I have a marble bathtub that weights around 2400lbs which I have calculated is about 42 cubic feet; capacity of 314 gallons of water (@8.3lbs=2600lbs).

The total weight of the bathtub with water and two people would be about 5300 lbs. The tub is approximately 20.10 square feet. The load per square foot is approx 259-264PSF.

The floor is concrete. The joists are 3x8x14 and they are sistered (doubled along their length) as well as with perpendicular supports in between (2x4s). The tub would sit on approximately 4 of these sistered joists (it has a width of approx 3ft).

I am unfamiliar with calculating the PSF supported by the beams.

Is this sufficient support for the bathtub?

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    "The joists are 3x8x14" 3X8X14 ? are you sure about the 3 ? Two 2x8x14 boards sistered together are pretty beefy, but i am not an engineer. – Alaska Man Jun 24 at 22:14
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    @Barry, Alaska Man was just asking a clarification question which is fine on this forum. In fact, he could answer the question with completely wrong information too. That's what the voting is for, if you don't like the answer you vote it down. Your comment recommending an engineering review is on-point... – Jimmy Fix-it Jun 24 at 22:54
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    @Barry You made a good point, i said nothing to contradict it. I was addressing my comment to the OP, I offered no advise, only a question and a comment. I do not need your approval or opinion on what i am qualified for. Expressing Your feelings about my comments are not necessary. ( it seems a bit like chest thumping ) There are some here with the structural expertise to inform the the OP as to whether or not it is good idea to pay for an engineer to explore the issue but they need as much pertinent info as they can get. – Alaska Man Jun 24 at 22:57
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    Arguably the tub weight is dead load and the water/people are live loads. And we don't know how long the beams are or where the tub is in relation to the beam supports. Mind you, even if the floor would support it, getting this more-than-a-metric-ton monster in place on the second floor seems ripe for disaster. – Ecnerwal Jun 25 at 3:34
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    Seems weird to have a concrete floor...with wood joists. – Huesmann Jun 25 at 15:26

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