6x6 treated posts in ground

[tractorgp]

In this video I'm repairing one of my high back chairs. Two of the three legs had rot at ground level and snapped off in high winds. I had to cut the third leg. When I dug down to remove the buried part of the legs and cross members I also found a fair amount of rot (3:20 in the video shows this). The chairs were installed about 8 years ago and I picked up the CCA 4x4's at a home center. Don't have any other details on the level of treatment etc. I live in a damp climate.
(Posted this video some time ago on TBN so just putting a link to it here.)

High back chair repair Kubota BX big player - YouTube

 

[PeterK]

The treated lumber that is sold here has a label which states 'Not for direct ground contact" which I always thought was kind of odd. So as far as sinking it in the ground without additional protection might be problematic in the long run.

What I've started to do is spray then bottom ends of any outdoor wood (even metal fence posts) with truck bed liner for the length under and near under the ground. Cheap insurance. Just my 2 cents though.

 

[TemporaryKubotaOwnerMark]

Concrete increases decay by trapping water.

Educate me on this. I'm willing to learn something new.

Lots of reading available.

Concrete increases wooden post decay by trapping water. at DuckDuckGo

 

[jimmysisson]

If these are for a building, where there interior faces, you can drill a hole down at 45* just above grade and squirt thin oil into it every so often. Or do that on the outsides, where the rot starts. That small amt if oil will not escape into the ground. Posts only really rot in the top 8" below grade. Concreting around them won't help with that. Agreed w the "below ground contact" grades. I would not be afraid to expect 40-50 years if the sun is kept off the post.
Jim

 

[joecoin]

Use Osage Orange for posts.

 

[RNeumann]

Lots of reading available.

Concrete increases wooden post decay by trapping water. at DuckDuckGo

Double tap this- concrete should be thought of as a sponge. If you insist on putting wood in the ground the goal is to keep it dry. Second best is to provide excellent drainage- stone and or crushed stone works.

 

[crazyal]

Finding PT 4x4 posts around here isn't easy. Most everything is for above ground use. OTOH the 6x6 posts are landscaping timbers designed to be for ground contact. Ground contact doesn't mean burying but will last longer than those designed for above ground use. Back in the day I would just say get some creosote and brush on a nice heavy cote but the EPA has ruled it out. I had access to old telephone poles but now the EPA makes power companies treat them like toxic waste so they don't give them away anymore.

 

[TemporaryKubotaOwnerMark]

Use Osage Orange for posts.

Also called "hedge", correct? I have heard that that stuff is nearly indestructible. But, not all of us can get it. We have a bit of it where I live, but it's not plentiful enough to use for any large projects.

Double tap this- concrete should be thought of as a sponge. If you insist on putting wood in the ground the goal is to keep it dry. Second best is to provide excellent drainage- stone and or crushed stone works.

Yes, I have wondered if it would be worth the time to auger down about 3 or 4 feet, fill with crushed stone to the level where the post sits, then tamp in dirt to hold the post. It would provide good drainage for the post, I think.

 

[s219]

Yes, I have wondered if it would be worth the time to auger down about 3 or 4 feet, fill with crushed stone to the level where the post sits, then tamp in dirt to hold the post. It would provide good drainage for the post, I think.

The real answer depends on the soil and the size of footings required for the design roof loads. When my barn was planned out, roof loads were computed down to the footing requirements on each post, and that dictated the required pre-cast cookie footer size as well as the requirement to bore down to undisturbed soil. Then, for shear loads, holes were required to be back filled with dry concrete mix, as the spoils from digging the holes would not have provided sufficient resistance to keep a pole from going over with a wind load on a wall. There was a lot more to it than I expected.

For decks, where these requirements are not an issue, many people will rest the post on a concrete footer in the ground and then backfill the hole with pea gravel or a fine #8 gravel. I haven't ever tried that but I hear it works well and helps the post last a lot longer.

 

[EddieWalker]

I think most people confuse what they have seen happen to fence posts and assume that the same thing is happening to deck posts or pole barn posts. In 100% of the time where I've come across a rotted post, it's rotted away at ground level, and the ground is lower around the post then anywhere else. Water sits there longer. For wood to rot, it has to go from wet to dry many many times. If you build up the area around a post so that water runs away from it, that post will last for many decades. 30 to 100 years depending on all the other factors that it has to deal with. If you put a roof over that post and cover it with a wall and the ground slopes away from the building, that wood post will easily last 100 years.

