“Insulating Your House” an article by Canada Mortgage and Housing Corporation
I recently ran across an article by the Canada Mortgage and Housing Corporation on insulating your house. Insulating your home may be fresh in your mind today, especially if you live in the areas that are currently experiencing snowfall in April!
I encourage you to read on about CMHC’s thoughts on insulation.
While previous generations may have been content to live in drafty houses, most people now want comfortable warm houses. A healthy house today is well sealed, well insulated and properly ventilated.
A well-insulated house is a bit like dressing for the weather. A wool sweater will keep you warm if the wind is not blowing and it is not raining. On a windy, rainy day, wearing a nylon shell over your wool sweater helps keep you reasonably dry and warm. A house is similar. On the outside, underneath the brick or siding, there is an air barrier that does the same thing as the nylon — it keeps the wind from blowing through. Then there is the insulation (like your sweater) and a vapour barrier, which helps keep moisture away from the house structure where it can do damage.
Basement walls are unique because they must handle significant moisture flows from both inside and outside the house. The preferred method, from a building science perspective, is to insulate the wall on the outside with rigid insulation suitable for below-grade installations, such as extruded polystyrene or rigid fibreglass.
The advantages are as follows:
•Insulating the outside of the basement works well with dampproofing and foundation drainage. Rigid fibreglass or mineral wool acts as a drainage layer, keeping surface and ground water away from the foundation.
•The basement walls are kept at room temperature, protecting the structure, reducing the risk of interior condensation and increasing comfort.The disadvantages are the disturbance of landscaping, the need to cover the insulation above grade, and the relatively high cost.
Interior insulation can be used. This can be done when finishing the basement by using batt insulation in the stud cavities or by installing extruded polystyrene and strapping on the face of the perimeter walls. If the basement won’t be finished, you can install rolls of polyethylene-encapsulated fibreglass over the wall. The advantages of interior installation are cost and ease of construction. The disadvantages of interior installations are as follows:
•The basement walls are now at the temperature of the soil or the outside. Any moist air moving through the wall from the inside will condense on the wall.
•Usually, there is a moisture barrier against the foundation wall and a vapour retarder on the room side of the insulation. As a result, the wall has poor drying potential. Never apply interior insulation to a basement with moisture problems. Fix the moisture entry problems before insulating (see CMHC’s publication A Guide to Fixing Your Damp Basement).
Read the full article from the CMHC: http://www.cmhc-schl.gc.ca/en/co/maho/enefcosa/enefcosa_002.cfm