After you've repaired sources of water entry, insulated and planned the physical layout of your basement renovation, you should consider heating and ventilation systems to make the space more comfortable.
The National Building Code of Canada (NBCC) sets minimum standards for water and waste piping in kitchens and bathrooms and for heat and ventilation in "habitable" rooms.
And Canada Mortgage and Housing Corp., the national housing agency, offers plenty of helpful advice about basement systems.
Providing your basement with a heating and ventilation system that equals the one in the rest of the house should improve air quality and comfort during the heating season.
Electric baseboard heaters supply warmth, but provide no circulation. If your house has a forced-air heating system, the furnace can provide heat and air circulation to the basement.
Most furnaces provide circulation by pushing heated air out of registers and pulling cooler air into return-air grilles. The supply registers should be near cold surfaces, such as windows, and close to the floor in all rooms to allow the room air to mix effectively. Return-air grilles also should be near the floor in all rooms, except the furnace room, to remove the layer of cooler air that tends to collect there and to ensure proper air circulation.
But what about when the furnace is off and there is no air movement? Excessive humidity and insufficient air movement contribute to two common problems in basements: mould growth and stale air.
It is advisable to run the furnace fan year-round, or use a furnace cycling device to circulate the air throughout the house. Because fan operation consumes energy, consider replacing a conventional furnace with one equipped with an electronically controlled motor.
Opening windows usually increases humidity during the warm season, because this is the period when the outside air contains the greatest concentration of moisture. Dehumidifiers and air conditioners can be effective for drying and cooling indoor air during the non-heating months.
A heat recovery ventilator (HRV) is a valuable addition to a ventilation system because it exhausts stale air and replaces it with fresh outside air. The fresh air is warmed with heat from the exhaust air, mixed with house air, heated and circulated by the furnace.
Humidity is a common source of discomfort in basements that can contribute to odours, staining, mould growth and wood decay.
Excessive humidity can be caused by: leaks; damp materials; improperly installed insulation, air barriers and vapour retarders; weather conditions; and the home's occupants.
High humidity can result in mould, wood rot and fungal growth, progressively damaging organic materials, such as wood and wood-based products, and natural fibres in carpets and upholstery. It also can lead to health concerns.
Therefore, it's important to keep room humidity levels within an acceptable range. If you put a bathroom or kitchen in your basement, you're introducing a potential moisture source.
You can install humidistats on kitchen and bathroom fans, to start them automatically when relative humidity exceeds a selected level, and shut them off when the humidity drops.
This relatively inexpensive step removes humidity at its source and ensures that fans run when they're needed most, during cooking and bathing.
All building codes require that these fans must vent directly to the exterior.