Controlling Moisture in the Home

January 22nd 2007
Controlling Moisture in the Home

The most often talked about problem in the home is moisture control and how to get rid of it. Moisture usually becomes a problem as soon as the weather turns cold and we close up our windows and doors. The moisture looks for places to vent and if there isn't sufficient ventilation, you may begin to find excess moisture showing up on windows or as stains on the ceiling.

Anywhere that water enters your home, you have the potential for damage, such as musty odors, wallboard staining near windows or plaster or drywall that crumbles. Moisture causes odors to linger in crawl spaces and basement rooms allowing fungus and mildew to grow.

There are several ways to reduce indoor humidity such as increasing ventilation using exhaust fans when cooking, washing and cleaning. Using HRV's (heat recovery ventilators) and venting bathrooms, laundry rooms and other areas that exhaust moisture to the outside.


1. Bathroom exhaust fans should be controlled by a DEHUMIDISTAT moving air at an average rate of 105 feet per minute.

2. If a forced air furnace has only a single speed blower motor have a conversion made to a two speed motor allowing air to be circulated 24 hours a day 365 days a year throughout your home. If after installing a two-speed motor, you start to feel drafts at some of your floor registers, you should consider installing a HOYME DAMPER. This is installed in the inflow cold air duct on your furnace and prevents cold air from coming in the home through your heating system.

3. Electric or Hot Water Heated Homes Radiant or Convection. With those types of heating systems it is important to have the best exhaust ventilation system you can afford. You should install a HEAT RECOVERY VENTILATOR SYSTEM-HRV. This will recover up to 70% of the heat within the moist stale air being exhausted from your home. Check out the Lifebreath website at for more information on HRV's.

4. Bathing & Showers.  Bathroom fans should be left on one hour after bath or shower use. Also, wipe or squeegee excess water after each shower.

5. Condensation on Windows.  This is the first sign of too much moisture (relative humidity) in the home. When this happens, venting must begin.

6. Damp basements and crawl spaces. High moisture in a crawlspace will eventually work its way up into your living area. To rectify this problem, consider insulating the perimeter walls in the crawlspace and between the joists overtop of the concrete walls with rigid foam insulation and sealing with acoustic caulking.

Also, installing a HUMIDEX crawlspace ventilation device will expel damp, cold air to the outside and replace it with dry air from the higher levels of your home. Since the Humidex eliminates only the damp air at the lowest level of your home (the basement), the potential for losing heat is low.

Why Control Moisture Flow?
Control of moisture in all its forms is important in order to make our homes durable and comfortable. Building components and practices such as flashing, roofing and basement damp-proofing successfully protect the home from liquid water.

It is equally important to control the movement of water vapour, providing added protection for the house structure and helping to maintain indoor humidity at a comfortable level.

Controlling moisture involves the following three strategies:
1. Construction techniques that keep moisture away from the structure
2. Producing less moisture
3. Exhausting excess moisture

Where does all the moisture come from? There are a number of major sources that are not always obvious:
- Occupants and their activities
- Wind-blown rain in walls
- Damp basements and crawl spaces
- Moisture that is stored in building materials and furnishings

To find out more valuable information about moisture control in the home visit Natural Resources Canada website.

Contact the HouseSmart Referral Network for more information on where any of the above mentioned products are available in your area 604.542.2236.