Thread: Foam on the Flue

The builder rep said the township requires them to do this. Type B vent for gas water heater.

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That appears to be fire caulk.

It was draft stop foam. Everything I have heard, learned, or read regarding flue pipes is that no foam or insulation (combustible or not) should ever be in contact with type B or single walled flue pipes. And I believe draft-stopping foam is considered combustible.

Nope that's wrong. And yes that's foam and no that's not high temp caulk.On occupied 2nd floor must be enclosed/separated. The foam goes to draft stop the enclosure not directly on the firestop and bvent. Insulated hot ring deteriorates "innards" right quick. On the stop/wood perhaps. The penetration stop isn't flat or installed correctly.Plenty of useful info and references towards the end of this recent thread: http://www.inspectionnews.net/home_i...fire-stop.html

Bob Harper could probably confirm this but the draft stop collar doesn't appear to be a listed stop. It looks like sheet metal that was cut and fabricated on the spot.

Both the firestop support and firestop spacer are wrong.

Collars are "decorative" and go ceiling side of firestop support.

Where is the appliance? first floor below or basement/crawl?

Basement.

Yep Nick, that's plain ol' site fabricated sheetmetal. There should be a listed 'firestop' at each floor or ceiling with 'fireblocking' per the IRC filling in the space around that. The listed firestop serves as a spacer to ensure clearance to combustibles, act as a lateral support/ spacer and to limit the migration of heat, smoke and gases in the event of an unfriendly fire. A mfr. of the vent or appliance may specify acceptable caulks or sealants but never foam. Even if you have a sealant that passed ASTM E-136, you still should not put a ring of foam at a point in proximity to combustibles because it will tend to create a hot spot. The problem with insulation is, it works. Insulation keeps hot things hot. We want air flow to cool the vent, hence the stated clearance to combustibles is always an air space. A thin bead of high temp. silicone is usually acceptable to the mfr. and AHJ and has an excellent performance record. I'm not aware of any fires caused by silicone caulk at firestops but I am aware of fires caused by foam and insulation.

Note: you should never caulk around a factory chimney at a listed firestop unless it is expressly approved with a prescribed material & method.

HTH,
bob