Attached garage code in Alberta: doors, drywall, curbs and CO alarms

In Alberta, an attached garage needs an air barrier against fumes between it and the house, a self-closing, weather-stripped door into the home that can't open into a bedroom, and at least 12.7 mm (0.5 in) gypsum board on its walls and ceiling (NBC(AE) 2023, 9.10.9.18, 9.10.13.15 and 9.35.4.1). A garage that serves only the home it's attached to needs no fire-rated separation from that home. These rules are in the second printing of the National Building Code, 2023 Alberta Edition, in force since 17 August 2026 (Government of Alberta, 2026).

What goes between an attached garage and the house?

Mainly a barrier to car exhaust and fuel vapour, not a fire wall. A storage garage normally needs a fire separation from the rest of a building: 1.5 h, or 1 h for a garage of 5 vehicles or fewer. Where the garage serves only the home it's attached to or built into, the code treats it as part of that home and waives the separation (NBC(AE) 2023, 9.10.9.18).

What stays is the air barrier. An attached or built-in garage needs an air barrier system between it and the rest of the building, as an effective barrier to gas and exhaust fumes, and every door through it must meet the garage door rule. Where membranes provide the airtightness, every joint must be sealed and supported.

The code's note explains the aim: keeping carbon monoxide and gasoline fumes out of the home. It adds that if the garage is open to an attic over the house, a gas-tight ceiling in the house does the job, and that masonry walls need sealer, plaster or gypsum on the garage side (NBC(AE) 2023, Note A-9.10.9.18.(4)). Notes explain intent; they aren't requirements.

These are the rules for the wall between the garage and the home, as of October 2026:

Note: rules for a garage serving one home. The City of Calgary checks them at plan review and inspection.

A house with a secondary suite needs more care. The waiver covers only the home the garage serves, so if the garage shares a wall or floor with the suite, check with the City which separation it wants on that side. Calgary's suite page notes suites can sit above an attached garage (The City of Calgary, secondary suites). The secondary suite fire separation guide covers the rules between the two units.

Can a door from the garage open into a bedroom?

No: a doorway between an attached or built-in garage and a home can't be in a room intended for sleeping (NBC(AE) 2023, 9.10.13.15). That decides a lot of main-floor plans. The garage door lands in a mudroom, laundry or hall, and a main-floor bedroom beside the garage has its door somewhere else. A den you might later use as a guest room is worth checking against this rule.

The drawing sets a single stall at the City of Calgary's minimum for a stall between two walls, 3 000 mm by 5 900 mm (9 ft 10 in by 19 ft 4 in) (The City of Calgary, garages). Beside it, a 2 900 mm strip of house holds a mudroom and a bedroom, making a 5 900 mm square. The 760 mm door is the garage's swinging door, which the note allows to be the door into the house.

Steps up from the garage follow the home's stair rules, because a garage serving one home is treated as part of it for stairs, landings, handrails and guards (NBC(AE) 2023, 9.8.1.2). Inside stairs of 2 risers or fewer need no handrail (NBC(AE) 2023, 9.8.7.1). A door at the top that swings into the house, away from the steps, needs no landing in front of it (NBC(AE) 2023, 9.8.6.2). And where the bottom step meets a sloping garage floor, its riser can vary across the stair by no more than 1 in 12 (NBC(AE) 2023, 9.8.4.4). The stair guide has the rise and run limits.

How should the garage floor meet the house floor?

With a 50 mm (2.0 in) step, a curb or a sloped floor. Where the spaces next to an attached garage are less than 50 mm above the garage floor, either the garage floor slopes to the outdoors or, in a garage for no more than 3 vehicles, an airtight curb or partition at least 50 mm high runs along the edge next to the house (NBC(AE) 2023, 9.35.2.2).

The note gives the reason: wiring and appliances near the floor can ignite gas or vapour released in a garage (NBC(AE) 2023, Note A-9.35.2.2.(1)). It also explains how this usually works out:

• A cast-in-place concrete foundation wall rising at least 50 mm above the garage floor can serve as the curb.
• A connecting door must be raised at least 50 mm off the garage floor, or close against the curb.
• Garage capacity is read from the doors: a single or double overhead door sets the number of bays.
• For a garage bigger than 3 vehicles, with wiring within 50 mm of the floor, the note points to Alberta's Electrical Code Regulation.

The garage also needs a clear height of at least 2 m (6 ft 7 in) (NBC(AE) 2023, 9.5.3.3). Stall sizes and garage dimensions are on the garage size guide.

Does an attached garage need a side door and a CO alarm?

It needs a swinging door, and the home needs carbon monoxide alarms. These are the other garage rules worth planning for, as of October 2026:

Note: code minimums. The 5 m is measured following corridors and doorways, not in a straight line.

The code's note says an overhead door isn't a dependable way out in an emergency, and that a door from an attached garage into the home meets the intent, since the door needn't lead outside (NBC(AE) 2023, Note A-9.7.2.3.(1)). So most attached garages already have it in the house door, as long as that door is at least 760 mm by 1 980 mm.

CO alarms must meet CSA 6.19, have no disconnect switch where they're wired to the house, and be fixed at the manufacturer's height. In a house with a secondary suite, one CO alarm sounding must set off all of them, and the smoke and CO alarm guide shows where each one goes (NBC(AE) 2023, 9.32.3.9).

A wall-mounted light, or a ceiling light away from where the car parks, can use a fixture with its own switch if an average adult can reach it (NBC(AE) 2023, 9.34.2.6).

What does Calgary add for an attached garage?

A permit, every time. Calgary treats an attached garage as an addition, because it increases the area of your home, and all additions need at least a building permit (The City of Calgary, additions). Electrical work needs its own permit. A design that doesn't meet the Land Use Bylaw needs a development permit too.

A detached garage is a different case. It must stay at least 1.0 m (3 ft 3 in) from the house, measured wall to wall including cantilevers and bay windows, or it needs a development permit; join it to the house and it becomes an addition (The City of Calgary, garages). The Calgary building permit guide lists the fees, and the home addition cost guide covers what an addition involves.

What does a walkthrough show for a garage?

On the LED floor, the garage is drawn at full size beside the rooms it connects to, so you can stand in the stall, walk to the house door and see where it lands. You can check that the door from the garage opens into a mudroom or hall, how the steps fall, and whether the swing clears the bench or the washer. Changes are made on the spot, and the session is recorded for you to keep.

Sessions are quoted for your plan, with nothing to pay at booking (how quotes work). Read the other building code guides and the detached garage cost guide, or book a session.