Do You Need a Permit for a Carport? Size, Sides, and Foundations

Short answer: often yes. Several cities require a building permit for every carport, kits included, and a carport has to stay open on at least two sides, or it is treated as a garage.

A kit arrives on a flatbed and the seller says it is "just a cover," so no building permit.

Sometimes that is true for a tiny shed. A carport is usually not that project. A carport building permit is the local approval for a covered parking structure that stays open on enough sides to stay a carport, not a garage. Cities disagree on whether every carport needs a permit, how many sides must stay open, and whether a big-box kit needs a local engineer. PermitCove is an independent homeowner guide, not your building department. The numbers below belong to the cities named next to them. See our disclaimer.

Related: detached garage building permits · shed permit requirements · pergola and patio cover permits · driveway and curb-cut permits · zoning variance and setbacks · how to apply for a building permit.

Carport, garage, shed, or patio cover?

City of Kirkland, Washington, defines a carport as a parking structure open on at least two sides, attached or detached from a single-family house. The city requires a permit to add a carport of any size, including pre-manufactured kits from home improvement stores. That is Kirkland's rule, not a national kit exemption.

City of Lakewood, Colorado, requires a building permit for any residential carport or patio cover on a single-family lot, regardless of size. On that handout, a patio cover is a roof over a patio without walls. A patio cover with walls becomes a porch, sunroom, or three-season room and is treated as a residential addition. Carports must remain open on at least two sides. Enclosure of more than two sides is reviewed as a garage. No fire-separation is required between a residence and a carport under that handout. The carport floor must be non-combustible and sloped to drain toward an open side.

San Diego's Information Bulletin 205 (August 2022) defines a carport as a covered motor vehicle parking structure accessory to a one- or two-family dwelling. It may be freestanding or attached. Under that bulletin, a carport cannot exceed 1,000 square feet or one story, must be entirely open on two or more sides except for structural supports (California Residential Code R309.2), and cannot have enclosed use above it. Anything that fails that definition must meet private garage rules. A building permit is required for any new carport or for repair or enclosure of an existing one.

If you are building walls, heat, or living space, stop. Use the detached garage guide or the living-space path. A shed square-footage exemption is not automatically a carport free pass. Read the shed guide only for storage buildings that match your city's shed sentence.

The kit box says “carport.” The building department counts the open sides.

What “open on two sides” means in practice

Almost every carport rule above leans on the same phrase from the model residential code. Section R309.2 says carports “shall be open on not less than two sides,” that the floor has to be an approved noncombustible material, and that a carport not open on two or more sides “shall be considered to be a garage.” There is one exception people miss: asphalt is allowed at ground level in a carport, which a garage floor does not get.

What counts as a side is less obvious than it sounds. In January 2025 the North Carolina Office of State Fire Marshal answered a formal question about a parking space under a building that was open at the front and open to the sky above. The office noted that the code is silent on how the two open sides have to be arranged, and concluded that the opening to the sky could count as the second open side for that design (NC OSFM formal interpretation, R309.2). That is one state reading one set of drawings, not a national rule. The lesson is simpler: if your design is close to the line, ask the building official how they count sides before you buy the panels.

And if you already know you want walls and a door, you are not choosing between carport kits anymore. That is a detached garage, with its own foundation and setback questions.

When a carport needs a permit

You usually need a permit when any of these are true in the cities below:

• Kirkland: any size carport, including kits.
• Lakewood: any size carport or patio cover on a single-family lot.
• San Diego: any new carport, or repair or enclosure of an existing carport.
• Council Bluffs, Iowa: a building permit for detached accessory structures such as garages, carports, or sheds with a floor area of 120 square feet or more, even if prefabricated.

Council Bluffs' 120-square-foot line is that city's accessory threshold. It is not Kirkland's or Lakewood's rule. Virginia's Department of Housing and Community Development notes that, in general, a building permit is required to construct a carport, garage, or shed, and that prefabricated structures delivered assembled are not treated differently from site-built ones. The same memo describes a one-story detached exemption for tool and storage sheds and similar uses not exceeding 256 square feet under the Uniform Statewide Building Code — and tells readers to ask the local building official whether a specific structure qualifies. Do not invent a 256-square-foot carport exemption for another state.

Zoning still applies when building review is light. Kirkland tells applicants to ask a planner about lot coverage and setbacks before they talk about framing. Lakewood wants the Planner-of-the-Day to confirm setbacks. If the only place the carport fits is inside a required yard, that is a variance conversation, not a framing detail.

Local triggers. Copy Kirkland's "any size" rule or Council Bluffs' 120-square-foot line only after you confirm them.

Foundations, attachment, and kit engineering

Lakewood is unusually clear on posts. Patio cover and carport columns must sit on piers extending below frost line: minimum 8-inch diameter for 4x4 posts and 10-inch diameter for 6x6 posts, at least 36 inches deep. Columns cannot be supported on a slab or a thickened edge slab. Roofs are designed for a minimum 30 psf live (snow) load plus a nominal 10 psf dead load. West of the 10,000 block of Lakewood (Kipling), special wind zone rules require design, stamp, and signature by a Colorado professional engineer. Factory-built trusses need sealed shop drawings. Unless the structure is completely self-supporting, it must attach to the house with one of the city's approved methods — not to rafter tails, lookouts, or fascia without site-specific engineering. Ledger boards cannot be supported by or through brick or stone veneer, and roofing under a new ledger must be removed first.

