12x24 concrete pad in pole building

[Zaffer]

So I am finally getting around to having a pad poured in my pole building/garage. The concrete guy came out to start today: he leveled the floor and used the existing stone, which is bigger than 57. He said it’s fine and it’s deep enough, though I need to check, there’s dirt mixed in with it, so I have my doubts. The pad will be 5” deep with a 6mil vapor barrier, allegedly.

The dirt it’s on is fill, but it’s been like this for decades, though I did have to fill one end back due to a groundhog.

Is the stone necessary and shouldn’t it be at least four inches deep and compacted? Does it have to be? I just want to make sure before I approach the guy doing the work.

I’ll post pics when I get back home.

Thank you!

 

[Zeke]

How much dirt?

 

[Spud McGee]

What's the surrounding grade look like? If the ground slopes away from the building and its all nice and dry, you may not need any stone or gravel.

 

[Zaffer]

This is what it looks like afterwards. I moved the “top” surface of rocks out of the way and, yup, all dirt underneath.

 

[Zaffer]

Spruce,

It sits on a slight downward grade, with the slope into the front of the building. Not much water gets in now, but I don’t want issues in the future.

 

[mike93lx]

I don't think I'd pour concrete on that at my house

 

[Zaffer]

That’s where I am right now. Of all of the research I’ve done, everything tells me to cut ties and find someone else. A friend of mine told me to ask for insurance and credentials and if he can’t provide those, find someone else, which I might do anyway as when I asked the guy about the gravel, he said there was about 3”-4” there, which there isn’t. I confirmed this with my *gasp* shovel!

 

[Wolley]

Sounds like your requirements are unclear to the concrete guy. If you want existing material removed you should have started with that. Concrete guy likely just works with what's there most of the time.

 

[Zaffer]

I stated to him, and he to me, that there would be at least 3”-4” of stone under the slab. He saw the stone and, I guess, assumed it was good? His helper was spreading the stone around by a hand tool, so I’d think he would notice that the stone wasn’t the correct depth. Don’t know as he was gone when I got back home. He also did not compact it, which I feel should have also been done.

Either way, I’m going to bring it up to him tomorrow and get it corrected.

 

[Firebrick43]

That’s where I am right now. Of all of the research I’ve done, everything tells me to cut ties and find someone else. A friend of mine told me to ask for insurance and credentials and if he can’t provide those, find someone else, which I might do anyway as when I asked the guy about the gravel, he said there was about 3”-4” there, which there isn’t. I confirmed this with my *gasp* shovel!

It should be more like at least 8" of 3/4 minus clean crushed stone if not 12", well compacted in lifts. 3 times the thickness of the concrete pad is the gold standard.

 

[240sxguy]

Looks a lot like the detached "shanty" at my house that I had a floor poured in. I even had the groundhog hole. I didn't have gravel brought in, there was remnants of old gravel there but I don't know how much was left after they leveled the floor as they did it all in one day. I do know the ground was hard as a dang rock there when we tried to dig a hole before they came. The soil by my garage drains extremely well, and was never wet inside before the concrete. They put down a vapor barrier and 4" slab over 2 years ago and it's been fine since.

 

[Zaffer]

So, if I’m reading everything correctly, I need to have a talk with this guy and lay everything out to make sure it’s done the correct way. The stone i hang up is right now, mainly because he lied to me about the depth and didn’t compact anything, unless he considers running over it with a skid steer compacting, which I know it’s not.

He states he is insured and licensed, but I’ll have him send me his policy and license DBA before we move forward with anything. I want to make sure he can’t hold me liable should something happen.

 

[mike93lx]

So, if I’m reading everything correctly, I need to have a talk with this guy and lay everything out to make sure it’s done the correct way. The stone i hang up is right now, mainly because he lied to me about the depth and didn’t compact anything, unless he considers running over it with a skid steer compacting, which I know it’s not.

He states he is insured and licensed, but I’ll have him send me his policy and license DBA before we move forward with anything. I want to make sure he can’t hold me liable should something happen.

The time to ask for that stuff was before he started. And coming in after the fact to tell him how to do his job will not go over well, either.

Not sure on how to recover this with him, to be honest.

 

[ConCretin]

The fact that he has insurance doesn't prevent him from 'holding you liable', it protects you and your property from harm resulting from his actions. Obviously very important but not what you think.

