NCC, not an older one.