First-timer Building a Pole Barn

[dianewolfe]

We are in the preliminary stages of building a pole barn. The holes are dug. They are 24" in diameter. They will have a 10" concrete layer in the bottom of the pole. The poles are 14" at the butt. This allows for 10" of concrete around each hole, 48" deep. Can you tell me what strength concrete I will need? Thank you!

 

[DJ54]

Myself, I would backfill with a granular type material, not concrete. It's OK for a pad to set on, but a pole surrounded by concrete will hold water, and eventually rot off. If it's poured clear to the top, usually at the surface line.

Granular material will let water eventually leach away. Limestone screeenings work well, or grit type gravel.

Just my opinion...

 

[dianewolfe]

To: DJ54

Thank you for your reply. Unfortunately, the code here calls for concrete backfill. The poles are telephone poles that have been treated with creosote. Hopefully, that will prevent the rot.

 

[DuckHunterJon]

That's too bad that code requires it, as I would agree that generally it is bad to use concrete as a backfill. I personally replaced 30 posts on a pool deck once that had rotted off at the top of the concrete. These were only PT 4x4's, but had rotted completely thru in 7 years. Sorry I can't help with the concrete strength, but I'd encourage you to push back on the code if you can.

 

[LD1]

If the code doesn't specific a specific strength, then just the cheapest bags of quickcrete will work just fine. Concrete is rated in compressive strength. And since it is just backfill, whatever is the cheapest is pleanty strong enough.

 

[Gizmo2]

Myself, I would backfill with a granular type material, not concrete. It's OK for a pad to set on, but a pole surrounded by concrete will hold water, and eventually rot off. If it's poured clear to the top, usually at the surface line.

Granular material will let water eventually leach away. Limestone screeenings work well, or grit type gravel.

Just my opinion...

That is my opinion also. And if I may be so bold, I will say that is what is going to happen.

 

[TXCYCLE]

I would say the previous poster is correct, Quickcrete list a compressive strength of 4000PSI so your post, roof or walls would fail before the concrete. Just a suggestion, to keep the water from standing, could you put three or four 1/2" or 3/4" pieces of pipe or re-bar in the concrete when you pour it-make sure they reach all the way to the ground below. Then pull the pipe or rebar out of the concrete when it's firm but not set-that way water would migrate to the bottom of the hole???

 

[dianewolfe]

To: TXCYCLE,

That sounds like a good idea. I am not giving up on the idea of a gravel mixture as backfill. I will check with the county here and see if the code applies strictly to pole barns. But I really like your idea of constructing a wicking system in the concrete. There might also be some kind of piping materials that provide for drainage. I have another resource as well that might be able to shed some light on this (a college professor/no-charge engineer source of information). We are not done with this yet.

Thanks for your input.

 

[Scotty370]

I can see pouring the "Pucks" in the standard 'wet-pour' fashion and letting them cure, but then I've just pouring the dry-mix in the hole as backfill. It absorbs ground water to fully 'set'! Not sure if that would keep them porous enough to allow water to drain away from the captured post. Hey, seems you'd meet 'code' doing that! ~Scotty

 

[Willl]

When they did my PB, they tossed 2 bags of concrete in the hole (still in the bag), set the pole on top of the bags and back filled with what they called 'torpedo' sand.

 

[Gizmo2]

Could maybe use this...
Rotten Posts - Not a Worry with SmartPost®

or this..
Post Protection For Pole Building, Pole Barns, Decks | Post Protector

 

[jdonovan]

Why not use a form, like a sonotube, and cary the concrete to 4" above grade?

Then you could have a bit of slope away from the post to the edge of the form, and hopefully have very little water drain between post and concrete.

 

[Scotty370]

Diane-I'm thinking a 14" Creosoted Pole is going to give you lots of years of service! There're not like the 4X4 PT a lot of people use, and have 'rotting' problems with. I know you only asked about the Concrete strength, and 3500-4000psi is more that adequate for your base. I can no longer get used poles in NY, as the State has classified them as hazardous waste, since they've been creasote treated!! Thanks NYS! Landfill them, instead of reuse!!
Since this 'Thread' has 'morfed' into a pole barn issue, I just thought I'd throw out this link:

Wood Joinery System | Socket Systems | Home

In the video, "Chuck's Barn" is exactly what I want! In this construction, the wood never goes in the ground! Just stuff, for the group..........~Scotty

 

[Keuka]

Like someone already stated, one of the best backfill materials is limestone screenings. Limestone compacts very well but also lets the water drain away. Concrete encased poles will rot at ground level if the water has no way to drain at the bottom of the hole.

