Submitted by CancelCultAntifaLol t3_11a4o6c in vermont
Anyone here build a fence before? The frost depth is 60 inches, which seems aggressive for a post hole. I found a USDA technical guide saying 3 feet works in Vermont for corner/brace posts.
I’m curious about experiences others have had.
Edit: I’m using Quickrete and 6 foot by 8 foot wooden panels, anchored by 4x4 posts.
My mailbox is a treated 4x4 about 4-5 feet down. It's been 3 years and still straight. My horse fencing was fresh cut logs 2 feet. No problems with the posts stoutness, some of the skinny ones broke at ground level when I tried to remove them.
May your dig be rock free.
> May your dig be rock free.
I built a new garden last spring... Leveled the plot with a box blade and dug up all the rocks I could see. Then I drug a plow through it a couple times and pulled out every rock I could see. Then I dug the entire plot about 1.5 ft deep with an excavator, working through every scoop by hand pulling out every-single-rock. I leveled the ground again but somehow found more rocks. Finally, I tilled in a couple yards of compost, and managed to hit another bucket load worth of rocks... When I pulled up plants at the end of the season, guess what I found?
Planning on adding a fence this spring to the garden, and I fully expect to be digging out car size boulders that somehow appeared out of nowhere in the past 12 months...
Hahaha 🤪 not anywhere in New England.
There is not a single rock in the ground in the mallets bay area. It is all sand here.
Depends on what you are using, what you are keeping in (or out) and how much maintenance you want to do.
I fenced in a yard for my dogs with 4x4’s and packed driveway stone around them. 4 years in they haven’t budged, they are at MOST 3 feet deep probably closer to 2.5
Pounded cedar posts in for livestock, tend not to go as deep, but you may have to do some maintenance every year or so to pound a few back in or straighten some out.
I dig until I hit my first boulder or ledge. Usually 4-6 inches.
But seriously, 3' it ideal. Less if the digging is tough!
they will heave at three feet and need to driven back down every coupe years depends also what your soil is like if you are on well drained light sandy soil 18 inches will work heavy wet clay even at 4 feet they will heave
This is correct.
well thank you i am just a old farmer speaking from past experience was all
I am not sure about fences, but I had an old deck that i tore out that had poured footings going down about 3 feet. In heavy clay, you can imagine how badly everything heaved!
I did 4 feet, don’t recall why. Anyway, it’s holding up great!
Its those wind gusts that’ll get you. Every panel is a wind resistant sail and considerable force will push over your fence. Go the four feet down (its only 48”) It’ll be solid.
Post depth should generally be equal to half the height. Clean 3/4” in the bottom of the hole can help especially if you have poorly drained soils. If you are on clay maybe go deeper. If you’re going to use concrete and you’re on sand, you’ll be fine with 3’. Better yet use a ground screw, there’s very little surface area for the frost to push against.
Are you pouring your concrete into the bottom of the hole as a footing? Or are you going to pour it around the posts? If the second, are you going to use sono tubes to pour your concrete into? The reason I ask, is because frost needs to get under something to lift it, if you pour concrete directly into a dug hole it takes the shape of that cavity, giving the frost ample opportunities to latch onto all the inconsistencies of the rough surface. So even if the post is 4’ deep the frost could grab onto the rough concrete at 6” and still lift your post. If your assembly has a smooth outer surface the frost can’t lift it unless it can actually get under the bottom of it. All that said, I would not advise the use of concrete to backfill pressure treated posts to begin with. But if you’re going to do it, at least use sono tubes.
It depends on how you shape the whole because if you create a trapezoid with the longer side on top it will heave upward but if you create a trapezoid with the longest side on the bottom then frost will actually push it down and compact it more.
just a nice post about setting posts nicely.
As deep as the post hole digger can go, or ledge.
I built a fence with 4x4s maybe 4-5 years ago. Dug the holes to 3ft and it's been fine. No movement or anything. Still looks good.
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Where were you able to rent a ditch witch in Vermont? I’ve been looking for one.
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Thanks so much for sharing this info!
If you are going down 3 feet by hand then you may as well spend another 10 min and go another foot if you can. 4' is the rule that i grew up with and deeper is better cause you can add drainage first, which is always a good idea. I had to reset a meter post that was at 3 feet that i didnt set after like 25 years so take from that what you will.
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For my pergola I did 48” then gravel in the bottom of the hole an some in the sono-tube. No movement in 3+ years. But I was mostly sand in south Burlington.
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3’ minimum. 4’ you should be fine.
8' 4x4 just needs to go down 2' or a little more to match up with the top rail of your fence panel.
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https://www.hammerpedia.com/frost-line-map/
Who knew frost went that deep here. Always thought 4 foot was safe
24 inches is plenty for corners and 18 inches in between corners
Generic_Commenter-X t1_j9psnu6 wrote
As far as fences go, forget about the frost. It's irrelevant. Just dig a hole deep enough to keep your post from tipping over.