Garage apartments on the North Carolina coast

From the address alone, we can find your town's rule for a garage apartment and how tall it lets the building go. What the garage itself can hold doesn't show on any map.

Over a new garage, or the one you have

A new garage is built for two stories from the start, with the apartment and its stair drawn together.

Want to build over the garage you already have? It was built to hold up its own roof. The code sizes a footing by the number of stories above it, so a one-story garage may sit on footings sized for one story. How a footing is sized explains why. Before a floor goes on, we find out what your slab, footings and walls can carry.

Attached or detached decides the rule.

Under the state's residential code, a garage joined to the house is part of the house. So an apartment over it falls under your town's rule for an attached unit, where the town has one. Over a garage that stands apart, the town's rule for a detached unit applies.

New Hanover and Pender Counties write their ADU rule for a detached unit only, so a detached garage gives the clear path there. Over an attached garage, the county planning office decides how the apartment reads.

Inside stair or outside stair

The stair can climb inside the building or up an outside wall. Either way, the apartment gets its own door to the outdoors, and the way out never passes through the garage. An inside stair works when it ends at that door.

You make these calls.

• A new garage, or the one you have
• Joined to the house, or standing apart
• An inside stair or an outside one
• How many bedrooms (on septic, they size the system)
• The kitchen and the bath
• The garage bays and doors below

When another kind fits better

A bonus room over the garage for your own household, with no kitchen, is a renovation addition.

Weighing the other kinds? A detached ADU stands on a foundation of its own, apart from the garage. Where your town and your lot allow it, a garage conversion turns the garage itself into the apartment and keeps the building one story. An in-law suite is built onto the house or made inside it. Our ADU page sets all four side by side.

Several codes name it outright.

Calabash allows a garage apartment detached from the house in its residential districts, on the town's terms. Boiling Spring Lakes allows a unit as a second story inside a detached garage, on a lot with no other separate garage. Southport makes it a special use and caps the detached garage under it at a 530-square-foot footprint. Oak Island lists it as a special use in R-6MF alone.

Wilmington counts detached garage apartments among its detached units, built new or converted. A Wilmington lot still in a legacy district, such as R-20, follows the rules in force before December 2021. New Hanover County keeps a unit behind the front of the house unless it sits over a detached garage. That rule reaches Masonboro, Ogden, Porters Neck, Castle Hayne and Myrtle Grove.

Everywhere else, the garage decides the rule.

Leland and Shallotte write rules for both kinds, each with a height cap. Winnabow follows Brunswick County, which approves one at staff level. Pender County's detached rule reaches a unit over a detached garage around Hampstead and Rocky Point. Surf City allows one on the mainland. St. James asks for a special use permit from its Town Council. In Burgaw, an apartment over an attached garage reads as an accessory apartment.

Height decides it at the beach.

Carolina Beach stops a detached accessory building at 15 feet and bars it from serving as a dwelling unit. Kure Beach holds accessory buildings to one story and 15 feet. In Wrightsville Beach, a detached garage stops at 14 feet and holds no living space. Elsewhere, the caps written for a unit or an accessory building run from 20 feet in Oak Island to 35 feet in Leland. Where does your town draw the line?

Topsail Beach and Sunset Beach name an accessory dwelling only in business districts. The ADU town table gives the rule for every town in one place.

Where the code names no ADU

Holden Beach, Caswell Beach, Ocean Isle Beach and Kure Beach name no ADU, so the office that applies the code answers lot by lot. That is Planning and Inspections in Holden Beach and the zoning administrator in Caswell Beach. In Ocean Isle Beach it is the planning office, and in Kure Beach the Building Inspector.

Code in force

2018 North Carolina Residential Code

The garage ceiling

Fire-rated board under the rooms above, and board on whatever holds it up (Table R302.6)

Doors from the garage

None into a bedroom; any other is solid or fire-rated (Section R302.5.1)

The garage door wall

Braced for the floor it carries (Section R602.10.2.2)

The way out

Its own door outdoors, with no path through the garage (Section R311.1)

The garage below carries the apartment.

The code sizes footings by the number of stories they carry, so a footing poured for one story was sized for one. Where a part goes past the code's standard framing rules, the code calls for an engineered design.

A wide garage door leaves little wall to brace. When a floor sits over that opening, the code braces the wall with portal frames, stiff panels beside the door. They can be skipped only where that whole level meets every bracing rule.

Fire-rated board goes over the cars.

The garage ceiling under the apartment gets Type X gypsum board, a fire-rated grade. The walls and beams that hold that ceiling up get gypsum board too. No door may open from the garage straight into a bedroom. Any other door between them is solid wood, steel or fire-rated.

The floor also keeps garage air out. Ducts in the garage, or through the ceiling over it, are sheet steel or another approved material, with no openings into the garage. The apartment's heating and cooling takes no return air from the garage, and the code asks for air sealing between the garage and the rooms.

Your way out never runs through the garage.

The apartment needs its own door to the outside, and the path to it can't cross the garage. Each bedroom also gets an emergency escape opening, a window or door big enough to climb out of. The stair meets the code's limits on rise, run, width and headroom.

An outside stair gets a light at the top landing, a handrail, and a guard on a high landing. Wood touching the ground is treated for it, with fasteners made for treated wood, such as hot-dipped galvanized or stainless steel.

A sloped ceiling counts where it's tall enough.

Rooms over a garage often sit under the slope of the roof, and the code allows for it. At least half of a room's required floor area needs a ceiling 7 feet high, and none of that area can sit under 5 feet.

Over an attached garage, two homes share one building.

An apartment over a garage joined to the house puts two homes in one building. The code separates two homes in one building with walls and floors that resist fire for an hour. The inspections office that issues your permit decides how it classifies the building, and so whether that rating applies. We build them either way.

If a door joins the garage to the apartment, the apartment gets carbon monoxide alarms. So does one with a fuel-burning appliance or a fireplace.

Over a detached garage, the apartment makes a second dwelling on the lot. Its walls facing the house resist fire for an hour if they stand less than 5 feet from an imaginary line between the two buildings. New Hanover County, Surf City and St. James keep the buildings at least 10 feet apart, which clears that line.

The floor over the garage is part of the shell.

The rooms above are heated and cooled, so the floor under them is insulated, as the outside walls are. Its insulation sits tight to the subfloor or to the air barrier below. A small home also needs careful heating and cooling, which our ADU page explains.

On septic, bedrooms set the size.

State rules size an apartment's septic flow by its bedrooms, and that flow adds to the house's. For the tank, the house and the apartment are sized together, by the bedrooms in both. The added flow needs approval before work starts, from the county's Environmental Health office or a private evaluator the state authorizes.

Over the garage you have

We check what's under it before the apartment is designed: the slab, the footings, the walls and the beam over the door. What we find decides the path. The garage carries the floor as it stands, or it needs work below first.

Over a new garage

A new garage is the ground floor of a two-story building from day one. Its footings, walls and door header are drawn for the apartment above, and the stair is placed with them.

Design and permits come first, through our six steps. The ADU process shows how those steps settle your town's rule before anything is drawn.