Wet Areas

Poor wet area design or installation can compromise safety, comfort and convenience for building users, and lead to significant structural damage.

Wet area wall structure

Wet area walls may be concrete, or timber or steel framed. Each has different requirements.

On this page:

  • timber and steel framing
  • concrete and concrete masonry.

Timber and steel framing

Timber and steel framing must:

  • have sufficient depth to install plumbing services (pipes)
  • include dwangs and support for fixtures (e.g. wall-mounted WC, cabinets, built-in cistern, grab rails, plumbing outlets)
  • be insulated on external walls
  • have an appropriate level of treatment for the risk of water damage
  • be sufficiently rigid for the selected finish.

Framed walls are not good sound insulators – wall linings need to be carefully considered and specified to reduce sound travelling from bathrooms to other parts of the house.

Steel frames must include a thermal break on external faces of the framing on exterior walls.

Concrete and concrete masonry

Concrete and concrete masonry provide a firm base for wet area finishes such as plaster, terrazzo and tiles. They must:

  • for concrete masonry and plastered finishes, have a waterproof finish to prevent moisture absorption (e.g. paint finish in accordance with E3/AS1) – a steel trowelled concrete surface finish is deemed impervious as for floors
  • for exterior walls, meet the requirements of E3/AS1 and H1
  • must have plumbing and electrical services pre-installed as they can’t easily be accommodated retrospectively.

Updated: 24 May 2016