How to deal with a beam with a bow....

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Old 10-21-15, 08:35 AM
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How to deal with a beam with a bow....

Hi,

Deck is coming along - now I'm facing an issue I'm not sure of how to resolve. I'm doing a beam on post - the beam is made up of 2 2x8x20s nailed together. The type of setup is show in this picture below.
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I bought the 2x8s a couple of weeks ago, they appeared straight at the time but one of them has a bow in the middle and one is fine. So I clamped the two together, bringing the bow down and then I nailed the two together. I probably should have paused at that point () and look that the beam, while the bow went down, the good one went up. So now I have a 20' beam with a somewhat significant bow. The middle is high, one end in particular is low.

So now my question is how to deal with this? Some initial thoughts:

1. Have the high end of the beam facing up - put some weight on where it bows (couple of concrete bags, for example) and let gravity hopefully straighten it out. Not sure it will though or how long it would take. I could then shim the low end.

2. Replace the whole unit. Maybe I could cut the beam apart and use the straight 2x8, not sure if it is good enough to do it.

Any other thoughts?

Thanks,
Bob
 
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Old 10-21-15, 09:19 AM
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How much is significant? 1/2 inch? 1 inch? If it's more than that, I'd probably replace them. I doubt you'll have much luck getting it to bend back and stay with weight. IIWM, and it's no more than 1/2" or so, I'd plane down the high spot and cut long PT tapered shims for the low end.

2bys that long will almost always have some warp, especially pt; about the best you can do is put the crowns up on all of them.
 
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Old 10-21-15, 09:29 AM
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Thanks for the reply - I'd say no more than 1/2", probably closer to 3/8" at the worse. Sounds like a plan!
 
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Old 10-21-15, 01:11 PM
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Set all your posts to dead level and notch for the beam. Then use your body weight to bend the beam down and bolt it to the posts. I think you will be able to get it to sit down. Call a good size neighbor over for a beer and have him sit on it while you drill and through bolt.

Here is a copy of the currently followed code for decks. The attachment of beams to 6x6 posts is different from your illustration. http://www.awc.org/pdf/codes-standar...Guide-1405.pdf
 
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