If you are required to use concrete as a backfill, here's a suggestion. Set the pole on the concrete foundation as stated. Backfill the bottom six inches of the pole with compacted limestone screening or sand. This will form a weep allowing the water a way to drain out at the bottom of the pole.

Keep in mind, the existing soil you dug the holes into should also allow water to freely drain. If the existing soil is clay and the holes hold water, the limestone will do little if any good, unless you daylight the weep.

Creosote poles will last a long time, like a life time, if they're new and in good shape. The new preasure treated aren't so good.

The concrete strength is probably stated but if not, 2500 to 3000 psi will more than handle your situation. Ready mix may be cheaper than bags.

 

[mad_planter]

I plan on pouring concrete piers to about a foot above grade and then attaching the posts to the top with steel. This will allow me to avoid wood in ground contact and use green lumber or untreated kiln dried lumber.

 

[jcaron2]

Even just sloping the concrete away from the posts goes a long way toward preventing rot.

One other thing: If you're in a tornado- or hurricane-prone area, it's cheap and easy to drive a few spikes or some pieces of rebar into (or through) the bottoms of the posts before you set them so that they stick out sideways into the concrete. That anchors the posts even more into the concrete, for further uplift protection in high winds.

 

[Army grunt]

I built a pole barn over 25 years ago in Ct. where the frost will go down 48", I put 2 bags( in the bag)Back filled with crushed stone to 12" from surface then top soil graded away from barn, poured a floating pad for floor. Its still there not rotten, an has not moved. You need to look at the back fill with concrete, An look at it in type, **** the reason for building with poles is to keep the cost down..If its true then do as said above an use sona tubes use a fixture on top[ to hold the pole high an dry...
Army Grunt

 

[BHD]

look in to this, Pervious Concrete Pavement for Green, Sustainable Porous & Permeable Stormwater Drainage

it is basically concrete with out sand, and lets water through it, and yet it is still concrete,

http://www.pervious.info/

What is Pervious Concrete?

Pervious concrete is a mixture of coarse aggregate, Portland cement, water and little to no sand. A typical pervious concrete pavement has a 15-25% void structure and allows 3-8 gallons of water per minute to pass through each square foot.

Carefully controlled amounts of water and cementitious materials are used to create a paste that forms a thick coating around aggregate particles without flowing off during mixing and placing. Using just enough paste to coat the particles maintains a system of interconnected voids.

The result is a very high permeability concrete that drains quickly. Due to the high void content, pervious concrete is also lightweight, 1600 to 1900 kg/m3 (100 to 120 lb/ft3).

After placement, pervious concrete resembles popcorn. Its low paste content and low fine aggregate content make the mixture harsh, with a very low slump. The compressive strength of pervious concrete is limited since the void content is so high. However, compressive strengths of 3.5 to 27.5 MPa (500 psi to 4000 psi) are typical and sufficient for many applications.

 

[dianewolfe]

First, I would like to reply to jdonovan:

J, an engineer told me that he has seen the sonatubes actually work their way up out of the ground, or dissintegrate in place. Then, he says that the pole is loose in the hole; no longer in contact with the earth and it undermines the integrity of the structure. I would guess its kind of like the same reason you attach the 2 x 6's or 2 x 8's to the bottom of the pole, to anchor it to the ground.

The post protectors look like a good idea, but the telephone poles are round and not uniform in shape. I would definitely keep the pole protectors in mind for next year when we put up a privacy fence.

I want to thank everyone for their input. This is such a great website! I have never been one to "chat" online, but I am really enjoying the interchange.

We have decided to put 10" of crushed rock in the bottom of the holes (also acceptable by code). This is Colorado and its a very dry climate here, but at certain times of the year, it can be a real mud bath out here. I need time to look at more of the suggestions I've received and I do want to check with the AHJ (Authority Having Jurisdiction), but I'd really like to put rock in the hole (or someone suggested limestone??? Need to check into that too). Anyway, thanks so much for all of your responses.

 

[JJZ 109]

Since this 'Thread' has 'morfed' into a pole barn issue, I just thought I'd throw out this link:

Wood Joinery System | Socket Systems | Home

In the video, "Chuck's Barn" is exactly what I want! In this construction, the wood never goes in the ground! Just stuff, for the group..........~Scotty

Those look interesting, but I know that in at least some parts of NYS trusses have to be of the manufactured variety. Not sure if it goes by building square footage or what the criteria is.
I'd love to put up a small to medium sized building like that to keep my boom lift out of the elements and to store wood pellets.
The concept looks similar to a steel building that I put up a few years ago. Bolt the "arches" together, stand them up, on to the next. I could stand those up with the boom lift, no need for winch/chain/tree method.