I am in the process of installing a bath tub on my second floor. One of my friends has raised the issue of structural support for the weight of a bathtub full with one or two people in it. I would like a deep tub about 18" deep, other than that standard dimensions. Any ideas? Are we going to fall into my living room the first time we fill it up? Do we really need to do only a stand up shower? Our joists are 2"*8" Thanks for any help.