Whilst theoretically you could use these tiles for the shower floor, the issue would be that you would have to lift them up from time to time to clean underneath them. The other issue is the wood species that is used on the tiles. You really need to use a very durable wood species that will not rot or absorb water especially in a bathroom situation because otherwise you will be facing problems with mold and mildew all the time. The best species to use would normally be Ipe wood tiles e.g. from handydeck.com . But basically I wouldn't normally recommend using wood tiles for a bathroom floor unless it was a very light room with sunlight and dried out very quickly.