Creating a 2x8 built-up deck beam joint spacing


Old 09-10-05, 09:31 AM
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Creating a 2x8 built-up deck beam joint spacing

I have 6x6 posts spaced approx. 5.5ft apart with a notched beam and post design with two 2x8s sitting in the notch. The deck design software at home depot apparently gave me 2x8x8 boards to build up the beam (will be a 40ft total length beam). However, since the 8ft boards do not span more than two posts and I have read that joints (on each beam) should be placed over the posts, I don't see how I can do that with the 8ft lengths without simply having a bunch of 5.5ft beam sections that span two posts since the 8ft length is not enough to span 3 posts to allow a staggered joint spacing on the built-up beam. If going with the 5.5ft beam, then each board joist will end at a post together but then there is no structural integregity in the sections joining at the posts. Am I missing something or should I go back to home depot and get longer boards or is having staggered spacing necessary?

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Old 09-10-05, 09:22 PM
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Location: Arlington, WA
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First, you need longer boards. With a 5-1/2' post spacing, use 20' boards so each 2X8 spans 3 posts. Stagger the joints.

Second, you really need to shop someplace other than the big orange box. They don't carry 20' boards, and 16's (the longest they have) won't span 3 posts.

And your joints in the beam HAVE to occur on a post.
Old 09-11-05, 07:18 AM
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Thanks for the reply

Thanks a lot for the advice. That is what I will do. I appreciate the time you take to answer these questions from DIY.

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