I recently had some spray foam installed in the attic and the crew put it right up against the chimney pipe. Is this a concern? Should I carve out 2" and replace with something?

Pictures:http://m.imgur.com/a/OUz57 enter image description here enter image description here

It says 2" from combustible material. Is spray foam insulation combustible? And if I need to carve away the insulation, that means a insulation radiation shield? But won't that let in cold air to the attic?

UL sticker on chimney

  • 1
    Can you get us a closeup shot of that UL label on your chimney? Commented Dec 11, 2015 at 3:47
  • [IMG]i.imgur.com/f34dF94.jpg[/IMG]
    – Slobvrflw
    Commented Dec 11, 2015 at 19:08
  • 1
    Did you do this yourself? If a business did this in my state they would get fined out the ass.
    – DMoore
    Commented Dec 11, 2015 at 21:42
  • It was a local company. I will figure out a way to delicately inform them.
    – Slobvrflw
    Commented Dec 12, 2015 at 23:22

4 Answers 4


Yes, spray foam is combustible. What you have there is almost certainly a building code violation as well as violation of the spray foam manufacturer's installation instructions and as such you have a legal right to make the company you hired come back to fix it.

It's also a fire hazard. Sprayed polyurethane foam will start to burn at about 650 degrees Fahrenheit, which is within the range of a wood stove's chimney temperature. The only insulation that should be touching that flue pipe is something that's rated for high temperatures, like mineral wool, and even then only in accordance to the manufacturer's instructions.


That would depend on the pipe, and its required clearance to combustibles.

  • If it's 0" - no problem.
  • If it's 2" - get carving.

That label says 2" minimum clearance. So yes, you want to get rid of the spray foam near the pipe. Burning foam is nasty stuff.

You can then replace it with fire-proof insulation. Your local fireplace store should be able to sell you some. It looks like fiberglass and you can just stuff it all around it as needed.


Cut the foam away. Rock wool is the way to go. Look Roxul website, Canadian Co., Rock wool is a FIRE BARRIER. It stops fire.

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