San Diego's bulletin gives post sizes by height above the slab (4x4 up to 8 feet; 6x6 from 8 to 10 feet), square pad footings from its tables, diagonal bracing, and approved post bases. Attached carports may use a ledger the same size as the rafters on the house side. Rafters shall not be solely supported by existing rafter tails or eave fascia. Concrete for footings and slab is called out at a minimum f'c of 2,500 psi. If posts are less than five feet from the property line, a one-hour fire-resistive wall may be required on the side parallel to the line, with opening limits between three and five feet. No fire protection is required for the common wall between a dwelling and a carport that has no enclosed space above and at least two completely open sides. If dwelling openings for light or ventilation open into an attached carport, the carport roof must sit at least seven feet above the parking surface to the underside of the rafters. Curb cuts and driveway work in the public right-of-way need a separate permit under Information Bulletin 165 — the same family of problems as our driveway guide.

Kirkland requires lateral engineering for wind and seismic, gravity design for snow and self-weight, and a carport roof able to support a minimum of 25 psf snow load. For kits, the city advises verifying engineering by a current Washington State licensed engineer. Without that, the kit often will not be permitted. Fire separation distance under five feet to a property line generally means a one-hour rated nearest wall; greater than five feet requires no fire protection on that rule.

What to bring to the counter

Kirkland's application list is a useful packet even if you do not live there: site plan with lot coverage and setbacks; elevations of all four sides with height; foundation, floor, and roof framing with footing sizes and depths, posts, members, and positive connections; roof drainage; structural calculations; and snow/wind/seismic design. Lakewood wants a plot plan at 1"=30' or larger, framing plan, building section with pier spacing and depth, beam and rafter sizes, attachment methods, and roof slope and covering. San Diego accepts its building permit template with highlighted footing, rafter, and beam sizes, an ICC-ES evaluation report plan from a supplier, or custom plans that may need calculations. For carports within six feet of a dwelling, San Diego also wants a floor plan of adjacent rooms with window and door sizes.

Draw every side of the carport and label which ones stay open.

Carport rules in the cities above

Carport checklist

1. Confirm you are building a parking cover open on at least two sides — not a garage or storage room with walls.
2. Ask planning for setbacks, height, lot coverage, and how many accessory structures your lot allows.
3. Ask building whether your size needs a building permit in that city (any size vs a square-footage trigger).
4. Decide attached vs freestanding before you buy a kit that assumes a ledger.
5. Budget frost-depth piers or pad footings the way your handout writes them — not "posts on the slab" unless the city allows it.
6. If it is a kit, get the evaluation report or local engineer stamp your city requires before you schedule delivery.
7. Plan driveway or curb-cut work as its own right-of-way question.
8. Show lights or outlets and the power source if you are adding electrical; exterior wiring follows exterior rules (San Diego).
9. Use the how to apply guide for the general sequence, then follow your city's carport handout for drawings.

Carport mistakes to avoid

• Closing in a third side later and still calling it a carport. Lakewood reviews that as a garage, and the garage rules then apply.
• Buying a kit with no local engineer documentation where Kirkland-style engineering is required.
• Setting posts on a slab only where frost-depth piers are required (Lakewood).
• Hanging rafters from house fascia without a proper ledger detail (San Diego and Lakewood both warn against that).

Decide on open sides and footings before the kit ships, not after.

FAQ

Do I need a permit for a metal carport kit?

In many cities, yes. Kirkland says any size carport, including pre-manufactured kits, needs a permit, and Tukwila requires a building permit for all carports regardless of size. Buying a kit doesn't waive the permit.

How many sides of a carport have to stay open?

The model residential code (R309.2) says at least two. A carport that is not open on two or more sides is treated as a garage.

Can a carport sit right next to the property line?

Ask first. San Diego and Kirkland may require a one-hour fire-resistive wall when the carport is less than 5 feet from a property line, and Tukwila's pre-designed guide doesn't cover carports closer than 5 feet.

Can I build a carport without an engineer?

Sometimes. Tukwila publishes a pre-designed guide for detached carports up to 20 by 20 feet with posts no taller than 10 feet. Anything larger needs calculations from a Washington-registered engineer. Other cities may want an engineer stamp for any kit.

Is a carport the same as a patio cover?

No. A carport is covered parking. Lakewood treats a patio cover as a roof over a patio with no walls, and a patio cover with walls becomes a porch, sunroom, or addition.

Last checked: October 31, 2026.

Official sources

• City of Kirkland — Carport Additions
• City of Lakewood, CO — Residential Carports and Patio Covers
• City of San Diego — Information Bulletin 205, Carports (August 2022)
• City of Council Bluffs — Residential One Story Detached Accessory Structure (Updated 2025)
• Virginia DHCD — Carports, Garages, and Sheds information bulletin
• North Carolina Office of State Fire Marshal: Formal interpretation of R309.2, Carports (Jan. 15, 2025)
• City of Tukwila, WA — Predesigned Carport Guide (Residential, rev. 11.2025)

Before the posts go in

A carport is a zoning location problem and a building construction problem. Kirkland and Lakewood want a permit for any size. Council Bluffs starts the detached accessory permit at 120 square feet. San Diego caps the carport definition at 1,000 square feet, one story, and two or more open sides. Foundations, kit engineering, and fire separation near the property line are local sentences. Confirm the packet with your building department before the posts go in the ground.

Edited by Ahmed Khalifa, founder of PermitCove. Sources are linked inline; see our Editorial Policy.