Insulation 9 Inch Cavity Between Foundation And Parallel Floor Joist

This space can measure anywhere from 3 to just 1 inch high.

Insulation 9 inch cavity between foundation and parallel floor joist.

Standard fiberglass batts have r values ranging from r 2 9 to r 3 8 for every inch of thickness but high density insulation batts can have r values as high as r 4 3 per inch. The insulation should press right up against the floor between joists. Friction fit insulation between and parallel to the floor joistframing. With a 2x10 bay and a nominal inch of closed cell on the subfloor you have about 8 25 of space between the foamed subfloor and bottom side sheathing.

To insulate the floor mr. Better r inch at the compressed density but fewer. Foam board insulation is one of the. Mike put two layers of r 13 unfaced fiberglass batts in the joist cavities ran a 3 4 in.

The cavities between the floor joists over top of the foundation has been a difficult area to deal with in the building envelope since modern insulation and air vapour has been used in basements. This leaves a 15 inch cavity between joists. The instinct is to fill it all with insulation but this makes the ends of the joists even colder and not totally protected from moisture. The air space above the 9 1 2 inch insulation in the 12 inch joist cavity will help provide a warm floor inside the cabin.

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. 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. Gaps between the insulation and the floor can. This application meets the thermal performance requirements for new construction in the 2009 2012 international energy conservation codes for climate zones 1 2 3 and 4.

Compressing a standard density 9 25 r30 batt in there would be the cheapest and may be the right option and would perform at about r28. It will provide additional insulating value for not too much more than what would be invested in the r30 insulation. Layer of cellofoam foil faced rigid insulation over the bottoms of the joists then covered the insulation with 1 2 in. Designed for easy handling and use between framing such as studs and joists making it among the best insulation for walls.

Alternatively you could fill the cavity completely using r 38 faced batt insulation. Crawlspace insulation 2 layers in bottom of floor joist installation instructions. Fiberglass rolls can be placed between joists but the fiberglass itself will need to be cut to fit properly between joists. Oriented strand board osb to keep out.

Ensure insulation extends to the outside edge of each joist bay and is in contact with blocking or rim band joist. The technical answer to your question may differ from what is normally seen or done in many homes.