Before the Slab Pours: What a St. Louis Garage Really Costs
Revised October 13, 2026
What is the average cost to build a 24x24 garage?
A standard 24x24 two-car garage typically costs $35,000 to $50,000 at national averages, depending on materials, local labor and whether it is attached or detached. Basic builds come in near $35 a square foot, finished ones $90 or more. Inside St. Louis city, the building permit adds $10 per $1,000 of estimated cost plus a $25 application fee.
Keep reading ↓Twenty-five dollars, cash or check at the counter, and you don’t get it back. That’s the first money a garage costs you inside the city of St. Louis, paid at a permit counter at 1200 Market before anyone has looked at a single drawing. Everything after that is bigger. But it’s a good place to start, because it’s the one number in this whole project that never moves. Nobody walks up to that counter because of a spreadsheet, though. They walk up because of a morning like this one.
The alley behind a brick house in Dutchtown at 6:40 on a January morning. Gravel crunching under your boots, a dumpster lid banging somewhere down the row, the windshield white again. You’re scraping it with a library card because the real scraper is under the back seat, and the cold has gone through your gloves into your knuckles. Two doors down, a neighbor’s old garage door rattles up on its track and their car backs out dry. You stand there with the card in your teeth, breath fogging, doing the math you’ve put off since November. That’s when the garage stops being a someday number.
The big money is concrete, lumber, a door and the people who put them together. The small money is local, and it fits on a sticky note: in St. Louis city, a garage permit is $10 for every thousand dollars of estimated cost, plus a $25 application fee. Text that to the brother-in-law who swears permits cost a fortune. To apply you need the property address, the $25, your project plans, and, if your builder files instead of you, a letter of authorization from you as the owner. Questions go to the Permit Section at (314) 622-3313.
What is the average cost to build a 24x24 garage?
A standard two-car garage at 24 by 24 feet typically costs $35,000 to $50,000 at national averages, depending on size, materials, local labor rates and whether it’s attached or detached. That’s about 576 square feet of slab, which is why the number lands where it does. Basic builds can come in closer to $35 a square foot. Custom, fully finished garages with premium materials and upgraded doors can run $90 a square foot or more.
Those are national figures, and here’s the twist most guides miss: Missouri builds this exact garage for less. BuildCost puts a typical 576-square-foot detached garage in Missouri at $18,432 to $46,080, averaging $28,800. That average sits below the $35,000 floor of the national range. Screenshot that before the first bid comes in, because a builder quoting you the national number is quoting you somebody else’s state. Inside St. Louis city limits, that $28,800 average works out to a $290 permit fee plus the $25 application fee. Past the city line, that schedule stops applying. St. Louis County alone has 90 municipalities, so the only honest number for your lot is the one your own city hall gives you. Treat every range here as a frame, not a quote. Your number gets real the day a builder stands on your lot, kicks at the grass where the slab will go, and looks at how the yard drains after a storm.
The gap between $35 and $90 a square foot is mostly choices you control. Bare stud walls or drywall. One door or two. Vinyl siding, or brick to match a house that was built when Truman was president. Windows. A floored attic. A subpanel so the table saw doesn’t trip the breaker every time the freezer kicks on. Two people can both say they built a 24x24 garage and be talking about two very different checks.
The permit check, worked out before you sign anything
Inside city limits, the permit runs through the City of St. Louis Building Division, and the fee schedule is posted in plain dollars. Every application carries a $25 application fee. For any project over $3,000, the permit fee adds $10 per thousand dollars of estimated construction cost, or fraction thereof. So a garage your builder estimates at $30,000 means a $300 permit fee on top of the $25. A $45,000 garage means $450.
Two details on that page matter more than the math. First, only the application fee is due when you file. The permit fee comes later, when final approvals are in and the permit is ready to issue, so you aren’t floating the whole amount while you wait. Second, every fee paid to the city for building permits is non-refundable. If you file, then change your mind about the attached version and switch to detached, the first $25 is gone. Settle the design before you file. Sit at the kitchen table with the drawing, a pencil and a cup of coffee going cold, argue it out with whoever shares the driveway, then file once.
