I have a raised brick hearth extension in front of my masonry fireplace. The hearth extension is raised about 10-1/2″ and is about 17″ deep. The hearth extension runs along an entire brick wall and is about 14′ long. The hearth extension has a brick ledge overhang on top of about 3/4″. I want to tile the entire hearth extension (top and front face) and want to eliminate the 3/4″ brick ledge overhang. Is it safe as far as heat output from the fireplace is concerned to “furr out” the front vertical face of the hearth extension using 3/4″ plywood? I plan to add cement backerboard on top of the plywood so that the brick ledge overhang will be buried behind the cement backerboard and then plan to tile on top of the cement backerboard.
Thanks for any help!
Replies
Just use the cement backer for the shim with thinset first to get flush to the brick lip. no good reason to encapsulate flamables there, and wood will move far more than the CMUs and will break the bond.
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Thanks. If I build out with just CMUs, I'd need three layers (with thinset between each one): 1/2" + 1/4" (to make flush with the 3/4" brick lip) and then another 1/2" layer to "bury" the brick lip. I thought the plywood method was easier. I've been looking at the building codes, but didn't see anything that would preclude using plywood on the vertical face of the hearth extension at that distance from the fireplace opening.
I thought that I wouldn't have a problem with attaching the CMU to plywood because it wouldn't be any different than attaching CMU to a plywood subfloor.
use 1/2" ccement board set in 3/16" notched tropel to seat at 1/8" and then butter another 1/8" over it.
1/2" plus 1/8" plus 1/8" equals 3/4"
see how easy that is?
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What are you going to do about the added height of the tile on the horizontal surface?
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