Setting arbor posts in the ground - Woodworking Talk - Woodworkers Forum
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post #1 of 21 Old 04-29-2011, 01:10 PM Thread Starter
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Setting arbor posts in the ground

I am making redwood arbor and I am trying to decided if I should use column base (CB44) to mount it to the ground, or if I should gid in polls.

The are 2 4x4 polls supporting 2 14' 2x6 across (11' spam), and there would be 8-10 40" 2x6 on top of the long 2x6.

On one side, I like idea ot column base, sence wood will not be in the ground, it will prolong life of the wood, and I can carefully cut wood and install it independent of digging/cementing.

On other hand, I am worried if column base will provide enogh stenghts (Strong Tie says "not recommended for non top-supported installations").

Thank you,

Vadim
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post #2 of 21 Old 04-29-2011, 01:29 PM
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I'm personally just a lot more comfortable with setting posts IN the ground in concrete. While the Simpson ties may be adequate, I just can't help but feel posts in the ground is a far superior method. I built a pergola last year using fir/hemlock (standard grade building wood) but used copious amounts of the treatment stuff you get at Home Depot/Lowe's on the embedded ends to prolong the life of the wood that's in the ground.

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post #3 of 21 Old 04-29-2011, 03:33 PM
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The way this is built depends largely what state your in. From the specs provided it would seem strong enough to hold it's own weight. However, you must take in exterior conditions like wind, rain and snow fall ECT.
Check local code and conform to those specs for best results.
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post #4 of 21 Old 04-29-2011, 03:37 PM Thread Starter
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Quote:
Originally Posted by Corbin3388 View Post
The way this is built depends largely what state your in. From the specs provided it would seem strong enough to hold it's own weight. However, you must take in exterior conditions like wind, rain and snow fall ECT.
Check local code and conform to those specs for best results.
I am in California (San Francisco Bay Area), so next snow is expected in another 30 years . I called city and they said that threre are no requirements for arbors, but if anyone can point me to somekind of code, I would highly appritiate it.

Thanks,

Vadim
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post #5 of 21 Old 04-29-2011, 04:28 PM
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Quote:
Originally Posted by kutsyy View Post
I am making redwood arbor and I am trying to decided if I should use column base (CB44) to mount it to the ground, or if I should gid in polls.

The are 2 4x4 polls supporting 2 14' 2x6 across (11' spam), and there would be 8-10 40" 2x6 on top of the long 2x6.

On one side, I like idea ot column base, sence wood will not be in the ground, it will prolong life of the wood, and I can carefully cut wood and install it independent of digging/cementing.

On other hand, I am worried if column base will provide enogh stenghts (Strong Tie says "not recommended for non top-supported installations").

Thank you,

Vadim
If I am reading your plan correctly you are spanning 11' with a 2x6? I think you are far exceeding the spanning capability of a 2x6, probably 4-5' would as much as you could do and even at that I think it would sag pretty quickly.

As far as in the ground or not, if you have some really good bracing at the top it might be stable enough sitting on concrete pilings, think that is what you are implying. However a good pressure treated 4x4s about 2' into the ground will really provide some rigidity. I would recommend going to a library, online, or a bookstore and glance at some outdoor project magazine for plans on building an arbor and try to follow them. What appears to be a simple project can be a lot trickier than you would ever imagine.
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post #6 of 21 Old 04-29-2011, 04:33 PM Thread Starter
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However a good pressure treated 4x4s about 2' into the ground will really provide some rigidity.
Sorry, but no chemicals. I am using redwood.
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post #7 of 21 Old 04-29-2011, 04:39 PM Thread Starter
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I think you are far exceeding the spanning capability of a 2x6, probably 4-5' would as much as you could do and even at that I think it would sag pretty quickly.
Based on http://www.awc.org/calculators/span/...rcalcstyle.asp the maximum horizontal span is 10'3" if used as ceiling joists or roof rafter. So 11' for arbor should be just fine.
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post #8 of 21 Old 04-29-2011, 04:44 PM
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Sorry, but no chemicals. I am using redwood.
In that case I think you would be better off setting them on concrete pilings with good fastening hardware and then having a big angle brace at the top to make the arbor more stable. I don't think Redwood has much strength and isn't necessarily very good for ground contact but I am not sure about that. If you concrete in the posts be sure to slope the top of the concrete away from the post, like an anthill, so that rain won't be directed against the post. What kind of soil are you working with? Hard clay or loose sand?
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post #9 of 21 Old 04-29-2011, 04:47 PM Thread Starter
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Hard clay or loose sand?
loam, closer to clay
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post #10 of 21 Old 04-29-2011, 04:49 PM
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Well being a general in SoCal I can tell you that doesn't sound right.
If you want send me a sketch and dimensions of what your planning to do and I will take A look at it.
At very least you should go down to building and safety and tell them what your planning to do and they will assist you
Any project in Cali over $500 requires a permit which you can pull yourself as owner builder if you own the property.
Any structure over 6' requires a permit and has codes associated with it.
Before you dig call 811 they will mark any underground lines for ya for free.
This type of structure will have codes associated with it regarding earthquakes for sure.
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Last edited by Corbin3388; 04-29-2011 at 04:54 PM.
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post #11 of 21 Old 04-29-2011, 05:58 PM
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In my opinion do not do the hardware on a 2 post arbor unless it is something that is made up with a very wide base, 6-8 inch tall wrap arround collar with weep holes and braces. I am not a fan of planting wood in the ground but in this case it is the safest thing to do (life expectancy will be your biggest problem even on pressure treated wood.

