How To Install Insulation Against Roof To Make Attic Conditioned

If there is a desire to make that space conditioned to protect stored belongings if moving everything out to air seal and insulate at the attic floor would be a hassle and or if insulating at the attic floor would remove storage space then insulating at the roof line is a better option.

How to install insulation against roof to make attic conditioned.

The first layer should have the facing against the drywall to act as a vapor barrier. For this application the roof framing is typically truss construction with 2x4 or 2x6 truss top chords. The first layer will sit between the joists and the second layer will run perpendicular over the joists. In finished attic rooms with or without dormer insulate 2a between the studs of knee walls 2b between the studs and rafters of exterior walls and roof 2c and ceilings with cold spaces above.

If you want to install fiberglass between your rafters you have two basic choices. This allows you to install your bulkheads above the ceiling plane without the need for spray foam insulation. 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. An alternate to spray foam insulation in an unvented attic is plenum trusses which allow you create a reverse bulkhead above the ceiling plane that is insulated.

If you don t already have a ridge vent you ll have to do a bit of work to install one. Either include a ventilation channel between the top of the fiberglass insulation and the underside of the roof sheathing or install enough rigid foam above the roof sheathing to keep the roof sheathing above the dew point during the winter. You should install two layers of insulation in your attic. Foam insulation above the roof deck to keep its temperature above 45 f throughout the year or spray foam insulation under the roof deck to keep interior moist air from contacting it.

Box out light fixtures. Remove the existing ridge cap shingles. Wood joists must be covered to allow the air to move. 2d extend insulation into joist space to reduce air flows.

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. Senior engineer manager at icynene john broniek makes the case for the unvented attic assembly and why insulating the underside of the roof makes sense. When securing the batts to the roof deck it is critical that the batts be held firmly up against the roof with minimal compression of each batt and minimal gaps between batts. Experts usually advise builders that you can t install fiberglass insulation directly against the underside of roof sheathing.

Using a circular saw set to the appropriate depth rip a straight line along both sides of the ridge. Now that you have proper ventilation it s time to think about keeping the conditioned air in the conditioned space. Insulation is then installed up to the bottom of the roof deck. Closed cell spray foam can be used in any climate.