Best Insulation Between Floor Joists

First insulation will be going between the floor joist i only filled gaps with foam.

Best insulation between floor joists. Fill the ends of joist bays with rectangles cut from rigid board insulation. The insulation should press right up against the floor between joists. We chose 2 in thick r 10 extruded polystyrene don t use expanded polystyrene which is a less effective air and moisture barrier. Use caulk or foam sealant to seal the joint between the top.

It is moisture and mold susceptible though. Rigid foam is the best insulation for rim 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. 4b slab floors built directly on the ground.

Second i have foundation vent all around the house should the remain unblock or do the need to be covered. Fiberglass insulation batts or rolls are the most economical and easiest diy choice for insulating between the floor joist in a crawl space. 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. Installing this type of insulation is an inexpensive and diy friendly project since the materials are designed to fit into the standard width between wall studs attic rafters and floor joists.

Joist bays the open spaces between floor joists are prime hosts for insulation under specific circumstances. Use foam sealant such as great stuff to seal the joints. Also insulate 4a any portion of the floor in a room that is cantilevered beyond the exterior wall below. You can insulate second floor rim joists following the same steps shown here if you happen to tear out a ceiling during remodeling.

4d extend insulation into joist space to reduce air flows. 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. Fiberglass rolls can be placed between joists but the fiberglass itself will need to be cut to fit properly between joists. It will improve the sound absorption between floors and walls if it isn t compressed.

Department of energy recommends r 11 3 insulation under floors in warm climates and an r 25 6 to 8 in cold climates. 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. When the basement or crawl space has vents installed insulating joist bays.