Pole barn construction technique

[rtimgray]

From my experience, everything Eddie said is true. If you build an enclosed pole barn with good roof and sides that extend to the ground AND you have good drainage so that water runs away from the building, pretty much any kind of treated post (6x6 CCA or creosote) will last almost indefinately. We've got some barns that have old cedar posts that are in excess of 50 years old that meet the above criteria, and they're still solid.

It doesn't seem to matter if they are set in concrete or just set in dirt - the common denominator is water. One of the barns that is at my place was built in the late 50s or early 60s. It is mostly creosote utility poles and is built on a bit of a hill. The side that faces the hill (i.e. water runs down hill and sits near the edge of the barn - several poles have water damage/rotting right at the ground level. On the other side of the barn, where the ground slopes away, the poles are as solid as ever. In my opinion, keeping water drained away has a lot more to do with pole longevity than any other factor.

Good luck and take care.

 

[flusher]

You can use black automotive spray undercoating to protect the post at the ground interface where the rot occurs. Spray before setting the post.

 

[EddieWalker]

now, are we talking something like the green pt 6x6's you see at HD or lowes?

Or are we talking something else?

And are we talking about poles just buried in a hole, or poles set in concrete?

Wouldnt you want the poles in concrete, or is just buried in a hole sufficient for strength?
Maybe i should just bury posts in the ground for my foundation for the quonset hut? and not worry about concrete?

thoughts?

The older the post, the more mercury used in the treatment of that post. Newer treated posts use other compounds that tend to rust out fastners. I tored down an old barn with posts that where black in color that looked brand new. I know it was built before WWII, but nothing more specific then that. Might have been creosote, but it didn't smell or feel like it. They really just looked dark from age. As for fence posts, I deal with both concrete and just compaced. If you are in sand, you really need the concrete to lock them into place. If it's good clay, then you can compact the clay back in the hole and you don't need concrete. Other then that, it depends on how deep you need to be with freezing and upheave. Here, that's not a problem.

Remember that all the advice and comments you read on here are area specific. My thoughts don't work in other parts of the country. Your soil type and local codes are also going to be more accurate then anything I have to say.

Eddie

 

[rambler]

now, are we talking something like the green pt 6x6's you see at HD or lowes?

Or are we talking something else?

And are we talking about poles just buried in a hole, or poles set in concrete?

Wouldnt you want the poles in concrete, or is just buried in a hole sufficient for strength?
Maybe i should just bury posts in the ground for my foundation for the quonset hut? and not worry about concrete?

thoughts?

I read of different results in different areas, so I'm talking about here, where I am. Different soils, different climate may well need very different solutions. Ok?

The stuff at Home depot is junk, it's light treatment. If you want a burried post, you need it pressure treated to handle that. This is more, and will cost more, than the stuff they have sitting on their shelf. Perhaps they can order the better grade stuff, but they only have landscape treated (just a light soaking), and the lower pressure treated stuff. You will need the higher pressure treated stuff to bury in the ground and expect it to last over 20 years for a building. This is important, you need the right grade of pressure treatment, not the lighter 2 grades!

So - we are talking 'something else'. Actually, the best is laminated 2x6 or 2x8 that are pressure treated heavy. Today's wood is poor, knotty, and twisted, the lambinated columns will be straighter, stronger, and the treatment will get through the entire wood, not just the outer inch or 2. I'd not consider a 'pole' any more, they are just poor quality any more. With the laminated poles made from 3 2x6 you can spend more for better pressure treated wood in the hole, and the above ground portions of the pole can be staggered non-treated wood to save money, and avoid the rusted fastener issues with current pt matierials. Put the money where it's needed, at the soil surface.

'Here' in my clay, high-lime, wet soils a wood post set in concrete is a rotted off post. Quickly. That does _not_ last at all, bad idea, will fail, for sure. (I understand this works in some other climates tho?) Here you put a little donut of concrete around the bottom of the pole down in the hole - this helps anchor the pole into the ground. But you do not want any concrete around the pole near the ground surface at all, and you really don't want the bottom of the pole cupped in concrete - that holds water in the pole. Generally, 'here', concrete and poles is a major mistake. Don't know how it is where you are, but not good at all 'here.' The doughnut, and a few spikes in the pole to hold to the doughnut, is needed.

