Pergola Design

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Old 07-04-14, 08:27 AM
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Pergola Design

Iím designing a Cedar Pergola to cover my existing cedar deck.
Attached is the latest design images.
My questions are:

1) Post Notching: Do I really need to notch the 6x6 post 1" on each side so the 2x12 (or possiblily 2x10) Beams have a resting spot? My thoughts are the load from the 2x8 joist (or possibily 2x6) and rafters above the beam are that heavy compared to a fully covered roof. And I'm thinking by notching the post, this leaves an area where moisture can reside which may lead to premature wood rotting. Your thoughts?

2) Beam Size: I've shown 2x12 beams on each side of the post, but thinking 2x10's would be sufficient, again as the load above is rather light. The distance between each post is 11í. Iíve even had some recommendations that 2x8 beams would be sufficient for an open Pergola such as this. What is the reccomended beam size for 11í span between post for an open Pergola style such as this, using cedar?

3) Joist size: Similar to be beam size question, Iíve shown 2x8 joists spanning from beam to beam. The distance is 12í. Would 2x6ís be sufficient or should I stick with 2x8ís?. Above the joists I plan on having 2x2 rafters.
 
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Old 07-04-14, 12:46 PM
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I would hang the 2x12s or whatever you use between the 6x6 posts, with joist hangers. What is going to support the 6x6s?
 
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Old 07-06-14, 05:07 AM
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For the 6x6 post, I do plan on using knee bracing from post to beam, and post to joist.
The post will be anchored to ground using Simpson post bases. One installed onto a concrete footing I am building, and the other onto an existing slab that is under the deck.
 
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Old 07-06-14, 07:21 AM
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I don't think that you have to be concerned about a frost line in TX. but there still might be a code of 2' deep for the footings.
 
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Old 07-06-14, 10:10 AM
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In one corner, I have the opportunity to cement the cedar post in the ground. But was advised to make a footing and use a metal base with a steel rod to tie the post to the footing.
That would make all. 6 post using metal bases. Do you see any problem with this?
 
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Old 07-06-14, 01:55 PM
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Metal bases are okay as long as the correct footing is under it.
 
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Old 07-06-14, 03:38 PM
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I'd notch the posts. Hangers on that design would be ugly IMO. With notching, all you see are the carriage bolt heads and nuts and washers. Much more appealing than ugly metal hangers and nails. After notching/cutting put several heavy coats of Copper Green on the cut areas, though cedar is naturally rot resistant.

I have a free standing 8x10 grape arbor/pergola (no permit since it's "temporary") with plenty of areas notched and angle cut where moisture and pine needles can collect, no rot issues in 5 yrs.

I do seem to remember that the post has to be notched full thickness of the beams? Not 1/2 as shown in your pic. Not sure, maybe that was only for decks? Not a code guru.

I also think a 2x6 would bow at that span. Like I said, mine is only 8" wide and the 2x6s bowed ever so slightly. Could have been the way I built it. Instead of toe nailing or screwing the joists to the beam, I notched them both so that the fit together sort of like Lincoln logs.
 
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Old 07-06-14, 07:37 PM
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New Pergola design

After lots of research, the design has changed.
The beams are now 2x8's, running perpendicular from the house. The span between the post with the double 2x8 beams are longer (13') than the other direction (11'), so figure the larger boards should span the longer distance.
The joists are still 2x6 and now spanning the shorter distance of 11'. Separate 2x6 boards meet at the center post, butted together. Those meeting at the post are bolted thru the 6x6 post. This forms some support to racking, but I do plan on adding knee braces (not shown yet).
All 6 posts are attached to concrete using Simpson ABA66RZ metal post bases.
Appreciate any feedback on this latest Pergola design.
 
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