Controlling Moisture in your home

oday's energy-efficient homes are built tightly to seal out the cold weather in winter and keep in the air conditioning in summer. Because of this, it is possible that a new home can be severely damaged by lack of ventilation or by excess moisture.

It is important to remember that moisture damage caused by improper or inadequate use of your ventilation system, is not covered by the new home warranty.

What causes moisture damage? 

Your home can be damaged if weather-related water is allowed to enter and remain in the structure. Water from leaking pipes or fixtures that is not immediately cleaned up, and indoor humidity levels that are not properly controlled, can have serious consequences. Sometimes this damage is easily seen, at other times the damage is hidden inside wall and roof spaces. Regardless of where it occurs, moisture damage can lead to serious problems, such as rot, mould, and even structural failure.​

How can I control moisture?

Always use your home ventilation system to control moisture. In a typical home, over 20 litres of water are added to the indoor environment every day. That’s 7,300 litres in a year, enough to fill a medium-sized swimming pool. Bathroom fans, kitchen range hoods and packaged ventilators such as heat-recovery ventilators are specifically installed in your home to help you control moisture and contaminants. Regular use of your home ventilation system will exhaust excess airborne moisture caused by bathing, showering, doing laundry and cooking.​

What else can I do to control moisture?

Here are some extra tips you can follow to help prevent moisture damage to your home. 

Outside the home

  1. Keep flowerbeds or landscaping at least six inches or 150 mm away from the top of the foundation. Placing soil near or above the top of the foundation allows moisture to come into direct contact with the structure of the building.
  2. Ensure that land adjacent to the foundation slopes away from the home so that rainwater and snow melt will run away from the foundation.
  3. Clear eavestroughs of debris regularly and extend downspouts so that water is directed away from the building. Water flow can erode the ground near the foundation and create depressions where water collects. Standing water near the foundation can force its way into the basement.
  4. Fix the caulking around windows and doors and on the roof if it becomes cracked or separated.
  5. Have your roof inspected regularly to ensure shingles, flashing and chimney caps are in place and sealed properly.
Inside the home
  1. In the winter, keep the relative humidity in your home in the range of 30-45%. Lower humidity levels may affect your health and cause things made of wood to shrink. Excess humidity can cause condensation on windows and damage the surrounding wall. When using a humidifier, follow the manufacturer’s instructions.
  2. In the summer, dehumidify the basement to avoid condensation buildup on the cool foundation walls. Relative humidity levels should not exceed 60%.
  3. Repair leaky pipes and fixtures immediately. Clean and completely dry any areas that are dampened or wet within 48 hours.
  4. Store organic materials such as newspapers and clothes away from cool, damp areas. Keep storage areas tidy so that air circulates freely.
  5. Purchase a “hygrometer” to monitor the relative humidity in your home.
  6. If you are adding a hot tub to your home, or have a large collection of plants, consider the amount of moisture they will add to your indoor air and ventilate accordingly.
  7. Never vent your clothes dryer inside your home. If you have a gas- or propane-fired dryer you may also be venting carbon monoxide inside your home!
  8. Investigate and identify any musty smells and odours. They are often an indicator that there is a hidden moisture problem.​


Ericka Fowler

Ericka Fowler

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