fence posts: how do I dig deep holes in this hard clay and rock

purplelotusApril 8, 2007

hi

our soil is very hard clay and rock. how do I dig holes for putting fence?

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double_g

You need a heavy digging bar and post hole diggers. The digging bar has a sharp cutting part on one end for digging the other end is for tamping. Try to break off pieces or dig around rocks. I also made a pointed bar to break rock.
You can rent a gas powered post hole digger. 1 man or 2 man. Be careful, if it hits a rock and gets away from you, don't try to grab it while it is spinning.
If I only have 1 or two holes to dig, I dig by hand, up to 20 holes I use my one man gas powered digger. More than 20 I'm using the tractor auger.
Your holes should be 3' deep. The must be at least 2' deep.
1' deeper is twice as strong. 1" bigger post diameter is equal to 1' deeper.40% of the post in the ground is best.
If you are tamping post, the bottom 6-8" of dirt is critical.Only a little dirt at a time, tamp it good and then a little more dirt. If the bottom is not tight, you will never get the post tight.
The easiest way is use concrete. Make sure all the dirt is out of the hole, post in, pour dry sacrete, quicrete or whatever brand is cheaper, add water. You can't add to much water, so don't worry. You don't need to mix it with water before you pour it. You don't need the mix that is especially for posts.
Set your end posts first,make sure the ends are plum. Then use 2 strings, one high one low, to keep the line posts plum. Step back and "eyeball" from a distance, frequently.
I was a fence contractor for 15 years, now I'm to old. You can email me with any questions. Good Luck!

    Bookmark   April 10, 2007 at 11:10AM
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jazzyjack

How do I plum the posts? If I am building a fence 57 linear ft. how would i know that the 2 end posts are inline?.
How much cement should I put per post?

Thanks

    Bookmark   April 8, 2008 at 4:15PM
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Belgianpup(Wa/Zone 7b)

There is a right-angle plastic level that you can tie to a fencepost. Then you can make minor adjustments to get it perfectly straight. Look at BOTH bubbles

(Here's a photo of the post level: http://www.amazon.co.uk/Fisco-LB-000PL-Post-Level/dp/B0001GRWAO but any hardware store should know what you want if you describe it; not very expensive.)

Just make sure you get your end or corner posts in the right place, then do as Double G describes above, which is all good advice. Three feet is a good depth, but here in my part of western WA, the rocks won't usually allow it.

If you're using wooden posts, don't even THINK of not using concrete. Just tamp dirt and they'll rot away in just a very few years and you'll be doing it all over again. Fencing just isn't that much fun.

Sue

    Bookmark   April 13, 2008 at 9:28PM
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sandsquid(7a)

I have found (by lots of trail and error) that painting the fence-posts (at least the part in teh gorund) with KILZ Exterior primer, goes a LONG way in protecting the wood.

    Bookmark   April 15, 2008 at 10:49AM
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Belgianpup(Wa/Zone 7b)

Now, isn't THAT a great idea! I use Kilz for everything, but never thought of using it to protect fenceposts.

Sue

    Bookmark   April 16, 2008 at 12:54AM
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hjvanbur_rochester_rr_com

I am going to set posts and use 10ft 4x4 The fence is 6 ft and I want the posts 1 ft above the top of the fence - can I set the posts 3 ft deep? We get serious cold weather and I don't know if 36 inches is deep enough. Can I lay in 6 inches of cement in a 42 inch hole then set the post on top of this cement? I will still cement the post in place from there

    Bookmark   June 23, 2008 at 8:06AM
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jollyrd(Richmond VA)

I needed to secure wooden pallets to create compost bins, thought I would have to dig holes to put posts in my clay soil. Husband said "we can get you fence posts from farmers supply store and then pound them in with a special tool, no problem." So he comes home with posts and this heavy cast metal tube with one side closed, and two-handles, you slide the tube over the post, hold the handles and lift-drop the tube over the post; you need to have a second person hold the post for first few hits until it's in the ground, it does require lots of upper body strength, but no digging and filling in around the base. I did it myself too after I also tried using a mallet to pound the posts in - much harder, so the tube is the way to do it. I then slide my wooden pallets so that the posts are inside the pallet, but the posts are made for fencing -- they are green and come in different length - 3, 4 , 6 ft and longer.

    Bookmark   July 10, 2008 at 3:16PM
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dellinger

I'm digging 42" holes. How do you get the dirt out of the bottom 6"? My arm doesn't reach, and I can't open the post-hole digger wide enough because it's so far down.

Thanks!

    Bookmark   August 5, 2008 at 12:03PM
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