Wet Areas

Designing and detailing to ensure water remains within the wet area and to deal with the effects of humidity and moisture.

Common wet area problems

Water that enters the building structure can travel and penetrate through cracks and gaps in joints, causing damage to wall and floor framing, and to finishes and fixtures. Wet zones can also present hazards and barriers to users.

Common wet area problems include:

  • causes and consequences of internal moisture damage
  • wet area hazards
  • barriers to access in wet areas
  • discomfort to users.

Causes and consequences of internal moisture damage

Water and moisture may enter into the building structure due to:

  • poor design and construction, particularly at junctions and penetrations
  • inappropriate material selection
  • failure of waterproofing membranes
  • fixtures that overflow
  • water spill from baths and showers (particularly open showers and flexible hose shower heads)
  • leaking pipes and fixtures
  • faulty appliances
  • blocked WC pans
  • blocked water traps.

The results of water damage include:

  • rotting timber wall and floor framing
  • deterioration and/or disintegration of wall linings
  • swelling and disintegration of particleboard flooring
  • swelling and disintegration of cabinetry (MDF construction)
  • deterioration of mirror backing
  • peeling paint
  • pooling of water in subfloors.

As well as water damage in wet areas, high levels of moisture generated from showers, baths and cookers can cause condensation damage to surfaces, finishes and fixtures that result in:

  • mould growth
  • coldness
  • health hazard
  • occupant discomfort.

Wet area hazards

Hazards in wet areas include compromised occupant safety due to:

  • floors that are slippery when wet
  • broken glass (shower screens, windows) where non-safety glass is used – NZS 4223.3:1999 Code of practice for glazing in buildings – Human impact safety requirements requires grade A safety glass to be used in framed and unframed shower doors, screens and bath enclosures (either 5 mm or 6 mm thick), and all glazing including windows less that 1500 mm from the floor
  • the potential for scalding if water is too hot (elderly people and children)
  • blocked access door in a fall (elderly people)
  • incorrectly wired or used electrical appliances.

Barriers to access in wet areas

Wet areas can present a number of barriers to access for elderly and people with disabilities such as:

  • bath edge height too high
  • WC pan height too high/low
  • a shower hob
  • awkward or narrow access
  • insufficient manoeuvring space
  • insufficient number or placement of grab rails
  • poorly located fixtures and fittings
  • poorly selected fittings (e.g. taps which are difficult for some people to use).

Occupant comfort

Wet areas, particularly bathrooms, should not be uncomfortable or unpleasant spaces to use. Conditions that that will compromise occupant comfort include:

  • cold air/surfaces
  • high humidity environment (e.g. mirror steaming up)
  • lack of acoustic privacy (bathroom/toilet)
  • lack of hanging or storage space
  • unpleasant odours (e.g. from toilet, residual damp smell in bathroom, cooking smells in kitchen).