Basement Rim Joist Insulation
Insulating the rim joist or band joist area with fiberglass insulation is no longer recommended by building professionals and does not meet current building codes for air sealing.
Basement rim joist insulation. Alternatively the application of a spray foam usually done by a contractor can provide good insulation and air sealing. Class i e 84 fire retardant meets building code spec. Fiberglass insulation and expanding foam seal the open top of hollow concrete blocks. Pros and cons foam boards are rigid panels of insulation with the most common types of materials used in making them including polystyrene polyisocyanurate and polyurethane according to the u s.
This method is no longer recognized as best practice. How to finish a basement wall. The rim joist is located above grade and for many years we treated it similar to the wall insulation above by stuffing fiberglass batt insulation in the rim joist bays. Spray foam insulation that s convenient and easy to use.
Best practice for rim joist and sill plate is to seal all cracks against air leakage and then insulate the area. Foam boards can be used to insulate any part of the home from the roof to the basement walls. Airtight insulation reduces heat loss through the rim joist band joist. Spray foam does a great job not only insulating the rim joist but it also seals all the possible air infiltration points.
However spray foam insulationcomes at a serious price point and it is best left to professional installation. Rim joist foam board insulation. Spray foam insulation is the best way to insulate a rim joist in my opinion. R value of 7 in 1 inch 97 closed cell foam.
Because fiberglass easily allows air to travel through it is a very poor choice for insulating the drafty rim joist area. If you re ready to insulate the rim joists in your basement or crawlspace you have to decide between rigid foam and spray foam. Rim joist insulation install rigid foam pieces carefully sealing edges and around pipes wires and vents to prevent moisture from damaging wood framing.