Pouring a floor in a pole barn

AndyF · Sep 6, 2002

I built a 24X40 barn last year and am planning to pour a 14X24 floor underneath one of the lofts in the barn. I'll be enclosing this area and using it as a shop. I'll be installing a small heater also so that the shop doesn't go below 45 in the winter (I'm located in central NY and don't want paint to freeze or have condensation on the shop tools). The barn was built on a base of compacted #2 crusher run (sp?).

People around here have recommended that I pour the floor 4" thick using a 4000psi mix with fibermesh. They are also suggesting that all of the poles be isolated from the slab and that I dig down a little in the area where the door to the rest of the barn will be so that at the entrance the concrete will be 12" thick. Everyone has said that with the fiber I will not need to use reinforcing wire

My question to anyone who has poured floors is whether the 4" floor with fiber will be OK or if I should do it some other way. I'll occasionally drive the tractors into the shop, Kubota B7200 and B8200, and will have some small machine tools: mill, lathe, bandsaw, drill press and grinder on the floor.

gerard · Sep 6, 2002

I helped pour a 40 x 40 garage in central NY last year and it was 4 inches thick with the fiber mesh. We also used wire mesh because he had some around but was told it wasn't necessary with the fiber. 4 inches on a compacted base is standared for normal auto traffic and you should be fine although if you run the math, how much you would need to go 5 inches (ie if it wouldn't take another delivery etc) it woudln't hurt. I assume your doing this yourself so you're already saving quite a bit. (I think we poured about $2000 worth of material and the job would have cost about 10K if he would have had it all done including building the forms). If you're doing it yourself I'd try and get a power trowel and a long pole bull float. Having the right tools makes things a lot easier. I would also put down a sheet of 4-6 mil poly sheet on the base before you pour. Keeps the moisture in the mix and retards the curing process which means the concrete cures harder. (This was how they poured the concrete at the Anheuser Busch plant in Baldwinsville NY and many concrete people I've spoken to also advocate the use of poly. Cheap enough)

AndyF · Sep 7, 2002

Thanks for the mention of poly. I've seen it recommended as a vapor barrier for slab on grade construction, but hadn't thought about how it could help with the concrete cure.

Are the power trowels pretty easy to use? My original plan was 3 people with hand trowels to finish the floor, but if a power trowel is easy to use, I could be persuaded to go that route.

Anonymous Poster · Sep 7, 2002

Definitely isolate the poles.
Fiber mesh is good, Fiber + wire mesh is better.
A deep pour across the door is an excellent idea, especially if you put some rebar in the trench, and croshatch it to rebar running 3' back into the floor and out into the apron.
If you have access to a vibrator, definitely use it to knock the air out of any concrete that will be exposed to rain or snow to prevent spalling later.
If you think you will ever pour the rest of the building, install keyways and short rebar to link the floor to future pours.

gerard · Sep 7, 2002

Real easy, just have to go slow and let the machine do the work, very much like a floor buffer, real light tough by the operator, you just guide it a little. If you have access to one or can rent one it's well worth it. Got a real nice finish with it. Trick is knowing when to get on it. Too soon and you gouge things and dig in too easy, too late and you've lost a lot of the cream and the concrete's too hard to finish. I'd also consider going to a concrete supplier (Osbornes is one in Syracuse) and look into a sealer. I've used stuff called Intex. Looks like milk but dries clear. You can apply it to cured concrete or green. If applied to green it serves the same function as the poly underneath, forms a barrier that prevents moisture from evaporating out of the concrete so you get a better/harder cure. Also when dry gives you a clear finish so you don't get dusting/spalling/staining. Pretty good stuff and reasonably priced.

s1120 · Sep 7, 2002

<font color=red>Definitely isolate the poles</font color=red>

If you do that, how do you seal the walls to the floor? I have been thinking of building a pole barn, and pour the floor latter when I have the money, but want to seal the building to keep the heat in, and the vermin out. Any ideas?

s1120 · Sep 7, 2002

<font color=red>f you're doing it yourself I'd try and get a power trowel </font color=red>

I have seen one of these in use for the first time this year. A REAL cool tool!/w3tcompact/icons/cool.gif/w3tcompact/icons/smile.gif Looks like it leaves a nice finnish for a shop floor. Smooth, but not to smooth.

They have been expanding the shop at my work, and I have gotten to see some cool stuff. Cranes, forklifts, backhoes, trackhoes, etc. To bad I have been busy, have not been able to "borrow" any of them./w3tcompact/icons/smile.gif/w3tcompact/icons/grin.gif

alco141 · Sep 7, 2002

some people reccomend putting foam board down under the concreta and covering the ends to help insulate the slab.

alex

Argee · Sep 7, 2002

Toenail 1X material around the base of the poles before you pour. After it dries you can remove them easily. It will leave a 3/4" space between the concrete and the pole, that way if the floor heaves or settles it won't put any undue stress on the poles. It would have to get pretty cold though for that floor to heave. With a roof over it and the sides shut in, it would be pretty hard for the frost to work its way under the slab. There are proponents out there who will say there is a chemical reaction between the poles and the concrete. I don't know whether I buy that. Have dug up poles that have been in concrete for years and have seen no evidence of this. Just make sure you compact the floor before you pour, helps in reducing future cracking. You can bet concrete will eventually crack, especially in northern climates. Control joints are put in, in hopes of getting it to crack in them, but it often doesn't.