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.