Beam size vs. post placement

Old 04-11-02, 06:44 AM
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Beam size vs. post placement

My deck will have a 26' beam set 14 ' from the house using 2X10 joists 12" O.C. It will have a 2' cantilever with a double bay design that works out better without a support post in the middle. So, if I have the outside posts 18" from the end, I could go with 4 posts at 7'8" apart. Will this work if I use a triple
2X12 for the beam and 4X6 posts?
Old 04-13-02, 11:15 AM
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Be sure to block the joists @ 7 feet to prevent sagging..

sounds solid plan to me.. might i reccomend you "laminate" the beam with 1/2 cdx plywood in between the 2xs .. plywood is much stiffer and the cost and time is low to make much stronger beams.

Hope this helps---josh
Old 04-14-02, 04:13 PM
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You are going to span 14' between your ledger and the only beam under this deck? Be prepared for it to sag, even with mid-span blocks. What I would do would be to use 2 beams -- one at 7' and the other at 14'. Use 2X8 joists. And why 12" O.C.? I would set them at 16", unless you plan on running the deck boards at a diagonal.
Old 04-15-02, 06:30 AM
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I'll go with five posts afterall

The problem with only four posts on a 26` beam is when you try lap the lumber, alternating the seams. If the posts are almost eight feet apart, and you have a foot or more overhang on each end, and you are working with lumber that comes in 16' max length…. Well, it won't work. Going with five posts is the answer. As to why the 12 O.C, yes the deck boards will be diagonal. My neighbor has a similar deck with 2X10 joists, 12'O.C. with a 14' span, and he doesn't have bounce or sag after three years

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