Written by Rocky Mountain Metal · Reviewed by Micah Hostetler, Owner · Based in Penrose, CO, serving Colorado.
Usually, yes. Enclosed steel garages, workshops and warehouses typically sit on a concrete slab or footings the frame anchors to. Some carports and open structures can use other approved anchoring. Your building's engineering and your county decide.
Key takeaways
- A steel frame has to be anchored properly; the foundation is part of the structure, not an add-on.
- Garages, shops and anything you'll heat want a concrete slab.
- Some carports and open ag structures may use other anchoring options, depending on the engineering and the county.
- Plan the concrete for the heaviest thing that will ever sit on it.
- A vapor barrier under the slab matters in a building you'll insulate or heat.
Why does the foundation matter so much for steel?
A steel-framed building carries its roof and wall loads down through the frame into its anchors. The foundation has to hold those anchors against snow pushing down and wind pulling up. That's why the foundation has to match the building's anchor plan and why it's done before the manufacturer's crew arrives. It's also a reason we chose steel: nothing structural is wood sitting in the ground. See why steel framing avoids rot.
When do you want a full concrete slab?
- Vehicles and trailers. Clean, dry, sweepable, and floor jacks work.
- Workshops. Tools, benches, welding, anything you'll stand on all day.
- Lifts and heavy equipment. A lift needs extra concrete under its posts, to the lift maker's requirements.
- Anything heated or insulated. A slab with a vapor barrier is part of the building's envelope. See insulating and heating a shop.
- Small warehouses and RV storage, where a durable, level floor matters.
When might another option work?
- Carports and open shelters, depending on the engineering and your county, may be anchored to other approved surfaces.
- Ag structures used for hay or equipment may sometimes use concrete footings with a gravel floor inside, depending on the design.
Ask before you assume. The anchoring method has to match the building's engineering and your county's requirements, and we'll walk you through what yours requires.
How heavy should the concrete be?
That depends on the heaviest thing that will ever sit on the floor:
| Use | What to plan for |
|---|---|
| Cars, light trucks, storage | A standard slab with control joints |
| Shop with tools and benches | A standard slab, with extra attention at door openings |
| Lift, heavy trucks, tractors | A heavier, reinforced slab and thicker areas under lifts |
| Heavy equipment or hoists | An engineered slab design |
Everything sits on a compacted base over a properly prepared subgrade. See how to prepare your site. On soils that shrink and swell with moisture, the base and slab design matter even more, and a soils report may be worth it.
What should you decide before the pour?
- Anchor locations that match the building's anchor plan exactly.
- Vapor barrier under the slab if the building will ever be insulated or heated.
- In-floor heat tubing, which is easy before the pour and impossible after.
- Floor drains and slope toward them for wash bays.
- Thicker areas for a lift, a hoist or a heavy machine.
- Door edges, where the slab takes the most abuse.
- Control joints to manage cracking.
Who handles the concrete?
Close to home in the Penrose and Fremont County area, Rocky Mountain Metal can coordinate the project start to finish, including site work and the foundation. Farther away, we supply and oversee the building itself, and we'll make sure your concrete contractor has what they need to match the building. Either way, we look at your site, plan the building with you and oversee the project, and the manufacturer's crew from Texas installs it. Start with a free quote anywhere in our service area.
Frequently asked questions
Should the slab be poured before or after the building?
Before. A steel frame is anchored to the foundation, so the concrete has to be in place and cured to match the anchor plan before the building is installed.
Is a gravel floor okay for a garage?
For a carport or simple storage, sometimes. For a working garage where you'll jack up vehicles or want a clean floor, concrete is worth it.
Do I need a vapor barrier?
If the building will ever be insulated, heated or finished, yes. It keeps ground moisture out of the slab and the building. See how to stop condensation.
Can I phase the cost?
You can plan interior finish, insulation and some options for later, but the foundation your building anchors to comes first. Ask about financing through Heartland or rent-to-own through RTO National. See financing a metal building.
