Ventilation Introduction

• It is best to remove moisture from where it is generated to outside the house before it has a chance to spread to other parts of the house. Use ducted fans, through-wall fans or window fans at all times. Do NOT use ceiling fans which discharge into the ceiling cavity - this only moves the problem. Moisture will permeate insulation and ceiling linings causing further problems.

• In particular with bathrooms think in terms of “room-conditioning”. Warm, moist air is immediately attracted to cold surfaces, where it condenses into water droplets. Cold surfaces include glass, mirrors, tiles, wet-wall linings, cold un-insulated ceiling linings, etc. You cannot remove all of this air at a rate fast enough to stop this happening and if you could, you would be standing in a wind tunnel. Use of a bathroom heater to warm the room prior to use greatly assists in reducing condensation.

Fan Placement

• Careful location of an extraction fan will ensure maximum air-flow through the room. Air extracted from a bathroom, for example, can be replaced with dry air drawn from an adjacent bedroom or hallway, in turn, drawn from an open window or door. This ensures that fresh air is being drawn into the entire house at regular periods.

• Switching the fan on before starting showering or cooking sets up effective air-flows before the associated condensation problems occur. Closing doors to adjacent living areas assists in stopping the transfer of moisture to those areas but ensure that sufficient air can enter under the door to replace extracted air.
  
  Use a door vent if necessary.

• For a fan to remove air effectively, the same amount of • air being extracted must be able to enter the room. e.g. air in = air out

• An air-tight room will mean no air movement. If the room is tightly sealed (e.g. a tight-fitting door, with no gap at the bottom), you may need to fit a through-door grille (see duct accessories) to allow replacement air into the room.