There does seem to be warning signs here but I wouldn't be too concerned about the base material. As long as the material is compacted and stable, it is fine to place a slab on. In geotechnical terms, the soil under a slab doesn't have to do much other than provide uniform support. A layer of stone is a good idea to provide a capillary break and provide a surface that doesn't get rutted and muddy from rain and construction traffic but it's not necessary. Since yours is inside the latter doesn't apply anyway.

Btw, stone doesn't generally need compaction like soil does. You'll hear differing opinions on this but I've placed many large commercial and industrial foundations on deep stone fills that were not compacted.

It is important to communicate your expectations to your contractor, preferably before he give's you a price. Take a look at my Guide to Floor Slabs in the link below for some thoughts on the process.

 

[Zaffer]

The stone was discussed (via text) before he started: “3 to 4 inches of stone poly 6 mill 5 inches of concrete 3500 psi” is what he responded with, so he’s already not doing what was discussed. The building floor does remain dry and the slope is not much to the building entrance, but I would still think the stone should be a good idea. I’ll be here when the truck comes for the concrete to make sure it’s 3500 fiber concrete.

I’m not trying to piss him off, but I do want him to hold to what we discussed.

 

[Old Moparz]

So I am finally getting around to having a pad poured in my pole building/garage. The concrete guy came out to start today: he leveled the floor and used the existing stone, which is bigger than 57. He said it’s fine and it’s deep enough, though I need to check, there’s dirt mixed in with it, so I have my doubts. The pad will be 5” deep with a 6mil vapor barrier, allegedly.

The dirt it’s on is fill, but it’s been like this for decades, though I did have to fill one end back due to a groundhog.

Is the stone necessary and shouldn’t it be at least four inches deep and compacted? Does it have to be? I just want to make sure before I approach the guy doing the work.

I’ll post pics when I get back home.

Thank you!

5" of concrete is more than enough for a basic garage even though 4" will work & is usually the standard. The amount of stone really depends on the ground conditions. I see 4" to 6" on most plans & it really needs to be well graded & compacted. If you don't have the depth of stone that you are supposed to have there already, then rent a plate tamper to compact, wet down the interior of the building & run the plate tamper. Once that's done, add the correct depth of stone & run the plate tamper again.

If the existing grade inside the building is too high you'll need to remove the existing material which is dirt & stone. This is the part that your concrete guy does not want to do. Wherever the final finished floor level has to be, you will need to dig out the combined thickness of the proposed concrete of 5" & stone of say 4" for a total of 9" deep. Once that is all removed it will have to be graded & compacted before any new stone is installed.

 

[Zaffer]

I think that’s where he is. I understand not wanting to do what’s desired/required, but if you say you’re going to do something a certain way, then do it; don’t tell me it’s correct only for me to check and find out it’s not. Gives me little faith the rest will be done correctly.

I’ll approach him about the stone and let him know that what was stated is not what has been done so far. Very little has to be done to have the concrete at the level I specified, so I guess I could have him reschedule the concrete, rent a compactor myself and do that to see where everything lies? Will the wet/damp dirt delay anything? If it rains for a couple of days, water does work it’s way to the middle of the floor via wicking action, so I’m guessing I’d want stone down for a capillary break, correct?

 

[Old Moparz]

I think that’s where he is. I understand not wanting to do what’s desired/required, but if you say you’re going to do something a certain way, then do it; don’t tell me it’s correct only for me to check and find out it’s not. Gives me little faith the rest will be done correctly.

I’ll approach him about the stone and let him know that what was stated is not what has been done so far. Very little has to be done to have the concrete at the level I specified, so I guess I could have him reschedule the concrete, rent a compactor myself and do that to see where everything lies? Will the wet/damp dirt delay anything? If it rains for a couple of days, water does work it’s way to the middle of the floor via wicking action, so I’m guessing I’d want stone down for a capillary break, correct?

You don't need to flood the stone with water, just make it wet enough to help settle & compress it. If you're getting water in there already it's a different issue with the existing grade around the garage being too high. Adding the stone & concrete may get your floor high enough to stop this but you should still address it by diverting it or lowering the grade.

 

[Zaffer]

I’m going to install a French drain along the front to address this, just wanted to get the concrete poured first.

