water joint compound?

[Richb]

10 years ago I re-did my bathroom shower. I re-sheet rocked it with cement board, then tiled it. My plumber at the time got me some sort of joint compound that was I think acrylic based. I am re-doing another bathroom and am no longer in contact with that plumber. Does anyone have any idea what to use to fill in the joints of the cement board. Thanks in advance all your help!

Rich

[RicodJour]

You shouldn't use joint compound. A typical installation would embed the mesh tape in latex-modified thinset and then set the tile in the same stuff. Some would coat all of the walls in a brush-on waterproofing like Redguard.

R