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Old 05-03-2012, 06:17 PM   #1
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16' joist span question.


If running 2x8 joist 16' and beams spanning about 4' and beams about 7' apart and a 2' cantilever. Rim joist and hangers at end. Where the joist crosses atop beams is toenailing sufficient or would you use like a hurricane strap to tie together? Is there much loss in structural integrity by running the joists in between beams using hangers at both connections to beams?
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Old 05-03-2012, 06:42 PM   #2
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16' joist span question.


it depends on what is on the end of the cantilever. weight put on the end of a cantilever wants to create uplift on the back span of the joist and reverse deflection of the joist. that's why the 2009 International Residential Code Section R502.3.3 states that "floor cantilever spans shall not exceed the nominal depth of the wood floor joist. Floor cantilevers constructed in accordance with Table R502.3.3(1) shall be permitted when supporting a light-framed bearing wall and roof only."

here is a link for the 2009 IRC http://publicecodes.citation.com/icod/irc/index.htm

check with your building official and find out what the provisions of your state building code require.

sure that's not the answer you were looking for but is the best course of action I can suggest
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Old 05-03-2012, 09:45 PM   #3
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16' joist span question.


Yeah I'm more concerned about the joists on top of beams compared to in between beams. Is it a matter of preference and job? Just a deck for above ground pool.
Tried getting in contact about codes but never get anywhere. We're just going to do piers and beams and make sure everything is beyond minimum spans, etc.
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Old 05-04-2012, 01:15 PM   #4
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16' joist span question.


Anyone else have input on joists resting on beams as opposed to in between beams? Thank you.

Mile
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Old 05-04-2012, 03:13 PM   #5
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16' joist span question.


Where I live it is permissible to place the joist over the beam or between the beams. If placed between the beams, generally a Simpson hanger is used on each end. If placed over the beam, the joist may be toenailed or may be attached to the beam using a hurricane clip. See Figure 6 of the 2006 International Residential Code for deck construction for diagrams. Your code may be different.
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Old 05-04-2012, 07:12 PM   #6
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16' joist span question.


If possible I like to have use drop beams (under the joists) instead of flush beams (flush to top and bottoms of joists).

The reason differs per job but as rule of thumb I like drop beams more.

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Old 05-05-2012, 12:07 AM   #7
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16' joist span question.


Here is the Deck Code that Daniel said: http://www.awc.org/Publications/DCA/DCA6/DCA6-09.pdf

Notice Fig. 1B and the commentary about flush beams not allowed on pp. 23 "Joists", and around "hangers" near fig. 6 (as per Daniel). The span tables are for beams/joists listed are for termination of joists, not where joists are on both sides of a beam. You need to check locally for spans then.

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Old 05-05-2012, 07:09 AM   #8
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16' joist span question.


toenailing joists down to a drooped beam is allowable if the deck is attached to the house at the other end of the joist. if it is a freestanding deck hurricane straps are required,at both beams. there is no difference structurally if you set joists onto a dropped beam or if you use correct size joist hangers and hang every joist between the beams.
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Old 05-05-2012, 08:50 AM   #9
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16' joist span question.


Hand drive, I agree there should be no difference structurally between a joist nailed or strapped to the top of the beam versus the joist flush attached to the beam using hangers. However, page 7 of the 2006 IRC code does NOT agree. Specifically, it states "joists shall not be attached to opposite sides of the same beam". I assume this is to minimize the chance of compromising beam strength by nails striking each other from opposite sides, so I suppose it would be OK if you offset the joists, but this is not very clear. Not always easy to understand the intent of code.
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Old 05-06-2012, 08:40 AM   #10
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16' joist span question.


Quote:
Originally Posted by Daniel Holzman View Post
Hand drive, I agree there should be no difference structurally between a joist nailed or strapped to the top of the beam versus the joist flush attached to the beam using hangers. However, page 7 of the 2006 IRC code does NOT agree. Specifically, it states "joists shall not be attached to opposite sides of the same beam". I assume this is to minimize the chance of compromising beam strength by nails striking each other from opposite sides, so I suppose it would be OK if you offset the joists, but this is not very clear. Not always easy to understand the intent of code.

Before I mentioned putting the joists on with hangers between the beams, what I meant was putting the joists in with joist hangers with a ledger attached at the house and a perimeter beam for the rest of the deck. of course this depends on which way ( in accordance with the house) the decking goes down on the deck. the joists could go parallel with the house with joist hangers nailed to double beams down the sides of the deck.

about attaching joists with hangers to both sides of a beam, I have done multiple decks with multiple girder beams breaking up the joist spans and we always did our hangers on both sides of the beam to hold up the joists. the girders are usually triple or quad beams built with the same size lumber as the joists and not just a double beam assembly. never had issues with inspections passing.
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