How To Insulate Floor Joist Pockets

Have a question about insulating my rim joists in basement.

How to insulate floor joist pockets.

At the rim joist area many building components come together the foundation wall the mudsill the rim joist the subfloor so it s also important to seal all cracks against air leakage. This may be a bit long so bear with me. A merry christmas to everyone. I filled the pockets with insulation 2 pieces of fibreglass to total 5 5 inches thick then sealed the pockets with a piece of polyethylene.

In cold humid or mixed climates the foam board thickness needs to be 2 thick to stop the condensation in the rim joist area. Use a box cutter to cut the insulation to length. We live in michigan and its cold now even without the snow. This is an effective method for air sealing this area while still being easy on the pocket book.

If the foam board is properly sealed additional fiberglass. The pockets between the joists were not insulated. Rim joists are above grade so it makes sense to insulate the joists to the same level as above grade walls. Quite often basement perimeter foundation walls are framed insulated and covered with 6mil poly to the underside of the floor joists and loosely stapled in place between these pockets.

Sealing and insulating rim joists. In better insulated situations these cavities are partially filled with high density foam or extruded foam pieces. On one side of my house where the joist runs parallel to the outside wall i insulated and put poly part way only but could not seal it because of a. Properly insulating and air sealing rim joists band joists takes patience so most builders simply stuff in some fiberglass and walk away.

Insulating rim joists pockets.