Loads for a 2x8?

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Old 06-21-06, 04:20 PM
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Question Loads for a 2x8?

Dose anyone know how I can find out what the load a 2x8 can carry? I have a whirlpool tub going in over some 2x8's on a 12 foot span. The tub filled with water weighs approx. 750 lbs. or 54 lbs per sq ft. Would like to know if I'm ok or in trouble.
 
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Old 06-21-06, 05:14 PM
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OK, you have some number of 2x8's on a 12' span. I would say that you have a problem.

Your calculation shows nearly 14 sq. ft. of footprint for that whirlpool tub. Let's say it's 5'x3' dimensionally. That load is too concentrated for a 12' span supported only at the ends. The 2x8 material will eventually deflect, particularly when a 200# person gets into the tub. Now you are nearly at 1/2 ton center loading a 12' span. Looks risky to me.
 
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Old 06-21-06, 05:44 PM
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Sorry, and thank you for your reply. the 2x8's are running the long way in a 5x8 bathroom The tub is a 32"x60" whirlpool. There are 5-2x8's. Hopefully this helps my situation?
 
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Old 06-21-06, 08:21 PM
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OK, it's a 5x8 bathroom. Where's that 12' span located? A bit more information please. The floor of the bathroom is
a) concrete
b) wood
c) located on the second floor of a house

The tub containing only water is 54 #/square foot. With a 200# adult in it, that's 67 #/square foot.
If you perform a Google search for 'span tables' you will see that the greatest span in this load range is about 8-10' spaced 12" O.C.

This load concentration would require some type of pier or pad beneath the floor with posts/beams supporting the floor from below.
 
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Old 06-28-06, 02:49 PM
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Not enough info!

As stated, 12' is too long a span for 2x8's. However, if the 2x8's are supported at mid-length with a girder (4x6 or 4x8) then it should be OK.

Also, the location of the tub makes a difference. Is it located near one end of the 2x8 joists. Judging by your statement that there are 5 joists supporting the tub then I would guess that the tub is adjacent to one of the support walls and parallel to it.

In order to determine what will work, a lot more info is needed than you've given so far. That's why Architects and Structural Engineers are so often recommended to look at these problems.

-Joe
 
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