can I install 18x18 ceramic tiles in a shower ceiling?

Yes, they are done same as the floor, but they are very heavy and will need to be supported until mortar or adhesive sets. Can you use smaller tiles?

Jazman?? Why inaccurate?

The size of the tiles has nothing to do will whether it's going to stick or fall off. The area the adhesive covers is directly increased in exact proportion as the tile size increases. So, a large tile will stick just as good as the same tile in a smaller size.

The only real matter is the weight per sq. ft. of the tiles, not the entire weight of the unit. I haven't seen any tile that is too heavy for this installation as long as the thinset is mixed and applied correctly. The tiles can actually stick better to a ceiling than on the walls. They're likely to sag on the wall and is why you need a ledger board.

Jaz

Jazman, I understand what you are saying, but Brian's advice to support large tiles is common advice on the internet for years now!

The fact is that homeowners aren't tile guys and they may NOT necessarily mix and apply the thinset mortar correctly so his advise to support the larger tiles is actually "BANG ON" in a way.

Had you simply shared your thoughts from the start I think Peter could have at least made a decision based on both suggestions!

I agree that support isn't needed, but I also know that when one of the larger tiles drop off (and even small tiles) the damage done to the tubs and floor tiles underneath can be absolutely catastrophic (up to and including tub replacement)!

Anyway, for future readers and DIY people, you don't need to support larger tiles, but you better be darn sure you have some experience tiling before you go trying to install 24"x24" tiles above a tub... otherwise, at a minimum, cover both the tub platform and the floor in front of the tub with plywood...just in case, OK?

That's my thoughts guys!

Mark

Spelling error above (couldn't correct in time): Advise = advice