Is it condensation & humidity or just water you’re seeing in your home?
When warm, moist air comes into contact with a surface that is too cold, moisture condenses. In winter, the water and frost that you see collecting on windows is a visible example of this. Condensation may also be collecting in your attic and inside the exterior walls. On the other hand, in summer if you have your basement windows open warm moist air from outdoors can condense on your cool basement foundation walls. Over time, if the air in your house is too humid, the result may be damage to the house structure, your possessions and possibly your health. Controlling humidity in your home is the best step to preventing mould problems.
Condensation can result from a number of areas, such as:
- excessive moisture production
- inadequate ventilation with outdoor air
- cold surfaces
- cool basement surfaces in the summer
You can try to control condensation by first reducing the level of moisture in the home and secondly keeping surfaces warm. All moist stale air in the home should be replaced with fresh air every 3 to 4 hours. Without the air exchange, your home can accumulate moisture, mould can become a problem and you can experience poor indoor air quality as a result.
While increased house air-tightness can improve energy efficiency, it may also lead to a greater need for mechanical ventilation. A sufficient air supply may also be needed to prevent combustion appliances from back drafting. People and pets produce moisture when they breathe or perspire. Even indoor plants produce moisture. We add water vapour to the indoor air through routine household activities such as cooking, showering, bathing, doing laundry, and dish washing. More moisture can enter your home from the surrounding soil through a basement or crawlspace.
We recommend that you measure the relative humidity (RH) in your home. CMHC (Canada Mortgage & Housing Corporation) suggest some rules of thumb to prevent window condensation during the heating season:
- recommended indoor RH of 30% to 50%; and,
- when it is below –10°C outdoors, that the indoor RH be 30%.
Uncontrolled condensation & humidity can lead to mould growth, poor indoor air quality and deterioration of building materials. If condensation or high humidity persist in your home, seek further professional advice.