How To Insulate Floor Joists In Basement

Cut the insulation to length using a square and sharp utility knife.

How to insulate floor joists in basement.

Use a box cutter to cut the insulation to length. Joist bays the open spaces between floor joists are prime hosts for insulation under specific circumstances. Insulating the space between the joists in a basement or crawlspace can help reduce your energy bills. The insulation should extend all the way down to the basement floor or at least to below the frost line the depth to which the ground freezes in winter.

4b slab floors built directly on the ground. 4d extend insulation into joist space to reduce air flows. If you have an unfinished basement you can properly insulate the rim joists in two or three hours. Properly insulating and air sealing rim joists band joists takes patience so most builders simply stuff in some fiberglass and walk away.

When insulating basement walls don t forget the band joist the piece of wood at the top of the wall that extends around the perimeter and encloses the ends of the floor joists. Department of energy recommends r 11 3 insulation under floors in warm climates and an r 25 6 to 8 in cold climates. Rigid foam is affordable. Fiberglass insulation batts or rolls are the most economical and easiest diy choice for insulating between the floor joist in a crawl space.

Here s how to insulate under a floor. Once the ceiling is buttoned up insulate the rim joist the floor framing around the perimeter of the house directly above the foundation wall. If you re ready to insulate the rim joists in your basement or crawlspace you have to decide between rigid foam and spray foam. If you need to insulate these rim joists it s best to hire a cellulose insulation contractor.

Also insulate 4a any portion of the floor in a room that is cantilevered beyond the exterior wall below. Two story homes usually have another ring of rim joists above the first floor ceiling.