Best way to set a treated post

[used red MN]

What does the YT brain trust suggest as the best way to set a treated 4x4 fence post for a yard privacy fence? I redid my fence about 15 years ago and now two posts have rotted off just above the concrete I poured them in. Searching for info I see it is okay to use concrete if the very bottom of the post is left in contact with soil. Which means you are essentially setting the post in a concrete sleeve. The reason for this is so moisture in the post covered with concrete can migrate down an go into the soil. This is opposed to the method of digging the post hole placing some cement in the hole and then setting the post then adding additional cement to set the post. I have yet to get the old post out to see how it was set but I am pretty sure we put the post in the hole and just poured the cement around it. By the way removing this post in cement is a very labor intensive job for a 60 year old man. I am actually surprised the concrete around the posts breaks up as easily as it does.

 

[DoubleO7]

Well, here in Florida privacy fences with the prefab 1x6x6 foot panels are prevalent.
No concrete what so ever, no gravel nor cement pad in the hole either.
Have pulled many posts to reuse here. The only ones not reusable were in virtually wet all the time ground.

Being not set in concrete also allows many fence lines to be pulled up right when a hcane was blown them over.
The ones in concrete snap off.

 

[SkipperII]

I have recently seen ads for posts with a steel pipe inserted in the bottom, to set in concrete, and keep the wood above ground level.

 

[fixerupper]

Dig a big oversized hole and tamp the post in with 3/4 inch washed crushed limestone. Probably not what you want to hear. It involves a lot of work for one post and the washed limestone does not pack as tight as dirty limestone but the water will get away from the post faster and hopefully the post will last longer. Even back in the heavily creosoted post days pouring concrete around a post guaranteed a rotted off post here in Iowa.

 

[rustred]

myself i dont see any reason for cement. setting posts in a 30 inch hole only requires the dirt that came out of the ground tamped good. then the top 6 inches can have gravel tamped real good and leave a slight build up by the post so no water can run in. its only the top 6 inches that rots off anyhow. that post will last at least 20 years. definitely dont need concrete on the bottom of any post, no air ,no rot. i have pulled untreated tamarack posts out of the ground here that were in from 50 years ago when i was a kid. and the bottom is as solid as when they were dug in.

 

[Geo-TH,In]

Make sure you are buying CCA treated posts.

I special ordered from Menards CCA 2x6 boards for my implement trailer. Menards owns the company that treats wood..

AC2 treated posts are junk...

In 1995 I put CCA posts in concrete. They are still good..

AC2 post in dirt lasts about 10 years..

 

[RobCons]

I agree on the cca treated post. There is an exception in the rules allowing cca to be used for agricultural purposes. Some lumber yards will order it, otgers wont. Down here I've installed them different way. End result is similar. Gravel may last a little longer. I still like concrete.

 

[MarkB_MI]

For a post frame building, you need to pour a concrete plug in the bottom of the hole to support the weight of the building. Fences aren't that heavy, so there's no need for a plug.

The most important thing is to use the right wood. It needs to say 'ground contact' on the label. If you don't see those words on your 4x4, go to a different store. You may have to get a different dimension, such as 4x6, to get wood that's treated for ground contact.

Post life is increased if you backfill the bottom few inches of the hole with gravel. That will allow some drainage around the post.

I usually don't use concrete when I set a post. But when I do, I pour it in DRY. That will lock the post in place and you can keep working without having to prop up the post. In a day or two, the dry redi-mix will absorb enough moisture from the surrounding ground to set up.

 

[Charles in Aus.]

The practice here is to use cement powder mixed with the sub soil taken out of the hole the post is going into .
CCA for preference and if you can be bothered upside down from when the tree grew ; feel the grain . Even when treated the capillaries in the timber will soak up water , more if they are put in in the way that they originally grew .
A few rocks or bits of the broken concrete to help it stay upright , then fill in the hole with dry cement and soil mixed well , tamping well after each shovel or two with the handle end of a crow bar .
Ground moisture will eventually harden the cement into a porous , stable, hard lump that will hold up the post for decades.

