dehumidifier time? Advice and information on tiling and fixing tiles to a variety of surfaces

[Edewakefield]

Hi folks,
Many thanks in advance for any advice anyone can give.

My little dilemma is that I believe I have damp in the bathroom walls behind the tiles. I thought I had dried out the walls sufficiently before tiling the bathroom.
I have concluded that using a dehumidifier would get the damp out and then I could treat the mould that has appeared in the grout. This has shown very badly in the bottom 18 inches of the shower tray in the shower end of that bathroom.The bathroom is a single story air cavity extension. Nine foot by five foot.
My questions are

a. What size dehumidifier would you recommend to get the damp out of the walls? As powerful as possible? 10 litre or much bigger?

b. What type of grout would you recommend to re grout affected parts of the shower? I have used bal on the floor tiles which seems better than the wall grout.

Many thanks,

Ede

[stoneyboy]

Edewakefield,
It is unlikely that damp in the walls behind the tiles is causing this problem. Try replacing the grout in the lower half of the shower use either bal or mapei but not ready mixed grout.
end