Tiling over internal window sill in bathroom

[JohnnyF]

Hi,

We had our bathroom refitted about 3 years ago and retiled. There is an internal window sill above the bath. The shower is over the bath so when people shower the water gathers on the window sill.

The grout has gone mouldy in places and looks pretty unsightly so i started to rake out the grout. However, some of the tiles became loose. So I stripped all the tiles of the window sill and removed the tile adhesive which was pretty damp to touch so I guess the water has been seeping through.

The tiles were stuck on to a wooden window sill.

My question is - how am i best to protect this wooden sill from getting rotten? Should I just paint some UPVA solution over it and then apply the tile adhesive and retile? Or is there some other product I should use?

My second question is - we also have the grout going slightly reddish in places where the shower is. I don't want to have to rake out the entire grout has some of it is still clean white. Am I ok to just regrout in patches or does this look unsightly Or could I just use some of the grout paint you get at B&Q or is this tacky?

Thanks in advance

 

[Diyisfun]

Use waterproof adhesive & waterproof grout, as you only have a few tiles to relay you might as well get adhesive & grout ready mixed. Ensure sill is dry, seal it with pva should be ok.

 

[sticky]

Do not use pva.....it breaks down in water and will lead to tile failure.
Waterproof adhesive is not waterproof it is only water resistant.
What you need is a waterproof membrane behind tiles,try looking at Bal tanking systems on their website,it will also tell you to use an acrylic based primer..
Id advise ripping all tiles off and doing the lot again,properly..seems
expensive but imho the only cure..