Tub surround, cement board to blue board.

[paintlady]

Hi everyone. The situation is this. Tub surround, wood stud, cement board then I transition to blue board for rest of bathroom. Now, have taped with fibre tape and mudded with thinset mortar. It is gritty, does not smooth out well. Have used Durabond 90 on all other blue board tape. Have the two muds meeting at one seam. Passed the Durabond over the mortar to level out at edge of tile line, is that OK? 1. Do I need to seal the Durabond with say, shellac to receive the tile glue? 2.Should the thinset mortar be applied all over the cement board or only at the seams?

[Davestone]

You're fine, just thinset the joints,i prefer unsanded to get a flatter finish,myself.No tile glue though..use thinset.

[John Bridge]

Hi Paintlady. Give us a first name.

You can't have joint compound on top where it's going to get wet all the time. Ideally, you would stop the thinset and commence the joint compound right where the shower door goes or just a little beyond.

On the backer board, you can use the tape as you tile. That way you won't have any bumps to go over.