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Bl19811
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# Posted: 21 Nov 2020 09:08am
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I am building a 24 x 32 cabin. Will I be able to run 2 x 8 ceiling joists the 24 foot span of cabin if I have a load bearing wall at 12 feet down entire length. Joists will be 16†OC. Or will I have to lab the joist? The roof rafters will be 2 x 8 16†OC.
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Nobadays
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# Posted: 21 Nov 2020 10:21am
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Here is a link to a span calculator. Span of ceiling joist will depend greatly on how you intend to use the space above the joist. If a sleeping loft are figured with a live load of 30/40psf and a dead load of 10psf. If it is a storage area, it can range from 20psf to 125psf dead load.
Use THIS calculator... then keep checking back as ICC is the code guru on here! He will give you the best advice!
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Aklogcabin
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# Posted: 21 Nov 2020 10:45am
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I would suggest going as wide as you can on both floor n roof joists. To reduce floor bounce and increase insulation and air flow in the lid. Good luck on your build
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Fanman
Member
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# Posted: 21 Nov 2020 05:10pm
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If you have a load bearing wall at 12' then you effectively have two sets of 12' joists. See what the span tables say.
For that matter, where can you get 24' long 2x8s anyway?
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NorthRick
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# Posted: 21 Nov 2020 07:57pm
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Quoting: Fanman For that matter, where can you get 24' long 2x8s anyway?
And, even if you can, what are the chances they will be straight?
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ICC
Member
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# Posted: 21 Nov 2020 08:03pm - Edited by: ICC
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The ceiling joists that rest on the center bearing wall must overlap a minimum of 3 inches, according to the IRC codebook, and be face nailed to each other with a minimum of three 10D nails. IRC chapter 5. Even if you do not have code inspections the general sizing rules should be followed in order to have a safe structure. And remember the code recommendations are the minimums. Don't be afraid to go the extra mile.
It is permissible to butt splice joists over the bearing wall with either a metal plate or a wood scab nailed over the butt splice to hold the two joists in alignment. A wood scab would need a minimum of three 10D nails face-nailed into each of the butted joist ends.
The overlap or splice should be laterally supported by solid blocking, the same size as the joists.
Code permissible floor live loads (LL) are 40 psf or 30 psf for sleeping areas, 10 psf for attic floors with NO storage, 20 psf for attics with limited storage. Most calculations use 10 psf for the dead load (DL).
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