Dampness and Condensation

Problems with moisture are commonplace in New Zealand homes and can have serious consequences. Damp homes are unhealthy to live in, difficult to heat and deteriorate more quickly requiring costly maintenance. Fortunately most dampness problems are relatively easy to solve.

Health effects

High moisture levels inside a home can contribute to a number of health problems. Dampness encourages the growth of mould and dust mites which can cause respiratory disorder such as asthma and bronchitis as well as allergies. Read more about the health effects of damp homes

Signs of a damp home

The most obvious signs of a damp house are a musty odour, mould and mildew growth and condensation on walls, ceilings and windows. Read more about identifying the signs and causes of dampness. If you are unsure if your home is damp purchase a Hygrometer to measure the humidity. Normal humidity levels should be between 40-70%.

Solving dampness problems

Solving Moisture Problems

The first step to fixing problems with moisture is to identify and eliminate the sources of the moisture within the home. Moisture is produced by a number of activities; indoor clothes drying, damp underfloor soil, unflued gas heaters and poorly ventilated showers all being common causes of dampness. Read more about sources of moisture.

Extracting moisture at the source is also crucial to solving moisture problems. Showering and cooking release considerable amounts of moisture in bathrooms and kitchens which can migrate into other areas of the house. Extractor fans or rangehoods should be fitted in bathrooms and kitchens to remove moisture as it is produced. These should always be vented to the exterior of the house to prevent moisture building up in the attic. Read more about extractor fans or rangehoods.

Once the sources of moisture have been addressed indoor humidity and condensation can be controlled by ensuring the house has adequate ventilation, insulation, and heating. Ventilating your home daily by opening windows and doors replaces damp indoor air with dry outdoor air. Read more about ventilating your home (link to CEA ventilation page) Insulation helps to reduce condensation by preventing internal surface temperatures on walls, ceilings and windows from becoming cold enough for water vapour to condense. Read more about insulating your home (link to CEA insulation page). Heating assists by raising the indoor air temperature which in turn increases the amount of moisture the air can hold. This makes it much easier to remove moisture from the house when ventilating. Read more about heating your home (link to CEA heating page)

Dehumidifiers

Dehumidifiers can be very helpful for reducing the symptoms of dampness in a home by removing moisture from the air. While it is always preferable to treat the causes of the dampness first, this is not always possible or affordable particularly for those in rental accommodation.  Dehumidifiers can significantly reduce indoor humidity levels, but all practical steps should still be taken to eliminate sources of moisture and provide adequate heating and ventilation. Read more about dehumidifiers.

FAQs

Do I need a home ventilation system to solve my dampness/condensation problems?  Home ventilation systems can be an effective ways to reduce the symptoms of dampness.  However they do not fix the cause of the problem and are expensive to install. In some circumstances home ventilation systems will have little effect or may even make moisture problems worse! Read more about home ventilation systems. It is always preferable to address the sources of moisture within the home first before considering a ventilation system.

I have a fan heater in the bathroom, why do I need an extractor fan as well?  While fan heaters help to keep your bathroom warm and dry, they do not actually remove the water vapour. Once the heater is turned off the air will cool and the moisture will condense on cool surfaces. Often the condensation may appear in other rooms as the warm moist air escapes from the bathroom before cooling. An extractor fan will remove moisture before it can condense. Running the extractor fan and the heater together will remove moisture even more effectively than running an extractor fan alone

I have taken steps to eliminate sources of moisture in my home but I still get condensation on my windows in winter. Is this normal?  Some condensation on single glazed winter is perfectly normal in winter. At normal humidity levels of 40-70% condensation will form on single glazed windows during cold winter nights. This is because the window pane becomes so cold that moisture in the air will condense against the cold surface, it does not necessarily indicate that the house is damp. It is recommended to wipe away condensation on windows to remove the moisture and prevent any damage to window frames.   Installing secondary or double glazing reduces heat loss through the windows and is the most effective way to eliminate window condensation.