Fence Posts

s219 · Jan 16, 2021

I think the main thing to remember is that the dry mix backfill method is generally recommended when the local soil is not suitable to backfill a hole. Around here, when you dig or drill a post hole, the spoils are not able to be used to backfill the hole because it's impossible to re-compact. On pole barns, you'd have poor resistance to wind loads, and snow loads could cause the structure to shear if the poles aren't held in tight. So engineers always spec dry mix to backfill the holes.

I don't think anyone is suggesting the dry mix is as strong as properly mixed and cured wet mix. You wouldn't want to use dry mix for pre-cast stuff, slabs, etc. But for backfilling posts, it's a great method and usually more than adequate. And the big plus is that you can immediately continue working after backfilling the post. No need to brace the post and wait for concrete to cure.

I did hear from an engineer here that due to our moist clay soil, dry mix will actually harden as good or better than wet mix due to the slow absorption and cure. It's a long term "ideal" situation for concrete. The only flaw is that you cannot guarantee uniformity. What goes in the hole is what comes out of the bag and how it comes out of the bag. In contrast, with wet mix, you are thoroughly mixing all the ingredients and uniformity is much better. That is something to keep in mind no matter which method you use.

beowulf · Jan 16, 2021

I have used concrete, used nothing, and also have tried to coat the posts with roofing tar or asphalt sealer (can't recall which I used as it was just something I had around here). Not enough time has passed to assess the 'tar' method, but I only coated the lower part that I put into the ground making sure the tar line was 4-5 inches above the ground level, and I did not coat the bottom of the post - thinking it would seal the bottom and would not let any moisture out. I then set them o a bit of gravel and tamped in the dirt. BTW - I tried this as some wooden posts I put in long ago would rot out along the ground line - as Eddie has stated.

forgeblast · Jan 20, 2021

I use this method, not for live stock, but for 3 rail fence, and a bit to keep our dogs in place (with a field fence backing).
Dig it out, pull out all the rocks, and then throw a shovel full of gravel in the bottom. To hold them in place I use modified and pack it in there good.
Even with our freeze/thaw I have not had any come loose. One that was taken out by a falling tree, was easy to replace.

Furu · Jan 21, 2021

Well I tried the dry concrete "new" method. It will be interesting to see how well it works and what I think in a year.

Redlands Okie · Jan 21, 2021

LouNY · Jan 21, 2021

Interesting reading all these posts.
All the fences I have been involved in building and repairing in over 60 years have been field fencing for livestock.
I have used an auger for maybe a dozen posts in all those years, that fence used railroad tyes for the corner and gate posts.
Every other post I have put in has been driven, as a youngster working for my father it involved using a bar to get the hole started,
then a 13 pound post maul to drive the post in. A post maul is similar to a sledge hammer except the driving end is about 6" in diameter.
Now days it's a hydraulic driver mounted on the FEL of the tractor, much handier then 3 point.
Enjoy your digging and concreting, not for me.

workinonit · Jan 21, 2021

Dig a hole here now and you won't have to worry about water. The mix forces water from the hole. It's literally at ground level right now.

forgeblast · Jan 27, 2021

workinonit said:
Dig a hole here now and you won't have to worry about water. The mix forces water from the hole. It's literally at ground level right now.

Just saw your location, Scranton, Sc I live near Scranton, PA. Never knew there was another Scranton....

workinonit · Jan 27, 2021

There's a very good reason. It's a hole in the road. No stop light. It does have an elementary school and a cop that loves to run radar and write tickets.