Best Insulation For 2x8 Floor Joists

According to the 2012 irc the minimum r value for floor assemblies is r 13 in zones 1 and 2 r 19 in zones 3 and 4 r 30 in zones 5 and 6 and r 38 in zones 7 and 9.

Best insulation for 2x8 floor joists.

The insulation should press right up against the floor between joists. Fiberglass rolls can be placed between joists but the fiberglass itself will need to be cut to fit properly between joists. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task. 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.

It is moisture and mold susceptible though. If you want to insulate a floor assembly by leaving the joist bays empty and installing rigid foam on the underside of the joists here are a few things to keep in mind. The floor joists are all fastened to the rim joist which runs along the. Gaps between the insulation and the floor can.

Once the insulation is in the wall and sealed up with drywall it is not easy to change out. Check between floor joists if vented and check perimeter walls if unvented. Turn off the electricity then remove an electrical outlet cover for a view of exterior insulation. Fiberglass r 19 batt insulation is about 6 inches thick and is available in 15 inch widths making it the correct size for insulating a two by eight floor joist system.

Owens corning has a 23 x39 roll of pink unfaced insulation that fits between trusses joists or studs adds 6 1 4 thick of insulation with an r 19 value and an nrc rating of 1 05. Exterior walls and floors. 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. Trim pieces of fiberglass insulation using a utility knife so the pieces fit into joist bays along the rim joist.

Ground should be covered with a 6 mil polyethylene sheet.