Pergola Spans

la15ota

Hello All,
Our designer has a free standing pergola that is 27 ft wide x 14 ft deep
she calls for 8x8 posts (3 on the long side, at 13.5ft spacing) and then sitting on top is a 8 x10 running 32 ft across, with 4x6's running perpendicular. The design is cost prohibitive, due to timber sizes.

I'm wondering if reducing the posts to 6x6's and rather then 1 large beam sitting on top. Sandwiching 2x10's or even 2x12's with carriage bolts to the posts. then run 4x6's or 4x4's perpendicular will work and not sag.

Also because of the long span, could I break the span in half and not risk sagging by adding bracing on the center posts.

Sorry no drawing at the moment, just questions.

joecaption

Does this designer have an engineering degree? If not find one and ask them.
I'm pretty sure no one on this site is going to try and design it for you over the net.
Someone would have to see the plans to even guess on this one.

AndyGump

Ha ha, that's funny, I design over the net all the time according to the clients needs. Not for free though.

I know you didn't mean it that way...I'm just messin'.


Andy.

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bill01

If you really want to know for sure you will have to pay a someone or try to figure it out yourself from the span tables. Since with a pergola all you really have is the wood framing and nothing else it is mostly a appearance issue. I would bet if you did the math and calculated the absolute minimum you could even use 4x4 posts. You could use 2x6 rather than 4x6 and just guessing a single 2x10 or 2x12 would support the sides.

You end up with a roofless sideless pole barn.

I would ask your designer why they chose these items. I strongly suspect it is more for appearance than structure.

Daniel Holzman

Presumably you are paying your designer to develop plans for your pergola. Hopefully you had a discussion upfront about the basis of design. In your case, the basis of design would have included the maximum price you were willing to pay for the pergola. If you forgot to have that discussion with your designer, now would be a good time, since it sounds like you don't like the price this pergola is going to cost. Redesigning your structure over the internet on a chat forum is going to end badly, and since by your own words you already have a designer, go back to them, explain the maximum amount of money you have available, and ask them to develop a design that meets your financial constraints.

la15ota

Yes I figured this might happen. Just wanted outside input but of course we'll be having her redesign it.