Pole barn concrete dilemma

jlesliel · May 23, 2014

I've been lurking on this site for a few years now and seen many pole barns built here and have seen some really nice ones. I finally decided to go with a pole building vs stick built. My dilemma is how to do the concrete. I see most of you guys that build are up north and half to worry about the frost line. My decision was based on wind and mainly tornadoes. My plan was also based on building as I had the money so I had a structure with a roof built with intentions of finishing it myself. I now have the cash for the concrete but have 2 estimates that are way far apart price wise. I am asking for advice on what to do. I know you guys like pictures but, where do you want me to start? I have pics from bare dirt to current state.

s219 · May 23, 2014

I got a high quote to start, but finally got more reasonable ones. So keep trying to get estimates. I think I called 8-9 contractors. Only three got back to me. Several did not return calls, and two were no-shows after promising to come by. Must be a nice business with more work than they need.

Typical price here in my area is $250-275 per yard for materials and labor.

whistlepig · May 23, 2014

For wind and tornadoes here we drilled holes in the poles and ran a full length of rebar across the floor through these holes. Then poured the concrete over this rebar.

jlesliel · May 24, 2014

I guess I should have been more clear. One guy wants to go in, put rebar on chairs and pour. The other says I need "beams" along withe the rebar . Beams are basically 6 inch wide, 6 inch deep trenches dug every 10 feet like a tic tac toe grid. Also he wants the same type of trench around the perimeter inside, between the poles. He then wants 1/2 inch rebar in those trenches. I don't see the need for all that after all I'm pouring 6 inches as it is to support a 15,000 lb motorhome.

Ken45101 · May 24, 2014

Geesh, no wonder the variation in price!

Personally, if you have good solid ground underneath, I do not believe in the trenches or rebar. I like 6" fiber reinforced concrete. We have 1500' of driveway coming up a steep hill that was done that way 40 years ago (except there was no fiber back then). It's in great shape.

If you want more than 6" alone, pour 8". Concrete is cheap compared to the labor for all the fancy trenches, etc.

leveled · May 24, 2014

In my barn we did 5" and I used a really heavy plate compactor (heaviest I could rent) I put expansion board around each pole then soft cut the floor at each post as close as i could get to them, about 1 - 3 " it did finish on its own :thumbsup:. My floor has been in for 3 years and i have zero cracks.

paulharvey · May 24, 2014

jlesliel said:
I guess I should have been more clear. One guy wants to go in, put rebar on chairs and pour. The other says I need "beams". Beams are basically 6 inch wide, 6 inch deep trenches dug every 10 feet like a tic tac toe grid. Also he wants the same type of trench around the perimeter, between the poles. He then wants 1/2 inch rebar in those trenches. I don't see the need for all that after all I'm pouring 6 inches as it is to support a 15,000 lb motorhome.

The outside trench is called a "thick edge" on a monolithic slab, but it's really just a footer. Being that the building weight isn't really on the slab in a pole barn, it's not technically needed; but I would make sure you have at least a 6" slab with wire on compacted dirt for anything you drive on. The grid of 6" with rebar sounds like a lot of trouble, when you really probably should go 6" thick throughout. At the door/entrance I would make sure I made the edge a bit thicker and have rebar in it. In between the poles, the edges have no stress put on them unless your driving in/out at that location. Fiber is cheap and easy, but nothing makes up for a well compacted ground free from fat clays and organics. I've personally demoed a lot of concrete drives, and the ones with WWF (welded wire fabric) hold up better to beating on it with a back hoe, and generally are in good shape after years, where as the 4" slabs without wire are normally pretty broken up just from car traffic.

jlesliel · May 24, 2014

Well, around here, rebar is a must, i already have that bought and the chairs. I can see going with the beams in the tic tac toe grid for strength but to me the perimeter beam is a waste. Around here pole buildings are not common. My thinking is he is so used to pouring footers for stick built that he thinks I need them too.

