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I am building a 190′ long 6′ high privacy fence. Using 8′ 6×6 pt as fence posts spaced 8′ apart. Should I,
1. Bury the posts in dirt
2. Dig a 30″ deep by 12″ hole, add 6″ of 3/4 crushed stone and backfill around the post with crushed stone.
3. Dig a 30″ deep by 12″ hole and set the post in cement.
I want this fence to last a long time.
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Convention wisdom says use concrete.
Newer thought is that concrete simply traps water between the post and the concrete and may actually accelerate rotting. So if you are so inclined, use only grave, but lots of it, below the post, and tightly compacted soil around the post.
*What kind of wood for the posts?Plodding onward, since it's a privacy (read: solid) fence, it will encouter a bit of wind-load, so concrete may be your best bet.If concrete, I'd dig the hole, put in a few inches of stone, compact, set the post, then put in a few more inches of stone to surround the bottom of the post. Compact again, then fill the remainder of the hole with concrete. Slope the concrete cap away from the post so water doesn't pool against the post.The idea is that the concrete will give a better grip on the post than just a dirt backfill, and by not encapsulating the bottom of the post in concrete, and water that does trickle down between the concrete and the post will flow through and not soak and rot the bottom of the post.
*Whadda you mean? I thought pt=pressure treated. I always thought the only 'choice' of pt was green and wet. I like your plan, though.
*My mistake! I read right over the "pt".I'd go with concrete if using pressure treated posts.
*Roman - I agree on the concrete fill - it doesn't take much, either to stabilize the posts. Don't over-excavate.Have you thought about the 6 x 6 posts? That seems a bit overkill for a 6' high fence, unless the whole fence is to be "chunky" in design.Just a thought ...Jeff
*Roman,I'm about halfway through with the identical task. I chose what the locals call "crusher run", which is gravel, not stone. It has a good deal of fines and dirt in it.This Old House Magazine recommends stone for drainage. I decided against concrete because we get some serious frost heave around here. Concrete is rough, and it gives the frost something to grip and the frost lifts the post right out of the ground. I'm concerned about wind load moving the fence as well, but figure it's less of an evil than frost heave. I figured crusher run would pack more tightly than stone, helping it resist wind load, yet provide the kind of drainage and movement that would limit frost heave.But I could be wrong too. Maybe it'll just buckle under the wind, and heave to boot!Let us know what you choose and how it works out. I'll report back on mine next spring.Steve
*Do you ever use dry concrete ?
*Plant a hedge. Nicer looking, grows instead of rots, and will outlast any wood fence.
*No. I like to control the water content in my mix for strength.
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Thomas
A hedge was plan A, then I got Goliath my 83 pound German Shephard. Here Boy! Good Dog. Now if I could only teach him to put my tools away.
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I guess I have the dissenting opinion. I rarely use concrete in a post hole for a fence. I'll use concrete where I think something might need a little strength but usually, just tamp the dirt real hard with a stick as I fill the hole.
I'll alsays go 2-1/2 to 3' deep with the posts and once the dirt is compacted, it's solid and much easier than mixing concrete all day.
To answer Roman's question: I've seen posts rot right at ground level, never below ground. I suspect the organisisms don't like it 3' deep.
Although I don't have any proof (Basically I'm just pulling this out of my @$$), I'd suspect that backfilling with pea gravel or clean sand would keep the post from staying wet at ground level better than concrete or dirt.
If you want it to last a long time, check your lumberyard to see about getting lumber treated to .60CCA instead of .40. It's an arm and a leg here but may be more available where you are.
*I'm with Ryan on this one ......spent a year plus installing fences many moons ago. Almost never put concrete around wood posts ......we installed just as Ryan describes. I think it allows for better drainage. The exception was beachfront property (sand). Just make sure the bottom of the post is below the frost line, cuts to the post are above ground, .......the .60 CCA is a good idea for any wood that is buried.
*#2.. ditto ryanconcrete is for sissies..
*Here I guess "crusher run" is called "3/4 minus" -- has a good bit of fines in it. They were using it as a base on a new highway close by and it really packed hard, so I used it as fill for my garage. Rented a "whacker packer" and compacted the heck out of it. Sets up really, really hard.My local hardware store has a "tamper" which is a large 6' pry bar with about a 2" dia. flat on one end. Weighs about 30 lbs. and I suspect it would pack "crusher run" just about as hard as concrete, but would still drain.
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I am building a 190' long 6' high privacy fence. Using 8' 6x6 pt as fence posts spaced 8' apart. Should I,
1. Bury the posts in dirt
2. Dig a 30" deep by 12" hole, add 6" of 3/4 crushed stone and backfill around the post with crushed stone.
3. Dig a 30" deep by 12" hole and set the post in cement.
I want this fence to last a long time.