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post #12 of 21 Old 04-29-2011, 08:03 PM Thread Starter
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Just went to the city. Yes they do require permit and they highly recommended to put post into the concrete (but they do not require doing it and would be ok with brackets).

So now question is, if I'll be making 3' deep 18" wide hole and I'll put post into it, can I use fast-setting concrete to be mixed in the hole (i.e. http://www.quikrete.com/AtHome/Setti...ructions.asp)?

Also, I've posted quick drawing of the arbor at http://vadim.kutsyy.com/Arbor.pdf and I would appropriate any comments (including what hardware to use or how to make which join). I will be use redwood heart B.

Vadim
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post #13 of 21 Old 04-29-2011, 08:59 PM
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If your going to pull the permit the planning department will want a drawing. As far as setting the posts I would use rapid set (green label). You should not mix concrete in the hole. Use a simple large plastic container (they sell em right close to the concrete) and mix it in there with a square shovel. Simpson makes joist hangers that work well or you will need to use 16d 3 1/2" nails. Each 2x6 will require 3 nails in each one centered one a above and one below.
They will also have to be spaced 16 O.C. (on center)
Your plans submitted to planning should specify which system you will be using & material list.
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post #14 of 21 Old 04-30-2011, 07:16 AM
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I get the impression that some repliers on here do not recognise that this poster is building an arbor in his yard.

Why would you put the beams on 16" centers for an arbor? Or why would an 11' span not be OK for an arbor? (I might want bigger for looks.)

George
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post #15 of 21 Old 04-30-2011, 10:55 AM
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George Im not sure how y'all do it in Florida but California especially cities with historical significance it can be tough to build. San Francisco and Santa Monica are about top of that list.
Though the structor is non load bearing will still see people traffic under it and you must account for deflection not only wind but earhquake. Most maximum span lists are for DF not redwood. So I would wager they use a decking max span chart which would be no larger then 16 O.C..
Hopefully Valdim will let us know how it all worked out with the planning department.
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post #16 of 21 Old 04-30-2011, 11:25 AM
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Originally Posted by Corbin3388 View Post
George Im not sure how y'all do it in Florida but California especially cities with historical significance it can be tough to build. San Francisco and Santa Monica are about top of that list.
Though the structor is non load bearing will still see people traffic under it and you must account for deflection not only wind but earhquake. Most maximum span lists are for DF not redwood. So I would wager they use a decking max span chart which would be no larger then 16 O.C..
Hopefully Valdim will let us know how it all worked out with the planning department.
He is not decking this!! It is a decoration in his yard. It is not structural.

Or am I not reading correctly what he is doing. The last time I looked an arbor was a yard decoration.

George
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post #17 of 21 Old 04-30-2011, 11:43 AM Thread Starter
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City said ok in general to the design, I submitted revision to my current permit (patio door+patio). I'll let you know when I'll get official approval. They would be ok with cb44 but highly recommended to dig post in the ground. They are requiring 36" deep and 18" wide hole for the concrete.

Vadim.
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post #18 of 21 Old 04-30-2011, 12:12 PM
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Originally Posted by kutsyy View Post
City said ok in general to the design, I submitted revision to my current permit (patio door+patio). I'll let you know when I'll get official approval. They would be ok with cb44 but highly recommended to dig post in the ground. They are requiring 36" deep and 18" wide hole for the concrete.

Vadim.
That is a huge hole for a post. I roughly calculated about 5 cubic feet of concrete per hole, assuming a round hole. An 80lb bag of concrete is about 2/3 a cubic foot so you would need 8 bags per hole to fill it. If you have mixed concrete before you know that is a big job by hand, you might want to consider renting a small mixer. I would recheck the size of the hole needed for a concrete footing.

I still think you will get a sag in the beams over time but maybe redwood is more rigid than I am thinking. Personally I would go with 8" or 10" beams across the span, I think it would look more aesthetically pleasing that way.

Last edited by would; 04-30-2011 at 12:20 PM.
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post #19 of 21 Old 04-30-2011, 01:09 PM
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He is not decking this!! It is a decoration in his yard. It is not structural.

Or am I not reading correctly what he is doing. The last time I looked an arbor was a yard decoration.

George
I'm with you, George. This seems like a lot of overkill to me. How could a 11' 2x6 sag under its own weight? OTH who am I to tell, maybe I misunderstood it all.
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post #20 of 21 Old 04-30-2011, 02:06 PM
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it depends on the size of the arbor, pour individual concrete pads , i did it for lights at the end of my driveway, worked great till i came home in a chevy abs van, launched her into the middle of the yard,
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