Barndominium with a Garage in Illinois

A barndominium with a garage is the practical middle ground between a plain house and a full shop-house. The garage is sized for vehicles rather than equipment, the doors stay at house height, and the plan puts the garage entry into a mudroom instead of the kitchen. The layout decisions are how many bays, which wall the doors go on, whether the garage sits inside the main footprint or in an attached wing, and how the garage floor steps down from the house. The permitting details depend on how the garage is built. A garage attached to the house on posts or piers rather than a continuous footing triggers a sealed-drawing requirement in some Illinois counties, and a garage with living space above it becomes part of the dwelling in others.

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What actually changes with this feature

The look is the easy part. These are the decisions that follow from it.

Two bays at 24 feet, three at 36

A comfortable two-car garage is about 24 feet wide and 24 deep; three cars need about 36 feet of width. On a 40-foot-wide barndominium, a 24-foot-deep garage across one gable end leaves a 16-foot strip beside it for a mudroom, laundry and storage. Add four feet of depth if you want a workbench along the back wall or a full-size pickup with room to walk around it.

Door placement: gable end, sidewall or drive-through

Doors on the gable end keep the long sidewall free for windows and a porch. Doors on the sidewall let the garage run the full depth of the building. A drive-through bay, with a door at each end, suits trailers and boats that you would rather not back in. Standard 8-foot-tall doors keep a 10-foot sidewall; a 10-foot door for a lifted truck needs about a 12-foot wall in that section.

The house wall and the step down

The wall between the garage and the living space needs a fire-separation assembly and a solid, self-closing door. The garage slab usually sits a step lower than the house floor and slopes toward the doors so meltwater and road salt drain out. Put the mudroom, with a bench, closet and laundry, right at that door.

Garage footings and the frost line

Garage footings and slab edges must reach the frost depth your county publishes. Tazewell County's garage handout tells builders to extend footings below the frost depth of 36 inches; McHenry, Kane, Will, DeKalb, Winnebago, Rock Island and Peoria counties each list 42 inches for unincorporated areas. In Rock Island County, proposed 2021-code amendments scheduled for 1 October 2026 would bar residential wood columns from being encased or embedded in concrete.

Attached, inside or detached

How the garage is attached decides which county rule it meets

A garage inside the main barndominium footprint is part of the house and is permitted with it. A garage in an attached wing built on posts or piers can trigger a sealed design: McHenry and DeKalb counties require roofed structures supported by something other than a continuous footing and attached to a primary structure to be signed and sealed by a design professional licensed in the State of Illinois. A detached garage is an accessory building. Kane County allows detached single-storey accessory buildings on a turned-down slab, or on piers designed and sealed by an Illinois licensed architect or structural engineer. Tazewell County's garage handout says non-conventional garages will require a design professional, and that any garage with habitable space goes through the new-dwelling application instead. None of this changes the floor plan much, but it changes the drawings, so decide the garage type early.

Common ways to build this

Common configurations we see. Yours does not have to match one exactly — this is a starting point for the conversation, not a catalog.

Two-car garage inside the footprint

576 sq ft garage / 1,824 sq ft living

A 40x60 with a 24x24 garage in one corner, a mudroom and laundry beside it, and a three-bedroom, two-bath home in the remaining space. One roof and one foundation keep it simple and cost-efficient. The garage doors face the gable end so the long sidewall can carry a porch.

Attached three-car wing

864 sq ft garage / 2,400 sq ft living

A full 40x60 home with a 36x24 garage wing on one side, joined through a mudroom. The wing can use a lower roof so the garage doors do not set the height of the whole building. Build the wing on a continuous footing or confirm with the county whether a post-supported wing needs a sealed design.

Garage with a bonus room above

576 sq ft garage / 576 sq ft bonus room / 1,600 sq ft main floor

A two-car garage with a room above it reached from inside the house: an office, a guest room or a teenager's space. The floor above a garage needs the right fire separation and insulation, and the stair adds about 40 square feet. Where the garage is separate from the house, Tazewell County's handout sends any garage with habitable space through the new-dwelling process, so keep the bonus room inside the main building.

Ways to build this size

A footprint can go together several ways. These are the service lines most relevant to it.

Pole Barn Homes (Post-Frame)

Pole barn homes built post-frame for Illinois acreage: wide clear spans, fewer footings, and posts and footings set to your county's rules.

Metal Homes

Metal building homes for Illinois winters: steel or wood frame, metal skin, and an insulation plan that stops condensation before it starts.

Custom Plans

Custom and modified barndominium plans drawn for your Illinois lot, your county's code and the kit or build we quote — sealed where your county requires.

Permitting & Approvals

Barndominium permits in Illinois, handled: we find out who has authority over your parcel and take the zoning, building, septic and well approvals through.

Barndominium with a Garage: common questions

6 questions we get asked most often about this footprint. If yours is not on the list, ask it directly.

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Should the garage be inside the barndominium or attached?

Inside the main footprint is usually simpler and less costly: one roof, one foundation and no valley where two roofs meet. An attached wing lets the garage have its own roof height and keeps garage noise and cold away from the living space. Detached garages suit large lots and buyers who want the house footprint entirely for living, but they are accessory buildings with their own permit.

Does a garage on posts need sealed drawings?

In some counties, yes. McHenry and DeKalb counties require roofed structures attached to a house and supported by something other than a continuous footing to be signed and sealed by a design professional licensed in the State of Illinois. Kane County requires a sealed pier design for detached accessory buildings not on a turned-down slab. Tazewell County says non-conventional garages will require a design professional. Where it is required, a licensed Illinois structural engineer seals the design.

How big should a barndominium garage be?

For two cars, 24 by 24 feet is comfortable; 22 by 22 is the minimum most people are happy with. For three cars, plan 36 by 24. If you drive a full-size crew-cab pickup, add depth: 26 to 28 feet lets you close the door with room to walk around the front. A few extra feet of depth is inexpensive when you are already building the frame.

Do I need a permit for a detached garage?

In most jurisdictions with a building code, yes. Madison County requires a building permit for any accessory structure over 200 square feet. McHenry County exempts only sheds under 150 square feet. Sangamon County lists garages, sheds, carports and barns among the accessory structures it permits. In counties without a building code, a zoning permit may still apply.

Can I add living space above a detached garage?

It depends on the county, and it changes the permit. Tazewell County's garage handout says that if the structure will include habitable space, you stop and apply for a new dwelling instead. In Kendall County's agricultural zoning, the general rule is one home for each 40 acres, which limits a second dwelling on a smaller ag parcel. Ask the zoning office before you design a garage apartment.

What doors work best on a barndominium garage?

Insulated steel sectional doors are the standard choice for an attached garage because they seal well and match the steel siding. Choose the door height for your tallest vehicle, plus a little clearance for a roof rack. Windows in the top panel bring light in without adding wall openings, and a side man-door saves opening the big door every time you walk out.

Want this drawn for your program and your parcel? That is where a build actually starts.

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Start your plans

Tell us what you want to build and we will draw this for your program, then confirm what it looks like on your parcel, who issues the permit, and a realistic budget range. That conversation costs nothing.

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