Finished Basements – Subfloor & Insulation

Whether renovating or finishing a new concrete basement, it can be a tough job. Worse yet, having to select the proper building materials in order to avoid mold from forming later on. This article will cover the points necessary to complete a worry free basement for many years to come.


– One of the major problems with subfloors in concrete basements is the moisture which builds up over time beneath the subfloor itself. Concrete is a very porous material which absorbs water out of the earth that surrounds it and then finding its way underneath your subfloor. Wood subfloors can be used effectively with proper vapor barrier. I prefer to use 100% plastic floor tiles which snap together and create a guaranteed water vapor tight seal. Another benefit of this subfloor are its mold resistance qualities.


– When finishing your basement insurance is one of the most important factors if you are trying to achieve a comfortable basement. If a finished basement is still cool in winter, it is not a very comfortable space to occupy. However when finished properly it really does not even feel like your in the basement of a house. Fiberglass or rock-wool are the most common insulation's used. Common problems with these insulation's in a basement are:

-insulation's fit too tight or too loose

-insulation installed against unsealed concrete (I recommend certified vapor barrier against concrete wall and wrap to underneath subfloor)

-cold air from the concrete walls infiltrates into the insulation, giving less R value (measure of thermal resistance)

-difficult to insulate and seal with vapor barrier and batt. insulation around main floor end plates

Spray foam is by far the best insulation to use for any application. It fills all cavities leaving absolutely no room for moisture. Closed cell spray foam is certified for use in Canada for insulation, however a CSA certified vapor barrier should still need to be used according to many different building codes. It also adds structural rigidity to the house. Another plus of spray foam is the gener Soy based spray foam. It contains polyurethane and recycled plastics and soy oils. It offers approximately the same R value factors as the original polyurethane spray foams. With Less Volatile Organic Compounds

Insulation R Values

-locked cell spray foam – R-6.33 per inch

-fiberglass insulation – R-3.42 per inch

-rock-wool insulation – R-4 per inch