Thursday, February 25, 2010

Green Thursday: Your Basement Band Joists

As we have discussed in our earlier Green Thoughts posts, sealing you home's building shell and air ducts is vitally important for making sure that you and your family living and breathing in clean & conditioned air and not wasting in your good air and energy dollars to inefficiency or leaks. We have worked from the top down, first demonstrating ways to seal your attic and then showing how to seal the duct system throughout your house. Now, we are going to focus on correcting a major trouble spot for leaky basements- the band joists (also called rim joists).

In basements where the interior walls are the foundation walls (or are right up against them), Edge Energy, our Green Energy Experts, often finds major air leaks along the band joist, which is located at the basement ceiling. The band joist is the joist that surrounds all the rest of the joists in the floor above the basement. The floor sits on top of the foundation wall and, because the band joist is on the outside, this joist is the part of the floor that comes in direct contact with the foundation wall itself.

This seam along the band joist above the foundation wall is often left unsealed by builders and thus allows air to stream into your home. There is no really simple way to fix this and since the gap is usually a long seam and not just a small hole, retrofitters (like Edge) have to cut holes in the ceiling along this seam to sprayfoam and seal the gaps. They then close up all the holes, re-paint the ceiling and leave your basement looking just like it did before they started, but with a lot less of a draft.

--Band Joist Sealing

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Full Disclosure: EDGE Energy hired us, as Sum of Change not individuals, to produce several videos for them including the ones in this post. We have not been hired to distribute, recommend, or advertise for EDGE Energy, rather we are using these videos to explain a vital service and we appreciate them letting us do so.

To learn more about the energy audit from Edge and see more of our videos, please go to and see Edge's youtube page
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