I have a windowsill in a shower which had regular 6" ceramic wall tiles over drywall.
Some water had obviously pooled on this, got under the joint at the lip of the tiles and rotted the drywall. So I removed the drywall, left it to dry for a month and now I have to repair it.
I have some waterproof, for bathrooms, grout some special bathroom grade drywall and the same tiles.
Is there anything else I can do to prevent it happening again?