Should I Be Afraid of a Pole Barn

[Gizmo2]

If the post is not setting on top of a pad of concrete, the area that is supporting the weight of the building has been reduced to the cross sectional area of the post, which is pretty small. The weight of the building will force the post through the concrete collar, so I don't see what the value of the concrete is. Normally a building will require about a 16" diameter concrete pad to achieve sufficient area for soil loading.

IMO, So water can get trapped and rot the pole.

 

[Nissan197]

I have a pole barn and also live in KS. My posts are treated and were placed in a hole with gravel and concrete. It has been through many wind storms and has held up.

 

[Depmandog]

If the post is not setting on top of a pad of concrete, the area that is supporting the weight of the building has been reduced to the cross sectional area of the post, which is pretty small. The weight of the building will force the post through the concrete collar, so I don't see what the value of the concrete is. Normally a building will require about a 16" diameter concrete pad to achieve sufficient area for soil loading.

The bottom of the holes were virgin undisturbed soil. Gravel was placed in the hole (6") to keep water away from the base of the posts. Once the post was placed, it was dropped up and down repeatedly to compact the gravel. So the post was setting on a solid footing.

Have you ever tried to pull out a post (any post) that has been concreted in place? It's almost impossible without digging the dirt from around the concrete. Use whatever you want to pull it. It is held in-place by the bond of the concrete to the post and the resistance of the concrete to the soil. If it is so hard to pull up, likewise it just as hard to push down (even more difficult because it is resting on a compacted base.)

Don't mean to be argumentative, but I have considerable experience building structures. My methods work fine for Missouri soil. If I were building in sandy soil or other I would reconsider my methods.

My building has not (nor will not) settle. It has been 10 years.

Have a great day!

Dean

 

[BeezFun]

The bottom of the holes were virgin undisturbed soil. Gravel was placed in the hole (6") to keep water away from the base of the posts. Once the post was placed, it was dropped up and down repeatedly to compact the gravel. So the post was setting on a solid footing.

Clay soil can support about 2000psf, pure gravel is around 5000psf. So unless the concrete collar was engineered to become an integral part of the post, ignore it and figure out how much load the post can support directly on the gravel. Either the gravel or the soil will shear first, need to figure out which. If it's 6x6, each post is 1/4 square foot. The gravel supports 5000psf so that post will support 1/4x5000= 1250 pounds into the gravel. Loading spreads about 60degrees from horizontal in gravel so if there's 6" of gravel, the load is projected out to the side about:
6*tan30= 3.46 inches. Post is square but assume it's round 6" diameter to make things easier, so the increase in area is about a factor of 10, which means the 1/4 square foot post loading is spread over about 10/4 sf of soil, call it 2.5sf. So that's 1250lb/2.5sf= ~500 psf, which is well below the capacity of most soils. So the limiting loading is into the gravel and you can have about 1250 pounds on each post.

Not sure what a building weighs but it's not that hard to add it all up and divide by the number of posts. If that number is less than 1500 it should be OK, if it's greater, probably not so good.

For comparison, a post sitting on a 16" round concrete pad has area:
3.14x8**2/144 = 1.4sf
If it's on 2000psf soil it can support:
1.4sf*2000psf = 2800 pounds
Which is about two and a half times putting it on gravel. That means you might have to have 2.5 times as many posts in a pole barn set on gravel to support the same weight as if you put it on 16" concrete pads. That assumes it's all well drained, add water and all bets are off.

 

[two_bit_score]

I removed a wooden fence from my former property in Harris County Texas in 2004 that I had owned for more than 20 years and the fence was built in 1970
The boards and runners were somewhat rotten, but the post when pulled from the ground (embeded in concrete) were just like new. Some of the bottoms were bare of concrete for 4" or more with no signs of rot. These were in a poorly draining area and stayed wet during the winter months. I dont think you would have any problem with rot in a properly treated and concreted in post. When placing concrete around post, I like to place a bit of concrete in the hole first then place my post to insure complete encasement, then I mound up the concrete around the top to form a conical shape that drains all the water away from the post. Concrete bonds to the wood well enough to form a water tight barrier. That being said, my preferred method would be to pour a concrete pillar with 4 vertical rebar reinforcement and 6x6 wire mesh cage around the rebar, embed galvanized anchor bolts and then using L shaped brackets, bolt the post to the concrete pile.

Concrete keeps the termites away from the wood.

 

[timswi]

Built a 30x30 6x6 PT pole barn is 1994 and it still looks like the day I built it...Built one at the new house 7 years ago (30x48 6x6 posts), and it still looks like day one..Don't be afraid.

 

[Luremaker]

The State of Colorado wants at minimum a 24" concrete pad. Does not matter what the guys here put under their post. You must follow the local code and put what your local building official wants under the posts.

 

[BeezFun]

The State of Colorado wants at minimum a 24" concrete pad. Does not matter what the guys here put under their post. You must follow the local code and put what your local building official wants under the posts.

Yes, it's good guidance, that's what I would do whether it's code or not. There is nothing more important or difficult to fix later than the foundation of a building.

 

[whistlepig]

A concrete pad under the posts is a given. Without the pads under the posts the poles will sink. That's code around here and truly just plain common sense.

 

[Duffster]

The State of Colorado wants at minimum a 24" concrete pad. Does not matter what the guys here put under their post. You must follow the local code and put what your local building official wants under the posts.

It's pretty ingnorant on their part to say that a 24" cookie is needed.

