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Pergola

68K views 25 replies 11 participants last post by  chrisjj 
#1 ·
I am building myself a pergola. It will have 6x6 posts, 2x8 beams bolted to each side of the posts spanning approx. 17 ft. across the back patio. 2x6 rafters every 12 inches will run atop the beams. It will be free standing anchored in concrete. The size will be approx 17 ft wide by 8 ft deep. I would prefer to go with just 4 posts but I am concerned the span is too far and sagging could result over time due to the weight. Opinions?

Matt
 
#3 ·
shamrock is right. in order to span 17 ft, you'd need a double or triple ply 2 by 10, and even then its going to sag abit over time with its own weight and the weight of the lath or louvers sitting on them. you'd be best off putting an intermediate post at 8.5 ft. you could get away with 4 by 4 posts, but you probably like the beefy look of the 6 by 6. build the structure out of pressure treated wood, or better yet, some kind of naturally rot resistant wood like cedar or tamarack. you can hire a fence guy to come drill your holes with a bobcat. he'll sink them for a small fee, which is worth paying. or you could just put them on concrete pads. either way you'd be best off with some diagonal bracing to keep it sturdy. all in all, a pretty simple project. just take your time to think it through. don't be afraid to surf the web for design ideas. good luck!
 
#6 ·
Chris, Strong work on the pergola. are the corner brackets wood (painted) or powder coated metal?
Renov: 17' is WAY too much to span. I would highly recomend adding an intermediary post (or 2) equally spaced between the ends. Don't substitute strength for asthetics. You want to be able to enjoy your product for years to come. :thumbsup:
 
#11 ·
Renov: 17' is WAY too much to span. I would highly recomend adding an intermediary post (or 2) equally spaced between the ends.
Huh? Just beef up your beams and you can span 17', no problem. Usually, if you're spanning a roof beam over a back deck, the middle of that span will fall right near the sliding glass door. You don't want a post right near the door.

That being said, don't even think about a single 2x to span it, I don't care if it's a 2x12, it ain't enough. For a 17' span w/ 2x6s spaced 12" o.c., I'd go with a 4x10 beam sitting on notched 6x6 posts.
Drop your 6x6s 3' into the ground with the bottom end sitting on packed gravel.
Pour a 16" dia. x 4' tall concrete ring (w/ rebar) around the posts so concrete is 1' above grade.
Slope the top of the concrete so water drips away from the post.
Simpson's got 4x6 post caps that you can get powdercoated, or use a metal guy in town.

To cut down on sway for a top heavy, 4 post structure, run beams from front post to back post, perpendicular to your support beams.
Then you can run knee bracing in 3 planes - post to support beam, post to perp. beam and a horizontal knee brace from perp. beam to support beam.
Do that on all four corners and you've got a solid structure (esp. since it's only 8' deep.)

ChrWright, nice looking work, man! Got any close-up pics? Is that a reverse shed-style rain roof over the front porch? How do you support the back end of the roof (over the house roof)?

Here's one I did similar in style to that. Patio roof hangs over house roof by 18" or so so rain is collected in existing gutter system. I cut 6"x6" blocks, buttered that bottoms w/ a crapload of black tar-like roof caulk, positioned them every 4' over a rafter and ran a LedgerLock through into the rafter. I set a 4x4 beam on those blocks, screwed into place and set my rafter tails on that.

Mac
 

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#10 ·
Reiss Ornamental, on Illinois & 38th street.

For high end railings (w/glass panels, etc.) I've also used Suburban Steel.

I have another smaller guy for more simple tubular railings & such. If you want his name/#, PM me.
 
#12 · (Edited)
Thanks MAC...Nice work yourself. Here are a few additional pics:

\


We did all of the cedar shake work on this house as well.

There are three posts which set on the existing porch. The remainder are sunk 3' in concrete.
 
#21 ·
Thats really a beautiful piece of work. Adds alot of charm to the place. I've always enjoyed doing a pergola job. Relatively simple and easy to modify to suit customer input. I generally will use 6x6 as a rule just cause I like the bigger timber look. I also like to to notch both sides of the 6x6 with a girder beam fastened to each side. Not as strong as a sistered beam on one side but I prefer the look. Hides the top of the pole. It's pretty rare I get involved with anything too elaborate. Homeowners here are generally just looking for an inexpensive way to cut down on the brutal summer sun.
 
#13 ·
I am building myself a pergola. It will have 6x6 posts, 2x8 beams bolted to each side of the posts spanning approx. 17 ft.

Mac: I dont recall ever seeing where it says a single 2x8 can span 17'. The way the OP stated it there would be a single 2x8 on each side of the 6x6 post. Unless you know something more about this??????? Let me in on the secret.:confused:
 
#14 ·
No secrets here, I was referring to single 2x stock as opposed to solid-sawn or built-up beams made of multiple 2x stock that are glued and screwed together. A pair of 2x8s on either side of a 6x post don't have the same strength that they would have if they were set on top of the posts and glued and lagged together.

With that scenario, you're resting the entire weight of the pergola on the bolts. They might not fail but the weak point would be the 2x hanging off the side of the post. Better to position the beam on top of the post so the post bears the weight.

Kind of a moot point though, 'cause the OP's disappeared. I stayed away from this thread to begin with because it "felt" like a HO post.

think I was right...

Mac
 
#15 ·
I think I might give it a go with 2X12 and spacer blocks.
It's not holding any weight, and according to "code"
you can span 13' with 2X8 for second floor BR joist!
I'd like to find a span chart for "unloaded" members.
I know that I've over built this kind of stuff in the past.
 
#18 ·
Mac: I think you were right the post did sound somewhat uneducated. Especially the 17' span. Normally lumber comes in even lengths and 2x8 not longer than 16'. Anyway, I really like the pics posted here. Nice Work guys keep up the good work and professionalism.:thumbsup:
 
#23 ·
No problems with a 17' span in itself - just buy 18's and have 6" of overhang or buy 20's and have 18" overhang beyond the posts...OR buy 18's and cut off a foot. Not sure where you're located but I've got no problems getting 20' stock of most dimensions...

just wanted to mention that from an architectural point of view it is more astheticaly pleasing to have an odd number of spaces between columns or posts. Source: What Not to Build by Sandra Edelman, Judy Gaman, Robby Reid, R.A.
What would be considered a "space" between posts - gaps between the rafters? I guess I'd have to read that book to understand the context of the statement...

Mac
 
#19 ·
just a little tidbit

just wanted to mention that from an architectural point of view it is more astheticaly pleasing to have an odd number of spaces between columns or posts. Source: What Not to Build by Sandra Edelman, Judy Gaman, Robby Reid, R.A.
 
#24 ·
Maybe I didn't express it very well, If you have an even number of posts then you have an odd number of spaces between posts, which is supposed to be more pleasing to the eye. I don't think it really applies to the pergola, more like to a porch etc. It was just an interesting tidbit to throw out, wasn't criticizing the pergola. :thumbup:
 
#25 · (Edited)
I think this would be news to the Greeks.
The spaces should be symmetrical.
Think 4 column porch, entry in the center,
equal flanking spaces.
Ugly? Or classic?

OOps:stupid:
Misread.
Of course, main example....ta-da
The Parthenon.
Front elevation, 8 columns!
 
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