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How to Insulate a Basement Floor

There are quite a few benefits of choosing to insulate your basement floor with spray foam.  First, it prevents exterior air from entering your basement and home, which makes it more energy efficient.  Also, it keeps the air that is in your home, running through your HVAC system, a more consistent temperature.  Installing closed cell insulation foam in your basement floors will also prevent the buildup of moisture, and unlike fiberglass insulation, it will not rot or wear out over time.  In addition, spray foam insulation expands and cures to fill all gaps and crevices effectively, which means a more effective air and moisture barrier, and that in turn means better energy efficiency.  In addition, spray foam insulation has a higher R-value, protecting your home more effectively.  For those of you who enjoy being do-it-yourselfers, here are a few tips on how to insulate your basement floor:


  • Be sure to read the instructions carefully before use.  Though all foams may seem the same, it is important to follow the specific instructions for the foam you are using.
  • Closed-cell insulation is best for sub slab insulation.  The denser the foam, the greater the compressive strength
  • It is also important to consider thickness.  At least two inches is recommended, and a thicker layer can be applied if desired and beneficial
  • Protect walls and other areas with newspaper or a drop cloth
  • Always wear gloves and safety goggles when using spray foam
  • Before dispensing the foam into the floor, practice on some newspapers or into a trash can
  • You can slightly mist the area to speed up curing with some foams
  • Be cautious of overfilling the space.  Overfilling means a messier cleanup once the foam expands
  • Once the foam has cured, overfills can be trimmed away with a serrated blade or utility knife
  • It is important to try to fill any voids with a continuous flow in order to achieve the best seal


There are several other things to think about when considering how to insulate your basement floor.  One of the considerations is the use of a vapor barrier.  The concrete or block in your basement floor can capture moisture during humid times, and then during drier times, that moisture evaporates, creating vapor.  In addition, sometimes the moisture in the air can create condensation on the concrete or block.  In these cases, a vapor barrier can be a good idea.  If you do choose to insulate the basement floor yourself, it is also important to be sure that every gap is filled to avoid trapping air and moisture into any unfilled spaces.


If you have further questions about using spray foam insulation, about how to insulate your basement floor, or about the cost of using spray foam insulation in your basement, feel free to contact us at Airseal.  We can give you tips, answer questions, and if you’d rather leave this important job to the professionals, we can promise you great value and top-notch service as well.  And once your basement floor is well-insulated, you’ll enjoy years of consistent temperatures and energy savings.