Concrete in Pole Barn advice

[crowbar032]

I have a 32x60 pole barn that is about 20 years old and currently has a gravel floor. Has anyone ever went back and poured concrete in a barn after that many years? What is a standard thickness...3" or 4" thick...rebar or wire or none? I know I want a vapor barrier if I proceed. The heaviest thing I will have on it will be a tractor (see sig). The location it is in was a turn lot/barn yard so there is a good base under it so that should not be an issue. However, there is about 6" of grade from front to back, so I know I've got some leveling work to do inside. I think the worse part will be cleaning all my junk out, although I think I should be able to leave everything nailed to the walls. I would do the cleaning out and leveling myself, but contract the actual pour. Any advice is appreciated. Any thoughts on price (just for a reference point for quotes).

 

[wolftree]

Consider using fiberglass mixed into the concrete for re-enforcing instead of wire/bar. It looks like cat hair. It is mixed in at concrete plant.

Use limestone screenings(very small limestone) to fill and be sure and use a vibrating tamper to pack it down good.

The very minimum floor thickness should be at least 4 inches. Five inches would be better.

Talk with your concrete plant about recomended mix and pricing. They can also recommend someone to do the pour if you do not know anyone.

My last concrete was $70 a yard, I am sure it has went up.

 

[EddieWalker]

What you want to do is pretty common. I would go to Angieslist.com to find a contractor or the BBB. My experience with recommendations from places that sell materials is they push a buddy, or somebody that needs work. Cost varies all over the country, so there isn't any good way to know what it will cost there based on what it costs here.

I hate wire in concrete. It is one of those things that works great in small applications and in theory, should work good on pads, but doesn't. What happens is everyone walks on it when spreading the concrete and pushes it to the bottom of the concrete. They say that they will pull it up, and they do, but then they walk on it again and it ends up at the bottom. Wire is fast, cheap and easy to lay down for the contractor, but it doesn't actually do anything.

Fiberglass helps with cracking, but it's highly over rated and never to be used instead of rebar. It can be added to the mix and used with rebar, but mostly it's a "feel good" material that people use to save money on rebar and think that it's just as good. It isn't. The other drawback to fiberglass, or plastic, or any of those types of products is when it's all said and done, they stick up through the top of the concrete. You can burn them off, sand and polish them off, or just hope they all wear off in time. It's something that might not bother you, or it might drive you crazy.

Vapor Barrier is one of those things that has a purpose, but is highly misunderstood. It will not stop condensation from forming. It will allow the concrete to cure more evenly by not letting the moisture in the concrete to leach out into the soil, but if you already have an established gravel floor, it's not going to do anything. But it's also cheap and easy to do, so it's up to you if you want to spend the money or not.

3 1/2 inches is the standard pour for most non load bearing pads. 5 1/2 inches is better, but it's a lot more money and only needed if you are parking something very heavy on it. Most every driveway is 3 1/2 inches thick. The ones that crack usually don't have rebar in them, or they soil under them wasn't compacted very well. With your established rock floor, it shouldn't be an issue.

Eddie

 

[kieramax]

Another point is to use no less than 30MPA concrete at 3.5 to 4 inch thickness. It is our standard mix for a driveway slab or garage. It will handle the load of of your vehicle / tractor as well as provide some resistance to salt erosion from road salt or other source.

 

[Oliver1655]

I agree with Eddie for the most part. Rebar will not keep concrete from cracking, but will help keep the concrete from shifting after cracking. I gave up on using wire mesh for the above reasons. The rebar is typically used on 2' centers. It can be laid out in grids & the joints wired together or if a smaller pour such as sidewalks, patios, after the concrete is poured & screed (leveled) you can lay the rebar on the concrete & push it down into the concrete with a shovel or stick. I have seen some use old cattle / hog panels but they can be a pain to work around without stepping them down to the ground.

If you haven't poured concrete before, I would recommend having a knowledgeable person involved. If you have a church you attend, ask around, there are normally very informed member who can point you to reputable contractors.

Think about how smooth you want you surface, heavy or light textured to where you have traction, smooth to make it easier to roll carts, ...

If you do not use a vapor barrier, (not required), it is common practice to wet the ground first to help prevent the concrete from drying too fast. The dryer the concrete is poured within reason & the slower it drys/cures, the stronger it will be. For this reason I strongly recommend spraying the surface with a sealer right after finishing it. Concrete sealer is not always easy to find but can be purchased from the concrete plant in 5 gallon pail. Just have them deliver it with the concrete. Just spray it on with a hand pump sprayer. The sealer also makes it much easier to clean up spill on the concrete later on.

