Shower niche off center

[dbtarz]

I have made a custom shower niche and its to the point where I have applied red guard to it. I'm getting ready to tile and found that its off center about an inch. I was wondering if I could mortar enough tiles back to back and apply to the side of the niche to decrease its with by 1" thus making it centered.

[jadnashua]

I think I'd rather attach a couple of layers of 1/2" cbu, tape then add Redgard over it - this will provide less material that can absorb moisture.

But, before I did anything, I'd check how the tile layout will end up so that I didn't have any slivers of cuts around the niche - that may be more obnoxious than being off-center a bit.