pergola questions


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Old 04-16-08, 06:11 AM
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pergola questions

Hello, I am planning on building a pergola in my backyard and I have a few questions. I want to use 6" x 6" x 12' posts, buried in the ground in concrete footings, and use 2" x 6" and 2" x 4" crossbeams on top.

1) What type fasteners should I use, bolts, self tapping screws, nails? What will stand up to weather the best?

2) After installing the fasteners into the wood, do I then need to seal the area where the fastener entered the wood to prevent water from getting in?

3) I am planning on using pressure treated wood (cedar), but do I need to treat it any further like with Thompsons water seal afterwards?

Thanks!
 
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Old 04-16-08, 10:32 AM
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Hi Dave,

Definitely bolts and washers! Stainless steel would be best...I don't know if you can get them at the big box stores, though. You may have to call around for a building materials center that will sell to you.

I would seal those holes after drilling, before inserting bolts.

Connie
 
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Old 04-16-08, 01:41 PM
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I wouldn't bury the 6X6's in the ground -- they'll rot!

Instead, dig your footings and embed a Simpson CBSQ or similar post base or column base in the concrete and set the 6X6's in those once the concrete has set.

Staining/sealing it (as you go or afterwards) is a good idea, but don't your $$ on Thompson's. Use something along the line of Cabot's Sikken's, Super Deck, ... that will last for a year or two.

It'll cost more -- about 30% to 50% more. but it'll last 2 to 3 times as long. You'll save $$ in the long run by not having to redo it as often.
 
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Old 04-21-08, 05:16 AM
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Originally Posted by lefty
I wouldn't bury the 6X6's in the ground -- they'll rot!

Instead, dig your footings and embed a Simpson CBSQ or similar post base or column base in the concrete and set the 6X6's in those once the concrete has set.

Staining/sealing it (as you go or afterwards) is a good idea, but don't your $$ on Thompson's. Use something along the line of Cabot's Sikken's, Super Deck, ... that will last for a year or two.

It'll cost more -- about 30% to 50% more. but it'll last 2 to 3 times as long. You'll save $$ in the long run by not having to redo it as often.

I am planning on encasing the posts in concrete footings, so there will be no contact of the wood with the ground. Plus I am going to use presure treated southern yellow pine (SYP...I think that is what it stands for). Do you think the wood will still rot?
 
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Old 04-21-08, 04:21 PM
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It'll rot. SYP will just take about 15 years or so to do so. It's not the dirt contact that'll get you, it's the moisture between the wood and the concrete.

And once it starts to rot, you'll need to change the posts. THAT'S gonna be a PITA if you embed the posts.
 
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Old 04-22-08, 12:11 PM
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I don't think anyone embeds posts anymore. It's usually cheaper and easier to just pour a footer and mount the post on top. If you go with buried posts, make sure you get lumber rated for ground contact. I have some CCA ties that form a retaining wall and a half dozen flower beds. They are all over 20 years old and are not showing signs of rot but the important thing to note is that ties and small retaining walls are not structurat and your deck supports are.

Stainless fasteners are nice, but expensive and probably unneccessary. A good grade of hot dipped galvanized fastener will work fine.

I would use bolts for the structural fasteners and deck screws for deck boards and galvanized ring shanks for sheathing.

I don't usually seal holes in PT lumber, but it probably wouldn't hurt.
 
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Old 04-23-08, 06:30 PM
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Thank you everyone for the replies and ideas. When I looked up CBSQ boxes I found this link.

Is this what I use to mount the post to the footing? I've never worked with these before and am not sure how to mount these to the footing. Is there any info out there that can explain the method?

Thanks again.
 
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Old 04-23-08, 06:59 PM
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Hi Dave,

Yes, that's the hardware. Go to this page and mouse over the illustration to show how it is installed:

http://www.strongtie.com/products/connectors/CBQ.asp

Connie
 
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Old 04-26-08, 05:44 PM
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dzdave00,

That's the stuff. You don't MOUNT the hardware -- you EMBED it into the wet concrete. Have the CBSQ's on hand when you pour the footings. STRING, STRING, STRING -- (and did I mention STRING??) -- Align the post bases so your posts will sit in them and be in a perfect row and square.
 
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Old 04-26-08, 08:21 PM
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Wayne Mitchell,

What your CCA has done doesn't matter -- That stuff is no longer legal or AVAILABLE!! What you can get now is ACQ.

Burying wood in either dirt or concrete is not a good plan. It's not the dirt that rots the wood, it's the MOISTURE!

Embed the CBSQ (or similar column or post base) in the concrete. Steel is impervious to rot. Being galvanized, it'll last about 50 years or so -- a lot longer than whatever you put on top of it!!

Raise the plate of the post or column base so that the wood doesn't sit in water and can't draw moisture.
 
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Old 04-27-08, 06:37 AM
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Actually, you can buy ACQ treated lumber that is rated for ground contact. I don't think ground contact rated ACQ has been around long enough to say that it will or will not rot if buried.

BTW - CCA treated lumber is still around, it's still available (not at your local big box) and it's not illegal, it use is restricted. It's application is now very limited but it's still used.

Lefty - I'm sitting here looking out my window at a 30 year old split rail fence. The posts (locust I think) are buried directly in the dirt. They're not rotted. It all depends on the wood.
 
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Old 04-27-08, 08:35 PM
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cwbuff,

Of course the kind of wood that you are burying in the ground will detemine how long it'll last.

CCA MAY be available where you're at, but it's illegal in CA! I couldn't find it here (other than a tear out of something pretty old) even if I wanted to.
 
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Old 04-03-09, 12:15 PM
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Hello! I decided to put off this project to this spring. I am getting ready to dig the holes, run the string, and pour my footings. I already bought the CBSQ post bases. I have seen some talk of using Sonotubes for the footings.

My plan is to dig ~10" round holes, 36" deep (I am in the Indianapolis, IN area). I think I need to run my string before I dig, but then the string will get in the way of digging. So I guess I run the strings, mark where the holes need to be, remove the string, dig, and re-run the string before pouring the concrete?

Once I get the post bases set in the concrete, I will go buy the posts first. I don't think I can afford the cedar, so I want to use the pressure treated and once it is installed and dry, I'll plan on staining it to get the color improved.

My questions are as follows:

1) Are the sonotubes (or something similar) available to the public, or does one have to be a contractor? Are they necessary or is it a convenience thing?

2) I am not sure how I am supposed to run the string so that I know the placement of the bases will be correct.

3) Will the concrete be thick enough that the post base will not sink down too much or move? How do I ensure that the post base will not shift at all while the concrete is setting?

Thanks in advance!
 
 

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