Woodstove pipe wall insulation

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.


Mar 13, 2017
Edinboro, Pa
Greetings all!
Finishing up reconstruction of a fireplace backdrop at my camp, the situation neverr bothered my father but I felt the former situation was more than a bit of a fire hazard. Prior platform was simply tile on drywall and back corners of a small Timberline woodstove were only 6" from the wall.
Tore everything out to studs and installed 1/2" hardibacker cement board to walls and replaced tile, stove platform extended significantly to provide much more clearance. Entire wall is now tiled and non combustable but i am looking for input on whether I handled the chimney nipple adequately.
Didn't take pics of the tear out but found that the only shield at the cast iron chimney nipple within the wall was some kind of 1950s asbestos like mache that was packed over the top of the nipple with wood studs nearby. Was masked up but tried to quit breathing as the stuff fell apart.
Elected to shield the nipple with a fabricated box of hardibacker board mortared into place.
Is there any need or merit to packing the nipple cavity with ceramic fiber loose chimney pipe insulation prior to hooking up the stovepipe?
Studs near chimney nipple are 2x4s for reference.
Any input appreciated.
Thanks, RSliker

IMG_2477.jpeg IMG_2460.jpeg IMG_2452.jpeg stove1.jpg


Staff member
Nov 18, 2005
South Puget Sound, WA
The wall thimble doesn't look like it meets NFPA requirement of at least 12" clearance from the surrounding studs. It looks like it will need an insulated thimble here.

Wall Thimble.png
Last edited:


Staff member
You’ll want to use an insulated thimble inside a combustible wall.



Chimney sweep
Staff member
Jan 14, 2014
central pa
You also didn't gain any reduction in clearance from the wall the way you did the tile