Pole Barn Site Prep: Stumps, Topsoil, and an Old Slab
Pole barn site prep is two jobs. Get the organic matter out from under the building, then get the ground level. An Oregon owner on the Northwest Craftsman channel did both himself, with a tractor, before handing the site to a pole barn crew.
He got most of it right, and he's candid about the part he didn't. There are no prices in the video, and we won't add any.
What was in the way
The spot used to hold a shed. When the shed came out, it left three things behind:
- Three stumps. He'd already tried burning two of them out. It didn't work.
- The shed's concrete slab.
- Topsoil across the whole footprint.
He's clear about what he isn't. He says outright that he's not an engineer, and that there are a million and one ways to do this. What follows is one owner's version, with his own second thoughts left in.
Stumps: check your transmission before you borrow a grinder
He borrowed a PTO-driven stump grinder from his brother and ran it off the tractor. The first thing he did was snap a shear bolt. His note to self: too heavy, too fast.
That part is cheap to fix. Take the broken bolt to the store and match its grade, which is marked on the head. His was a grade 5, with three lines. No lines is a grade 2.
The lower the grade, the sooner it shears, and shearing is the bolt doing its job.
The expensive lesson came later. A PTO grinder wants a tractor with a hydrostatic transmission, and his has a traditional clutch. To creep slowly enough for the grinder to cut, he had to feather the clutch for long stretches. That's how you wear one out.
So he stopped. One stump is mostly gone, and he'll rent a stump grinder for the rest. His math is simple: a day's rental costs less than a clutch. If your tractor is hydrostatic, he says to go ahead, because the grinder itself was great.
The old slab: he could have left it
This is the answer people don't expect. He says the slab could have stayed under the new building. It's stable, and it's only a problem if he ever has to dig through it.
He pulled it anyway, because he wants the concrete somewhere else on the property. He cut it into squares with a concrete saw and carried them off on the tractor's forks.
He wasn't sure the squares would survive the trip. His fallback was a good one: if they fell apart, he'd have concrete fill for under the shop, and that much less fill to buy.
Topsoil: the part he'd do differently
He scraped the top layer off and piled it out of the way. He didn't get all of it. His tractor wasn't powerful enough, and he says an excavator would have scraped it cleaner.
Does that matter? He thinks it's best practice to get it all, and he explains the risk plainly.
Whatever topsoil is left will settle. The gravel on top settles into those low spots. A slab poured over that can crack.
Leftover topsoil doesn't threaten the building. It threatens the slab.
That distinction is why he's comfortable. On his building the structure comes from the posts, not the floor, which is the point we made in setting pole barn posts. And he isn't pouring a slab for at least a couple of years. The ground gets that time to settle, and he can bring in more gravel and smooth it before any concrete goes down.
If you're pouring right away, you don't have that cushion. Scrape it clean, with the machine that can do it. An owner who built the same shop twice calls the concrete the one decision you can't revisit.
Level is a choice
You can build a pole barn on a slope, and he says so. He leveled his because he wants a level floor inside.
It's worth deciding on purpose, because level costs money. The owners in our 40x60 cost breakdown paid $5,200 for excavation, fill, and a gravel pad on ground that looked level to the eye, then another $1,000 when the pad turned out too small. That's their number, on their site, and yours will differ. But it tells you which line to ask about.
Level also isn't the same thing as drained. Where the water goes is the first item in what to know before building a pole barn, and it gets settled at this stage or not at all.
Gravel before the crew shows up
His last step before the crew arrives is gravel. The reason isn't structural. It's winter in Oregon, snow is falling in the video, and rain is coming. A scraped site is mud.
Gravel gives the crew something better to work on. It's a small courtesy that also keeps the job moving.
Where the owner's work ends
He drew the line where a lot of owners do. Clearing, grinding, scraping, and gravel are his. The building is the crew's.
That split only works if both sides agree on it. Before you sign, ask the builder what condition they expect the site in, whether any site prep is in their price, and who pays if the pad is wrong.
Get the organic matter out. Get it level. Then hand it over.
Frequently asked questions
How do you prep a site for a pole barn?
The owner in this video reduces it to two jobs: get as much organic matter out from under the building as you can, then level the site. For him that meant grinding three stumps, cutting up and moving an old shed slab, and scraping off the topsoil. Gravel went down after that so the crew had something to work on.
Do you have to remove topsoil before building a pole barn?
Best practice is yes, and the owner here says so even though he couldn't get all of his. Topsoil left under the pad settles, the gravel settles into it, and a slab poured on top can crack. On his style of building the posts carry the structure, so it's the future slab that's at risk and not the frame.
Can you build a pole barn on a slope?
You can. The owner says so directly, and chose to level his site anyway because he wants a level floor inside. Leveling can mean bringing in fill, which is its own line on the bill.
Can you leave an old concrete slab under a pole barn?
The owner's view is that he could have. It's stable, and it only becomes a problem if you ever need to dig through it. He pulled his up anyway because he wanted the concrete elsewhere on the property, and figured that broken pieces would at least make good fill.
Should you put gravel down before the pole barn crew arrives?
He did, and his reason is practical. A scraped site turns to mud when it rains, and it rains in Oregon in winter. Gravel gives the crew a cleaner surface to work on. He isn't pouring a slab for a couple of years, so he also has time to add more gravel after the ground settles.