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Shaky Pergola

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R

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8 Posts
Discussion Starter · #1 ·
Hello,

I'm a veteran in the construction biz having been a licensed contractor for 20+ years in FL (the state that can't count-see Presidential election in 2000, when President Gore was elected.)

I've not been involved with a forum or chat room before but I was looking for a couple of solutions for something I just built and thought I'd give it a try.

Don't know if this is where to start asking a question but just tell me if I screw up and I'll catch on.

My client wanted a pergola which I call an arbor. I looked at a couple of photos of these things and they looked pretty simple. We built a 16' x10' one using three 4x6 PT posts along it side. Posts are about 32" in the ground with a bag of sacrete each. These are 8'6" high and on top of these we placed double 2x10's secured using Simpson BC46 hardware. Over those we have 2x8s, 16' OC going 10' and in the other direction we placed another layer of 2x8's, 24" OC. We notched the shorter 2x8's about 3/4" on top so the top layer would sit in the notches. Of course we nailed everything together where they crossed. It looks fine and the client likes it but when we finished, I noticed it was pretty easy for me to shake it when i was standing on the ladder. I hate that. I'm prepared to add additional structural support but instead of re-inventing the wheel perhaps someone can help with a couple of suggestions and/or photos.

Thanks

Remodeler21
 
R

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8 Posts
Discussion Starter · #7 ·
Thanks for the welcome guys.

I'll try to get over there and take a photo tomorrow, its the time of day for glazed eyes..

Thanks for the pic from Mac's site.

I plan to add 45* angle bracing and yes, G, I actually do know how to stiffen up a structure. Actually, too many ways.

Is there an opinion of whether its better to use 4x4's at 45* angles on the same plane as the posts and 2x10's (which my buddy suggeseted or the exterior applied 2 by material. Because I used 2x8 & 2x10's I thought 2x8s should be used as the 45*s pieces instead of the suggested 2x6's.?

Of course, I'm second guessing myself about using hte simpson BC46 hardware. Wonder if i should have put one of the 2x10's on each side of the 4x6, blocked between them between the posts and bolted the whole thing together. Am considering placing a 3-4' long 2x8 over the side of the posts vertically, covering over this hardware by running it all the way to the top and using bolts through it, and the posts at top and bottom of this piece plus the 45* applications.

Collar ties on rafters used to be something like 1/3 down from the top, is there a rule of thumb for the height of the 45s?

Ok, i've droned on too long, but thanks again for the input. I'll check back in the am.

Remodeler21
 
B

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3,359 Posts
#9 ·
Problems w/ your current setup:

For a freestanding structure, your posts are undersized, too shallow (below grade) and don't have enough concrete around them.
Your post/beam connection is undersized too - BC46 is a minimum connector, thin gauge metal fastened w/ Tecos.

You've got a lot of weight w/ 2 levels of 2x8 rafters, all sitting on 6 legs w/ a little bit of concrete around them.

Solution for this project:
Knee bracing...in both lateral directions and in third plane as well for add'l stability. That is, knee bracing running up from your corner posts to your beam in one direction, your rafters in another and a third brace horizontal nailed to the bottoms of three rafters. With a little work, you can make it look fairly nice.

Your question re: 4x4s in line or 2x8s/10s on outside?
2x8s/10s nailed and glued to the outside of the posts/beams will create more stability than 4x4s lagged into the sides of both.

Length of knee bracing...3' +/- long to long.
Depends on headroom, keep 'em high enough so you're not installing a bunch of headknockers...

Next time, use bigger posts, sink them deeper in the ground, surround them w/ more concrete (3-4 bags per post), use beefier post/beam connectors (or notch the connection and use through bolts).

And the pic SLS posted isn't one of mine... he was giving you an example of one and saying you could find some other examples on my site.






Side note - an arbor is a gateway to a garden, usually wide enough for one or two people to pass through, a pergola is a patio roof that provides shade, not protection against the rain.

Mac
 
R

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Discussion Starter · #11 ·
Ouch! Undersized post, insufficient depth, light weight hardware and not enough concrete. Been awhile since anything I build wasn't overbuilt.