 

[caterpillar guy]

Screw all that just use some of those ploe banr pole repair deals and put some one direction and some the other so it will stay standing up. The will bolt fasten down to the semsnt there and then bolt por to it. Or just cut the post off a few inches get the old bottom out then put about a 3/4 rod in the cement to fit in to the bottom of the old post to hold it and with a hole drilled in the bottom end it will be solid.

 

[DIM]

I never put cement around a post. The hole will always be tapered and freeze and thawn will push the post out of the ground. If the post is going to carry a lot of weight I pour some sacket in the hole to make a large base.I just put in a new deck and only two post of the 9 post were rotten off.The deck was there 43 years

 

[rustred]

the frost pushes the posts up when they are installed upside down, with big end down as should be frost actually would help keep it in the ground.

 

[Stephen Newell]

Any post will rot eventually however if it's properly done the post should last at least 30 years. The problem with treated though is some brands they just wet the posts in open tanks instead of putting it in a tank under pressure. Yellawood is one of the worst offenders. I made a screen door out of Yellawood treated onetime and painted all surfaces and within two years the bottom of the door rotted off. I now use Lifewood brand and have had good luck with.

 

[showcrop]

It depends on your ground and how well drained it is. If your ground tends to hold moisture you need to provide a way for the moisture to drain away, as opposed to holding it inside a concrete sleeve. Just fill around the post with crusher run gravel and tamp it in with a bar. I have never seen a 4x4 that has a big end. The gravel to use again depends on local conditions. Don't use limestone if it has to be trucked from 100 miles away.

 

[Tony in SD]

Posts will rot when exposed to air and water. The post can be wet or it can be in air and survive. But if it is wet and exposed to air it will rot. Where the post meets the ground is where the rot will start since that is where the water will settle and of course it is exposed to air. So it is most important to treat the post at and a little below ground level.

 

[Charles in Aus.]

(quoted from post at 12:43:34 07/18/22) the frost pushes the posts up when they are installed upside down.

That's interesting rustred , the soil never freezes here , frost only really kills grass and new shoots once in a while .
I don't think '' Big end first '' really applies here though , the post is said to be a four by four .
Isn't setting posts upside down to growth a practice in the US ?

 

[DIM]

Right you are that's my point the cement will have big end on top.As for freeze holding it down I think that would depend on the depth of post and depth of freeze

 

[rustred]

yes i know but i have seen fence posts upside down and it is just not correct. frost squeezes on the post so when the big end is down as it
should be how can it come up? with small end down the frost will push the post up , the same as squeezing a slippery jack fish by the tail.
its gone!

 

[rustred]

well just how far do u think it freezes??? a lot deeper that the post is that for sure. frost can be from 3-4 feet quite easily and even deeper where you drive. i am talking canadian winters here.

 

[rustred]

mr. red mn. did not give us his view either. must have forgot to look at our suggestions.

 

[Bruce(OR)]

I have seen 12 rubber sleeves that go around a 4x4 post to insulate it from premature rot.
I have also seen planting steel supports in concrete and the the 4x4 post attaches to the steel support.
PT post then treated with Cuprinol might also slow down your rot.

Me? The wife's father had his two teen age kids make 5 fence posts per weekend. Now planted about 20 feet apart around the top 3 acres.
8 foot length, 6x 6 concrete, 2 sections of rebar down the center, wire ties across every 12 inches, 4' Livestock wire 4 feet on the inside, barb wire every 12 inches on the outside, a threaded stud on the top of each post with future dreams, never realized, of a 'V' bracket on top of each one with concertina wire on top of the brackets. That was back in the early 70's The wife was about 18 at the time with platform shoes driving a 5 ton dump and wearing a mini skirt.
That's another story.

 

[ASEguy]

I live within 5 miles of an electric company lot, so I use their newer poles cut to size. They make great posts. I paint the bottom 40 with whatever outdoor paint I have on hand. I sink them 36 inches or so on dirt. I use wetted concrete about 4 inches from the top and fill in and mound up the dirt around the pole out of the ground to prevent it from sitting in water.

 

[ASEguy]

I also cut an aluminum cap out of old downspouts because I've seen a lot of posts that rot on top too. I go from the top to 2 below the top on the sides.