I realize using 1/4” cement board for a tiled shower wall is a general no-no, but I’m trying to find a creative work around here.
I’m trying to build a tile enclosure for an existing shower pan in a basement bathroom. The existing shower pan is set against a block wall. The block wall is plumb in the upper half, but in the lower half it leans outward gradually. My plan was to furr out the lower half of the wall using tapcon screws to make it totally plumb for tile. Right above the shower pan flange will require a 5/8” furring strip. However, when I consider a 5/8” furring strip, 1/2” cement board, 1/8” thinset, and 5/16” thick 3x6” subway tile, my total distance from the block is 1-9/16”. The distance from the block wall to where the shower pan lip ends is also 1-9/16”. So it would be flush to where the pan lip ends, while there would be a 5/8” reveal of the shower pan lip on the other two walls of my alcove shower. So what I’m wondering is- do you think if I placed my furring strips closer together, say 8” apart, I would have enough rigidity to go down to 1/4” cement board on this block wall?