Concrete & Treated Posts Debate

[Spencer]

This has been touched on before but I wanted a central discussion on the topic. I set the first five posts of my pole barn last night and I want to get the holes filled as soon as possible. Some of you have said to use no concrete at all around the posts because it will make them rot sooner. Some of you have said to pour a 6" or so collar of concrete around the base and then back fill the rest of the hole with dirt or stone.

I submitted my pole barn plans to the township which stated that I would be setting the posts on concrete cookies and then pouring concrete around the posts. I did not state how high I would pour the concrete around the posts or the diameter of the cookie to be used. The only addition/correction the that building inspector who reviewed my plans made was to state that the cookie had to be a minimum of 14" in diameter. He did not state anything about the concrete around the posts. Now in reviewing all the documents I got from the township I found a sheet that they gave me which is a cross section of one wall of a pole barn (see attachment). They make you fill this out and submit it with your plans. As you can see on this sheet it shows concrete filled all the way up to grade and it says "concrete min. 4" cover".

Before I read on TBN about the possible problems with concrete around posts I was planning on filling them up fairly high. I have a very high water table here for half of the year and thought that concrete against the posts was better than water. After reading about the subject on TBN I was convinced to just pour a 6" or 8" collar of concrete around the posts and back fill them with sand. Now it looks as if I may have to fill them all the way up. I will try to get clarification from my township today but I wanted to hear your opinions again of the subject in case the inspector leaves the decision up to me.

Please post any links with solid information on this subject along with your opinions if you can. I am really interested in seeing some evidence about the concrete making the posts rot sooner or causing problems with heaving from frost.

 

[Mosey]

Great subject! I've been wondering the same thing myself. I just bought a book on pole buildings "Monte Burche's Pole Building Projects" copyright 1993. It says the poles can be wholly or partially embedded in concrete and they say to round the top of the concrete off so water will run away from the pole. I talked to the guy the local building codes office and he said there are no codes covering it and there are varying opinions on whether to use concrete or not. One opinion is that the concrete leaves no way for water to drain away from the pole if it does get in between the concrete and the pole. So, if was sealed off good at the top it would be OK. He said some people use gravel to backfill the poles so moisture can drain away easier. He said around here most people just backfill with the dirt. He agreed with me on the opinion that there is not much advantage to concrete since it's going to meet up with dirt eventually anyway, all the concrete is going to do is increase the dia of the pole at the bottom.

My opinion is that unless you're going to pour a concrete floor at the same time and tie the concrete for the poles in with the concrete floor using rebar, then there's no reason to use concrete. So, I don't plan to use concrete on the pole barn I'm planning to build this fall. I'm planning to just put the dirt back in, or might go with the gravel idea, I'm not sure yet. It seems like the gravel wouldn't pack as well though. One idea I though of is to put a layer of gravel or maybe some sand about 6 inches thick, then put the dirt back in. That would give the water a place to drain out at the bottom of the pole, while still have the clay packed around the rest of the pole.

Hopefully this thread will help me out too!

One more thing I just thought of is this. The pressure on the pole is straight down (unless the builder didn’t get it plumb), so what is the advantage of concrete around it? The footer on the bottom is the important thing – it’s purpose is to keep the pole from sinking or settling vertically. Nothing is going to try to move the pole horizontally, unless someone drives into it in which case it would probably break before it moved, with or without concrete. I can see where if the footer at the bottom was a smooth surface and not level, then the bottom of the pole might want to slide one way or another. But, since the pole is in 3 feet of dirt, the dirt should be enough to keep it in place. At least it seems like it to me, but I’m not an expert!

 

[Chuck52]

When I built my pole shed last year, the inspector said he had heard that concrete encased treated lumber tended to rot faster than if it was just in dirt. There was a pretty long discussion about that here last year, but I can't recall if we came to a consesus of opinion. I poured a pad for each pole. I spiked each pole with 60d nails on all four sides and then coated the bottom four feet of each pole with the tar-like sealant that's used on foundation walls. I poured maybe 6" of concrete around each pole, and then packed in the dirt. The spiking and concrete were at the recommendation of the inspector, who pointed out that we get some fairly high winds around here, and he had seen poles pulled out of the ground. I added the tar just because I had it and thought it might help prevent wet rot.

