# Insulation around Exhaust Pipe

**URL:** <https://forum.nachi.org/t/insulation-around-exhaust-pipe/5096>\
**Category:** Plumbing Inspections\
**Created:** [June 17, 2006, 2:53pm UTC](https://forum.nachi.org/t/insulation-around-exhaust-pipe/5096 "2006-06-17T14:53:11Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![rchewning](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rchewning/32/2127_2.png) [@rchewning](https://forum.nachi.org/u/rchewning)\
**Post date:** [June 17, 2006, 2:53pm UTC](https://forum.nachi.org/t/insulation-around-exhaust-pipe/5096/1 "2006-06-17T14:53:11Z")

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I can’t find anything specific about blown insulation around the exhaust piping as seen from the attic. I figure that the insulation should be removed since 1) it could be considered a fire hazard and 2) when it does get cold here, the insulation will become damp from condensation… Any suggestions?

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**Author:** ![jfunderburk](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jfunderburk/32/187920_2.png) [@jfunderburk](https://forum.nachi.org/u/jfunderburk)\
**Post date:** [June 17, 2006, 2:59pm UTC](https://forum.nachi.org/t/insulation-around-exhaust-pipe/5096/2 "2006-06-17T14:59:15Z")

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If it’s combustible (cellulose), it should be no closer than the manufacturer’s recommendations (1 inch for a B-vent). If it’s fiberglass, I don’t see a problem.

If you’ve got wet insulation in an attic, that seems like a problem all by itself. Nevertheless, I doubt it would not be wet around a hot pipe.

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**Author:** ![rchewning](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rchewning/32/2127_2.png) [@rchewning](https://forum.nachi.org/u/rchewning)\
**Post date:** [June 17, 2006, 9:55pm UTC](https://forum.nachi.org/t/insulation-around-exhaust-pipe/5096/3 "2006-06-17T21:55:54Z")

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It’s fiberglass… Just didn’t look right… I’ll have to add a comment about “Manufacturers Specs”… I couldn’t upload a photo cuz it was too big… Thanks Joe! I’ve seen water stains at the drywall around the exhaust on a few houses, with no stains at the roof cut… I thought condensation on the metal “plate” at the drywall cut was a good explaination…

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**Author:** ![cbuell](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/cbuell/32/1773_2.png) [@cbuell](https://forum.nachi.org/u/cbuell)\
**Post date:** [June 17, 2006, 11:45pm UTC](https://forum.nachi.org/t/insulation-around-exhaust-pipe/5096/4 "2006-06-17T23:45:53Z")

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I have called both Dura-vent and Amerivent and they both require 1" clearance of all materials whether combustible or not. What they say is that non-combustible materials can “conduct” heat to combustible materials and therefore should be kept away from the pipe. I know that sometimes it says right on the pipe “1 inch to combustibles” but some of the manufacturers say “1 inch clearance”. Confusing I know. Perhaps they should say “1 inch to conductibles”😃

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**Author:** ![jfunderburk](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jfunderburk/32/187920_2.png) [@jfunderburk](https://forum.nachi.org/u/jfunderburk)\
**Post date:** [June 18, 2006, 1:01pm UTC](https://forum.nachi.org/t/insulation-around-exhaust-pipe/5096/5 "2006-06-18T13:01:51Z")

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Duravent quote from their website–B-vent installation instructions: “Where pipe passes through the roof, maintain 1-inch minimum clearance to all combustibles.”

By your reasoning Charles, you can’t use metal straps to support the flue because the straps are nailed to wood on the other end.