Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls.
Roof deck foam insulation.
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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.
This measure will convert a vented attic to a nonvented attic.
Generally more insulation is needed for condensation control in colder climates.
The spray foam can also serve as the thermal and vapor control layers in both new and retrofit construction.
Also the higher the indoor humidity the more insulation is needed to avoid condensation.
Insulate an attic in an existing home by installing spray foam open cell or closed cell on the underside of the roof deck.
Inspect the existing roof shingles or roofing membrane for any deficiencies.
Spray foam insulation applied on the underside of the roof deck in cold climate commercial buildings allows for a significant reduction in condensation potential particularly compared to interior air permeable batt systems.
The installation steps are as follows.
As air impermeable insulation spray foam insulation can be used in such applications.
The ratio of insulation above the roof deck or air permeable insulation below the roof deck is a matter of climate and interior conditions.