Second floor bath tub issues

I am in the midst of remodelling a second story bathroom and adding a 90 gallon bath tub with a granite deck. My contractor did not mention anything anything about reinformcing the floor. How can I be sure that the floor can hold the additional weight?

Thanks,
Liz

tub

You can't until you know the size of the joists under the floor, their spacing, and the span between supporting walls. Once you know all that then you can compute the load per square foot it will support and thus how much tub it can carry.

Bath tub floor joists

The joists are 2 x 8 with spacing of 16" and the tub will sit across the joists not parallel. The room is about 15 feet wide so I am assuming that is the length of the span. The tub is situated in a corner next to an exterior wall on the long axis and a wall next to the bedroom on the short axis. Directly under the tub on the exterier wall of the first floor is an 8 ft. sliding glass door.

I have not had the final inspection yet, but we added the granite deck after submitting the permit. Will that make a difference. I would like to have peace of mind when the remodel is finished.

Thanks for your help.

Liz

new measurements

The contractor tells me that the joists are 2x 10 with 16" spacing. Any help would be much appreciated.

Liz

floor support

your contractor is probably right not to be concerned, but "only" an engineer or architect can certify that he is. there is more to structural calculations than just floor joist size.

basic rule of thumb
2 x 10 at 16"o.c. normal span is 13' 6"
2 x 12 " " " " " " " " " " " " " 15'6"
this is for normal live load with no bearing wall on the span.
sounds like you need to double them up or install a header mid span below. maybe you will get lucky and an engineer will chime in, but they usually charge $350 to spec a beam.