If you’re looking for a garage builder in Idaho Falls, the first thing you want is a real number, not a brochure. I’m Bryce Swager, owner and lead builder at SwagerBuilds out of Rigby, and we put up detached two-car garages, three-car garages, oversized RV and shop buildings, and bonus-room-over-garage builds all across Bonneville County and the rest of Eastern Idaho. This post is the same honest breakdown I’d give you standing in your driveway.
Garage pricing in this market moves with size, slab spec, door count, and how far you take the finish. Below are 2026 ballpark ranges, the things that actually move the price, and how permitting works here. No single magic quote, because anyone who hands you one before seeing your lot is guessing.
What a garage builder in Idaho Falls actually charges in 2026
Here are the ranges we see most often on real Eastern Idaho garage projects. These cover the building, foundation, doors, basic electrical, and standard finish. Heavy site work, full interior finish, and high-end add-ons push you toward the top of each band.
| Garage type | Approx. size | 2026 cost range |
|---|---|---|
| Detached 2-car | 480 to 600 sq ft | $35,000 to $60,000 |
| Detached 3-car | 720 to 900 sq ft | $55,000 to $95,000 |
| Oversized / RV / shop-garage | 1,000 to 1,500+ sq ft | $90,000 to $160,000+ |
| Finished bonus room above garage | add-on | add $40,000 to $90,000 |
| Per finished square foot | n/a | about $70 to $130 / sq ft |
These are 2026 ballpark ranges for Eastern Idaho. Your real number depends on lot, site work, finish level, and scope.
What drives the cost of a garage in Idaho Falls
Two garages of the same square footage can be twenty grand apart, and it’s almost never random. Here’s what actually moves your number:
- Size and ceiling height. More footprint costs more, but taller walls for an RV bay or a car lift add framing, door, and material cost on top of the square footage.
- Foundation and slab. A 4-inch slab with mesh is fine for parking cars. A 5 to 6 inch slab with rebar is what you want under a real shop or anything you’ll roll heavy equipment across. Frost footings and poor soil add cost.
- Doors and openers. Door count, size, insulation, and opener quality add up fast. A good insulated overhead door and a solid opener are worth it on every build.
- Electrical and heat. Lights and outlets are baseline. A subpanel, 240V for a welder or EV charger, and a heater or mini-split are the upgrades that quietly add thousands.
- Finish level. Bare studs and a slab is the cheap end. Insulation, drywall, paint, finished floor, and trim is where the per-square-foot number climbs.
- Site work. Excavation, fill, grading, a new driveway approach, and utility runs to a detached building are often the hidden line items that surprise people.
Attached vs. detached: which is cheaper
People assume attached is cheaper because it shares a wall. In practice attached often costs more per square foot, because you’re tying into the existing structure, matching the roofline and siding, and frequently upgrading the home’s electrical service to feed it. Detached gives you more freedom on size, height, and placement, and it keeps shop noise and fumes away from the house. If you want a true workshop or an RV bay, I almost always steer you detached. If you want to walk from the kitchen to the car without stepping into the cold, attached wins. Either way, build bigger than you think you need. Nobody has ever called me a year later wishing they’d gone smaller.
If a garage is one piece of a bigger picture for you, it’s worth reading how we think about budgets on our cost reality page, and if you’re weighing a shop-home combo, our Idaho barndominium work covers that ground too.
What’s included in the price, and what’s not
This is where most garage quotes get people in trouble, so let me be blunt about it. When I give you a fixed price on a detached garage, the building itself is the easy part. The base number covers the foundation and slab, the framing, the roof and roofing, the siding, the overhead door and opener, a service entrance with basic lighting and outlets, and a man door. That’s a weather-tight, code-compliant, lockable garage you can park in the day we hand it over.
