We are remodeling our master bathroom, which is home to a brick chimney (currently not in use). This chimney vents the fireplace in our living room, and we would eventually like to have it lined so that we can either burn wood in the fireplace or have it fitted for a gas insert. However, one side of the chimney forms part of the wall of the shower in the master bath. I have no idea what materials the previous owners used when they built the shower, but I want to make sure we use fire-rated materials in the remodel so that if we do eventually line the chimney for use with the fireplace, we don't burn the house down. Is there a waterproofing product that is recommended for this use? Or is cement board adequate? If not, does a poured-in-place liner provide adequate fireproofing even if the cement board/waterproofing/tile in the shower is not fireproof? Would appreciate your insight - thanks!
Acceptable cladding for chimney in bathroom?
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You could cement board, then add tile over the cement board. Just make sure to use non-combustible adhesive, or a good mortar. No issues with non-combustibles. A photo would be very helpful.
In a shower the cement board should be sealed before tiling with an elastomeric waterproofing membrane. At least that is what our tile person insisted on. I don't recall the product, but it was black and brushed or rolled on. Maybe this stuff? It should flex with the heating and cooling of the chimney.
https://www.nacproducts.com/subseal
Our shower tiles have been up for 16 yrs so I guess she knew what she was doing.
https://www.nacproducts.com/subseal
Our shower tiles have been up for 16 yrs so I guess she knew what she was doing.
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Yes, I plan to ask my tile installer to use Subseal or Redguard or another elastomeric membrane on top of cement board before tiling, but I was concerned about whether that membrane would create a fire hazard. I understand that cement board, tile and non-combustable mortar will be fine, but we have to have a waterproofing layer and I'm not finding any information about the combustability of these elastomeric products. The other option would be tar paper underneath the cement board, but apparently tar paper is quite flammable so I'm not sure it's suitable either.
Just make sure that when you line the chimney you use an insulated liner that gives you zero clearance to combustibles on the outside of the chimney and it won't be an issue. Chances are there are other combustibles that are to close as well.
Thank you! Just so I know what to ask about when I talk to the chimney guys, what are some recommended zero clearance liners? Is a flexible stainless liner acceptable if it is well-insulated?
An insulated, flexible stainless liner will qualify for 0 clearance and is preferable to a poured in liner. Ask for a quality, heavy-duty liner and don't get a 2-ply smooth-wall liner.
Some rigid double wall pre-insulated liner is also 0 clearance rated. Duraliner is one of them, I'm sure there are others.
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