Chuck

 

[Mosey]

I just finished reading the post <A target="_blank" HREF=http://www.tractorbynet.com/cgi-bin/compact/showflat.pl?Cat=&Board=projects&Number=181341&page=0&view=collapsed&sb=5&o=0&fpart=>books on building pole barns</A> (which I stopped reading earlier when it diverted to friction piles. I can’t use friction piles because I’ll be using this building as a garage with electrical, so it’s not a barn.). So, I see now that one of the concerns is that wind could cause the poles to be lifted. I didn’t realize that. In that case, I can see where the concrete would be useful. I still don’t plan to use concrete though, unless something said here or someone else says something to change my mind. My property is right next to a hill with lots of tall trees, so most wind just tends to go over us.

 

[Mosey]

Spencer - I'm a little disappointed how fast this thread died out! I bought some <A target="_blank" HREF=http://www.hometime.com/Admin/shopsite/p_7074.htm>plans</A> at a lumberyard this weekend that has plans for 5 sizes of pole barns, 24'x24' through 40'x64', with 8', 10', or 12' high walls. The plans are from a company called Garlinghouse. They show a footer at the bottom of the post, then a gap of a mix of sand and gravel, then a layer of concrete 18" long going all the way to the top, so it doesn't form a cup and leaves a place for the water to run out.

 

[wroughtn_harv]

Let me weigh in for concrete, lots of concrete. It's sorta like being thin or rich. Too much is all in your mind.

But, and this a butt or Rosanne Barr proportions, why do we insist upon putting the post into the ground along with the concrete?

Think about it. The guys and gals who design this stuff usually draw it up where wood post is attached to a bracket that's attached to the reinforcing steel in the concrete footing.

When I built the fancy pavillions and arbor out of the cedar beams I used stainless pins into the cocrete footings with a stainless plate welded to it about an inch an a half off the deck. That way the cedar wasn't exposed to sitting in water.

You can buy plates at your local box store, Home Depot or Lowes. They are designed to grip and support the post and some of them have a spacer to keep it up off the deck so it won't be sitting in water.

Another thing to consider is the soil. If it's well drained the water will not stand just around the post. In that circumstance I can see where the concrete will hold the water where the soil wouldn't.

But if the soil is a thick clay like we have in norte tejas it will form a vessel around the post just as bad as the concrete for holding in the moisture. So under those circumstances I see it as half dozen one way and six the other.

The most important thing is that there isn't a place for the moisture to pool and sit around the wood.

Morton Barns who make the best wood beamed barns I've ever seen. They have great attention to detail and quality of materials and construction. They concrete in their posts.

If you ever want to have your clock wound be at a Morton Barn building site when the truck arrives to deliver the materials. A semi shows up with it's forty foot trailer with all these neat bundles of this and that and some of the other. But everything there including the sacks of redimix concrete on the truck to be unloaded.

The semi drops the trailer. Then like magic from behind the cab unfolds a fork lift attachment. It works off the truck and the driver operates it from the cab via his mirrors. He backs up and picks up one bundle after another and places them where he wants. When the trailer is empty he folds the forklift thingy dingy up and reattaches the trailer and he's off to bigger and better things.

Then when the installation crew shows up they have the tractor of tractors to work with. It's the rube goldberg of tractors. It's portable scaffolding, three point auger post hole digger, front loader, and just about anything else imaginable to be needed to put up a barn all on one machine about the size of a 570 Case.

 

[Spencer]

Danny,
That sounds like a logical way of doing it. I might have done it that way had you came across that earlier. I went down to the township offices to see what I "had" to do. The inspector wasn't in so one of the girls in the office called him on the two-way. He said that the concrete cookie was all that was neccessary.

I already had the posts sitting on the cookies and I had already put spikes through the posts about 4" to 6" from the bottom. I poured in about 10" of concrete, angled it away from the post on all sides, and let that cure overnite. I then put in about 6" of the 60/40 gravel-sand mixture and filled the rest with clean fill sand. I put in about 5 shovel fulls at a time and then tamped that down. Each tamped layer was about 3" thick so it took me all day just to do five posts. I was using a 2"x4" to tamp with on the first five holes. I stated the next two posts on Sunday and I switched over to using a landscape timber to tamp with. I didn't measure it but it is probably around 3"x5" (2.5"x4.5" actual). It sure does go a lot faster tamping with the landscape timber but I don't think I am getting it quite as compact as when I used the 2"x4".

 

[wasabi]

Re: Tractor of tractors...

<font color=blue>Then when the installation crew shows up they have the tractor of tractors to work with. It's the rube goldberg of tractors. It's portable scaffolding, three point auger post hole digger, front loader, and just about anything else imaginable to be needed to put up a barn all on one machine about the size of a 570 Case. </font color=blue>

WHarv....you just described my PT 2445 to a Tee!