Building a Corner Heat Shield with Cement Board over Uneven Drywall

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yooperkb

New Member
Aug 13, 2022
5
Michigan
Hi everyone - I am building a heat shield for my corner-installed stove. I would like to use cement board floating 1" from the wall (and of course 1" from the floor and 3" from the ceiling) and tile over the board. However, the drywall in my house is not a flat surface. Heck, there's not one straight or square surface in this old house at all. So my question is how would I install the cement board to correct for any wonky surfaces? I was thinking of using metal or plastic washers to build up length on the ceramic spacers in places that the wall dips in, and I see that they make high-temp washers, but they are expensive and I was wondering if regular metal washers would do the trick, or if that would be unsafe? Does this even make sense? Thanks in advance for your advice!
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,483
South Puget Sound, WA
Regular, cheap, metal washers would work. As an alternative you could use 3/8" or 1/2" tubing and cut spacers to the desired length. Another option would be to make firring strips out of the 1/2" cement board. Cut them 3" wide by 3' or 5' long and double them up to make the 1" spacer. These are attached vertically to the studs. The first layer can be shimmed so that the second layer of firring is plumb.