When a backyard shed is too small and a stick-built garage is too expensive, a small pole barn often lands in the sweet spot. Instead of a continuous foundation and framed walls, a pole barn stands on posts set deep in the ground, with trusses spanning between them and steel panels on the roof and walls. The result is a wide, open building that can hold a tractor, a boat, a workshop or a car for much less than conventional construction.
Post-frame buildings go up quickly, but they are real structures that carry wind and snow loads, and a mistake at the post-setting stage follows you for decades. This guide covers popular sizes, how the build works step by step, how pole barns compare with metal storage buildings and steel frame sheds, and what you can expect to spend.
Before you buy materials, call your local building department. Most jurisdictions require a permit for a building this size, and your plans may need engineered truss drawings rated for your area’s snow and wind loads. HOAs and zoning setbacks also apply.
Common Small Pole Barn Sizes and Uses
A small pole barn usually means anything from about 12×16 up to 30×40. Posts are typically spaced 8 to 12 feet apart along the long walls, so lengths often come in multiples of 8 or 12. Popular sizes include:
- 12×16 to 12×24: oversized shed, garden tractor storage, small workshop
- 20×24 to 24×24: single-car garage with workbench space, or a two-stall horse shelter
- 24×30 to 24×36: two-car garage or boat and trailer storage
- 30×40: hobby shop, RV cover or combined garage and storage
Eave height matters as much as footprint. An 8-foot eave suits lawn equipment, 10 feet handles most pickups and garage doors, and 12 to 14 feet is needed for RVs or a car lift. Taller walls add material and wind load, so decide early.
Pole Barn vs Metal Storage Buildings
Many people shopping for large storage buildings compare pole barns with steel storage buildings, which use welded or bolted steel frames on a concrete slab. Here is how they differ:
| Type | Frame and foundation | Best for |
|---|---|---|
| Pole barn (post-frame) | Wood posts set in ground or on piers; slab optional | DIY-friendly builds, gravel floors, rural lots |
| Steel frame shed or building | Steel columns and rafters bolted to a slab | Wide clear spans, pest resistance, fire resistance |
| Stick-built garage | Framed walls on a continuous foundation | Attached garages, full living-space finishes |
A pole barn is usually the cheapest per square foot because it skips the full foundation, and it is easy to fasten interior finishes, shelving and insulation to wood girts. Metal storage buildings resist termites and fire better and can span wider without interior posts, but they almost always require a poured slab and precise anchor bolt layout.
Tools and Materials
- Pressure-treated posts rated for ground contact (6×6 or laminated 3-ply 2×6 columns)
- Concrete for footings, or precast footing pads
- Engineered roof trusses sized for your snow and wind loads
- 2×4 or 2×6 girts and purlins
- Steel roof and wall panels, trim, closures and gasketed screws
- Skirt board (treated) at grade
- Post-hole auger (rental), transit or laser level, string lines
- Scaffolding or a rented lift, full-body harness for roof work
- Circular saw, impact driver, metal snips
Step-by-Step Build Overview
1. Plan, permit and call before you dig
Draw the layout, get permits and order trusses early because engineered trusses can take weeks. Always call 811 at least a few days before digging so utility lines are marked. Post holes in the wrong spot can hit gas, electric or water lines.
2. Prepare the site and lay out the posts
Clear and grade the site so water drains away, then build batter boards and pull string lines. Square the layout by measuring both diagonals until they match. Mark every post location.
3. Dig and set posts
Auger holes below your frost line, often 36 to 48 inches deep or more depending on climate and engineering. Place a concrete footing pad at the bottom of each hole so the post does not sink, then set the post, plumb it in two directions, and brace it. Many builders backfill with compacted gravel or add a concrete collar at the base for uplift resistance. Follow the engineered plan exactly here, because post embedment is what resists wind uplift.
4. Cut posts to height and install girts
Mark the eave height with a laser level, cut all posts level, then attach the treated skirt board at grade and girts every 24 inches or so up the walls. Girts give the steel panels something to fasten to and help brace the frame.