The Permit Section sits at 1200 Market, Room 425, open Monday through Friday from 8:00 AM to 4:30 PM, and the phone is (314) 622-3313. Paying in person, they take check or cash only. You can also apply online, and there’s a Permit Cost Estimator next to the Start Application button that does this same arithmetic for you. That city permit covers property inside St. Louis City. If you live in St. Ann, Eureka, Union, O’Fallon or East St. Louis, call your own city hall before you budget. A five-minute call beats a stalled job in October.
Then there’s the ground itself. Before a shovel or an excavator touches your yard in Missouri, someone has to call Missouri 811, at 811 or 800-344-7483, so the gas, electric and water lines get marked with little flags and spray paint. Ask your builder who makes that call and when. The answer tells you a lot about the builder.
Where the money goes, from the dirt up
Walk out to the spot where it’ll go and kick at the grass. You’re standing on most of the budget. It lands in four places: the slab, the shell, the labor and the door. Then come electrical and the finishes you can always add later.
The slab nobody admires
Nobody ever walks guests out to look at the concrete. But it’s the part you can’t redo. A basic slab runs about $6 to $12 per square foot for materials and labor, before footings and grading. On a flat, well-drained lot that’s the whole story. On a yard that slopes toward the house, or one where the old maple’s roots run under the spot you picked, excavation and fill get added before a wall goes up. Smell of wet concrete on a hot morning, the screed scraping across the forms, the crew working fast because the truck is on the clock. That’s the day the garage actually starts.
Framing, roof and siding
The shell is the week the neighbors start watching: nail guns popping, the smell of fresh-cut lumber drifting over the fence, trusses swinging up one at a time. It’s usually the biggest materials line: framing, trusses, sheathing, shingles and siding. Matching your house is where it climbs. A plain rectangle with vinyl siding is the cheap version. Brick to match a red-brick two-family, or a steeper roof so you get a usable attic, pushes it up fast.
Labor, and the bid that looks too good
Every pickup that parks in your alley is somebody on the clock. You’re paying excavators, concrete finishers, framers, roofers, an electrician and someone to keep them all in order. Labor is the hardest thing to shop on price alone, and a bid that comes in thousands under the others usually left something out on purpose. Before you sign, here’s how to check if a contractor is licensed in Missouri.
The door is smaller money than you think
People brace for the garage door. They shouldn’t. An installed double-car door typically runs $1,600 to $3,200, and a single-car door $700 to $1,800, depending on insulation and openers. Put that next to a basic slab at $6 to $12 a square foot across 576 square feet, and here’s the line worth repeating to whoever shares the driveway: the door you’ll hear rumble open every morning can cost less than the concrete nobody will ever look at.
Get three itemized bids on the same plan, and make every builder walk your lot first. Browse garage builders across the St. Louis metro on St Louis Near Me Directory, then ask each one for the slab, the shell, the door and the permit as separate lines so you can compare them side by side.
If you’re the garage builder, the concrete crew or the one-person framing outfit reading this, these are the homeowners pricing jobs tonight. A listing puts your work where they’re looking, so you get more customers from the search they’re already doing. See how a listing works.
Does a detached or attached garage cost more?
Usually detached. Attached garages typically land 15% to 25% below detached on a per-square-foot basis, because they share a wall and part of the foundation with the house. You skip one whole wall. The electrical panel is right there.
The catch is that an attached garage has to look like it was always there. Rooflines have to meet. Siding has to match. Somebody has to cut a doorway into the house and seal it so January air doesn’t pour into your kitchen. On a lot of older St. Louis city parcels, though, the question answers itself. The house sits forward, the yard runs back to the alley, and detached is the only garage that fits. You’ll walk to it with keys in your fist past the tomato cages and the trash cans, and in July you’ll be glad the hot-car smell stays out by the alley instead of drifting into the hallway.
