September 13, 2009

I have talked a lot about the building shell and the importance of having an air tight home. When you look at a home, the most vulnerable areas for air infiltration would be at the box sill. The box sill is located on the outside wall where your floor system meets the outside wall. It is impossible to use standard practices with fiberglass batts to create a air tight system. That is why we use 3" of spray foam insulation in all the box sills. The foam is a closed cell foam which does not allow water and air molecules to transfer through the foam. It is also recognized as a vapor barrier so plastic does not need to be applied over that area.

In the lower level of the home we spray the box sill with foam and carry that foam over the treated 2 x 6 sill and onto the concrete. This creates a complete seal from your framing to your foundation wall.

This can also be done in existing homes if your lower level is not finished. This is a great way to make your existing home more energy efficient.