Best Insulation For 2x8 Floor Joists

Gaps between the insulation and the floor can.

Best insulation for 2x8 floor joists.

Ground should be covered with a 6 mil polyethylene sheet. 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. Check between floor joists if vented and check perimeter walls if unvented. Fiberglass rolls can be placed between joists but the fiberglass itself will need to be cut to fit properly between joists.

Fiberglass insulation is usually the best option though handling fiberglass can be dangerous and it is not the most eco friendly option in some cases. The floor joists are all fastened to the rim joist which runs along the. 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. Exterior walls and floors.

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. The insulation should press right up against the floor between joists. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task. Turn off the electricity then remove an electrical outlet cover for a view of exterior insulation.

Insulation radiant and vapor barriers insulating 2x8 floor on 16 centers from what i m reading hamilton county tennessee only requires r19 for the floor but i can achieve r25 with 2x8 s. Trim pieces of fiberglass insulation using a utility knife so the pieces fit into joist bays along the rim joist. 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. When you are insulating two by four 2x4 and two by six 2x6 framed exterior walls and want to use fiberglass insulation what thickness is best the question becomes all more critical because of the permanent nature of wall assemblies and wall insulation.

Once the insulation is in the wall and sealed up with drywall it is not easy to change out.