I have a second story bathroom which I am renovating. I want to replace the existing tub (30x60) with a larger whirlpool tub (42x72). I am also moving the new tub to the outside wall (the old tub us on an inside wall). My joists are 16" on center, span appx. 11 feet and are 2x8. The joists are old (house built ca. 1900)and actually measure 2 inches by 8 inches (not the current nominal size). Generally speaking, will the current floor adequately support the tub/H20/2 adults/tub weight/etc. based on 50#/sf? The floor appears stiff (acceptable bounce test). Would it be advised to bolster the current joists or abandon the idea altogether. Any info you could provide would be appreciated.
Thanks
John

Unfortunately, since we cannot see all condtions which might affect your structure, we must decline to answer your question. I'm not sure that 50 lbs. per square foot is an adequate representation of the weight of a large whirlpool tunb full of water and occupants. You need to provide information from the tub manufacturer about the weight they recommend to design for, and you should have a qualified design professional, who can examine things on site, evaluate your structure for its ability to support the new load.