I wasn’t going to wet it to a soupy mixture or anything, just enough to do what you stated above. I’m just trying to do what’s best to prevent settling/cracking in the future. Like I said previously, my biggest area of concern is at the back wall (as seen in the pictures above) where I had to fill in a groundhog entrance.

 

[Poolshark314]

I would expect it to look closer to this inside:

 

[Zaffer]

That’s what I was expecting and why I guess I need to let him know that he needs to remove some soil and add gravel like we discussed before work commenced.

 

[Zaffer]

He’s coming by tomorrow to dig out the space and install 4-5” of stone, since that’s what we agreed upon, so we’ll see what happens. Thanks for all of the advice!

 

[Rusted Nut]

The only reason to have stone under a slab to make a capillary break. If the dirt below is wet, a cap break prevents the concrete slab from wicking moisture up through the slab. If you don’t have moisture issues, it’s fine to place concrete on dirt. This doesn’t mean your contractor doesn’t have to follow what was agreed to.

The thing that concerns me is “the dirt is on fill”. You could place 3’ of stone, but if your underlying soil is not compacted, you will have issues. I’d dig everything up, place appropriate fill in appropriate lifts, and compact.

 

[JeepYJ]

The thing that concerns me is “the dirt is on fill”. You could place 3’ of stone, but if your underlying soil is not compacted, you will have issues. I’d dig everything up, place appropriate fill in appropriate lifts, and compact.

From the pics in the beginning of the thread I’d say that pole barn has been there for a long time. Any fill has probably settled by this point.

 

[Zaffer]

Yes, fill has DEFINITELY settled by this point. The siding is attached with square nails! I am slowly retrofitting/renovating the building as I like the design and that it’s original to the property, just need to repair/update/modify it.

I dug 2 holes to set posts for the new doorway and the dirt is definitely hard enough, so not too concerned about settling. He came back out yesterday, dug down 5”, and filled with stone, so it’s going well so far. Pad gets poured today, so we’ll see…..

 

[Zaffer]

How long do I need to wait before I can store stuff on the concrete? I’m wetting it to cure, but we MAY need the space so my wife can have a concrete aisle and floor poured in the barn and tack room. Stored stuff would mostly be tack trunks and similar weighted items, about 50 - 60 lbs per trunk.

 

[mike93lx]

How long do I need to wait before I can store stuff on the concrete? I’m wetting it to cure, but we MAY need the space so my wife can have a concrete aisle and floor poured in the barn and tack room. Stored stuff would mostly be tack trunks and similar weighted items, about 50 - 60 lbs per trunk.

I wouldn't put anything on it that will trap moisture, but it's more than strong enough for that kind of weight after a day or two.

 

[Zaffer]

I figured as much, just figured I’d ask.

 

[like2wheel]

I think you actually do want to trap moisture to help the cure.
But the whole slab, not just under the trunks

 

[Sumboodie]

How long do I need to wait before I can store stuff on the concrete? I’m wetting it to cure, but we MAY need the space so my wife can have a concrete aisle and floor poured in the barn and tack room. Stored stuff would mostly be tack trunks and similar weighted items, about 50 - 60 lbs per trunk.

24hrs

 

[mike93lx]

I think you actually do want to trap moisture to help the cure.
But the whole slab, not just under the trunks

Yeah I'm concerned about mold/damage to the stuff

 

[Zaffer]

I’m wetting the concrete every 3 hours (except while I’m sleeping) as I have the next 3 days off. I figure by day 5, 2-3 times a day should suffice. Worst case scenario is that I’ll cover it with plastic starting day 5, if that’s suggested.

We can find other spots to store the stuff, just curious.

I was wetting it down last night and was amazed by the amount of heat the concrete was releasing due to curing! Not like it was boiling, but could definitely feel heat rising off of it, and it wasn’t due to the day as it was relatively cool here and it’s covered.

 

[racecougar]

I’m wetting the concrete every 3 hours (except while I’m sleeping) as I have the next 3 days off. I figure by day 5, 2-3 times a day should suffice.

That's going way above and beyond what 99% of people do.

 

[Zaffer]

I’m sure it is, but if it aids in preventing cracking, it’s worth it to me. I’d rather be overly cautious as I want this to last with as little issues as possible.