A barndominium with a smaller attached in-law suite wing that has its own separate covered entry, distinct from the main entry.

Barndominium Floor Plans with Garage in Oklahoma

An attached garage is the simplest way to get the truck out of the weather and give the house a real back door. In a barndominium the garage usually sits under the same roof as the living space, which makes the wall between them, the doors through it and the slab under it the parts of the plan that need the most care. In Oklahoma the garage slab is also the most common place for an in-floor storm shelter.

What actually changes with this feature

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

A walk door out of the garage

Oklahoma's amendments to the 2024 IRC require at least one egress door for each dwelling unit or garage: side-hinged, at least 32 inches of clear width and 78 inches of clear height, openable from inside without a key. The garage's egress may pass through the house; the house's may not pass through the garage. The overhead door does not count.

The separation wall and its door

The model code requires at least 1/2-inch gypsum board on the garage side of the wall between garage and house, 5/8-inch Type X gypsum under any part of the dwelling above, no opening from the garage directly into a sleeping room, and a door of solid wood or steel at least 1-3/8 inches thick, or a 20-minute fire-rated door, that self-latches and self-closes.

Bays for Oklahoma trucks

Measure the longest vehicle you own, bumper to hitch, and add room to walk around it and close the door; a crew-cab long-bed pickup outgrows a shallow garage quickly. Plan at least one deep bay, a wide door, and headroom for a ladder rack or a lifted truck. A barndominium's clear-span frame makes a 30- or 40-foot-deep garage no harder to build than a shallow one.

A mudroom as the buffer

Put a mudroom and laundry between the garage and the living space. It is the natural place for the fire-rated door, keeps red clay and wet boots out of the house, and means the garage door never opens onto a bedroom hall.

A barndominium with a smaller attached in-law suite wing that has its own separate covered entry, distinct from the main entry.
The shelter in the garage floor

An in-garage shelter has one Oklahoma rule of its own

Oklahoma does not require a new home to include a storm shelter. If you add one, the State's adopted code, the 2024 International Residential Code with Oklahoma amendments, requires it to be built to ICC 500 with a 250 mph design wind speed, and it adds a rule for the most common Oklahoma installation: when a storm shelter is installed in the floor of a garage, its rim must be raised at least 1 inch above the highest point of the adjacent garage floor, and the floor around it must have an apron sloping away, so surface water does not run into it. FEMA's guidance adds that prefabricated units depend on their anchorage, and that most existing slabs are not adequate for a safe room without work. Plan the shelter's location, the slab recess and the apron before the garage slab is formed.

Common ways to build this

Three common ways to lay this out. Yours does not have to match one exactly — this is a starting point for the conversation, not a catalog.

Two-bay attached garage

1,800 sq ft living / 720 sq ft garage (24' x 30')

A deep two-bay garage at one end of the building, entered from the house through the mudroom. The in-floor shelter sits in the back corner of the slab, clear of the parking path, with its rim and apron formed into the pour.

Three-bay garage with a workshop corner

2,000 sq ft living / 1,080 sq ft garage (36' x 30')

Two parking bays and a third bay for a bench, tools and a mower. The side-hinged egress door opens from the workshop corner to the yard.

Garage with a suite above

1,900 sq ft living / 720 sq ft garage / 600 sq ft suite above

A garage with a guest suite or office overhead, reached from inside the house. The garage ceiling carries 5/8-inch Type X gypsum under the suite, and the suite has its own egress window.

Barndominium with a Garage: common questions

6 questions worth settling before this plan is drawn. If yours is not on the list, put it in the survey.

Does the garage need a door other than the overhead door?
Under Oklahoma's amendments to the 2024 IRC, yes: at least one side-hinged egress door for each garage, at least 32 inches wide and 78 inches high in the clear, openable from inside without a key. It may lead through the house.
Can I put a storm shelter in the garage floor?
Yes, it is a common choice. If you add one, Oklahoma's code requires ICC 500 construction and a 250 mph design wind speed, and a shelter in a garage floor must have its rim at least 1 inch above the highest point of the surrounding floor with an apron sloping away. Oklahoma does not require a shelter at all.
Can a car block the shelter hatch?
It can, which is why the hatch belongs in a corner or along a wall, clear of where vehicles park. Plan the parking layout and the shelter location together.
What fire protection does the wall between the garage and house need?
The 2024 IRC calls for at least 1/2-inch gypsum on the garage side, 5/8-inch Type X under living space above, no door from the garage into a bedroom, and a solid, steel or 20-minute rated door that self-closes and self-latches.
Can the garage door open into the kitchen?
The model code allows a properly rated door into a non-sleeping room, but a mudroom in between is the better plan: it contains mess, noise and exhaust, and gives the family somewhere to drop gear.
Should the garage be attached or detached?
Attached is more convenient and makes an in-garage shelter reachable without going outside. Detached keeps fumes and noise away and simplifies the fire separation. Most barndominium owners attach it under the same roof.

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

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