Q&A / 

Fence Posts

DEAR TIM: What is the preferred method to set fence posts? My 5-foot-tall solid-picket privacy fence has had some issues over the past ten years. The latest problem is posts set in concrete that have snapped. I have installed some temporary steel fence posts to stabilize the fence as winter winds have caused it to lean. How would you install wood fence posts? Should I be using treated fence posts? Ron W., Maumee, OH

DEAR RON: Fence posts can be a real hassle. I have fixed my fair share of them over the years. My guess is there are as many opinions as to the right way to set fence posts as there are posts encircling a one-acre field! But about fifteen years ago, I stumbled upon a method of setting wood fence posts that appears to be working really well.

Your fence posts have a tremendous amount of force against them each time the wind blows. You may not think a 5-foot-tall fence is high, but in terms of wind load, it is substantial. To get an idea of what I am talking about, lift a 4x8 sheet of plywood up and take it outdoors on a windy day. If you are not prepared, the wind may either knock you over or rip the plywood from your hands. Imagine the pressure on the entire fence being held back by a single fence post every 8 feet!

This 4-foot-tall fence post is as straight as the day it was installed. It was not set in concrete.  PHOTO CREDIT: Tim Carter

This 4-foot-tall fence post is as straight as the day it was installed. It was not set in concrete. PHOTO CREDIT: Tim Carter

The average wood fence post seems to be a square timber that is a 4-inch by 4-inch post or possibly a 6-inch by 6-inch post. The surface area of the post in the soil is what determines how quickly a fence will tip in the wind. Smaller fence posts will yield much faster than larger posts assuming both are buried at the same depth.

The trick I discovered is that you can use crushed, angular gravel to trick the wind into thinking a massive fence post is installed. The crushed gravel is affordable and it is easier to deal with than concrete that becomes as solid as a rock. You are about to discover how hard it is to deal with concrete that is deep in the ground around your fence posts. My guess is that you will be swearing like a sailor by the time you get to removing the concrete around your third fence post.

My method of setting fence posts is quite simple. If I am installing a 4x4 wood fence post, I dig a hole 10 inches in diameter. The depth of the hole is important. My tests over the years have shown that the amount of buried post should be half the length that extends above the ground. In your case my guess is your fence posts were taller than the fence, so your wood fence posts should be in the ground at least 3 feet.

When it is time to install the fence post, be sure it is in line with the other posts and it is plumb. It is also important that the fence post is centered in the hole. Start to add the crushed gravel in 5-inch lifts. This means add 5 inches of gravel around the post and use a long heavy 2x4 to tamp and compact the gravel. Each time you are finished tamping the gravel, check to make sure the fence post is still in the correct position.

Continue to install the crushed gravel until it is just a few inches from the top of the hole. You can add top soil to finish off filling the hole in case you want vegetation around the fence post. Some people like the look of gravel, so it can extend to the surface. You can even use a decorative, colored gravel if you like to finish off the hole.

The mass of interlocking gravel acts like an anchor when wind blows against the fence. It also can facilitate drainage of water away from the fence post as the soil moisture drops in late spring and all summer long.

The gravel is also easier to remove than solid concrete in the event you need to work on the fence in the future. A metal spud bar will quickly loosen crushed gravel that has been in the ground for many years.

Fences that are not solid have less wind load against them. A split-rail fence or a regular picket fence that has spaces between the individual pickets allows much of the wind to pass through the fence thus lowering the tipping force. In these instances the fence posts do not have to be buried as deeply.

If you decide to use treated fence posts, be sure to use the proper timbers. Not all treated lumber is approved for burial in the ground. The treated fence posts should be labeled that they are approved for direct burial.

Always be sure to call the national Call-Before-You-Dig Number a few days before you start your fence project. Simply dial 811 or go to their website www.call811.com. You may prevent death, serious injury or substantial expense by doing this. You would not be the first person to strike an electric line, phone line or even a buried natural gas line with a posthole digger!

Column 713


47 Responses to Fence Posts

  1. Tim,

    I was bouncing around the web looking for the best method to set wood fence post and found this comment. I live in Oklahoma where the winds
    Can get pretty strong and actually just snapped my neighbors posts. I am building a 6' privacy with little to know space between planks. Is this method you are using good for this or should I dry pack with concrete? I would
    Really like your opinion.

  2. Can we put a fence up over a drain field? Septic tank itself is right outside the back porch. What would you suggest? Will it be harmful for the dogs to be out there?

  3. I live in illinois, on a hill. winds are not too bad but can get pretty gusty at times as i live just off the mississippi. I want to put a Easy Gardener 7 ft. tall. DeerBlock Protective Mesh around my garden, and was planning on using 4x4x10' posts for this fencing. it is aproximately a 20' square garden and plon on myabe 8 posts. How deep should i sink the posts and would this be effective enough and enough poles for this style fencing? Or do you think wooden poles would be over kill?

  4. Good article Tim, thinking about doing this myself and wondering if you have any recommendations on what size crushed gravel to use, or does it matter? Thanks!

