Moisture Problems – Humidity
Keep humidity levels within a healthy range
Health Canada recommends that your home’s relative humidity be kept between 30 and 55 percent in winter. Lower levels aggravate skin allergies and respiratory infections, and higher levels increase the spread of mould, bacteria and viruses. Dust mites spread when the humidity is above 50 percent.
Piggyback!
If you are undertaking a major renovation, such as finishing a basement or gutting an interior, don’t lose the opportunity to “piggyback” solutions to moisture problems. Some measures – such as adding insulation, a polyethylene air/vapour barrier or a balanced ventilation system – are much easier and less expensive to implement during construction than afterward.
Use dehumidifiers wisely
Dehumidifiers are generally not effective in winter, since they can lower humidity levels to between 50 and 60 percent only. However, running a dehumidifier in the basement on muggy summer days can be effective in reducing condensation on foundation walls and floors. Exhausting moist air from the basement may help, unless the replacement air from outside is just as moist.
Don’t Become a Statistic!
If your house has high humidity levels and no obvious moisture sources, it is essential to check any fuel-burning equipment – furnaces, hot water heaters, boilers, fireplaces and wood stoves – to ensure that they are venting properly. A blocked chimney could mean that combustion products, including large amounts of water vapour, are spilling into your house. Along with that moisture come dangerous combustion gases, such as carbon monoxide, which kill more than a dozen Canadians every year. Have heating equipment and venting systems checked by a trained service person. Also, if your moisture remedial work or energy retrofit includes extensive air sealing, ensure that all fuel burning equipment has an adequate supply of combustion air. Advanced equipment such as high efficiency furnaces have their own air supplies and exhaust fans. However, conventional equipment may rely on house air for combustion and on “natural draft” to move combustion products up the chimney flue. If starved for air or overpowered by a powerful exhaust fan somewhere else in the house, such equipment can spill combustion gases indoors. Examples of combustion spillage include stains near the vent of a gas water heater, smoke entering the room from a wood- burning fireplace or stove, and pilot lights being blown out.
Where Can I Get More Information?
This fact sheet is meant only to give you an introduction to the importance of moisture problems and how to solve them. The following publications contain more detailed information.
Air-Leakage Control
Consumer’s Guide to Buying Energy-Efficient Windows and Doors
Improving Window Energy Efficiency
Keeping the Heat In
Operating and Maintaining Your Heat Recovery Ventilator (HRV)
To obtain additional copies of this or other free publications on energy efficiency, contact:
Energy Publications
Office of Energy Efficiency
Natural Resources Canada
St. Joseph Communications
Order Processing Unit
1165 Kenaston Street
PO Box 9809 Station T
Ottawa ON K1G 6S1
Telephone: 1-800-387-2000 (toll-free)
613-995-2943 (National Capital Region)
Fax: 613-740-3114
Web site: oee.nrcan.gc.ca/infosource
TTY: 613-996-4397 (teletype for the hearing-impaired)
_________________________________________________
About Your House: Hiring a Contractor
Clean-Up Procedures for Mould in Houses
Investigating, Diagnosing & Treating Your Damp Basement
Canada Mortgage and Housing Corporation (CMHC)
Canadian Housing Information Centre
700 Montreal Road
Ottawa ON K1A 0P7
Telephone: 1-800-668-2642
Fax: 1-800-245-9274
Web site: www.cmhc-schl.gc.ca
Renovation Contractors
If you want to hire a contractor to help solve moisture problems, read CMHC’s publication About Your House: Hiring a Contractor before you start. Make sure the contractor has a sound understanding of the causes of moisture problems. Supply a copy of this fact sheet and ask if the contractor has read any of the publications listed above or has taken a training course on moisture problems. If you have had basement flooding, look for a professional in the Yellow Pages™ under “Water Damage”.
