Fibreglass Insulation in Basements is a Poor Choice

Fiberglass insulation is no longer code compliant in flood prone areas of Alberta.  This trend is gaining momentum and with upcoming stricter building codes, it may soon be enforced throughout Canada. If fiberglass doesn’t work in Alberta basements, why would it work elsewhere?  Basements, no matter where you live are subject to wetting.  Besides flooding; sewer backups, water pipe leaks and toilet over flow are other ways your basement can get soaked with water. Even if none of these events happens, without the proper insulation system, a conventionally insulated basement is generally a damp, cool, uncomfortable, unhealthy and inefficient living environment.

Up until now, fiberglass has been the most traditional method of insulating basements.  The batt and stud method has been used for decades but it has one serious issue – it absorbs moisture and promotes mold growth.  Just like a blotter, fiberglass insulation soaks up moisture which gets trapped behind the vapor barrier.  Moisture that enters the foundation from the outside also contributes to the problem.  As the concrete dries it releases a great deal of moisture directly into the fiberglass insulation.  Consequently, as the fiberglass saturates it loses its R-value.  The wetter it gets the worse it performs.  Mold will grow in and on fiberglass insulation as well as the surrounding surfaces.  Over time, this causes studs, floor joists and drywall to rot.  Mold and rot combined, guarantee a stinky and unhealthy basement.

So what’s the best way to insulate basement walls?  Exterior insulation is not practical due to the high cost and difficulty of protecting the insulation from damage.  Exterior basement insulation saves energy dollars; however the inside of the concrete wall is still cool to the touch.  If you plan to use your basement for added living space, you want warm interior walls.  Because of its lower cost, superior performance and ease of installation the most common method of insulating basements walls will continue to be – insulation on the inside.

Since fiberglass insulation is not an option, what’s the best technology for insulating the inside of concrete basement walls?  A better question might be; what inherent qualities are required for an insulation system to be suitable for basements?  First off, basement insulation must not absorb moisture.  Therefore basement insulation needs to contain an accepted code compliant material that performs as a vapour barrier.   Secondly, we don’t want warm air to escape or cold air to infiltrate into the basement through cracks and crevices.  That means the insulation system should also include an approved air barrier.  Thirdly, the insulation must be a high performance insulator that has been proven to work in below grade applications.  And lastly, the framing system should be impervious to moisture.  If the insulation system you are considering doesn’t meet these specifications it should not be installed in your basement.

In conclusion, it is important to look at all levels of a home when trying to maximize its energy efficiency.  The days of cold, dark, and damp basements are in the past; today’s homes utilize every square inch of space, including the basement.  Protect your investment and your family by choosing the best method of insulation that is long-lasting, safe, easy to install and environmentally responsible.  The best and most cost effective insulation system for basement walls can be found at

Read More on Alberta Flood Mitigation

Read More about Mold in Finished Basements by CMHC