  5. Tim, I want to install a volleyball net over my above ground swimming pool. I live near Chicago so we get every sort of weather. My ground is clay after a foot or so. I bought 2 6"X6"X14' PT postsand plan on renting a hole auger and going 4' or as deep as I can get it. Once the net is installed it will try to pull the two poles in towrds themselves so I was thinking about pouring another concrete footing about 6' away from the poles to attach guy lines. My fear is that if these posts rot they may fall in on the pool and collapse the whole thing. The guy lines are also insurance for this - they would pull the posts in the opposite direction of the pool. What is the best way to set these posts? They need tol be stable and remain straight. Thanks, Brian.

  6. I am constructing a 6ft privacy fence, and on one side I have encountered a problem with a hole right in the middle of the fence line. The hole has water seeping up from the bottom. We have bailed out the hole, but water continues to seep in. What can we do to fix this, or can it be fixed at all?

  7. Tim, thanks so much for just reading my question, It's my hope you can/will advice me in building my fence. I lived in Mississippi and I purchased my home over twenty years ago and I think I've had to replace or repair my privacy cedar fence if not every year, at least every other year as I'm close to the Gulf Coast and we get those one-hundred and thirty-five mph wind as in Katrina. This time I'm installing treated pine 6"x6"x10' post 72 inches apart on center and using a concrete tube 48 inches in length 12 inches in diameter and putting them 42 inches in the ground and letting 6" rise above ground level and hopefully preventing the post from ever rottening over time. I'm putting four and half bags of 80 lbs 5000 psi concrete in each hole, as well as using four runners 2" x 6" x6 feet, my pickets are cedar 51/2 inches in width and 84 inches high as I raised them off the ground four inches in hope the weed trimmer or rain water level won't distory them as well. Do you think this fence will withstand hurricane force winds and if not what should I do different, please.

  8. I'm replacing an existing fence in south Florida . The ground is some type of coral with about 2 inches of top soil . It's a wooden fence and the cement has bonded with the coral preventing me from digging around the cement and pulling the post out .what is the best way to remove the posts? What equipment is needed? Do I need a tractor to pull out the posts?

  9. Hello Tim.
    I would like to put up some 4'x8' sections of privacy lattice (lengthwise across) since I live in an HOA with houses very close together with NO privacy. When I voiced my concern to my realtor she said to just "plant it out." Well, I found out that is not possible as the soil is clay and the drainage is terrible! My two neighbor's gutters and downspouts drain into my front mini yard and my backyard (and they refuse to correct the problem) -so even though I had 2 French drains put in the back which was quite costly, the water still pools and stands, so nothing will grow there. I cannot plant trees as the distance of my yard to the neighbors' houses is very narow and quite close. I'd also like to do something that will work now in my immediate lifetime. My idea is to put a row of 4-8' lattice panels end to end on 4x4 treated fence posts length-wise across three sections of my yard and then plant some kind of evergreen vine at the ends perhaps on a berm or raised brick flower box. The lattice can be 8 ft. high (as a "trellis") but cannot be attached to the (very decrepit) fence as fences can only be 6 ft. tall. I got HOA permission for the 8' trellis. SO! My big concern is putting fence posts in a swampy area, which is often since I live in Vancouver, WA where it rains a lot. I am a senior on very limited income so can't afford to hire a company to do the project. After 5 years my son has finally said that he and his visiting friend from out of state will do the job, but I know he prefers to cut corners and do it quickly. He wants to put the 10 ft. posts 2 ft. down in quick-set concrete and slap the lattice panels up. I fear the posts will rot out quickly in this soil and climate and have also been told that the lattice panels (cedar) should be painted with clear penetrating sealer before installing. I don't think either of them plan to stick around long enough to do that. I'm 71 and 5' tall so can't do it after they are up, and could not get to the other side to paint it. "Time" is a huge factor before his friend leaves, and my son goes back to work. I have spent several hours reading about fence posts online, (finding so much contradiction) and it seems to me that it may be best to not have the posts in the ground at all, but to have them sit above ground level on a metal post support that is itself sunk into the cement. Cost is a huge factor for me, and I looked at all kinds of metal supports and spikes on line, and would very much like to have your professional opinion on the best way to go about this project, and in the most economical way that will last. I do hope it will be possible to hear back from you very soon as I think there is little time to corral my son and his friend (before he leaves) to do this job for me.

  10. I live in Toronto and the frost line last year was 4 1/2 feet. I am going to use 6 x 6 x 10' posts and I'm going to cement them in the ground 4 feet with a 10 or 12 inch Sono tube. I want the fence to be 6 feet high .Do you think that will be sufficient? Thanks for your time.

  11. I'm building a 6-ft-high lattice-topped cedar fence. The basic 8-ft-wide panels are solid. Instead of setting the 10 panels close to the ground as is usually done, wouldn't it be better wind-wise to place them, say, 6 inches off the ground, giving the wind a place to pass through? Rabbits and other flora-eating varmints will have easy access, of course, but they can get through via about 200 ft. of open lawn anyway. Thanks.

