Art wrote:
I should have provided some additional info with my post:

The house is 10 years old and built by Toll Brothers. Generally speaking it
is sloppily built but the floors were at least well spec'd out. For
example, under the kitchen there are all double joists even though the span
is not particularly long. According to the blueprint the double joists are
"to support the cabinets". Thru out the house the joists are 10 inches
wide, 16 inches apart.



"Art" wrote in message
ink.net...
We are pulling out a Jacuzzi brand whirlpool and replacing it with a
Sanijet. According to Jacuzzi, they require floor strength of about 55
lbs per sq feet. Surprisingly, Sanijet wants 100 lbs per sq feet. I am
looking for ideas on strengthening the floor. I have access from
underneath. I plan on adding an additional piece of sheet rock on top and
screwing it to the joists. Sistering the joists would probably be
difficult because a portion of the floor is cantilevered but I could put
in a bunch of blocking between joists underneath the whirlpool if that
would help. Any suggestions would be appreciated.

Generally speaking (real general), you can cantilever up to 3x the joist
size for normal loading.

You mention the joists are doubled in the kitchen, and are vague on the
span. Are we to take it as you are putting the tub in the kitchen?



Anyways, try a span table for your loads.
http://www.southernpine.com/spantables.shtml