[strath44]

it sometimes easier just to pull the whole lot off and start fresh. putting new tiles on top of repairs and cement can produce an uneven finish, having said that it doesn 't look too bad just at the base.

If you are fixing the floor a shower tray might be an easier more watertight solution than an wet floor which are prone to leaks and dirty grout lines. Also if there is any movement in the sub floor then a tray will allow some flex especially when its sealed to the base row of tiles by silicon.

Go for as big tiles as possible in this environment as they are easier to clean and again if they are continually wet there is less grout to go off colour. i like 300x600mm tiles they are big but not too bad to work with.

There are some good new grouts out there that have almost resin based properties and set very hard and resist water well. There are even some premixed ones that are good now for grout but just be careful they can be tricky to clean off the tiles if left too long. Avoid ready mixed tubs of tile adhesive at all costs they generally perform badly under shower room conditions, seen a lot of loose tiles with ready mixed tubs of adhesive.