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pergola design help

Posted by glaecia (My Page) on
Sat, May 22, 10 at 15:53

I'm having a 14' x 11' pergola built in the back yard. The posts and beams are 6x6. The rafters are 2x6. I think it's a pretty simple design but I am concerned about the 14' span on the 6x6 beams. I fear that without a post in the middle of that 14' span there will be dipping and warping. Can you recommend a method to engineer the beams so they don't dip without putting a post in between? Maybe some connectors? Also please note that the beams are attached to the posts (not resting on top of them).

Please see the link below for design specs:

Follow-Up Postings:

RE: pergola design help

really nice design. let me ask you this: what are the members you are using. if it is treated lumber i can guarantee you that is is going to warp and look terrible after one season if you dont put blockings between your rafters, at least every 2'. of course that is going to mess this nice and simple design. i strongly suggest that you invest little more an use parallam or gluelam beams for exterior applications. this way you will be able to enjoy nice and straight pergola instead of having to fix it after one season.

RE: pergola design help

A very nice clean look.

Ours spans only 12' and is constructed from 2 x 12 cedar. It has been standing for 3 years without any sagging. The posts are 6 x 6 PT but clad with 1x cedar.

Here is a link and the plans are included. Without the corner ornamentation, both of our basic concepts are reasonably similar. Good luck with your build.

Here is a link that might be useful: Pergola

RE: pergola design help

look at roberts design, how he has his cedar members supporting each other to prevent warping. i dont think sagging is a issue with 2x12 members on 12' span, neither will it be with 2x6 members. they just support themselves, not additional load sitting on them. i would worry more about warping. also cedar is more stable than treated lumber.

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