  12. I am having a home built and they put up my 8 ft fence board on board with steel post and it looks great all except they put a big deep in the middle of the fence that runs along down the side of the house. It looks goofy and I don't like it. I believe they made a mistake but builder said has to be that way. Can you tell my why or is he lying to cover up a mistake.

  13. We purchased a home with an existing fence and it appears that the fence posts were not tamped very good as the posts are loose. How can we firm the posts up without taking the whole fence apart ?

  14. Interesting article.

    Couldn't help but think that if people really wanna know how this trick works you can do the same thing with a jar of rice and a pencil. If you keep poking down the pencil into the rice, eventually it gets such a grip that you can pick up the whole jar of rice with the pencil due to the high friction forces ! Try it.

  15. I live in Tampa, Florida and was considering using this method to build a pergola. Will be using a total of four 4x4 12 foot posts 3 feet deep. Would this method work?

  16. Hi Tim, I am putting up a four feet picket fence. I am using 8ft premade panels, or at least this is how long they should be. If I am wanting to use the toe nailed hanging look, how far apart should my 4X4 posts be set apart?

  17. I have a 5' rock wall and I want to extend the height 2-3 feet. Since only a few feet will be exposed to the wind, how deep should the posts be in the ground; also, I found various sizes of angular crushed gravel, what size should I use?

  18. I have tried looking for answer or even just the formula to calculate my own answer.
    The issue is i had 3 stock fence panels(4'Wx6'H) that fell over. The old post rotted. I cant dig hole because of all the tree roots. So i planned on building raised beds/flower boxes but can figure out how big/depth i need to make them to hold up the fence.

    Height is 2' width is 6' depth unknown.

  19. Tim,

    Do you also recommend the gravel method for decorative aluminum fencing? I live in northern Ohio and am setting 82", 2X2 posts for 54" tall panels. Manufacturer recommends a 36" deep hole with 12" of gravel in the bottom and remaining 24" concrete.

    I am concerned that the gravel will allow too much water to collect (heavy clay soil with slow percolation) and will actually facilitate heaving of the concrete.


    Chuck Z.

  20. What is an easy way to nail a fence panel to a post when a neighbors fence is back to back with your new fence

  21. Hello,

    I bought a house with a 6 foot wood fence and wood fence posts. Can I replace the 6 foot pickets with 8 foot pickets? It has 3 rails from post to post and the posts are 5-6 feet apart. The posts feel solid in the ground.

  22. I'm putting up a 6foot wood privacy fence, with the root of a tree I can only get two of the holes 1 1/2 foot deep. Will this work. Live in my. Thank you for the help.

  23. Tim,

    As someone who has installed a few fences for family and friends, I can attest to the difficulty of removing concrete footings from fence old fence posts. I live in NH just as you do, so digging a hole 3' deep and trying to remove concrete is terrible. Thanks for sharing your method for securing the posts. I am always perusing your site, but I failed to see this posting. Great ideas, advice, and knowledge. Thanks again!

  24. Hey Tim
    Just wondering if the 71yr old who couldn't afford to hire fence company ever called?(Cheri)
    "lots" of conversation at $49.95 for 15 min?or if you offered your "expertise" out of the goodness of your heart ?
    You must have a PHD in fence posts at that price!!

  25. Hello we are replacing a 15ft section of our wood fence (front part the rest is chainlink :-(.) but we are unsure on how many 1x4's & how many posts we need. The fence will be 5ft tall with roughly a 5ft gate (also making the gate). Please help

  26. This method really works! I have used it for years on various projects using 3/4" crushed rock. I like to line the hole with a heavy duty garbage bag with the bottom removed for drainage. Why? To keep the dirt from sloughing into the gravel over time. I did a solid 9' fence with 3' deep footings 20 years ago still standing straight.

  27. Tim,

    I just put up a 4x4 x 6' horizontal fence with 1/4" spacing between each panel (panels are 23/32" treated plywood approximately 11" wide. I buried my posts 17" down with a little over half a bag of quickrete per hole.

    This was my first fence install ever and on my own property.

    Based on your experience, Do you know if I'll ever encounter any problems with this setup? I live in North Texas.

  28. I'm planning on building a 6' wide wooden gate, 5' in height utilizing a 4'x4' post. Is your gravel method still adequate to resist the side loads exerted on the supporting post? Thanks

  29. I have existing hedges that run 120 ft on my property front to back. On my side of the yard all I see are roots, bare branches, and dirt, my neighbor see's the green full hedge. For years we have wanted to remove the hedges but because of the drop, we are afraid that the land will slide. I want privacy and wonder if a fence can hold back the hillside. The drop between the properties can go anywhere from 1 ft to 4-5 feet from his side to mine. If i level the yard with dirt, it will cause a bigger drop or steeper slope towards the middle of my yard. Any suggestions on how to handle this problem?

  30. Does anyone know if the crushed stone fill will work if you're setting 2 5/8 " diameter steel posts 2 feet deep for a 6' high stockade fence?

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