Thread: Great Foam Insulation

Great foam insulation was used to seal the ceiling gap in the furnace closet around the vent firestop collar. I read on the can that it is not rated to be near combustible material. At this location, would you say that being located near and on the firestop collar is wrong?

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Originally Posted by John Stephenson

Great foam insulation was used to seal the ceiling gap in the furnace closet around the vent firestop collar. I read on the can that it is not rated to be near combustible material. At this location, would you say that being located near and on the firestop collar is wrong?

I think that you have already answered your question!

Yes you answered your own question

It is also a situation that I would notify the current resident or I would note in my report that the current resident should be notified.

Assuming (as there is no picture) that the collar was designed to be in contact with flammable material where it met a wall or ceiling, why would a bead of foam caulk - assuming (again) that it was a bead, and not an attempt to flood the junction and overflowing into or behind the collar - be a problem?

Yes, but what's the difference between Greatstuff and any other "combustible" material in contact with the collar? After all, it can be used for some fireblocking applications:


http://tinyurl.com/2hoy2e

Need to differentiate here.

If it is touching the vent pipe or encroaching in the stated clearances, it needs to be removed. If it is being used as "fireblocking" and is accepted by the local AHJ such as sealing stud bays, gaps in the fireblocking not near the vent components, I would say it is ok. If you tried to foam around a listed firestop assembly where it meets the ceiling or fireblocking, I would be concerned it oozes into the stated clearanc zone. Otherwise, I wouldn't lose too much sleep over it. Are they caulking the B-vent with it to the thimble/ ceiling firestop?

Another aspect is the mass. If you have a huge glob of foam, it will absorb much more heat than a thin cauling bead. For future reference, I would suggest they use high temp. silicone caulk for draft stopping near hot things.