Big difference between a 24' building on 8 foot center vs. a 80' or more on a 10 or 12 foot center.

 

[300UGUY]

The State of Colorado wants at minimum a 24" concrete pad. Does not matter what the guys here put under their post. You must follow the local code and put what your local building official wants under the posts.

Lots of guy down here in the states will do whatever they can get away with. Local authorities are chasing a guy around now that put a trailer on a foundation, in a sub of stick built homes. I'm thinking he will lose, but the case has been ongoing for years.

 

[Luremaker]

Lots of guy down here in the states will do whatever they can get away with. Local authorities are chasing a guy around now that put a trailer on a foundation, in a sub of stick built homes. I'm thinking he will lose, but the case has been ongoing for years.

I am sure that goes on everywhere! I say if you are going to do you might as well do it right the first time!

 

[buck12]

We have 4 pole barns from 40 years old to 10 years old. Have not had any trouble.
The treated post used in a pole building, whether laminated or not, with good drainage will last a very very very long time. Typically the post will rot because of poor drainage due to no over hang or gutters to keep the water running away from the poles. The poles will rot where the post meets the ground with poor drainage not below the ground. Lack of oxygen helps preserve the part in the ground and if treated properly no bugs will eat it either. The best part of a utility pole is typically the part below the ground. The top is in the weather and will show splitting as the sun drys it out and where its meets the soil is where it will rot, same as a fence post.
Concrete should always go under the post to act a footer, not around it as this wil premote rotting. Sand or a mellow well drained soil should go around the post. Most of the post building companies in our area have a preformed round concrete footers to put under the post. A bag of powdered premixed concrete will work as well.
Now since some areas that have drainage issues there is what is called a perma collumn which is a cyclinder form you place in the ground and pour concrete in. It should come up above the ground. You then have a bracket you bolt the post to above ground. These are used to repair post that have rotted at the ground and are used in new constuction as well.
I wouldn't be afraid of a pole/post building as they go up fast and are economical alternative to a foundation building. :thumbsup:

We used a similar process to repair a rotted post on my Dad's barn. The barn is 30 plus years old. I helped Dad build it when I was a kid. Probably more in the way than help. Any way one post out of the original ten rotted at ground level a few years ago. We temporally jacked that corner of the barn, poured a concrete base with steel uprights, cut out rotted post section and secured post to steel. Good as new. I don't know if the post rotted due to poor drainage or if the treatment didn't penetrate the one post. To the op this building has held up fine for 30 plus years with one post repair so I would not shy away from a pole barn.

 

[Gizmo2]

It's pretty ingnorant on their part to say that a 24" cookie is needed.

Big difference between a 24' building on 8 foot center vs. a 80' or more on a 10 or 12 foot center.

Well I was thinking the same thing.

 

[ray66v]

You call it ignorant, I call it doing it right.

Codes are not usually based on unknown factors, they are based on previous failures. Most builders know what it takes to do it right, rather than the minimum they can get away with. If they would do it right that all the time, we would not need inspectors.

I don't go for precast plugs, or throwing a bag of dry cement or two in the hole, and putting a building on top of it. Yes, they can work. But, I have also seen these settle. Is that going to matter much if it is a chicken barn? Nope. It will matter though, if it is a finished garage.

10" x 24" poured, does not take a lot of cement or time, and it certainly is solid.

That's doing it right.

 

[Gizmo2]

You call it ignorant, I call it doing it right.

Codes are not usually based on unknown factors, they are based on previous failures. Most builders know what it takes to do it right, rather than the minimum they can get away with. If they would do it right that all the time, we would not need inspectors.

I don't go for precast plugs, or throwing a bag of dry cement or two in the hole, and putting a building on top of it. Yes, they can work. But, I have also seen these settle. Is that going to matter much if it is a chicken barn? Nope. It will matter though, if it is a finished garage.

10" x 24" poured, does not take a lot of cement or time, and it certainly is solid.

That's doing it right.

Really?
In this case I think the code is a one code fits all.

 

[deereman75]

My uncle has a few pole barns on a lease, and he is required not to use any concrete. They are still holding just fine years later. If you are on a lease, you can only use wood foundations, no pouring.

 

[Bigkrank]

Don't think in all my years of digging I've ever seen any piece of wood that was buried more than a foot deep rot. They always rot near the top of the ground. I've dug up old fence post anchors 100 years old that looked almost new.

On my 4 pole barns concrete went under and around the posts until a foot below the surface, then gravel. Still like new.

 

[slowzuki]

Exactly, they try to simply what is really needed.

We've got 50+ psf snow loading on low slope roofs here. My sister has a 24 x 60 something pole machine shed with 12 ft spacing on the untreated spruce posts set directly into clay about 2 feet deep. (No we didn't build it)

It is 30+ years old now and I had to replace the first posts last year. The previous owner spent barely anything on it and it lasted quite well. Depends what you want to do with your building.

Really?
In this case I think the code is a one code fits all.

 

[Duffster]

You call it ignorant, I call it doing it right.

Codes are not usually based on unknown factors, they are based on previous failures. Most builders know what it takes to do it right, rather than the minimum they can get away with. If they would do it right that all the time, we would not need inspectors.

I don't go for precast plugs, or throwing a bag of dry cement or two in the hole, and putting a building on top of it. Yes, they can work. But, I have also seen these settle. Is that going to matter much if it is a chicken barn? Nope. It will matter though, if it is a finished garage.

10" x 24" poured, does not take a lot of cement or time, and it certainly is solid.

That's overkill.

Fixed it fir you.