Q about installing Wonderboard (concrete backer board)

[zxcvbob]

When two pieces of backer board meet at an inside corner, do I leave a little gap, fill it with thinset, then embed a strip of fiberglass tape like I would a wall seam? Or do I *not* use the tape, and (knowing it will eventually crack down the center of the joint) use caulk instead of grout where the tiles meet in the corner? Maybe I'm supposed to tape the corners

*and* use caulk instead of grout?

Thanks, Bob

[Rich]

Use the tape like its a drywall joint, put the tape on then imbed with a nice coat of thinset press it into the corner so it keys the two pieces together good when it sets. Just don't build up the corner thickness to much because the tiles will not sit right.

Rich

[RicodJour]

I thinset/tape the backer board corner, and color-matched caulk the inside tile corner. Belt and suspenders.

R

[krw]

That's always been my plan as well. Try to fix the backer board in place, but allow the two surfaces to move in case it didn't work. ;-)

It's amazing how close the color matched caulk is to the color of the grout.