To achieve satisfactory long-term performance from a suspended timber floor and to reduce the risk of timber pest attack from termites, fungal decay and the like, it is essential that correct sub-floor drainage and ventilation be in place. Provision of adequate sub-floor ventilation will help to avoid serious problems with floors such as swelling or shrinkage, decay and risk of termite attack
The recommended minimum area of openings for sub-floor ventilation is 6300 mm2/m length of external wall. The vents should be spaced not more than 600mm from each corner, evenly distributed and located to ensure cross-ventilation.
The under-floor ground surface should be graded and drained to prevent the ponding of water. Where the ground is excessively damp, an impervious membrane should be placed over the ground surface. Minimum ground clearance should be 400 mm to the underside of the timber framing.
The area around the building should be graded and drained to minimise water accumulating or moving under the building. Downpipes, outside taps and drains should also be well maintained and connected to stormwater drains to divert water away from the base of the building and prevent ground water ponding.