LEED for Schools Credit 4.6 - question about roofing insulation

Hi Peggy,The people who focus on material contributions to IAQ are pretty adamant that anything inside the weather barrier communicates directly with indoor air (through gaps in the roof deck, for example), so I suspect that their intention WAS to include roofing insulation. If you put the insulation on top of the membrane, then it would clearly be outside the weather barrier. But I can certainly see how this could be a gray area, and would love to hear from others with experience or informed opinions...

Yes, Nadav this is exactly how I see it. Insulation is generally inside the weather barrier and therefore would need to be included in this credit. For our projects, insulation is usually the sticking point of this credit but there are products out there. Good luck! Shannon

The issue here seems to be that "ceiling" means something very different than "roofing," and USGBC was not sensitive to that in writing this credit.However, USGBC is very consistent with these credits that all materials within the weatherproofing barrier are covered, so unless the insulation is outside of that barrier, it must be considered part of the "ceiling system" and comply with the credit.Also, the credit language is more clear than the name of the credit. The language itself says "All gypsum board, insulation, acoustical ceiling systems and wall coverings installed in the building interior..." are covered. So again, interior means within the weather barrier.Plywood is covered under IEQc4.4, so hopefully teams would pursue that as well. The point about metal is fair but for better or worse, LEED tends to avoid going into such detail as to prescribe different requirements depending on the roofing deck used.

Has anyone had any luck identifying isocyanurate roofing insulation that meets the credit requirements? In certain areas of our project, there is no roofing membrane, and the isocyanurate is fastened directly to the steel deck. I am researching the available products on the market, but would love to hear if anyone else has found anything.

I tend to think of "interior systems" whatever is on the interior side of the air barrier, NOT the weather barrier. For instance in a roof, you have the membrane (weather barrier) on the exterior, then you have your rigid insulation and below this, you typically install an air barrier above a board resting on the metal deck. There is no way VOCs from insulation will pass through the air barrier (unless installed defectively). Therefore I would consider the rigid insulation NOT to be on the interior, therefore out of the scope for this credit. Same reasoning applies to rigid insulation in exterior cavity walls on the exterior side or air/vapor barrier. Sheathing, on the other hand, would have to be listed. Does anybody have reasons to agree/disagree with this?

I think you have hit on something, which is that these definitions are anything but simple to parse out. What about the weather-resistive barrier vs. the weather barrier vs. the air barrier? All the same thing, or different concepts?