Insulating the Home

To improve the energy efficiency of our home we added insulation where accessible and sealed air leaks in the house.


Exterior walls:

The exterior walls use only an air gap for insulation have little to no insulation.

We could dramatically increase the R-value by removing the walls and adding insulation. To do it that we would need to remove the drywall or remove the siding and wood sheeting on the outside then add insulation and reinstall the walls. Foam insulation could be added by drilling holes in the wall and spraying it in then patching and repainting. Since we are doing the work ourselves we have decided to go with less dramatic changes that will make a difference.


Reduce air flow in and out:
This was achieved using various methods. For our house the top three improvements in this field were:

  • Calk any gaps around windows and doors. Also at the base of the floor then cap the spaces with trim. If there are large gaps purchase a foam backer rod to fill space first.
  • Seal all outlets and switches with a closed foam pad behind the covers. This is a good practice to do in both indoor and outdoor locations to reduce air migration.
  • Seal any gaps where the foundation meets the sill. To do this use spray foam at the meeting point. I went a step further and cut Styrofoam insulation to fit in each of the joists and attached them with construction adhesive then used spray foam to close the surrounding gap.


R-value is a measure of thermal resistance meaning that the higher the R-value the better the insulation.

Examples of R-values per inch:

Material R-value
Air 1/2″ to 4″ R-1
Cellulose R-3 – R-3.8
Fiberglass batts R-3.1 – R-4.3
Cardboard R-3 – R-4
Brick R-0.2
Glass R-0.14
Concrete R-0.08
Drywall 1/2″ R-0.45

More on R-values

How much insulation is needed Home_sealing insulation table