One car, two cars, or room for the workbench
Size is the biggest lever on the total. Cost per square foot eases a little as garages grow, but every extra foot adds slab, wall and roof all at once. At national averages, a 1-car garage typically costs $12,000 to $20,000. A 2-car runs $18,000 to $38,000, with most homeowners landing between $24,000 and $30,000. A 3-car typically costs $32,000 to $65,000. Yes, that two-car range sits lower than the 24x24 figure above. It covers the smaller 20x20 builds too, and those extra feet are where the money goes.
Where the garage money goes
What's the most expensive part of building a garage?
Into the slab, the lumber, the door and the crew that puts them together. In Missouri a typical 576-square-foot detached garage runs $18,432 to $46,080, averaging $28,800. The city permit is the small part: a $25 application fee plus $10 per thousand dollars of estimated cost.
The two-car is the default for a reason. Standard width and depth run 20 to 24 feet, and those four extra feet each way are the difference between squeezing sideways past a mirror and having room to open both doors, set down the groceries and keep a bench along the back wall. A single-car may be all that fits a tight lot in St. Ann. A family in O’Fallon with a boat is pricing the three-car whether they planned to or not.
How to keep the number from running away
Save on the things you can add later, never on the things you can’t. Keep the footprint a plain rectangle on the flattest spot you have. Pick a standard size so the plans and materials are stock. Leave the walls bare for now; drywall, insulation and an epoxy floor can be a second round once the bank account recovers. The slab and the frame are the wrong places to get clever.
A bare garage still does the job on day one. The first sleet storm after it’s done, you pull in, kill the engine, and listen to ice tick against the roof instead of your windshield. The car is dry. Your hands are warm. Nobody is scraping anything. The drywall can wait a year, and you won’t miss it as much as you think.
When the bids come in, read what isn’t on them. Site prep and the concrete apron out to the driveway are the usual places a cheap bid quietly goes silent. And protect the back end too: know your options if a contractor won’t finish the job. For a wider hiring playbook, these tips for finding top home repair services are worth ten minutes before you sign.
Really after a quiet place to work, not a place to park? See the St. Louis coworking spaces worth a look.
Frequently asked questions
Is it cheaper to buy a garage or build one?
A prefab or metal kit is usually cheaper up front. A stick-built garage costs more but can match your house, hold up longer and count as a real improvement. If you only need seasonal storage, a kit can make sense. For a car you park every night, building a permanent, permitted garage is the stronger buy.
Can you build a garage for $10,000?
Not a contractor-built, permitted one in most cases. At national averages, even a basic 12x20 single-car garage starts around $12,000. Ten thousand dollars might cover a small kit, a carport, or a slab and shell if you do much of the labor yourself.
How much does a 20x20 garage cost to build?
A 20x20 garage, about 400 square feet, runs roughly $18,000 to $32,000 at national averages, with $25,000 as a typical middle. Inside St. Louis city, add the permit: $25 to apply plus $10 per thousand dollars of estimated cost.
What’s the most expensive part of building a garage?
The slab and the shell together, with labor close behind. A basic slab alone runs about $6 to $12 per square foot, and framing, roofing and siding stack on top. The door, at roughly $1,600 to $3,200 for a double, is smaller money than most people expect.
Is a 20x20 garage big enough for two cars?
Yes, but it’s snug. Two-car garages have a standard width and depth of 20 to 24 feet, and 20x20 is the small end. Two cars fit, but opening doors and storing tools gets tight. If the lot allows, 24x24 is far more comfortable, especially with a truck or SUV.
What is the most popular garage size?
The two-car garage, somewhere between 20x20 and 24x24. It fits two vehicles plus some storage, which is why builders quote it most. Single-car and three-car garages fill the niches on either side.
Written by a dedicated team of St. Louis locals who live, work, and play right here in the St. Louis metro. Founder Lane Forman and team are committed to building the region’s most trusted directory by verifying listings and connecting local businesses with loyal customers across Missouri and Illinois.