Ken45101 · May 24, 2014

As I understand it, rebar will not prevent cracks, that's more a function of the ground and the concrete pour. Rebar just prevents the cracked segments from shifting or moving.

s219 · May 24, 2014

Around here, we call the thickened edge a "turndown". I am doing one simply to keep the fill bed contained so that it does not put pressure on the skirt board and bow the wall if there was settling. Turndowns can be dug with a flat bottom to be load bearing, but mine simply taper down.

s219 · May 24, 2014

whistlepig said:
For wind and tornadoes here we drilled holes in the poles and ran a full length of rebar across the floor through these holes. Then poured the concrete over this rebar.

I looked into doing that too, but realized that it will transfer loads from the floor to the pole footings, so the footings must be large enough to handle the load (both weight of slab and what's on it). That was not in my footing calculations, so we're not doing it.

paulharvey · May 24, 2014

Compaction is key with a slab. No matter what else you do right, if you don't have a compact base, your slab will fail over time. Not to say things can't go wrong on top of a well compacted clean fill base, but as long as you pour 6" with fiber or WWF, a single or double #5 rebar at the edge you drive over, and pour a real 3000 psi concrete at a reasonable slump (6" slump is ok, but order a 5" and add no more than 10 gallons of water to a full truck; your good to go for 50 years.

brokenknee · May 24, 2014

Ken45101 said:
Geesh, no wonder the variation in price!

Personally, if you have good solid ground underneath, I do not believe in the trenches or rebar. I like 6" fiber reinforced concrete. We have 1500' of driveway coming up a steep hill that was done that way 40 years ago (except there was no fiber back then). It's in great shape.

If you want more than 6" alone, pour 8". Concrete is cheap compared to the labor for all the fancy trenches, etc.

I went with a 6 inch pour fiber reinforced concrete on my last shed, huge mistake, concrete cracked and heaved in a number of places 40 X 60 shed. I tried to save a few dollars by skipping the rebar. I would never do that again. Yes concrete will crack but the rebar will minimize the heaving issue. Have since sold the place and is no longer my issue.

Gary Fowler · May 24, 2014

I think everyone covered issues pretty well. I would put in the edge thickened slab at any point where I would be driving in or out. I personally like to see them around the whole perimeter especially on a pole barn simply because people change their mind about the use and with the full perimeter thickened, less likely for any edge cracking to occur. The "tic-tac" square that you mentioned are usually placed in load bearing areas to support the roof and walls in domestic construction and should not be needed for a pole barn. Make sure you use enough chair lugs to keep the wire off the ground even with weight of concrete and workers walking around on it when placing the concrete. The "Pull up" method where the worker uses a hook to raise the wire after placing the concrete which a lot of concrete contractors like to use is no good and wire just settles back on the ground.

The only way I know of to eliminate heaving due to frost heave is to pour your slab on top of a 6" thick or thicker piece of HD foam. This is what we used up in Northern Alberta Canada under all slabs. This allows the ground to heave a bit without affecting the concrete and also provides some insulation against the cold penetrating into the ground under the slab. The foam isn't cheap, but neither is repairing frost heaved concrete.

Most contractors don't actually do a slump test and just eyeball the consistency of concrete. Some are good at it while others usually get too much water in the mix which weakens the concrete. Many batch plants will send sub-standard concrete to users when they know concrete test cylinders are not going to be made to check for strength. These cylinders are worth the little bit of money it takes to have a test lab cure them and break them. You should in any case inform the batch plant that test cylinders will be made and that in itself will likely insure a good mix is delivered. You could put concrete slump testing and making cylinders in as part of your bid process. If a contractor cant do that, then he is not worthy of your money or project.

