Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Building & Construction

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 04-25-2012, 04:36 PM   #1
Cruising into the sunset
 
JulieMor's Avatar
 
Join Date: Apr 2012
Location: Chicago area
Posts: 448
Share |
Default

Building a Pergola


I'm planning on building a pergola over our hot tub. I posted the drawings below (4 views). This is how I plan to build it:

(4) 6x6x12' posts spaced 14' O.C., side to side, and 10' O.C., front to back.
(2) 2x10x16' across the 14' span.
(8) 4x6x14' spaced 24" O.C. across the top. Braces are either 6x6 or 4x6.

Right now I have 4x4x12' posts along two perimeters that I installed 20+ years ago for lattice fencing. I set them with lime screenings instead of concrete. They will be removed and the new 6x6 will be inserted/added to fit the new plan. I will dig 48" x 12" holes, fill the bottom 6" with 3/4" limestone, compact it and place the 6x6 posts on top of that then set it with lime screenings, compacted in lifts.

Now to the questions:

I've looked at pressure treated lumber, cedar and redwood. Redwood is out because of its price. The cedar will run around $1000, the PT around $400. My concern about the PT is in the weight. I wonder if the four posts with their 12" base will be sufficient to carry the weight?

Another concern I have with the PT is its appearance, particularly the knots. Some PT lumber I've seen is pretty gnarly. Considering the weight and appearance, would it be worth the extra $600 or so to go with cedar? We would stain the PT or use a natural sealant for the cedar. Paint is definitely out.

Opinions?

BTW, the wood will be exposed to Chicago weather.


JulieMor is offline   Reply With Quote
Old 04-25-2012, 05:04 PM   #2
Member
 
cortell's Avatar
 
Join Date: Nov 2010
Location: Austin, TX
Posts: 708
Default

Building a Pergola


Nice plan. I see two questions here.
1. Will a 12" X 48" footing with an embedded 6x6 post be enough to support 1/4 the weight of your pergola. I'm no engineer, but that certainly sounds sufficient to me. I assume you've made sure your frost line is less than 48". Personally, I wouldn't bury the post. You're going to brace the top of the pergola, so I'd prefer to keep the posts out of the ground. There's plenty of debate around this, so this is a preference as far as I'm concerned. I know for sure the wood won't wet-rot if it stays above ground. Yes; yes, PT and cedar shouldn't rot either. Lots of things shouldn't happen that occasionally can and do. Again; preference, not science.

2. Is the aesthetics of cedar worth an extra $600. It is to me, but I certainly don't know if it is to you

cortell is offline   Reply With Quote
Old 04-25-2012, 05:17 PM   #3
Civil Engineer
 
Join Date: Mar 2009
Location: Boston
Posts: 4,170
Default

Building a Pergola


There is almost no vertical load on the structure, since you have no roof, no snow load, no walking surface etc. So the posts will be fine to carry the vertical load. But I would not bury them, I would build the supports the same way one does a deck, use Simpson or equivalent stand off brackets on top of the concrete footers, and use diagonal braces to handle the sway bracing requirements, just like you would do for a free standing deck.
Daniel Holzman is offline   Reply With Quote
Old 04-25-2012, 05:38 PM   #4
In a little over my head
 
Join Date: Jan 2011
Location: Atlanta, GA
Posts: 732
Default

Building a Pergola


One more for not burying the posts. Pour footings with the round tubes. Use simpson metal connectors. Easier to build, easier to repair.
ratherbefishing is offline   Reply With Quote
Old 04-26-2012, 05:23 AM   #5
Cruising into the sunset
 
JulieMor's Avatar
 
Join Date: Apr 2012
Location: Chicago area
Posts: 448
Default

Building a Pergola


You make good points about the footings and the Simpson brackets. I was trying to avoid the concrete because of the physical work involved. I'd need about (5) 80 pound bags per footing. I get tired just thinking about lugging that into the back yard, let alone mixing it. The realities of aging!

I tried removing one of the 4x4s that are there now and I couldn't budge it or even wiggle it loose. They were set 25 years ago. But they were direct burial PT and if I went with cedar...? I have no experience with that.

