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Harry S Posted: Apr 16, 2009 01:34 PM	Another Thermal Barrier Question Mason....we've got a job that's a "refurbish" and part of the overhead calls for 10" of open cell between the joists. It's already firred out for a drop ceiling (they're reusing the old acustical tiles)so there will be approx. another 10' air space from the foam to the tile. What do I do for a thermal barrier in a case like this? It's a city contract so I'm assuming the inspections will be done properly & timely. Thanks in advance
mason Posted: Apr 16, 2009 03:40 PM	That 10 inch air space is a problem and will allow enough air for the foam to be a fire hazard if not covered. Ask your code official what they would require. you would most likely need an thermal barrier over the foam. Although I have seen code officials determine that the space between the ceiling tile and the foam would be the equivalent of a crawl space or attic space. In that case an igntion barrier would suffice. (Code tested coating or 1-1/5 inches of mineral fiber over the foam. assuming the ceiling tile is the equivalent of a thermal barrier such as 1/2 gypsum board). If you need a thermal barrier, you could drywall over the foam or add a thermal barrier coating that would stick to the foam.

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Harry S

Posted: Apr 16, 2009 01:34 PM

Another Thermal Barrier Question

Mason....we've got a job that's a "refurbish" and part of the overhead calls for 10" of open cell between the joists. It's already firred out for a drop ceiling (they're reusing the old acustical tiles)so there will be approx. another 10' air space from the foam to the tile. What do I do for a thermal barrier in a case like this? It's a city contract so I'm assuming the inspections will be done properly & timely. Thanks in advance

mason

Posted: Apr 16, 2009 03:40 PM

That 10 inch air space is a problem and will allow enough air for the foam to be a fire hazard if not covered. Ask your code official what they would require.

you would most likely need an thermal barrier over the foam. Although I have seen code officials determine that the space between the ceiling tile and the foam would be the equivalent of a crawl space or attic space. In that case an igntion barrier would suffice. (Code tested coating or 1-1/5 inches of mineral fiber over the foam. assuming the ceiling tile is the equivalent of a thermal barrier such as 1/2 gypsum board).

If you need a thermal barrier, you could drywall over the foam or add a thermal barrier coating that would stick to the foam.

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