Does the code allow for an attic sealed with Icynene?
The 2006 edition of the International Residential Code specifically addresses using the unvented/conditioned crawlspace and attic designs. Sections R408.3-408.7 address unvented crawlspaces, and Section R806.4 deals with the conditioned attic. An important detail of the unvented attic is addressed in paragraph 2:
"An air-impermeable insulation is applied in direct contact
to the underside/interior of the structural roof deck.
Air-impermeable shall be defined by ASTM E 283."
Icynene is the only
insulation material that meets the air barrier requirement as specified by ASTM E 283, and is therefor the only
insulation material that can be applied to the underside of a roof deck and pass code. This chart
compares the ASTM E 283 air permeance of 9 different, commonly available spray foams.
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