But the poured footings into Sonotube with the brackets may be the better option. I'd have to get really myself psyched for that one!

Cortell, you're right about the extra $600. It would look so much better.

Dan, I thought the load wouldn't be a problem but when you reminded me there would be no roof load, I realized there really isn't any real weight to support.

One of the things about the direct burial I like is the sway factor. The structure would be much more rigid. I need to think about that and do some homework about cedar in the ground. Maybe the reason the existing posts held so well over the decades is due to the lime screenings. Water that seeps in from the top has a place to seep out. With concrete, the water would take a lot longer to work its way through and that could lead to earlier wood rot.

Time to put the thinking cap back on.
JulieMor is offline   Reply With Quote
Old 04-26-2012, 07:49 AM   #6
Member
 
cortell's Avatar
 
Join Date: Nov 2010
Location: Austin, TX
Posts: 708
Default

Building a Pergola


Quote:
Originally Posted by JulieMor View Post
You make good points about the footings and the Simpson brackets. I was trying to avoid the concrete because of the physical work involved. I'd need about (5) 80 pound bags per footing. I get tired just thinking about lugging that into the back yard, let alone mixing it. The realities of aging!
If you were not to bury the posts, I'd investigate the possibility of going with a 10" diameter footer. I suspect that's still plenty strong, and will require less concrete.

Quote:
One of the things about the direct burial I like is the sway factor. The structure would be much more rigid.
A pergola has very little sail effect, unlike a picket fence, e.g--you'd never install a fence post above ground. Now, if you were not to use diagonal bracing at the top of the pergola posts, burring the posts would make more sense.
cortell is offline   Reply With Quote
Old 04-28-2012, 11:25 PM   #7
Member
 
Join Date: Mar 2008
Posts: 50
Default

Building a Pergola


I just put in a similar pergola (although it was attached to house on one side). I would go with concrete if you can. Yes, it seems like a ****load of concrete (my 18" holes each took about 9 60lb bags) but if you do one per weekend it is not that bad. Also you can have ready-mix come in and just squirt it in the hole for you and be done, or buy a small cheap mixer at Harbor Freight.

Anyway... where are you getting the cool "mod" lattice? Would like to pick me up some of that!
juryduty is offline   Reply With Quote
Old 04-29-2012, 04:40 PM   #8
Cruising into the sunset
 
JulieMor's Avatar
 
Join Date: Apr 2012
Location: Chicago area
Posts: 448
Default

Building a Pergola


Quote:
Originally Posted by juryduty View Post
Anyway... where are you getting the cool "mod" lattice? Would like to pick me up some of that!
The lattice, what I've been calling "Asian", is just 2x2s I planned to assemble myself. If I go that route, I will make a template that will allow me to repeat the pattern, maybe something in the 18" to 30" wide range. I would probably dado the joints and use pocket holes to connect to the top and bottom. It wouldn't be difficult but it would be a bit time consuming unless I came up with a fairly universal pattern template.

I asked a number of friends what they thought about the railing design and I got mixed reviews. Some said it was too taste specific and might pose a problem when selling the house, others seemed to like it. But no one loved it as much as I do.

When used in compliance with code (here any drop 30" or more requires a 36" high rail) you cannot have any spaces large enough to allow a 6" orb to fit through. So the pattern would have to satisfy that requirement.

Right now I have the standard 2x2 balusters for code-required railings (balcony and deck) and may do the Asian pattern for the pergola and see how it goes before replacing the other railings.

JulieMor is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pergola Beam Question jallred1 Building & Construction 7 07-08-2012 05:37 PM
Building a Cedar Pergola Nupe70 Building & Construction 2 06-07-2010 05:55 PM
Weather proofing a Pergola jad66 Building & Construction 14 05-29-2010 07:40 AM
Attached Pergola stubits Building & Construction 5 08-01-2009 01:07 PM
Pergola - paint or stain - then maintenance woodsglen Painting 2 07-15-2008 08:30 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.