11-16-13, 07:47 PM | #11 |
Apprentice EcoRenovator
Join Date: Nov 2013
Location: Moore Oklahoma
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Mastic is not designed for flue pipes, just ductwork. 250F is about has high as it's rated for, not sure what happens when you exceed that. It is EXCELLENT as sticking to just about anything that's clean.
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11-16-13, 09:19 PM | #12 |
Less usage=Cheaper bills
Join Date: Nov 2010
Location: Minneapolis, MN
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How elastomeric is mastic? Is it flexible if a joint moves or would it need to crack in order to yield to movement?
Seems foam isn't elastomeric at all either. I used it on a PVC plumbing penetration through a wood top plate in deep winter and when the pipe expanded and contracted over the season it separated. I had some remaining flexible silicone caulk from a different project so I covered the gap, not sure if will be permanently sealed or not. Either way even with it cracked, it still will be better than the fiberglass filled 1/2" gap it used to be. |
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