BHD · May 24, 2014

I would suggest some thicking of the edge, so animals cannot dig under it easily,

If the building is going to be heated in the winter, you may want to go below frost line, (the out side edge) if no heated and the building will get as cold as the out side, not as important, IMO, but like I said I would go some for keeping animals out, if it gets under minded you will have problems,

I would most likely run a premiter rebar, and across the door ways (equipment) and deepen them as well,

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

what kind of soils do you have, expansive clays or sands or what?

if your dealing with expansive clays, then the guy with the cross footers and rebar may be the better bet,

or one may want to dig it out and replace the clay with rock and gravel, and sand,

EddieWalker · May 24, 2014

Have you already built the pole barn? If you haven't started yet, and you are going to pour concrete, then you are better of going with stick frame construction. The advantage of a pole barn is that you don't need to spend the money on concrete to have a strong building. But if you are going to spend the money on concrete, then that advantage is lost and you are better off stick framing on top of a concrete footing.

If you have already built the pole barn and now want to add concrete, there is no advantage to having footings around the edge since there isn't a load to support.

Never use wire in any sort of flooring. It is 100% impossible to spread the concrete and have the wire in the middle of the concrete. Some contractors will tell you and even play the game that they pull it up as they work, but it's impossible to stand on the wire and pull it up into the mud and have it stay there. This game usually only lasts about ten minutes, and then they are too busy spreading the mud to pretend anymore anyway.

Fiber will help but it does not replace rebar. Nothing wrong with adding it, but I would never replace rebar with fiber.

Concrete will crack. Rebar holds it together and stops the cracks from spreading. You can cut expansion joints into the concrete, but all that does is make the concrete thinner in that spot and increase the likely hood of it cracking. You just don't notice is as much when it cracks in the cut line.

Going thicker will give you more strength, but adding a sack to the mix and pouring it as dry as possible will also give you that strength. If the soil is compacted, 4 inches is plenty for a full sized RV. Most parking lots, driveways and RV Pads at RV Parks are 4 inches thick.

Did you build up original soil and how was it compacted? You will never get soil compacted with a vibratory compact. A jumping jack does alright for small areas, but you really need a vibratory roller to do it right. I worked jobs where we failed compaction tests after days of running compactors over it. Getting new soil solid is very difficult!!!!!

The guy who recommended digging benches has me wondering what type of soil you have? That is done for really poor soil and highly expansive clay soil. Does he know something the others don't? Every type of soil has a load bearing rating. some soil is great, others never stop settling or moving. You have to know what you have to know how to design a foundation.

Eddie

jlesliel · May 24, 2014

BHD said:
I would suggest some thicking of the edge, so animals cannot dig under it easily,

If the building is going to be heated in the winter, you may want to go below frost line, (the out side edge) if no heated and the building will get as cold as the out side, not as important, IMO, but like I said I would go some for keeping animals out, if it gets under minded you will have problems,

I would most likely run a premiter rebar, and across the door ways (equipment) and deepen them as well,

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

what kind of soils do you have, expansive clays or sands or what?

if your dealing with expansive clays, then the guy with the cross footers and rebar may be the better bet,

or one may want to dig it out and replace the clay with rock and gravel, and sand,

It will not be heated. If it's too cold for me to be outside, I'm staying in the house!

As far as the animals, I have spread 6 to 8 inches of crushed concrete out 12 feet in each direction around the barn. Will that not deter animals? My soil is called "sandy Loam"

jlesliel · May 24, 2014

EddieWalker said:
Have you already built the pole barn? If you haven't started yet, and you are going to pour concrete, then you are better of going with stick frame construction. The advantage of a pole barn is that you don't need to spend the money on concrete to have a strong building. But if you are going to spend the money on concrete, then that advantage is lost and you are better off stick framing on top of a concrete footing.

If you have already built the pole barn and now want to add concrete, there is no advantage to having footings around the edge since there isn't a load to support.

Never use wire in any sort of flooring. It is 100% impossible to spread the concrete and have the wire in the middle of the concrete. Some contractors will tell you and even play the game that they pull it up as they work, but it's impossible to stand on the wire and pull it up into the mud and have it stay there. This game usually only lasts about ten minutes, and then they are too busy spreading the mud to pretend anymore anyway.

Fiber will help but it does not replace rebar. Nothing wrong with adding it, but I would never replace rebar with fiber.

Concrete will crack. Rebar holds it together and stops the cracks from spreading. You can cut expansion joints into the concrete, but all that does is make the concrete thinner in that spot and increase the likely hood of it cracking. You just don't notice is as much when it cracks in the cut line.

Going thicker will give you more strength, but adding a sack to the mix and pouring it as dry as possible will also give you that strength. If the soil is compacted, 4 inches is plenty for a full sized RV. Most parking lots, driveways and RV Pads at RV Parks are 4 inches thick.

Did you build up original soil and how was it compacted? You will never get soil compacted with a vibratory compact. A jumping jack does alright for small areas, but you really need a vibratory roller to do it right. I worked jobs where we failed compaction tests after days of running compactors over it. Getting new soil solid is very difficult!!!!!

The guy who recommended digging benches has me wondering what type of soil you have? That is done for really poor soil and highly expansive clay soil. Does he know something the others don't? Every type of soil has a load bearing rating. some soil is great, others never stop settling or moving. You have to know what you have to know how to design a foundation.

Eddie

I had a well known dirt guy in the area come out and make me a built up area before building the barn. I trust him to use the right type of dirt for what i'm doing. After the barn was built he came back and leveled the inside with what he refered to as "select fill" also called "cushion sand" around here.
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bcain1014 · May 24, 2014

EddieWalker said:
Have you already built the pole barn? If you haven't started yet, and you are going to pour concrete, then you are better of going with stick frame construction. The advantage of a pole barn is that you don't need to spend the money on concrete to have a strong building. But if you are going to spend the money on concrete, then that advantage is lost and you are better off stick framing on top of a concrete footing.

If you have already built the pole barn and now want to add concrete, there is no advantage to having footings around the edge since there isn't a load to support.

Never use wire in any sort of flooring. It is 100% impossible to spread the concrete and have the wire in the middle of the concrete. Some contractors will tell you and even play the game that they pull it up as they work, but it's impossible to stand on the wire and pull it up into the mud and have it stay there. This game usually only lasts about ten minutes, and then they are too busy spreading the mud to pretend anymore anyway.

Fiber will help but it does not replace rebar. Nothing wrong with adding it, but I would never replace rebar with fiber.

Concrete will crack. Rebar holds it together and stops the cracks from spreading. You can cut expansion joints into the concrete, but all that does is make the concrete thinner in that spot and increase the likely hood of it cracking. You just don't notice is as much when it cracks in the cut line.

Going thicker will give you more strength, but adding a sack to the mix and pouring it as dry as possible will also give you that strength. If the soil is compacted, 4 inches is plenty for a full sized RV. Most parking lots, driveways and RV Pads at RV Parks are 4 inches thick.

Did you build up original soil and how was it compacted? You will never get soil compacted with a vibratory compact. A jumping jack does alright for small areas, but you really need a vibratory roller to do it right. I worked jobs where we failed compaction tests after days of running compactors over it. Getting new soil solid is very difficult!!!!!

The guy who recommended digging benches has me wondering what type of soil you have? That is done for really poor soil and highly expansive clay soil. Does he know something the others don't? Every type of soil has a load bearing rating. some soil is great, others never stop settling or moving. You have to know what you have to know how to design a foundation.

Eddie

I'm planning to put up a 40x50 pole barn with (2) 15x50 sheds in the near future. This will be south of Houston, TX about 15 miles from the coast. Rob-Bilt has quoted me this with 130mph windstorm certification. I'm wanting to frame out 1000 sq/ft for living space.

I thought of pouring 4-6" of concrete inside the footer boards with beams dug and tied rebar. Should I dig out the grass/dirt and replace prior to construction? Or can I cover it with pond and fill dirt for 6 months or so and compact with a 3/4 ton truck prior to putting barn and concrete in? Any thoughts? The heaviest thing inside it will be an 18K pound 38' Toy-Hauler. The framing/building materials will be stored inside too.