How to Inject Foam Into a Floor Joist

There are several reasons to inject foam into the spaces between your floor joists. The two most common are to provide an extra level of noise dampening and to provide an extra level of insulation. This is commonly done between the floor joists separating the basement and first floor. Foam spray insulation kits make it a relatively simple job for the do-it-yourselfer.

Protective clothing
Goggles
Respirator
Spray foam kit

Instructions

- 1
  Put on a layer of protective clothing, including goggles and a respirator. Do not leave any skin or hair exposed.
- 2
  Connect your sprayer to the foam source, following the specific instructions for your sprayer unit.
- 3
  Spray a small area of the joists with foam. Note the degree of expansion. Since spray foam can expand greatly, you will want to be sure not to spray too much in the joists.
- 4
  Spray with even strokes, covering the area and moving to the next bare patch of joist.

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