 

[brucew44guns]

I'm on board for 5 inch thickness and rebar. My 40X60 slab in the barn has no cracks, the rebar was perched on top of short little pieces of PVC pipe to keep it elevated into the middle of the concrete, and so far it's been good. 6 year old slab that is slick and crack free, I drive a 6330 JD with loader in there all the time. You pay a bit more for an extra inch, but overkill is good I think,.

 

[Midniteoyl]

Fiberglass works good 0n small projects, like sidewalks and ramps and planters. Leave it out of the big slabs...

 

[Bigfoot62]

Fiberglass works good 0n small projects, like sidewalks and ramps and planters. Leave it out of the big slabs...

Agreed. If FRC cracks, there's nothing to hold it together.
Use the good, old-fashioned concrete wire.
And, 4 inches of concrete over a well compacted base will be fine for supporting your tractors. I would not recommend driving the track loader over it though.

 

[Kyle241]

It's funny how you get different advice from different sources. I'm no concrete guy but have 'poured' one garage/barn slab and had the other done. The one I poured I did with rebar and the 'cat hair' aka fibreglass and it went well however I only went 4". The garage pour I had done a two years ago is at my current property and I used rebar and wire mesh and had 6" poured. It's a much better slab IMHO and worked out well. I agree the wire mesh can get pushed down but if the contractor is good, they'll make sure it doesn't.

As for doing it yourself, that first pour was a bear and the second I paid for. It was well worth it even though I do like doing things myself but concrete is tough work and you have to do it right.

 

[crowbar032]

Since I have absolutely no equipment what so ever for concrete work and have never seen it done or worked in it at all, I will absolutely be contracting it out. No way I'm trying it myself, Eastwood on "a man's got to know his limitations" Eastwood off.

I would not recommend driving the track loader over it though.

Yeah, I'm not sure that much would stand up to that weight. The building isn't tall enough to get it in there anyway.

Thanks for all of the input. I at least have a starting point. Using an on-line calculator, it seems that a 4" pour is about 24 yards and 5" is about 30 yards. Using rough figures that 6 yards @ $100 a yard isn't that much money for an extra inch. I believe that for the <$1000 investment it would be worth the extra security and piece of mind. Now I've just got to find someone who wants to do it and does good work.

 

[KWentling]

Agree with Eddie, but would add to cut control joints 1" deep in a 10'x10' or so grid. If there is danger of getting water in the joints and it freezing, fill them with SL caulk.

Kim

 

[MarkV]

I am no concrete guy either but understood that rebar in a 4" pour, which is usually 3 1/2" with 2x4 forms, is not thick enough to use rebar. I always thought rebar needed more than an 1 to 1 1/2" concrete around it to be effective. Anyone know what is actually recommended for thickness around rebar?

MarkV

 

[vtsnowedin]

I'm a highway construction inspector so have the build it good and stout point of view. We use 4 inches for sidewalks that carry pedestrians and bicycles and go to six inches at each drive where a loaded truck will cross. Bridge decks are 8-1/2 inches thick with TWO layers of rebar #5s or bigger on eight inch centers one way and 12 inches the other. Any place you can stick your foot down through to the forms is "Wrong".
No need for vapor barrier in a barn. Your not trying to keep the basement dry or radon gas out.
For a tractor that goes 7000 wearing its loader etc. I'd go with #4s on 18 inch centers each way held up 2 inches from the bottom by chunks of brick or similar well tied together. You want it near the bottom of the slab as that is what goes into tension when the load is applied to the top of the slab.
I'd use 4000 psi mix with a water reducer and then not pour it more wet then needed to screed it level. (That will be overkill in most peoples book but I'm OK with that) And I'd pour it six inches thick just to be for sure for sure. Just my $.02, good luck with your project.
Oh I'd consider leaving the six inch grade if it drains to the door as that will let snow melting off the tractor find its way out without a illegal floor drain.

 

[SPIKER]

I had an Amish Crew do mine came high recommended by neighbors and co workers 4 people all used same guy and all had great slabs/drives/patios and the like. I went ~5" with the main GD side closer to 6" where tractor or cars will come in and out. I put slab out in front and inside my pole barn. My barn was put up in Nov 2002 and the slab went in in Sept 2011. I took some videos and pics if you want to see

Note PUT IN the vapor barrier, cost less than 40 bucks to put down some top of line 6 mil plastic that size.

