Damp homes promote mould and dust mites which can cause respiratory problems. While dehumidifiers and ventilation systems help reduce the symptoms of the problem, it’s important to track down the underlying cause of dampness in your home. The problem may be relatively cheap and easy to fix.
Condensation on windows, especially in bedrooms, isn't necessarily a sign of excessive dampness if it only happens occasionally during winter.
Where does excess moisture come from?InsideThe average NZ family produces up to 8 litres of moisture in the home each day from activities like cooking and showering. This is normal and can be managed by insulating, heating and ventilating.
Find out if your house is dampTo prevent mould growth, the amount of moisture in your home (relative humidity) should ideally be below 65% most of the time, and rooms should be heated to at least 18 degrees.
To assess the temperature and relative humidity in your house, try using a simple, low-cost hygrometer. Take readings over a few days or weeks in different rooms of your house, especially in winter, to find out where you might need to address dampness issues.
Learn more about hygrometers
OutsideSources of moisture, such as leaking pipes or damp rising from underneath your house, are often hidden and can go undetected for a long time, damaging to your home.
How to tackle sources of dampness insideTop tips
Bathroom, kitchen and laundry
Ensure extractor fans are:
Living areas and bedroomsAvoid unflued gas heatersUnflued gas heaters can be portable or have pipes fixed to the walls. They release large amounts of moisture and toxic gases into your house, and can also be a fire hazard.
If you’re using a gas heater or LPG portable heater without a vent or flue:
Whatever type of dehumidifier you use, run it together with a heater - a warm room makes it easier for a dehumidifier to extract moisture.
How to tackle sources of dampness outsideUnder floors
How to install a vapour barrier - NZ Standard for installing insulation
If you’re not sure about any of these actions, talk to a qualified builder.
Floors, walls and roofs
Registered building surveyors - New Zealand Institute of Building Surveyors website
Accredited building surveyors - Building Officials of New Zealand website
Concrete floors and walls
Find out if your home is warm, dry and healthyUse HomeFit to find out if your home is warm, dry and healthy - it's a free online check designed by the Green Building Council.
Do the online check at www.homefit.org.nz
Dean Norrie, Director/Building Inspector - LBP Qualified Builder, with 20+ years residential building experience, three generations of builder in the family.