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jetski0602 10-09-2012 04:28 PM

Pergola Base
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Ok, So a few months back I built a pergola that is 14' x 16'.

I dug holes and poured 24" deep footings. Good here in San Antonio, Tx. I mounted the four posts ontop of the concrete footings with metal brakets and a j-bolt in the cement when pouring.

I have 2x6 running the top perimeter, and the ladders going the other way are also 2x6 with 2x4 connecting them.

My issue is that I still have the supports on the ground, when I remove them the whole structure wiggles. Is there a way to fix this, is it a footing issue? I'm thinking pulling my concrete, putting new posts sunk in the ground. Or do I need middle supports??

See the pics attached, any help is much appreciated.

dvatt 10-09-2012 05:25 PM

I would have sunk the post in the ground to aide in lateral support. Can you make your diagonal bracing longer?

Daniel Holzman 10-09-2012 05:38 PM

I doubt this is a footer issue. Wiggle as you call it is restrained by lateral bracing, not by the foundation itself, except for those structures where the posts are rigidly connected to the foundation. Metal brackets are not intended to resist rotation, they simply keep the post aligned over the footer, and resist translation, so your brackets look like they are working as designed.

Dvatt is probably spot on. The lateral bracing you provided is inadequate to prevent movement of the frame. Lateral bracing works by making a rigid triangle shape, and the longer the triangle, the more rigid it is. This is the principle of the truss. Since you have no flooring on top of the pergola, all of the resistance to lateral movement is provided by the braces, so they need to be quit stiff to prevent wiggle, which means the braces need to be relatively long (5 feet or longer would be good), and firmly joined to the posts at each end, which can be accomplished using three bolts arranged in a triangular pattern on each end. The braces can also be installed as let in bracing, which adds stiffness due to the connection detail.

jetski0602 10-11-2012 06:26 PM

Thank you for the help.. I am going to go 6' on the lateral supports. That way when I do my 45 degree cut they will be 5 foot long.. I will be doing this this weekend and will update with what come of it.

Thanks again for the help

joecaption 10-11-2012 06:55 PM

Are those 4 X 4's:eek:
They should have been 6 X 6's. Not way to let in a 4 X 4, or properly through bolt it.

Daniel Holzman 10-11-2012 08:02 PM

Joe, if that were a deck, it would need to be 6x6 posts, but this is a pergola, much lower loading, 4x4 should be fine, unless local code says otherwise.

Flatop22 02-20-2013 04:02 PM

I just built a pergola using 6x6 cedar for post.

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