Mine has in floor radiant heat tube placed on 6x6 10awg steel mesh. It was put up on 1" plastic chairs on 2 foot grid to help keep it up into slab. I ended up having 60 yards & crew paid for concrete that I ordered. I had 6000PSI Mix With Fiber. I have 2" of styro-foam and radiant barrier insulation (foil bubble bubble plastic) under mine. The base was mostly clay, gravel and sand all compacted 10 years of settling so far only cracks are 2 hair lines on sides of roll up door and outside where cuts were made. I did not cut inside where heat tubing was



I have 5 pages of barn pics there so once ya see em you can keep clicking left/right for more.

Also be sure to add some under slab utilities service pipes if you have some now or not you will eventually probably want to run a wire or pipe or line in/out of the barn!



It is good also to keep the floor wet to help it hydrate & harden properly. If it drys out too fast it can be weaker than it should. The plastic under it helps this and spray on top after it helps this out after it has initial working surface. I kept mine wet for about a week inside the sealed up barn and it has some of the hardest chip resistant stuff I ever seen. I put STAIN on it that didnt even penetrate the floor 45 days after the pour & week prior to moving stuff back into it :/

One of hardest things was getting all my junk out and then having to put it all back in my clean pretty barn

Mark

 

[R_Walter]

You'll want to be sure to plan for a concrete apron outside the doors and access areas.

 

[KennyG]

I am no concrete guy either but understood that rebar in a 4" pour, which is usually 3 1/2" with 2x4 forms, is not thick enough to use rebar. I always thought rebar needed more than an 1 to 1 1/2" concrete around it to be effective. Anyone know what is actually recommended for thickness around rebar?

MarkV

The standard specification for any structural concrete is a minimum of 2" cover over the re-bar, so technically you are correct. However, for a residential/commercial slab, I wouldn't worry about the cover when putting rebar in a 3-1/2" slab as long as you can keep it reasonably well centered.

 

[paulharvey]

I'm a highway construction inspector so have the build it good and stout point of view. We use 4 inches for sidewalks that carry pedestrians and bicycles and go to six inches at each drive where a loaded truck will cross. Bridge decks are 8-1/2 inches thick with TWO layers of rebar #5s or bigger on eight inch centers one way and 12 inches the other. Any place you can stick your foot down through to the forms is "Wrong".
No need for vapor barrier in a barn. Your not trying to keep the basement dry or radon gas out.
For a tractor that goes 7000 wearing its loader etc. I'd go with #4s on 18 inch centers each way held up 2 inches from the bottom by chunks of brick or similar well tied together. You want it near the bottom of the slab as that is what goes into tension when the load is applied to the top of the slab.
I'd use 4000 psi mix with a water reducer and then not pour it more wet then needed to screed it level. (That will be overkill in most peoples book but I'm OK with that) And I'd pour it six inches thick just to be for sure for sure. Just my $.02, good luck with your project.
Oh I'd consider leaving the six inch grade if it drains to the door as that will let snow melting off the tractor find its way out without a illegal floor drain.

Agree for the most part. 6" 3000 psi concrete, wire, I personally like rebar. What I would add is if you form, grade, reinforce yourself, and only hire out the pour and finish you can save lots of $$$. As a note I am also a roadway/engineering inspector, but as a commericial construction superintendent we would often grade, form, reinforce, and buy the mud and just sub the pour/finish because for for roughly $750 you get a crew who can actually do the physical part. I like a light horse hair broom finish,

 

[Ken45101]

Around here they tell me that fiber is just as good as steel. IDK, but our driveway (1500' up a steep hill) was poured 40 years ago without steel (or fiber, I assume) and has held up very well, but they poured it 6" thick.

Extra concrete does add to the cost but shouldn't add to the finishing cost. When we did a new barn floor to handle the heavy campers, we did it with 6" and no steel.

 

[paulharvey]

The thing with any driveway (or anything you drive on) is if the base is good material, compacted well (typically 95-98% of maximiun density) the final wearing surface be it 4" concrete, 6" concrete, or any where from 1-2" of asphalt it will hold up well. On the flip side if you pour 6" of 4000 psi concrete with wire or fiber on uncompacted material, fat clay, or high organics it Will fail.

 

[bucktaker]

I have a 40x64 pole building that I store my Sundowner 4 Horse LG trailer 17k , 6600 lb boat and my in-laws 35 ft winnebago 12k all on 4" on fibered concrete control joints in a 10x10 grid with no issues of cracking or seperating. Its all about the base and how stable is is. I filled the majority of by building with bank run and allowed it to compact naturally by exposure and parking on the pad for two yrs then built the building and added 12 inches of limestone leveled and compacted, then my concrete. 6 yrs now no issues.