I rent the spa-in-a-box (as a business) and it's weight load is 80 lbs. per square foot. Don't know if it helps to think of it like that. Anyway, there have been lots of threads here about this same issue and people always say to set the tub up in the corner of the room. Of course, if you have the option to put it on the first floor then that might make you more comfortable, but if there's a basement under there I don't see any difference.