Detached Garage Builders in Bozeman, MT
Two, three and four-car detached garages built on their own frost footings and sized to what the lot and the setbacks allow, rather than to a catalogue drawing.
No obligation. Every estimate starts with a walkthrough of the lot, the access and where the building can actually sit.
Gallatin County, MTThe build
Why the detached one is the harder build
An attached garage borrows a wall, a roof line and a foundation from the house. A detached one borrows nothing.
A detached garage is a standalone building. It needs its own footings below the frost line, its own roof structure carrying full snow load, its own drainage away from the slab, and usually its own power feed from the house panel. None of that is shared with anything.
That independence is the reason people want one. It keeps noise, exhaust fumes and dust out of the house, it puts the building where the lot actually has room instead of where the house happens to be, and it does not eat into the living space. It is also the reason the price per square foot is higher than most people expect when they compare it to a bump-out.
Size is the first real decision and it is usually settled by the lot, not by preference. A 24 by 24 fits two vehicles and almost nothing else once the doors are open. A 24 by 36 gives you two bays plus a workbench wall and a real walking route around a parked truck. Past that you are into three and four-bay buildings where the roof structure changes and the door layout starts driving the framing.
The second decision is finish level, and it moves the price more than size does. An unheated shell and a heated, drywalled, in-floor-heated garage are the same building with a spread of roughly three to one on cost per square foot.
Included
What a detached garage build includes
Footings, frost walls and slab
Excavation to 36 inches, footings, frost wall, compacted base, vapour barrier and a reinforced slab with a thickened edge under bearing walls. Inside Bozeman a site-specific geotechnical report is required at permit application, with a final observation report before the footing inspection. It is a real line item and it belongs in your budget from the start, not as a surprise after design.
Frame, roof and envelope
Wall framing, engineered trusses designed to the site snow load, sheathing, roofing, house wrap, siding and trim, plus soffit and fascia detailed to match the house where that matters.
Doors, service door and wiring
Overhead doors with the opener and track, one service door, windows where the layout wants light, and a sub-panel fed from the house with the circuits and outlets a garage actually gets used for.
Sizing
Pick the size from the door swing, not the floor area
Square footage is a poor way to choose a garage. What decides whether the building works is the distance between a parked vehicle and the wall, and whether you can open a truck door without hitting a stud.
A modern half-ton pickup is roughly 20 feet long and about 6 feet 8 inches wide with the mirrors folded. Two of them side by side in a 24-foot-wide building leaves you a little over a foot at each end and about two feet between them. That is enough to walk through and not enough to work in.
The other constraint is the door. A single 16 foot door and two 9 foot doors cost about the same, but they frame differently, and the 16 foot header is a genuine structural element in a snow-load zone. Decide the door layout before the wall layout.
Footprints are the ones we build most often, not a code table. What fits your lot depends on setbacks, the septic field and its replacement area, and the approach.
Process
How a detached garage project runs
Walkthrough and siting
Where the building can sit, given setbacks, the drainfield, the approach and where roof snow will land.
Jurisdiction and scope
City permit or county land use permit, then a written cost range with the finish level named.
Design and truss engineering
Plans and a truss package engineered to the site snow load, plus the geotechnical report inside Bozeman.
Permit submission
Application, review, and any Certificate of Appropriateness if the property is in the conservation overlay.
Excavation and concrete
Dig, footings, frost wall, base, slab. This is the stage the whole building inherits.
Frame, roof, envelope, doors
Framing and truss set, roofing, siding, doors and openers, electrical, then final inspection.
Before you commit
Four things that change the number
Access for a concrete truck. A mixer needs a route in and something firm to sit on. A back garden with a narrow side gate means pumping, and pumping is a real line item rather than a rounding error.
How far the power has to travel. A sub-panel 20 feet from the house is straightforward. One 140 feet away across a driveway is a trench, a conduit run, a bigger cable and a different price.
What the ground is doing. Much of Bozeman sits on the alluvial fan below the Gallatin Range, which is a mix of cobbles, gravel, sand and clay rather than one consistent material. West of town toward the river the water table is shallower. Both matter for excavation and both are what the geotechnical report is for.
Whether you might want space above. Adding a loft or an apartment later is not a small change. It moves the footings from 36 to 48 inches and changes the floor and roof structure. Deciding at design costs nothing; deciding later means starting again.
Cost
See the range for the size you have in mind
The detached garage calculator uses the same bands we quote from, adjusted for finish level, door layout, site access and jurisdiction.
Questions
About detached garages
How much does a detached garage cost in Bozeman?
Unheated shell, $48 to $70 per square foot. Insulated, drywalled and wired, $66 to $95. Finished and heated, $88 to $128. On a 24 by 24 that is roughly $28,000 at the bottom to $74,000 at the top.
Nationally, HomeGuide, 2026 national cost guide for a two-car detached garage puts a two-car detached garage between $20,000 and $57,600 with an average near $38,800. Bozeman sits in the upper half of that, mostly because of footing depth and snow-rated roof structure.
How close to the property line can it go?
We are not publishing a setback number, and you should be careful with any site that does. Bozeman replaced its entire development code and zoning map on 1 February 2026, so most setback tables online now describe districts the city no longer uses. Outside the city, setbacks come from the county zoning district if there is one, and districts differ from each other substantially.
We check the current code against your parcel and its district. Source: City of Bozeman, Unified Development Code adoption.
Can it be built in winter?
Framing, yes. Concrete is the constraint, and it is a temperature question rather than a date question. Cold-weather pours are routine here with blankets, admixtures and protection, but they cost more and they need a weather window.
The practical effect is usually on sequence. Winter is a good time to be designing and permitting so the footings go in as soon as ground conditions allow.
Do I need engineered plans?
Montana's professional seal rules exempt residential construction of fewer than eight living units, so a detached residential garage does not need a stamped architectural design by licensing law. In practice the trusses arrive with sealed engineering from the truss manufacturer, which covers the part most likely to be questioned.
A building official can still ask for engineering on anything outside prescriptive limits, which usually means long spans, tall walls or a large door header.
Should the garage match the house?
Matching roof pitch and siding profile is what makes a new building read as part of the property. It is worth doing even when nobody requires it, because it affects resale more than the square footage does.
In Bozeman's Neighborhood Conservation Overlay District it is not optional. Exterior work and new construction there need a Certificate of Appropriateness reviewed against the city's design guidelines, and that review adds time to the schedule.
Can you build on my existing slab?
Sometimes, but the slab has to be assessed rather than assumed. Older garage slabs here were often poured on footings shallower than the current 36 inch requirement, and a slab that has heaved is telling you the footing under it failed.
We look at edge thickness, footing depth, cracking pattern and level before treating it as a foundation. See demolition and rebuild for how that assessment works.
Related
Other buildings people compare this with
Shops & Workshops
Heated, insulated working buildings with the ceiling height, power and floor drainage that real work needs.
What is involved →Garage With Loft
Storage or bonus space over the bays. A different roof, a different stair and a different structure from a single-storey build.
What is involved →Garage Slabs & Concrete
Footings, frost walls, slabs and aprons. The part of the build that is impossible to fix later.
What is involved →Next step
Send us the site, not just the size
An address and a rough footprint is enough to start. What the ground and the jurisdiction allow is usually the part that decides the project.