Around 1.2 million New Zealand houses have suspended timber ground floors. Common subfloor problems include dampness, rot, poor ventilation and structural issues. BRANZ house condition surveys have consistently found that damp subfloors are one of the most common problems in New Zealand houses with suspended timber floors.

Dampness and other subfloor problems can lead to poorer health for the house occupants and also to:

  • rot and corrosion of wood and metal and reduced durability
  • borer infestation in wood
  • loss of insulation performance
  • poorer earthquake performance, such as the house falling off the piles.

Ensuring that the subfloor remains or is brought up to good condition is an important part of home maintenance. A lot of the work involved in fixing subfloor problems – clearing blocked vents or replacing corroded fixings – isn’t very expensive. This guide shows you the steps to take regarding moisture, ventilation and structure.