I’m actually not sure – there might be, but IB keeps their formulation proprietary, so there is no way for me to know. I recommend you check out this article on environmental aspects of PVC roofing

Leo

Thanks
A.Hammer

Here’s how it works — day _and_ night, the roof is getting rid of heat by emitting it to the sky, so the roof can cool below the ambient outdoor temperature. If it cools below the “dew point” water condenses on the roofing, top and bottom, so you can get water condensing inside the attic as we did and dripping off the holddown screws.

It doesn’t have to be cold — the dewpoint in Minneapolis was 80 degrees last week. Explanation here:
http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=mpx&storyid=71067&source=0

We solved our problem (and could have avoided it if we’d done more research than our local roofers had done–this is new enough nobody understood it can be a problem with a new roof on an old house)

What you need is a sealed attic (no vents and no air leaks from the living space, so the attic always stays dry) or else a vapor barrier and insulation underneath the IB material, so humid air from either the living space or outdoors getting into the attic can’t get up against the bottom of the cool white roof where water condenses.

One example — this is routine for IB and others in areas where it gets really cold — would be a couple layers of isocyanate offset and taped.

What we found is that an old house leaks moist air from the living space; put a perfectly waterproof white IB “cool roof” onto the house, and you can get condensation even in mild climates and warm weather.

That’s dew point.

The IB is put on using screws through big round washers; those are underneath the next overlapping piece of the IB material.