In any case thanks Mac for the information, even if its embarrassing and the photos of some beautiful work.

Obviously new to the site so I've got questions: when I log in how do I go back to what I've written to pick up where it left off, or in this case to see what answers were sent to my inquiry. I got back this time by a link in my email .

2nd Q: how do I upload photos?

Thanks.

And for those comments about why I didn't know how to stiffen a structure, take a look at my comments last night where I was pondering the options, of which there were many of which I'm aware.

What I wanted and got were helpful sugggestions and good information from a pro because I didn't want to reinvent the wheel.

Thank you again Mac, you're obviously a professional and I appreciate you time.

Remodeler 21
 
B

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#14 ·
Remodeler21 said:
when I log in how do I go back to what I've written to pick up where it left off, or in this case to see what answers were sent to my inquiry. I got back this time by a link in my email .

2nd Q: how do I upload photos?
Click to expand...
In the Blue Bar above, click on User CP. It will take you to your control panel in which all your subscribed threads that have new replies show up.

You can upload photos after making 15 posts...maybe it's 20, I can't remember.

I remember that project, DecksEtc, that's some sweet work!

Mac
 
J

· John Hyatt
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3,673 Posts
#16 ·
Hi Ya new Guy!! welcome a board to the borad!!


Yo Mac,just a quick thanks for turning me on to Sundance for Lex Ann pannels. The alum channels were soooo much less trouble than the old one piece deals. We used more silacone than you see on the beach but the thing looks good. Thanks again:thumbsup: J.
 
deckman22

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17,682 Posts
#17 ·
I've found that really good post base, one that is embedded into the crete w/long sleeve on each side of the post & 3 thru bolts works better than angle braces. You can't find them in stores, but need a welder to make them for you. You'll have to box around the post base with wood or stone columns.

Pergolas are more effective for shade with a lower ceiling, therefore the angle braces always seem to be in the way, imo.
 
B

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#18 ·
John Hyatt said:
Yo Mac,just a quick thanks for turning me on to Sundance for Lex Ann pannels. The alum channels were soooo much less trouble than the old one piece deals.
Click to expand...
Not a problem at all, man! I was happy to find them myself - the aluminum channels are just a better way to build that type of roof - look better, last longer, less chance for failure or leaks.

deckman22 said:
I've found that really good post base, one that is embedded into the crete w/long sleeve on each side of the post & 3 thru bolts works better than angle braces. You can't find them in stores, but need a welder to make them for you. You'll have to box around the post base with wood or stone columns.
Click to expand...
Hey guy, care to share any specs on those? I've got a metalworker here whose done some custom stuff for me in the past. I'm assuming post stays above ground, but how tall do you take the metal? Do you leave a space between the two sides so the bolts can suck them hard against the wood? Any weepholes in the bottom of the sleeve? 1/4" thick? You powdercoat or prime and paint? Big question, ya got some pics?
Lotta questions, but ya got me thinkin'....
I've boxed around concrete bases before (12" sonotube brought up 3' above grade) The boxes can be end tables - keep the tops flat and make 'em big enough to put drinks on.

Thanks,

Mac
 
S

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16 Posts
#19 ·
Remodeler 21, If I understood your description correctly, there are two things I might suggest. The first would be to add some 2x10's running perpendicular to the ones that are carrying your load ("headers"). If you add these inside the current 2x10's it is nearly not noticeable and will add some rigidity to the structure. The second thing I would throw out there is to install the knee bracing horizontally rather than vertically. It certainly won't function as well as being installed vertically, but then again, you don't have to worry about anyone clipping their head on them either.
 
R

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#20 ·
I agree with those above, especially Mac.

If the arbor is large or has any mass to it, we sink 6x6 PT. posts, a minimum of 5' into the ground, with a lot of concrete. You won't need braces with this method.

Some localities frown upon sinking the wood directly into the ground and require something like Simp. CBS post anchors. This usually requires bracing, unless it is tied back to the house in both directions.

Here are a couple of bracing options. I much prefer the bottoms of my bracing to align, but maybe that's just me.
 

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