"Wayne Whitney" wrote in message
...
On 2007-07-13, BobK207 wrote:

On Jul 12, 8:37 pm, "Art" wrote:

Here is the new information. The portion of the floor with the tub
is cantilevered out 2 feet. That means that some of the tub will
be sitting on the sill plate.

Is the tub centered or nearly centered over the wall below? If so,
almost all the weight will be carried by the wall, and you need only
concern yourself with whether that wall is strong enough. Your 2x10
joists will be strong/stiff enough to carry the tub load to the wall.
[Imagine cutting through the joists at the edge of the tub over the 6'
span; the joists just have to be able to carry the weight back to the
wall as a cantilever on either side of the wall.] Sounds reasonable,
Bob?

since deflection goes as span^3 the 2 ft cantilever section is
actually stiffer than the 6 ft span section.

Hmm, that's not really true, is it? A unit point load at the end of
the 2' cantilever will induce a moment at the support of 2 ft-lbs. A
unit point load at the middle of the 6' span will induce a moment
there of 1.5 ft-lbs.

Cheers, Wayne

The position of the tub with respect to the sill plate certainly is key and
I should have included that in my original post:

The portion of the bottom of the tub that holds water is 29 inches wide.
Towards the top the tub widens to 44 inches wide plus figure a 5 inch
surround. So the heavy part of the tub starts 12 inches from the inside
wall which is 4 inches thick. So the heavy part of the tub starts 17 inches
inside from the cantilever joists. So 7 inches of the tub is cantilevered,
6 inches are sitting on joists directly above the sill plate (which is on a
concrete foundation wall), and 16 inches are on the other side of the sill
plate putting its weight on the joists that lead to the rim joist that
connects to a long joist which is part of the main floor system.