I have heard Roxul is safe and non-combustible, I need to wrap something around the vertical hot water tank piping leading up to the attic. This pipe can be seen in the basement ceiling and there is space around this pipe I want to use two layers of Roxul material to wrap around.

Could this become a fire hazard somehow by trapping the heat and causing nearby wood to ignite?

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  • What type of exhaust pipe is it? In general, Roxul is used to isolate hot exhaust from flammable surfaces. It is fireproof and does not transmit heat well, but that said, some types of pipe require minimum clearances.. Jul 31, 2016 at 19:31

2 Answers 2


No. As you seem to be aware, Roxul is a mineral wool product, and mineral wool is fireproof. You're right that it will "trap the heat" but this is exactly what you want and the result will be less heat transmitted to the surrounding wood, not more. Mineral wool is actually one of the few materials you can safely use for filling these kinds of spaces. Proceed with confidence.


100% you WILL start a fire. You'll be trapping heat to the point that it dries the wood and creates a "kindling" situation where a fire will start with the slightest bit of heat.

  • 1
    Could you expand on this some? What will the OP be turning into "kindling"?
    – FreeMan
    Dec 14, 2020 at 11:32
  • How would this heat the wood more? Dec 14, 2020 at 12:44

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