Do I Need a Permit for a Garage or Carport?

A new garage needs a building permit almost everywhere. Garages are full-size buildings with foundations, roof framing and, when attached, a shared wall with the house that has to slow a car fire. Carports are lighter, but they still carry snow and wind loads. The model code most of the country starts from, the International Residential Code (IRC), has no garage exemption at all; the only relief is a size limit that a typical garage is too big for.

This guide covers the model rules, the code requirements reviewers check, and how four jurisdictions handle garages and carports. If you don’t know which office covers your address, find your local building department.

What the model code says

IRC Section R105.2 lists work that does not need a building permit. The only item that can cover a garage or carport is item 1: “other than storm shelters, one-story detached accessory structures, provided that the floor area does not exceed 200 square feet.” Everything else needs a permit:

• Attached garages and carports are never covered by that exemption, because it applies only to detached structures.
• Detached garages over 200 square feet need a permit. A 12-by-20-foot one-car garage is 240 square feet; a 24-by-24-foot two-car garage is 576.
• Two-story garages, or garages with a loft or room above, are outside the exemption because it is limited to one story.

Section R105.2 also says that an exemption from a permit does not authorize work that violates the code or other local laws. A 200-square-foot carport that skips the building permit still has to meet zoning setbacks and the structural code.

Code rules a garage has to meet

These are the IRC provisions plan reviewers and inspectors usually focus on.

Attached garages (R302.5 and R302.6). The garage must be separated from the house by at least 1/2-inch gypsum board on the garage side, and by 5/8-inch Type X gypsum board where there are habitable rooms above the garage. Structure supporting that floor/ceiling also needs at least 1/2-inch gypsum board. A garage door may not open directly into a bedroom. Other doors between garage and house must be solid wood or solid or honeycomb-core steel at least 1-3/8 inches thick, or 20-minute fire-rated, and must be self-closing and self-latching. Ducts in the garage, and ducts that pass through the separation, must be at least No. 26 gauge sheet steel with no openings into the garage.

Detached garages close to the house. Table R302.6 requires 1/2-inch gypsum board on the interior side of exterior walls of a garage located less than 3 feet from a dwelling on the same lot.

Garages close to a property line (R302.1). Table R302.1(1) requires exterior walls with less than 5 feet of fire separation distance to be 1-hour fire-resistance rated, limits window and door openings within 3 to 5 feet of the line to 25 percent of the wall, and prohibits openings closer than 3 feet. A detached garage within 2 feet of a lot line may have eave projections of no more than 4 inches.

Floors and carports (R309). Garage floors must be an approved noncombustible material and sloped toward a drain or the vehicle door. A carport must be open on at least two sides, or it is treated as a garage. Carport floors must also be noncombustible, except that asphalt is allowed at ground level. Garages in mapped flood hazard areas must meet the flood provisions of R322, and automatic garage door openers must be listed to UL 325.

How the rules differ by city

Local rules set the size limits, setbacks and review paths. Four examples, checked against official sources in October 2026:

• Seattle. Most new garages need only a subject-to-field-inspection permit, where code compliance is checked in the field instead of a full plan review. To qualify, the garage must be 750 square feet or less, one story with no roof deck, have beams spanning 14 feet or less, and not be in an environmentally critical area. Larger garages need an addition/alteration permit. Seattle says you usually can’t put a garage in the front 20 feet or side 5 feet of the lot. It may go in the rear yard with size and height limits, and Neighborhood Residential zones cap total structure coverage at 50 to 60 percent of the lot.
• Denver. Every garage needs three permits: zoning, building, and a sewer use and drainage permit (SUDP). Covered structures, including carports, need zoning and building permits too. A property survey is required if you build within three feet of a property line. A new or modified driveway connection triggers a review of the adjacent sidewalks, curb ramps and alley, and you may have to make improvements in the public right-of-way.
• Montgomery County, Maryland. The county requires a permit for any accessory structure, naming detached garages specifically, and accessory structures must be in the rear yard. A contractor who pulls the permit needs a Montgomery County New Home Builder’s license. The fee schedule effective July 1, 2026 charges $136.80 for an accessory building of 200 square feet or less, and $0.88305 per square foot above that, plus a separate filing fee. A 576-square-foot two-car garage would be about $509 before the filing fee.
• Austin. Austin’s residential exemption is narrower than the model code. A detached accessory structure is exempt only if it is one story, no more than 200 square feet and 15 feet tall, contains no plumbing, does not create a dwelling, and is outside a flood hazard area. Any garage larger than that, or with a sink, needs a building permit.

Work that is often exempt

Depending on local rules, these commonly don’t need a building permit:

• Replacing an overhead garage door. Austin lists this as exempt.
• Painting, epoxy floor coatings and other finish work.
• A small detached carport or garage that meets every condition of the 200-square-foot exemption and any local add-ons.
• Like-for-like repairs that don’t touch structure, fire separation or wiring.

Converting a garage into living space is never in this category. That is a change of use that brings in egress, insulation, ceiling height and, often, parking rules. If the result is a separate unit, see the ADU guide.

What the inspections cover

A typical garage gets these inspections:

1. Footing or foundation, before concrete is placed: depth below frost line, footing size, and anchor bolt layout.
2. Slab, where required: base, vapor retarder and slope toward the door or drain.
3. Framing: wall bracing and shear walls, headers over the garage door, roof framing, and fire-rated wall assemblies near property lines.
4. Fire separation for attached garages: gypsum board type and coverage before it is taped, plus the door between house and garage.
5. Electrical, under its own permit if the garage is wired.
6. Final: grading away from the building, exterior finishes, and anything zoning required.

What to have ready when you apply

• Site plan drawn to scale with a north arrow: all lot lines, existing buildings and driveways, the new garage with its height, and distances to lot lines and other buildings.
• Survey, if you are building close to a property line. Denver requires one within three feet.
• Foundation plan with footing size, depth and slab details.
• Framing plans: stud size and spacing, header sizes over the garage door, rafter or truss layout, and shear wall or anchor bolt details.
• Elevations showing height, roof pitch, overhangs, doors and windows.
• Fire separation details: for attached garages, the gypsum board and door specifications; near lot lines, the rated wall assembly.
• Manufacturer drawings and anchoring details for prefab carports and metal buildings.
• Separate trade permit applications for electrical, plumbing or gas.
• Contractor license information, where your jurisdiction requires it.
• Historic district approval before you apply, if your property is in one. Denver strongly recommends getting it first.

Zoning and other approvals

The building permit covers construction. Zoning decides whether a garage can go where you want it, and it applies even to exempt carports:

• Setbacks from front, side and rear lot lines, which are often stricter for garages than for sheds.
• Lot coverage limits that count the garage footprint.
• Height limits for accessory buildings, sometimes lower than for the house.
• Easements, which usually prohibit permanent buildings.
• Driveway access. A new garage often needs a new or wider curb cut, which is a separate right-of-way permit. See the driveway guide.
• HOA covenants, which local governments generally don’t enforce. Montgomery County says so explicitly.

Call 811 before digging footings so buried utilities are marked.

Questions to ask your building department

• Does the city keep the IRC’s 200-square-foot exemption, lower it, or require a permit for every garage and carport?
• Is there a simplified permit or prescriptive plan for a standard detached garage?
• What setbacks and height limits apply to a detached garage on my lot?
• Do I need a survey, and when?
• Will a new curb cut or driveway widening be reviewed with the garage, or separately?
• Which trade permits will the garage need if I add lights, outlets, heat or a sink?

For permit costs elsewhere, see how much a building permit costs. If a garage or carport was built without a permit, the unpermitted work guide explains how to legalize it.