Pole Barn Concrete Floor — Base, Vapor Barrier, Forms and the Pour
A gravel floor you cannot roll a jack on, a dirt floor that turns to mud in April, or a new barn that needs its slab — the floor prepped right and poured as one job with one contractor to call.
JMB Builders puts a pole barn concrete floor into a new or existing pole building across the north metro and central Minnesota. Our crew strips the dirt or gravel floor to grade, compacts a class 5 base, lays the vapor barrier, sets forms and reinforcement, and preps around the posts. The slab is poured and finished with our concrete partner as part of the same job. Priced per project after a site visit.
- Priced per project after a site visit
- Grading, base, vapor barrier and forms by our crew
- Poured and finished with our concrete partner
- Floor drain and radiant tubing set before the pour
- Licensed MN contractor BC809005
A concrete floor in a pole barn is a base job with concrete on top. The slab is only as good as what is under it: a floor poured on soft fill or a wet base cracks and heaves the first winter, and a floor poured with no vapor barrier sweats every spring and rusts whatever is parked on it. We do the part under the slab ourselves, and the pour is done with our concrete partner as one job under our quote.
In an existing building, the old floor comes out or down: gravel is stripped and re-spread, dirt is cut to the right depth below the finished floor, and the grade is set so the slab drains to the door or to a floor drain. Class 5 base goes in and is compacted in lifts. A poly vapor barrier goes over the base, then forms at the doors and any thickened edges, and reinforcement on chairs. Around each post the slab is isolated so the posts and the floor can move on their own. A floor drain, a trench drain at the door, or radiant tubing for a heated floor is set before the pour by the plumber or heating contractor we bring in.
The pour: our concrete partner brings the trucks and the finishers, places and finishes the slab to the finish you want, and saw-cuts the control joints. We are on site for the pour and handle the forms, the edges and the cleanup. In a new barn the floor goes in after the shell is up and the doors are framed, so the pour is out of the weather. Permits are pulled where required.
What you supply
- Photos of the floor, the posts at the floor line, the doors and the low spots
- What the floor is for: parking, a shop with a lift or a hoist, horses, or storage, so the thickness and finish match
- Whether you want a floor drain, a trench drain at the door, or radiant tubing for heat
- The building emptied and the floor clear before we start
- Access for a skid loader and concrete trucks to the door
What JMB supplies
- A site visit to shoot grades, check the door sill heights and plan where the floor drains
- Stripping the old dirt or gravel floor to depth and hauling the spoils, or reusing clean gravel
- Class 5 base spread and compacted in lifts with a plate compactor
- Poly vapor barrier over the base, lapped and taped
- Forms at the doors and thickened edges, and reinforcement on chairs
- Isolation around each post so the slab and the posts move separately
- A plumber or heating contractor brought in for a floor drain or radiant tubing before the pour
- The pour, placing and finishing with our concrete partner, and saw-cut control joints
- Forms stripped, door sills and edges cleaned up, and photos of the finished floor in your job folder
How it is priced: per project
Quoted in writing from your photos within one business day. What moves the number:
- Square footage of the floor and the slab thickness the use calls for
- A dirt floor to be cut and hauled vs. a gravel floor that mostly needs re-grading and compacting
- How much fill it takes to bring a low floor up to the door sills
- Reinforcement: wire mesh vs. rebar for a shop with a lift or heavy equipment
- A floor drain, trench drain or radiant tubing, with the plumber's or heating contractor's numbers
- Finish: broom vs. smooth trowel, and a sealer or a cure-and-seal
- Concrete truck access to the door and pour distance to the far wall
- Whether the building is empty and clear or has to be worked around
Send photos of the floor from the door and from the far corner, with a tape from the floor up to the door sill. We schedule the site visit from that.
How long it takes
A garage-size floor: two to three days of prep, a pour day, and a few days before you drive on it. A full shop floor: about a week of prep before the pour. Heated floors add the tubing day.
