Insulating Attic Roof Joists

This construction approach was first used in the 1970s and it has been implemented much more widely since it was first included in the international code council s icc model building code in 2007 irc section 806 4.

Insulating attic roof joists.

Box out light fixtures. The advantage of this approach is that the heat that is generated and circulated in the floors below is not lost through the attic floor into the rooms above. Closed cell spf is an effective thermal air moisture and vapor barrier. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be.

You ll be installing insulation on top of this drywall ceiling. Closed cell spray polyurethane foam spf is an excellent choice for insulating attics and rim joists. They have floor joists or the bottom chords of roof trusses with drywall below. Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls.

Unless you re using mineral wool insulation or your fixtures are rated safe for contact with any type of insulation don t allow the material to touch or cover recessed cans or lights from the floor below it s a fire hazard. Then blow another layer on top of the roof rafters. Insulating the floor and the roof this is certainly the most interesting solution when the attic is also going to be used. Typically you will fill the insulation blower with the insulation and blow it between the attic floor joists.