Detached Garage Cost: What a Steel Garage Really Costs, Installed

Search for detached garage cost and you will find national averages that span tens of thousands of dollars, which is not much help when you are trying to decide whether a project is realistic. The range is so wide because “detached garage” covers everything from a single-bay steel building on gravel to a finished, stick-built structure with a matching shingled roof. This guide narrows it down. It uses the installed starting prices published on our own site for steel garages, then walks through the other costs you need to budget so the total is not a surprise.

Steel garage starting prices by size

These are “from” prices listed on our website at the time of writing in fall 2026, with delivery and installation included. They are estimates that vary by location, exclude sales tax and change over time. Use them to set expectations, then request a current quote.

• 20' x 30' x 10' (one car plus storage, or two small cars): from $8,060 — view model
• 20' x 20' x 10' (compact two-car): from $9,960 — view model
• 24' x 32' x 9' (two-car with workspace): from $13,080 — view model
• 24' x 40' x 11' (two-car plus shop or boat): from $15,305 — view model
• 24' x 26' x 11' (two-car, two roll-up doors): from $16,677 — view model
• 30' x 30' x 12' (three-car): from $16,800 — view model
• 30' x 60' x 12' (large garage and shop): from $27,344 — view model

You will notice the list is not in strict order of floor area. That is the first lesson of garage pricing: a model's price reflects its whole configuration — roof style, height, doors and openings — not just its square footage. Across these examples the installed building ranges from roughly $13 to $27 per square foot, before the foundation.

What drives the price of a detached garage

• Size. Width, length and height set the amount of steel. Longer is usually cheaper to add than wider. Our garage size guide helps you avoid paying for space you will not use, or building too small.
• Doors. The number, size and type of garage doors, plus walk-in doors and windows, is often the largest single variable between two garages of the same size.
• Roof style. A vertical roof costs more than a horizontal one and sheds snow better.
• Snow and wind certification. Requirements vary by county, and heavier loads need more steel.
• Frame gauge and siding. 12-gauge framing, vertical siding and wainscot are upgrades.
• Insulation. Optional, and cheapest to add at installation.

The costs outside the building price

Whatever kind of garage you build, these are separate line items:

• Foundation. Most enclosed garages go on a concrete slab. Concrete is priced locally, so get a contractor's quote for your slab size early. It is frequently the second-largest cost after the building.
• Site work. Clearing, leveling, drainage and a driveway or apron to reach the doors.
• Anchors. The anchors that certify the building for wind are an added cost and depend on the foundation.
• Permits. Fees are set by your municipality. We research permit requirements at no extra cost.
• Electrical. Running power from the house, a subpanel, lighting, outlets and a door opener are done by a local electrician.
• Finishing touches. Gutters, interior liner, shelving, heat.

A realistic budget is the installed building, plus the slab quote, plus an allowance for site work and electrical.

Detached vs. attached: which costs more?

It depends on what you are attaching to. An attached garage shares a wall with the house, but it also has to tie into the home's roof, foundation and siding, and it falls under the building code that applies to the house, including fire separation between the garage and living space. A detached garage stands on its own. In Wisconsin, for example, the state's Uniform Dwelling Code overview lists detached garages among the structures the dwelling code does not cover, so the rules come from your municipality instead. Local requirements still apply, and they vary.

For a pre-engineered steel garage, detached is the natural format: it is installed as a complete structure, usually in a day or two on site, without opening up the house.

Steel vs. stick-built detached garages

A wood-framed garage built on site can match your home's siding and roofing exactly, which matters in some neighborhoods and under some covenants. It is also labor-intensive, with framing, sheathing, roofing and siding each done as a separate trade. A steel garage arrives as an engineered package and goes up quickly with one crew, with a non-combustible frame that will not rot. For a deeper comparison with wood post-frame buildings, see pole barn vs. metal building.

Ways to control the total

1. Decide the size once. Extending later costs more than building the right length now.
2. Prioritize structure over extras. Roof style, height and certification are permanent; windows and shelving can wait.
3. Get three slab quotes. Concrete pricing varies more between contractors than building pricing does.
4. Bundle insulation and anchors into the building order rather than adding them afterwards.
5. Look at payment options. Financing and rent-to-own are available; see how rent-to-own metal buildings work.

For a broader introduction to steel garages, read Metal Garages 101.

Frequently asked questions

What is the average cost to build a detached garage?

It varies widely with size and construction type. For the steel garages on our site, installed starting prices at the time of writing run from about $8,000 for a single-bay building to about $27,000 for a 30' x 60', before foundation, site work and tax.

How much does a 20x20 detached garage cost?

Our 20' x 20' x 10' metal garage is listed from $9,960 installed at the time of writing. A concrete slab and electrical work are additional.

Is it cheaper to build a detached or attached garage?

A detached pre-engineered steel garage is often the lower-cost route because it does not require modifying the house. An attached garage can make sense when lot space is tight or you want direct indoor access.

How much does a 30x40 detached garage cost?

We cover that size in detail in our 30x40 metal building cost guide.

Get a real number for your garage

Tell us the size, doors and location and we will send an installed price for your address. Browse metal garages or check the prices page. Request a free quote, design it yourself in 3D, or call (262) 383-4347.

This guide is general information. All prices shown are estimated starting prices published at the time of writing; current pricing, taxes, foundation costs and local permit rules must be confirmed for your property with a Wisconsin Carports Building Specialist and your municipality.

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