Local codes do require anchoring the poles - a strong wind will pull them out of the ground, the building will fly like a kite. So you need a big butt on the poles, often that donut of concrete I mention. Some codes require the pole sits on a bigger circle of concrete, like a mini foundation. Keeps the pole from sinking in certain soil types.

Pole rot comes right at the soil surface, where the soil dries out, gets wet, dries out... This is ideal conditions for the little critters thsat eat on wood. Your pole will be fine above ground, and it will be fine 2 feet below ground. It is this 1 foot zone right at ground level that will rot off. I've been to many farm auctions, you look at their pole buildings, kick 3 inches of dirt away from a pole and it will be 1/2 gone. Looks like a new pole on the wall, and if you would dig to the bottom the bottomwould look new, but it's all rotted through in that few inches below ground. Seems stuff built in the 1980's & 90s is really going fast...

--->Paul

 

[rambler]

I was assuming the horizontal "beam" was at grade therefore becoming the bottom.

Typically those are a foot or 2 above ground. A true knee wall.

Even if it were at ground level, a typical shed is not like a house. A house, you tie the wall into the floor, so it has stability in all directions - the floor stablizes it.

In a true pole building, the poles are _not_ tied to the floor. Bad if you do - they need a slip surface for the floating floor to slide on the solid posts. So even if at ground level, there is no side to side support for your knee. If a wind blast hits your wall, there is nothing keeping it from blowing inward - no specific bracing at that joint. The joint is weak, always a joint is weaker than a soild (or laminated) piece of wood.

Be careful of that. Pole buildings or conventional buildings use about the same amount of wood. A pole building saves money with a cheaper foundation (the poles) and it goes up quicker saving labor. Be careful of combining the 2 styles of building. You can quickly run up the costs to where you aren't saving anything at all, and you can weaken the 'strength' of a pole design terribly when you don't use a full pole from bottom of footing hole to top of eve. Things get real weak when you compromise that. Then you need to add heavier materials or special bracing, and there went your cost savings, you might as well have built a real foundation with a real stud wall.

That's were some of the comments from some of the builders on here are coming from - folks are trying to take the cheapest parts of the different construction types and co-mingle them. That does _not_ work, you end up having to overbuild some areas making the building actually cost more.....

If you want a stud wall, embrace the need for a good footing and a building that will last generations.

If you want a cheaper pole building, realize it needs to be a pole building and it's cost savings come from using good poles for cheaper foundation and ease of building.

If you want a floating building on a slab, there are size limitations and realize the slab will crack some day, the building will float.

You won't win trying to find cheaper combinations of these systems, you only break the integrity of the different systems.

--->Paul

 

[EddieWalker]

the best is laminated 2x6 or 2x8 that are pressure treated heavy. Today's wood is poor, knotty, and twisted, the lambinated columns will be straighter, stronger, and the treatment will get through the entire wood, not just the outer inch or 2. I'd not consider a 'pole' any more, they are just poor quality any more.

I see this being done in some areas and question the reasoning behind it. I've cut open plenty of 6x6's and the green treatment goes all the way through in ever post. Each and every PT piece of lumber has a tag on it that states what percent of treatment it's treated for. I've never seen a 2x with anything close to the amount of treatment you find in a post. The next level up from post treatment is pier treatment, and that is something you have to special order.

While I agree that you can get a stronger post out of laminating three together with glue, the difference in strength isn't significant becase either are plenty strong enough to do the job. I've also found that it's a lot harder to find straight 2x material then it is to find straight 6x6's. On the other hand, it's very hard to find a straight 4x4.

I shop the box stores and several lumber yards. I'm a contractor and do this year round. Where are you getting your material? Especially the 2x's that are treated for in the ground, post, instalations?

