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 between floor joists.
First insulation will be going between the floor joist i only filled gaps with foam.
The insulation should press right up against the floor between joists.
Use caulk or foam sealant to seal the joint between the top.
Use foam sealant such as great stuff to seal the joints.
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.
Joist bays the open spaces between floor joists are prime hosts for insulation under specific circumstances.
Also insulate 4a any portion of the floor in a room that is cantilevered beyond the exterior wall below.
It is moisture and mold susceptible though.
Gaps between the insulation and the floor can.
It will improve the sound absorption between floors and walls if it isn t compressed.
Fiberglass insulation batts or rolls are the most economical and easiest diy choice for insulating between the floor joist in a crawl space.
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.
Rigid foam is the best insulation for rim joists.
You can insulate second floor rim joists following the same steps shown here if you happen to tear out a ceiling during remodeling.
4b slab floors built directly on the ground.
Fill the ends of joist bays with rectangles cut from rigid board insulation.
When the basement or crawl space has vents installed insulating joist bays.
Clarification for march 23rd e mail.
We chose 2 in thick r 10 extruded polystyrene don t use expanded polystyrene which is a less effective air and moisture barrier.
4c as an alternative to floor insulation foundation walls of unvented crawl spaces.
Department of energy recommends r 11 3 insulation under floors in warm climates and an r 25 6 to 8 in cold climates.
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.