How your project works
- 1
Send photos, get a written quote
Send three photos of the space and a sentence about what you want. You get a clear, itemized quote within one business day. We only come out to measure first when the job needs a tape measure — no pressure, no games.
- 2
Pick materials, or bring your own
We help you choose profiles and materials that fit the house and the budget, or match your existing millwork exactly — or you buy the door or trim yourself and we install it. Everything is confirmed before the crew is scheduled.
- 3
Clean, precise installation
The crew shows up on time, protects floors and furniture, and installs with tight joints and consistent reveals. Photos of the finished work go in your job folder.
- 4
Walkthrough and invoice
We walk the finished work with you. If anything is not right, we fix it before we call the job done. Then one invoice, paid by check or direct deposit — no card fees, no payment links.
Situations and options
Concrete floor in an existing pole barn
The dirt or gravel floor stripped to grade, base compacted, vapor barrier, forms and reinforcement set, and the slab poured with our concrete partner. The building has to be empty for the week.
Shop floor with a lift or hoist
A thicker slab with rebar, and a thickened pad where a two-post lift or a hoist post will bolt down. Tell us the equipment before the pour so the pad lands where it bolts.
Heated floor with radiant tubing
Insulation board under the slab, radiant tubing tied to the reinforcement by the heating contractor we bring in, and the slab poured over it. The best heat a shop can have; it has to be planned before the base goes in.
Floor with a drain
The slab graded to a floor drain or a trench drain at the overhead door, set by the plumber before the pour. For washing vehicles, melting snow off a truck, or a wash stall in a horse barn.
Floor for a new pole barn
On a barn we build, the floor goes in after the shell is up and the doors are framed, so the pour is under a roof and out of the wind. Planned with the building so the sills and the slab meet.
Pole Barn Concrete Floor — Base, Vapor Barrier, Forms and the Pour: questions, answered
Can you pour a concrete floor in an existing pole barn?
Yes. The building is emptied, the dirt or gravel floor is stripped to the right depth below the door sills, class 5 base is compacted in lifts, and a vapor barrier, forms and reinforcement go in. The slab is isolated around each post. Then the floor is poured and finished with our concrete partner, and control joints are saw-cut. You drive on it after it has cured for a few days.
Do you pour the concrete yourselves?
The prep is our crew: grading, base, vapor barrier, forms, reinforcement and the post isolation. The pour, placing and finishing are done with our concrete partner, on our quote, with us on site. You get one contractor to call for the floor from the first shovel to the saw cuts.
Why does my pole barn floor sweat?
Because there is no vapor barrier under it, or because warm damp spring air is hitting a slab that is still winter cold. Ground moisture comes up through a slab with no poly under it and shows up as a wet floor. A new floor gets a vapor barrier over the base. On an existing sweating floor, the fix is airflow and a sealer, or in a heated building a slab that stays warm.
What goes under a pole barn concrete floor?
Compacted class 5 base on a firm subgrade, a poly vapor barrier, and reinforcement on chairs so it sits in the slab and not on the ground. In a heated floor, insulation board goes under the slab too, with the radiant tubing tied to the reinforcement. The base is what stops the slab from settling and cracking, so it is compacted in lifts, not dumped in and leveled.
How thick should a shop floor be?
It depends on what parks on it: cars and a lawn tractor need less than a loaded truck, a two-post lift or a skid loader. We size the slab thickness and the reinforcement to the use you tell us, and we thicken the slab where a lift or a hoist post will bolt down. We do not give one number here because the use decides it.
Can you add a floor drain to a pole barn floor?
Yes, when it is planned before the base goes in. A floor drain or a trench drain at the door is set by a licensed plumber and the slab is graded to it. Where the drain goes depends on your city's rules for shop drains and what it can drain to, so we check that at the site visit before it is quoted.
Get a written quote for this job
Three photos and a sentence is enough. You hear back within one business day. Or text the photos to 763-204-2099.
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Read morePage reviewed September 24, 2026 · JMB Builders LLC, MN license BC809005 · All pole barns pages
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