5. Raise the trusses
Fasten a header or carrier beam along the post tops, then lift trusses into place, typically every 4 to 8 feet depending on design. This is heavy, high work: use a lift or a crew, never a single person on a ladder, and brace trusses temporarily as each goes up so they cannot domino. Add permanent diagonal and lateral bracing as specified.
6. Install purlins and metal roofing
Run purlins across the trusses, add any underlayment or anti-condensation membrane, then install roof panels from one end with the overlap facing away from prevailing wind. Drive gasketed screws snug, not overtightened. Add ridge cap, eave trim and closures.
7. Side the walls and frame openings
Frame openings for overhead doors, a walk door and windows with headers per the plan, then install wall panels and trim. Seal the base with foam closures to keep out rodents.
8. Floor and finish
Many small pole barns start with a compacted gravel floor and add a concrete slab later. If you plan to pour, set the slab inside the posts with an isolation joint and a vapor barrier.
Safety: Structure, Heights and Roof Work
Post-frame buildings must be anchored and braced to resist wind uplift and snow loads. Use engineered trusses, follow the embedment and bracing schedule, and never remove temporary braces until permanent bracing is complete. Roof work is where most injuries happen. Set ladders on firm, level ground at a 4-to-1 angle, extend them 3 feet above the landing, and keep three points of contact. For truss setting and roofing, scaffolding or a rented lift is much safer than a ladder, and fall protection is essential on metal panels, which are slippery when dusty or wet. For eave heights above one story or steep pitches, hiring a crew is the smart call.
Troubleshooting Common Problems
Condensation dripping from the roof: add a condensation-control membrane or insulation under the steel and ventilate the ridge and eaves.
Posts heaving or leaning: holes were above the frost line or backfill was not compacted. Consult an engineer or builder before trying to correct a structural post.
Leaks at screws: screws were overdriven or missed the purlin. Replace with oversized gasketed screws and seal.
Water running inside at the base: regrade so soil slopes away, and add gutters or a gravel drip line.
Small Pole Barn Cost by Size
Costs vary with region, eave height, snow load and finish level. As a general guide for a basic small pole barn shell with metal roof and siding and a gravel floor:
- DIY kit or materials only: roughly $15 to $30 per sq ft
- Professionally built shell: roughly $25 to $50 per sq ft
- 20×24 shell: roughly $12,000 to $25,000 built by a contractor
- 24×30 shell: roughly $18,000 to $35,000
- 30×40 shell: roughly $30,000 to $60,000
Add costs for a concrete slab, overhead doors, insulation, electrical service and permits. Finished workshops with slabs, insulation and power can reach double the shell price.
When to Call a Licensed Professional
Hire a post-frame builder or general contractor if you lack experience with structural framing, if your area has heavy snow or high wind loads, or if the eave height is over about 10 feet. An engineer should sign off on truss and post specifications where required. Electrical service to the barn, including a subpanel and outlets, belongs to a licensed electrician under permit, with GFCI protection for garage and outdoor outlets. Any plumbing, such as a utility sink or frost-free hydrant, should be done by a licensed plumber to code.
Frequently Asked Questions
How deep should pole barn posts be set?
Posts are usually set below the frost line, often 36 to 48 inches or deeper, on a concrete footing pad. Your engineered plan and local code set the exact depth.
Can I build a small pole barn myself?
Many homeowners build small pole barns with a helper crew, especially from a kit. Setting trusses and roofing are the riskiest parts, so rent a lift and consider hiring out that stage.
Is a pole barn cheaper than a steel storage building?
Usually, because pole barns do not require a full slab foundation. Steel buildings may compare well on larger spans or where a slab is already planned.
Does a small pole barn need a concrete floor?
No. Many start with compacted gravel, which is fine for equipment storage. Pour a slab later if you plan a workshop or garage use.
Do I need a permit for a pole barn?
Most areas require one for buildings above a small shed size. Agricultural exemptions exist in some rural areas, so check with your local building department.
