We are having my mothers tub turned into a shower, the guy has done a super job but the walk through has tile going up and on top but the top piece has the tile over hanging on each side quite a bit... I am worried to have the tile hanging free, also I think it would build mildrew as well as a place to trip. He said he has always done this and it is the way it should be done, I have never seen where tile has nothing under it by at least 1.5 inches or move hanging in mid air. Is this right?

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He has been doing it wrong for quite some time. Most of us keep the top edge flush by using a bullnose tile. You are correct and he is not.

The guy should have installed bullnose tile like Ballengerb1 suggested or should have installed a marble or granite threshold. Tile overhanging the edge like you suggest will be a problem down the road!

Good luck!