Your home’s basement provides a huge opportunity for energy savings. As much as 30% of your heat loss is due to an uninsulated basement. This is exacerbated by penetrations from plumbing and electrical that cause air infiltration and increase a Building Science phenomenon called the Stack Effect. Like in a chimney (smoke stack), the Stack Effect sees warm air rising and through the home, pulling in cool air from the basement. If you seal off this air, it slows the Stack Effect.
Basement Insulation – Good
Insulating your basement with Roxul or other rock wool batt is a good option, this type of batt withstands moisture problems that result in sagging in fiberglass insulation.
Basement Insulation – Better
A better option (in addition to the roxul) is to first use spray foam in all of the headers of your basement – this deals with air infiltration and Thermal Bridging. (Thermal bridging means cold air conducted along the structure from the outside to inside.)
Install spray foam prior to the Roxul for a superior air sealing job and you will create a much more comfortable environment.
Basement Insulation – Best
The best option (after you have ensured that you have no water problems) is to spray foam the full basement from floor to header creating a seamless air and vapour barrier for your basement. This eliminates both air infiltration and moisture issues. No more basement smells, drafts or chills. (Now if you are building new – start with an underslab sprayfoam insulation!)
Insulating an Existing Basement
When insulating your basement be very aware of plumbing on exterior walls. It is essential that you not put the insulation to the warm side of the plumbing as this risks freezing pipes. Always insulate behind all plumbing as in the project below: