Concrete Pad For A Pole Barn

hotrod coupe

Well-Known Member
I have a 40x80 pole barn that I would like to have completely poured. It is presently dirt except for the 20x25 pad that I had poured by a friend of a friend, cheap and not the quality that it should be but there are no problems with it yet and a dream to work on so I want to do the rest and would like to do it as close to correct as possible. We have no codes, be as stupid as you want but don't whine when it fails. I plan on installing a four post lift [ bendpack will probably be my choice] read your post on concrete and height and believe a 4 post will work better for my purposes. I don't see how a footing would work with an existing pole barn though as the first pour was just a slab. Your insight on this would be greatly appreciated.
Id select a 4500-5000 psi rated concrete its going to cost you about $15-$20 more than run of the mill concrete per cubic yard ,
and run some number 5 rebar about every 4 feet in a criss cross pattern,
and along the perimeter but it will be much less likely to crack later
Id specify no less than 4" thick that should take about 40 yards
as you stated you have about 3200 sq ft of surface, theres 9 cubic feet in a cubic yard so three times that at 4" thick, or 27 surface feet per yard if 4" thick
concrete varies a bit but lets $125-150 per yard.. thats $15000,to $16000 plus labor and rebar,
id expect a $19000-$21,000 bill
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The slab - 3200 square ft minus the 500 sq ft pad already poured is 2700 sq ft. In simple terms, a yard of concrete covers 81 sq ft when poured 4” thick.
In my opinion it’s a waste of money to pour 4500 to 5000 psi through out the whole pole barn unless commercial or industrial use is planed. You could just increase the weight for the area encompassing the 4 post lift, but even that makes little sense as all you need is to dig out for pier spots in the general area that is proposed for the lift. You can make the piers while preparing before the main pour (pouring over the piers) or you can dig out for the piers, reinforcing with rebar and make it a monolithic pour.

Now about cracks in concrete. I’m not familiar with the soil conditions in MO, but just as in painting a car, proper preparation is key to a good job and minimal defects appearing later. A minimum 3” to 4” of modified stone base to allow water drain not collect under the slab thereby avoiding unwanted pressure that is a common culprit for cracking concrete. A minimum #6 reinforcement wire is more important than rebar in any concrete pour. And last but not least is laying down a layer of plastic vapor barrier. It doesn’t matter that this is a pole barn, a basement or an attached garage, moisture that is wicked up from the ground Will evaporate into the enclosed space and even though you may not see it, it Will condense somewhere within the building and cause (in time) corrosion and/or mold growth. This may occur to the building or the contents contained within. The benefits far outweigh the little bit of additional cost of the few rolls of plastic!.

If you divide the floor area with a expansion grove very 16’ along the 80’ run and a grove division down the middle of the 40’ width. This is done so that when the pad moves, it will crack invisibility inside the grove. This grove can be tooled into still wet concrete as it’s being finished, or cut with a saw later after the concrete sets. Note* it’s a major pain in the ass to work splits into wet 5000 psi concrete with all that extra aggregate stone.
most of the above info is useful and valid, and bringing up the points with the people doing the construction before they start ,
and making sure they follow through, TO DO AS INSTRUCTED, during the process is well worth the time AND MINIMAL ADDED EXPENSE
but ID point out that the use of the stronger 4500-5000 psi concrete, and the added cost is a very minimal concern compared to the additional strength it adds
I found that the use of the higher strength concrete made the installation of my lift more rigid,,
in fact the people that installed my lift professionally commented that it was rather rare to find anyone who bothered to do the installation correctly
and I had my anchor bolts drilled and imbedded to a depth exceeding 10" and theres at least 10 bolts on each vertical pillar

this picture I found else ware is the result of crap concrete of limited depth and strength


I opted for the thicker base and the larger longer and much stronger base mount bolts now it might not look like much of a difference but its those minor extra options you do that mater
remember you can't bench press a car,, so making damn sure the lift is firmly anchored maters

read through this thread

I was rather shocked but not really surprised at this video of horrible sub standard work on a concrete pad
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This early spring I had a pad poured for my Mohawk 2 post lift. Any time you know what’s coming you know what to prepare for. I staked out for 12” X 12” - 36” deep piers exactly where the posts will stand and all the concrete is 4,000 psi for 6” thick concrete in the bay area of the lift. This is more than enough needed. I made sure the pour wasn’t done in the summer heat, I wanted a slow cure so I kept the pad wet down everyday and covered. The heat from the chemical curing process was slow and steady for really hard concrete.
It was far from easy not able to get on my knees, but I insisted on doing my own bull floating and mag trowel before steel troweling. Too many guys overwork the cream to the top on interior finished concrete. On a garage floor it makes the surface weak and stains permeate deeper - almost permanently.

Ask me how I know this crap.
I want to add that while it’s great idea to exceed acceptable standards, there comes a point when overkill can be a waste of time and money. Good sense and logic must be applied.