 

[Shaneard]

I think most people confuse what they have seen happen to fence posts and assume that the same thing is happening to deck posts or pole barn posts. In 100% of the time where I've come across a rotted post, it's rotted away at ground level, and the ground is lower around the post then anywhere else. Water sits there longer. For wood to rot, it has to go from wet to dry many many times. If you build up the area around a post so that water runs away from it, that post will last for many decades. 30 to 100 years depending on all the other factors that it has to deal with. If you put a roof over that post and cover it with a wall and the ground slopes away from the building, that wood post will easily last 100 years.

^^^^This has been my experience as well.

 

[Shaneard]

Lots of reading available.

Concrete increases wooden post decay by trapping water. at DuckDuckGo

I read some of what you posted, good read. Fence post will eventually rot regardless of what they are packed with or have concrete around them. There is a fence my parents neighbor put up about 32 years ago and he used locust post, they are rotten beyond rotten but lasted a really long time. A treated shed post if covered and water is diverted away from the post/shed (which it should be anyway) I would think will last our lifetime no matter what it's set in.

 

[ovrszd]

I think most people confuse what they have seen happen to fence posts and assume that the same thing is happening to deck posts or pole barn posts. In 100% of the time where I've come across a rotted post, it's rotted away at ground level, and the ground is lower around the post then anywhere else. Water sits there longer. For wood to rot, it has to go from wet to dry many many times. If you build up the area around a post so that water runs away from it, that post will last for many decades. 30 to 100 years depending on all the other factors that it has to deal with. If you put a roof over that post and cover it with a wall and the ground slopes away from the building, that wood post will easily last 100 years.

Well stated Eddie. Easy to find barns and sheds around here more than 100 years old, built with non treated posts buried in the ground. The rotted ones are where water was allowed to stand around the post. The dry ones are solid.

 

[ovrszd]

I read some of what you posted, good read. Fence post will eventually rot regardless of what they are packed with or have concrete around them. There is a fence my parents neighbor put up about 32 years ago and he used locust post, they are rotten beyond rotten but lasted a really long time. A treated shed post if covered and water is diverted away from the post/shed (which it should be anyway) I would think will last our lifetime no matter what it's set in.

I have access to Hedge here. Fenced my home property in 1979 using hedge posts averaging 5" diameter. All are rock solid. None have been replaced.

 

[bigdeano]

If you pack crushed rock around the post instead of dirt the post stays drier. The water can't wick through the rock like it does with dirt. You don't want fines in the rock, just approx 1" rocks.

 

[bcp]

These guys don't like short-lived wood fences. Even the fence "boards" are logs that go into the ground.



About 20-30 years ago they drilled about a 3/4 inch slanted hole in each log a few inches above ground level, poured in something, then put a wooden plug in the hole. I wonder what preservative it was.

Bruce

 

[Gunny]

These guys don't like short-lived wood fences. Even the fence "boards" are logs that go into the ground.

About 20-30 years ago they drilled about a 3/4 inch slanted hole in each log a few inches above ground level, poured in something, then put a wooden plug in the hole. I wonder what preservative it was.

Bruce

They did something on the order of that to all the utility poles around here, then dug down about four inches around each pole, stapled on some kind of treated paper, then shoved the dirt back.

When they did the one in front of the house, I asked one of the guys what they were doing and he claimed he didn't know what it was, that he just worked for the contractor.

 

[mechanic]

pole barn post in the ground will only survive if they are in a dry enviroment in the ground. Moisture breakes down the cca in the wood. Also if cracks develop in the post moisture can get past the outer treatment and start rot and termites.

 

[Oldoak]

I have not lost a single post in my 36 year old pole building. And here in northeast PA, the soil isn't exactly dry. When we constructed my 30x60' building, I just dug the holes with a post hole digger, set the 6"x6" treated post, and backfilled with the existing soil (hard pan) with no other special construction techniques.

Of course, it I were to put up a new building today, I would most likely do it differently. Our state and county building codes (more government regulations) require it.

 

[masscity]

All the huge buildings in Venice, Italy are sitting on untreated poles and for centuries.