The roof on our building is constructed as follows: structural steel framing, metal roof deck, vapor barrier, rigid insulation, ventilated nail base insulation panel (a pre-fabricated unit of OSB on top of intermittent wood blocking on top of rigid insulation), ice & water shield, and asphalt shingles.
IEQc4.4 credit information states the requirements apply to products "inside the weatherproofing system". Weather consists of both water and temperature. The OSB is inside the water protection system (shingles) but outside the the thermal protection system (rigid insulation). It would seemingly best be categorized as part of the weatherproofing system, not inside or outside it.
So the question is: Does the OSB from the ventilated nail base insulation panel needs to be included in the documentation for IEQc4.4.
Josh Jacobs
Technical Information & Public Affairs ManagerUL Environment
515 thumbs up
June 12, 2012 - 10:22 am
Normally the vapor barrier is viewed as the weatherproofing. So the OSB that is inside it would need to meet the criteria to get the credit. The concern is finding products that meet the requirements.