Best Insulation For 2x8 Floor Joists

Exterior walls and floors.

Best insulation for 2x8 floor joists.

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. 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. Turn off the electricity then remove an electrical outlet cover for a view of exterior insulation. The insulation should press right up against the floor between joists.

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

Ground should be covered with a 6 mil polyethylene sheet. 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. The floor joists are all fastened to the rim joist which runs along the. Fiberglass rolls can be placed between joists but the fiberglass itself will need to be cut to fit properly between joists.

Gaps between the insulation and the floor can. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task. Trim pieces of fiberglass insulation using a utility knife so the pieces fit into joist bays along the rim joist. 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.

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.