Paint finish on Kerdi - Tile Advice

[Liam D]

Hi All

Cheers for the advice on here so far my DIY bathroom build is moving well and the end is in sight.

I've used Kerdi board and there are parts of the board that will need painting - so not 100% tile coverage.

After some advice on here and from Schluter I'm going to run a layer of tile adhesive on any surfaces that need painting and then get a plasterer in to give it the plaster skim finish.

I'm thinking for adhesive layer of troweling on with a 4mm square notched trowel using my P9 mapei adhesive. I'm also thinking of leaving it combed so the ridges are in place for the plasterer. My thinking is (i) I know the combed surface will be uniform depth for the whole run... if i start trying to skim it, it will no doubt start to undulate (ii) the ridges from the trowel will give it a better surface for the plaster to adhere to.

That's my DIY thinking - what do you think? Am I missing something very obvious and will be causing problems for the plasterer? Would plastering over 4mm ridges work OK - maybe 3mm would be better?

Any pointers appreciated.

Cheers