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Old 12-18-2011, 07:10 PM   #1
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2x8 span

will a true 2"X8" span a 16' area and have enough support for a floor at 12" centers


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Old 12-18-2011, 07:19 PM   #2
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Old 12-18-2011, 07:28 PM   #3
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Yep, a sleeping room or attic floor, of certain few species and "Select structural" grade, if under the IRC; http://publicecodes.citation.com/ico...002_par017.htm

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Old 12-18-2011, 07:57 PM   #4
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go here and check it youself.

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Old 12-27-2011, 02:20 PM   #5
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You would be much better off using 2x12s at 16" O.C. If you have to stick with 2x8s, I would use double 2x8s at 16" O.C.
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Old 12-28-2011, 07:41 AM   #6
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I can't speak for a 16 foot span, but I have several 13 foot spans (true 2x8) in my old house which are holding up well. Granted, the lumber may be a bit better quality than what is available today..........and after 100 years there is admittedly a bit of sag here and there.
That's just my opinion. But it's free, so take it for what it's worth to you.
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Old 12-28-2011, 06:51 PM   #7
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if im using 2x8's i space them 12"o.c.. ive seen new decks that had 2x8 joists with a 12' span and had quite a bit of bounce in them . not a good thing for a new deck

i strongly suggest switching to 12 " o.c and adding 2 or 3 rows of blocking to help stiffen it up
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Old 12-28-2011, 07:52 PM   #8
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All joists used in residential construction must be evaluated both for strength and deflection. Without detailed information about the load your joists are required to carry, which is TYPICALLY determined by code considerations, it is not possible to determine if your joists are adequately strong or adequately stiff. If you happen to have lumber which meets the specific criteria in your code book, you can evaluate the stiffness and strength for a given room type loading, however you stated that you have "true" dimension lumber, therefore you are not going to be able to use standard tables. Of course, if you are planning to construct without a permit, and not to code, then you can evaluate the adequacy of your joists any way you see fit, including taking advice from an internet chat forum.


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