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Is my 8 ft fence doomed


Icewing726's Avatar
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09-11-17, 07:39 PM   #1 (permalink)  
Is my 8 ft fence doomed

Funny how you learn to ask things as you do a project. Anyway by the numbers:
1) New fence using 4x4 wood posts
2) Post holes are 40 inches
a) 4 inches gravel
b) 36 in depth for the post itself
c) 8-8.5 in diameter
3) Bout 60ish pounds of concrete per hole, some more then that
4) Mix of clay and gravel tamped into top portion of hole
5) 4 2x4 rails
6) Max of 8 ft between posts, average 7ish


As I said I haven't put the pickets up yet and I'm just worried that all the passerbys that watched me construct this fence over the last 7 weeks are gonna watch it blow over in one.
1) Did I do ok?
2) Should I gap the pickets? (Treated pine been in my garage since march stacked neatly, no noticeable warping)
a) if so how much?
3) Is there anything I can do to strengthen it or am I out of luck?

 
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09-11-17, 11:11 PM   #2 (permalink)  
I think I would have gone 10" dia holes and prob more concrete, the only issue being the thinner concrete at the corners of the posts is a weak point. I've seen plenty of fences built less sturdy than what you have that lasted 16+ years.

One thing I'm not clear on...8' posts? So only 5' above ground? Or 10' posts with 7' above ground? If the former, you should be fine, if the latter you're probably going to have issues as that's a heck of a wind load.


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Icewing726's Avatar
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09-12-17, 03:52 AM   #3 (permalink)  
The posts are about 10.5 long resulting in about 7.5 above ground. Any suggestions to shore it up? Dig around it to pour more concrete on the corners?

 
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09-12-17, 06:08 AM   #4 (permalink)  
Didn't see it mentioned, but does your town permit a fence that high, some don't.

Bud

 
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09-12-17, 07:01 AM   #5 (permalink)  
I never use concrete with wood posts. Concrete holds the moisture which rots the posts. The 36" depth is good. However, I don't think that the fence will fall. Bud is right about permits for that height. The inspectors might be worse than the wind.

 
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09-12-17, 07:18 AM   #6 (permalink)  
Permits not withstanding, you're doing a good job. I'm waffling on Donato's comment about concrete vs no concrete. I would like to see some statistics or test results about this.

 
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09-12-17, 07:49 AM   #7 (permalink)  
Rule of thumb is 1/3 of the post in the ground, which would be 3.5 feet for you. You're close.

 
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09-12-17, 07:58 AM   #8 (permalink)  
I installed many fences with a friend of mine. It was his company. His cousin had a bigger fence business. Anyway, we never used concrete for wood posts. We used it for chain link & PVC posts. Even if you don't think that the moisture from concrete can rot the posts, another reason not to use it is with high winds the fence will be less flexible & more likely to snap the posts. We would see more downed trees if they weren't flexible & bend with the wind. Even tall buildings are made to sway.

 
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09-12-17, 09:44 AM   #9 (permalink)  
Thanks for all the replies.
1) It is permitted
2) I heard about concrete potentially adding to the rot problem. I figured the gravel underneath would help stave that off (at least long enough for me to move).

 
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09-12-17, 03:11 PM   #10 (permalink)  
Gravel helps drainage but it doesn't add strength.

 
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09-12-17, 05:00 PM   #11 (permalink)  
When it comes to wind damage it won't much difference. If the wind is strong enough to snap the post then it will snap them in plain ground also. However, depending on ground conditions with high winds, using concrete could be a problem. In my location one section of ground becomes very soft during the spring. Having concrete is a real problem when trying straighten the post if wind causes them to lean.

 
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