Eddie

 

[mattbatson]

I know I'm straying from the original topic just a little...
btw, our land is in western NC and the soil is clay.

we are essentially building a deck, with about a two foot crawl space, and tongue and groove plywood, and then fastening a 20x40ft quonset hut onto it.

I think, from my reading/research so far, that we will just use the sonotubes full of concrete.
We will bell out the bottom of the hole that the sonotube sits into, and then when we pour we'll hopefully have something similar to the "doughnut" mentioned earlier, to anchor the post into the ground from uplift.

We will have the sonotubes end about a foot up from grade to help with water issues, and then mount the brackets for our 6x6 posts (I believe the brackets are sunk into the concrete after it is poured...but still learning)

I would think this would keep the wood far from the ground and from splashing water and other things that would rot it.

 

[rambler]

While I agree that you can get a stronger post out of laminating three together with glue, the difference in strength isn't significant becase either are plenty strong enough to do the job. I've also found that it's a lot harder to find straight 2x material then it is to find straight 6x6's. On the other hand, it's very hard to find a straight 4x4.
Eddie

Up here in MN the 6x6 stuff is typically pretty twisted and knots that make it look weak to me. If you pay enough and go to a non-box store you can get good quality southern pine 2x, but - most folks don't like paying enough....

Actually a lot of columns are a 2x6 on each side of a 2x8. They use the little ledge for nailing stuff together, the 'pole' is designed for our snow loads and wind loads.

You can order a shed (matierials list) from one of the box stores, Menard's is the popular one here.

Most of us go to Wicks, Cleary, Morton, or the like and order a turn-key building, put it up in 5 days and be done with it. I happened to get a Morton 45x81x15 built a few years ago, seems to have some good designs to it. The bottom of the posts are well treated, about 3 feet out of the ground is all regular wood. They set the sghort pressure treated parts first, then swing up the walls and spike together the pt and regular wood spices. Unfortunately the November they built it was a terrible harvest, and I wasn't able to watch them work much, needed to work myself, so didn't see as much of the construction as I'd wanted to.

I have a 15'9" high doors, as I have um, whatsitcalled, the bottom chord of the truss is also peaked, argh brain fade... The trusses cost more, but the poles could be cheaper by keeping the walls 15 feet instead of 16 feet. Real balancing act how they figure all that out. Morton brings in good wood from the southern pine of the USA. The northern woods stocked around here are all plantaion, fast growth, twisty wood. Good for 2x4s, but jeez it's getting poor stuff.

I follow your posts, always enjoy your good common sense ideas on building stuff, been reading your messages for years. Can't see anything wrong with the way you construct things.

--->Paul

 

[davedj1]

I think part of the reason for laminates (at least in a local brand pole shed) that above ground they don't use treated lumber. Treated only get's used for below grade to a foot or so above. Non treated lumber is much cheaper.
The company I've seen do this is Morton, they make a nice product. I would also think it might be quicker to set the 5', 6' and 7' pieces, lining them up and no big braces. Just my .02 though.

 

[MarkV]

Rambler I agree with most all you have said but still have questions about the laminated posts. I believe I was the one that first brought up the hinge point question. Still don't think it is a good idea if you ever have any kind of wind load. The first post mentioned that point being about 2' above grade. That was the part with, site built posts, I was concerned with.

Would not a laminated post, where you are switching materials with an overlap, also be a hinge point? I always liked the Morton style posts but read they were glue laminated in a press at a factory with heat curing. That is way different than site build posts spiked together. I could be wrong. How were they done on your Morton building? Also how did they do the connection between the PT wood and the white wood.

Interesting discussion. I can understand how a pile type of foundation, on a barn, would be a good idea in regions where you have to go deep to get below the frost line. A continuous perimeter foundation, when you had to go 40" plus deep, can get expensive to pour and form. I don't have that problem here in the South. When I lived in California it was common on hill sides to drill piers and set grade beams on top of them for structures. That was all concrete and rebar but the same principal. When I lived in the Florida gulf new or rebuilt beach houses were built on driven wood piers with a beam on top about 10 feet above grade, that was all wood. If it is common practice in the area I'll bet the engineering has been done.

MarkV