Here’s what is usually not in a base garage number, and what I make sure we talk about up front so nothing blindsides you. Site work beyond a normal pad, like extra excavation, imported fill, retaining, or a long utility trench to a detached building, gets priced separately because every lot is different. A concrete driveway or apron out to the road is its own line item; a lot of folks forget the garage needs something to drive on. Interior finish, meaning insulation, drywall, paint, and a coated or finished floor, is an upgrade, not a given. Heat, a subpanel, 240V circuits, and EV charging are add-ons. So are gutters, an upgraded door package, and any plumbing if you want a utility sink or a bathroom. None of that is hidden in my world; it’s just that an honest garage price tells you exactly where the line is between the shell and the extras, instead of burying a thin allowance and letting it balloon on you later.
Hidden cost drivers most people miss
Beyond the obvious size-and-finish stuff, a handful of things quietly move a garage budget, and they’re almost always tied to the specific lot. Here are the ones that catch people off guard in Bonneville County:
- Distance from the house and the power source. Every foot of trench for power, and every foot of driveway, is real money. A detached garage at the back of a deep lot can cost noticeably more than the same building parked next to the house.
- Soil and frost. Our frost depth means real footings, and if the soil is soft or full of clay we may need to over-excavate and bring in structural fill. You don’t see it in the finished building, but you feel it in the foundation number.
- Setbacks and easements. Where the county and your subdivision let you put the building can force a smaller footprint or a more expensive layout than you planned for.
- Drainage and grading. Water has to run away from the slab. On a flat or low lot that can mean extra fill and grading so you’re not parking in a puddle every spring melt.
- Ceiling height creep. Wanting a lift, an RV, or tall storage racks bumps your wall height, and taller walls drive up framing, siding, door, and sometimes engineering cost all at once.
None of these are reasons not to build. They’re just the reasons I won’t hand you a number until I’ve seen your lot. Once I have, the price I give you is the price you pay.
Permitting in Idaho Falls and Bonneville County
In Bonneville County, any structure over 200 square feet, or anything with electrical, needs a building permit. A licensed builder pulls the permit and schedules inspections for you, so you’re not chasing the county yourself. Garage permits typically run a few hundred dollars depending on size and valuation. The bigger thing permits buy you is a real foundation inspection, a framing inspection, and an electrical sign-off, which is exactly what protects your resale and your insurance later. Skipping the permit to save a few hundred bucks is the kind of shortcut that costs thousands when you sell.
How long a garage build takes
A standard detached two-car garage usually runs about 4 to 6 weeks once we break ground. A larger detached three-car runs 6 to 9 weeks. Attached garages take longer, figure 8 to 12 weeks, because of the tie-in work, siding match, and likely service upgrade. Adding a finished bonus room above pushes the timeline out further since you’re now building a small living space, not just a parking structure. Weather and inspection timing can move all of these a little either way, and the price stays predictable when you lock your selections before we start.
FAQ
How much does a garage builder in Idaho Falls cost per square foot?
Figure roughly $70 to $130 per finished square foot in 2026, depending on slab spec, door count, electrical, heat, and how far you take the interior finish. A bare detached shell lands at the low end; an insulated, drywalled, heated shop with upgraded doors lands at the top.
What does a detached 3-car garage cost in Eastern Idaho?
A detached three-car garage in the 720 to 900 square foot range typically runs $55,000 to $95,000 in 2026. Where you land depends on ceiling height, slab thickness, electrical, and finish level.
Can you build a finished room above the garage?
Yes. A finished bonus room above a garage typically adds $40,000 to $90,000 depending on size, whether it has a bathroom, and how it’s heated and finished. It’s one of the best ways to add usable square footage on a tight lot.
Do I need a permit to build a garage in Idaho Falls?
Yes. In Bonneville County, any garage over 200 square feet, or anything with electrical, requires a building permit. As your builder we pull the permit and schedule the inspections so the project is documented and code-compliant.
Get a real number for your garage
We build fixed-price garages with daily jobsite photos and a live budget you can actually watch, local crews, and a structural warranty behind the work. If you’re planning a bigger project, take a look at our Idaho Falls custom home builder page too. When you’re ready, send me your lot, your size, and what you want to use it for, and I’ll put a real number on it.
