How much of a 4 x 4 x 8' fence post I should bury underground for a 6' high fence?

Question

Essentially I have a 6' High dogeared picked fence that I'm making. How much of the 6' fence post should be burried underground that will support the fence. The fence will be roughly 30' x 24' (corner fence).

Also how much concrete (in bags) should be used for each hole?

Answer 1

You will need at least 7 posts unless you plan to put in a gate the you need 2 extra.
The frost line in your area if you have one depends on how deep. My area is 2 feet.....If you dig it 21/2 feet deep and put 6 inches of rock in for drainage you would need at least 7 - 9 bags of concrete, that leaves gives you a 2 foot depth to hold the fence.

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http://www.theworkshop.net/Tips/htm/fence_howtobuild.htm
4. Setting the posts
A good rule of thumb is that approximately two thirds of the fence post is above ground and at least one third of the post is in the ground. Dig the post hole about 6" deeper that the desired depth of the post and fill in the base of the hole with gravel or small stones. This will drain any moisture away from the post and help prevent the post from rotting. If using concrete to set the posts, ensure that the bottom end of the post extends down past the concrete to keep moisture from collecting around the post. Make the bottom of the post hole wider than the top to provide a solid base and to prevent frost from heaving the post if concrete is used. Setting the post below the frost line will also help prevent frost heaving. Use a plumb line or level to ensure the post is vertical while filling in the hole. To add extra rigidity to particularly a corner post, nail cleats onto the post. Brace posts until the concrete has set. After setting the corner posts, the intermediate posts may be set.
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Or go to your local home improvement store and ask them.
Have built 2 fences with the help of my daughter.

Answer 2

If you don't do this right, you will be replacing the posts in a few years. Look it up on a fence site, or ask when you buy. There should be gravel under the post, at least 4 inches, depending on drainage where you live. leave about 2 inches of post exposed to the gravel. For the longest lasting post, you can coat the part that is underground, except the bottom (for moisture drainage) with a tar substance. I use spray on rubber coating from the auto parts store. Works great! then either 1 bag per hole, or two. If you are using concrete, use the whole thing. If using the mix, use one half. (It is the same amount, one you mix with sand, gravel, one you don't) Put the cement in to about 2 inches from the ground, or level with the ground is better, but more unsightly. Obviously, 2 feet of post is underground. Actually 1 ft 10 inches. Good luck

Answer 3

My husband and I put our own 6' fence up ourselves. We put at least 1 1/2 foot of the post into the ground and used pretty close to a bag and a half of concrete in each hole. When you are putting up a fence of that height and the weight, you want to make sure the posts will hold the fence up. We've had ours up for over 5 years and have had no problems. It also helps to put some 16 Penny nails around the bottom of the posts that will be in the cement which will also help strengthen the posts into the ground.

We personally put up over 100' of fencing.

Answer 4

I used 4" X 4" X 10' posts planted three feet deep, then trimmed to height. Never allow the bottom of the fence to contact the ground, leave at least an inch of air space. Concrete the corners(first post, corner posts, last post) and use pea stone(gravel) for the posts in the run, tamp firmly. I installed my fence 8 yrs ago and it's still as straight as the day I put it in. I used 1 80# bag of concrete per post(4 bags) applied by installing half the mixed bag and letting set for 1 hour, 6 inches of gravel then the remaining concrete, this allows drainage around the post.
Good luck!
P.S. Never use dry concrete and rely on mother nature to add the water. She won't!

Answer 5

Subtract the distance from the finished post height from the existing grade on your post. Mark on post.
(Why cut it?if you don't have to.)
Then add 4" to 6" for gravel bed (for drainage) If its 33" fine. If its 29" fine. 37" Doesn't matter.
This is how deep the hole should be. Better to be deeper than shallower. I like to pull up my post to grade rather than cut it.
More in ground = more strength.

1. Dig your hole. A little wider at bottom.
2. Put 4-6" gravel in.
3. Put the post in hole.
4. Add mixed concrete. Don't put dry in and add water, shaking the post to mix it, this a shortcut that doesn't save you any time. Do it right, once.
5. Now with that stiff concrete in, move the post around, up, down, sideways until it is the right height and level and as straight as possible using your level, all sides.
You can put 2x4 kickers on 2 sides to keep it there while concrete cures.
If you keep water from sitting at base of post, it will stand tall for decades.

Answer 6

I hope you mis-spoke in your second paragraph, the 8 ft. post should be 2 and 1/2 ft in the ground. The concrete: easy trick-put dry concrete in hole and fill with water, keep adding dry concrete and use a stick to 'mix' it. This worked for our front deck. So I am sure it will work for a fence. Good luck. (if you are spanning 24 ft you need 4 posts.)

Answer 7

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Truth is, I've been a carpenter for almost 36 years, and I haven't found anything like this for less than 10's of thousands of dollars.

Answer 8

None of it! You should get a metal fence post holder bracket or pier and cement that into the ground and cut off what you don't need. Otherwise you invite termites into you yard and house! Termites love unprotected wood in moist soil and concrete won't slow them down one bit!

Answer 9

1) Well you want to bury about 2 1/2 feet worth of the post.
2) The hole should have about 3-4 inches of clearance between the post and the dirt.
3) Fill the hole about 2/3 full with the concrete

Answer 10

You will need to find out where the frost line is in the area where you live. The post must extend seveal inches beyond the frost line. In Illinois, my frost line was 42 inches so my posts had to be 44 to 46 inches in the ground. If you place your posts above frost line, the ground will heave them up.