Carports, Greater Seattle Area
How to Build a Carport: What You Should Expect
Building a carport is setting posts on footings, framing a roof over a parking slab and leaving at least two sides open. Expect a design, a building permit, footings and posts, roof framing, roofing and trim. Our covered patios with a solid roof tied to the house start at $70,000+. Our 2024 Auburn gable roof carport cost about $75,000.
Below is each stage, the Seattle code behind it and what we built in Auburn. To plan a carport for your home, Book a Consultation.
What is a carport, and when does it become a garage?
A carport is a roof on posts over a parking space, open on the sides. The 2021 Seattle Residential Code sets the line in Section R309.2 (Chapter 3, PDF page 48, read October 2026): "Carports shall be open on not less than two sides. Carport floor surfaces shall be of approved noncombustible material. Carports not open on two or more sides shall be considered to be a garage and shall comply with the provisions of this section for garages."
The same section says the parking floor "shall be sloped to facilitate the movement of liquids to a drain or toward the main vehicle entry doorway", and its exception allows asphalt at ground level. So plan the slab and its slope with the roof, and keep two sides open if you want the carport rules.
Should a carport be attached to the house or freestanding?
An attached carport uses the house wall to carry one side of the roof. A freestanding carport stands on its own posts anywhere the lot allows. An attached roof has to be tied into the house and flashed at the wall. On our Auburn carport, the new roof had to tie into the house along its whole length. Our guide How to Build a Covered Patio Attached to Your House covers that tie in step by step.
Which carport roof should you choose?
The old Auburn carport had a flat roof of translucent corrugated panels on thin posts. A gable roof with shingles can match the house. In Auburn in 2024 we replaced that long, flat carport with a gable roof: open wood trusses, roof sheathing, asphalt shingles and skylights between the trusses. The new roof ties into the house along its whole length, and its shingles line up with the main roof.
Whatever the roof, it is framed for local loads. Table R301.2 of the 2021 Seattle Residential Code lists a 20 psf ground snow load and a 98 mph wind speed (Chapter 3, PDF page 2, read October 2026). For the covering, our roof replacement prices show standing seam metal at about 1.9 to 2 times the shingle price for the same roof size. Top 6 Roofing Materials for Seattle Area Homes Compared sets out the choices, and Roofing Contractors Across the Greater Seattle Area covers our roofing service.
Do you need a permit to build a carport in Seattle?
Yes, plan on one. Section R105.1 of the 2021 Seattle Residential Code says "a building permit shall be obtained from the building official for each building or structure prior to erecting, constructing, enlarging, altering, repairing" it (Chapter 1, PDF page 6, read October 2026). The exempt list in R105.2 (page 1-7) does not name carports.
The nearest items in that list are narrow. Item 2 exempts "patio and concrete slabs on grade", "provided no changes are made to the building envelope". Item 3 covers "One-story detached accessory buildings used for greenhouse, tool or storage shed, playhouse, or similar uses" whose "projected roof area does not exceed 120 square feet" and that are not on a concrete foundation other than a slab on grade. Item 5 covers "Arbors and other open-framed landscape structures not exceeding 120 square feet in projected area." None of the items names a carport, so plan on a permit and confirm it with the city.
Other cities adopt their own code, so the rules in Auburn or Bellevue are checked with that city. We file the permit and book the inspections.
How deep do carport footings and posts go?
The plans for your carport set the footing size from its roof and loads. Seattle sets the floor for depth: "Exterior footings shall be placed not less than 12 inches (305 mm) below the undisturbed ground surface" (Section R403.1.4, 2021 Seattle Residential Code, Chapter 4, PDF page 11, read October 2026). Table R301.2 lists a 12 inch frost line for Seattle.
Before anyone digs, buried lines are located. Washington law requires notice to a one-number locator service "not less than two full business days and not more than 10 full business days before the scheduled work-to-begin date" (RCW 19.122.030(2), last amended 2025).
On top of the footings, posts carry beams, and the beams carry the roof. On our Auburn carport, wood posts and beams run the full side of the house, and a galvanized steel connector joins each post to its beam.
How is a carport built, step by step?
A carport goes up in seven stages. Each one is set before the next starts, and the permit sits between design and digging.
| Stage | What happens |
|---|---|
| 1. Design and price | Measure the space, choose attached or freestanding, size and roof shape. You get a written, itemized price. |
| 2. Permit | Plans go to the city for review. Review time is set by your city and your scope. |
| 3. Site and footings | Old structure out, buried lines located, footings dug and poured below the depth the plans set. |
| 4. Posts and beams | Posts stand on the footings and carry beams, joined with steel connectors. |
| 5. Roof framing | Rafters or trusses, then roof sheathing. An attached roof is tied into the house. |
| 6. Roofing | Shingles, metal or panels, with flashing at the house wall and any skylights. |
| 7. Finish and inspection | Gable end, trim, paint or stain, the slab with its slope, and the final inspection. |
Stages from our build process and the 2021 Seattle Residential Code sections cited above. Permit review time: How long does a remodel take in Seattle?
How long does it take to build a carport?
Our patio price list puts a covered patio at 4 to 8 weeks on site after the permit, and it lists our Auburn carport as its covered patio project. Design and the permit come first, and each city sets its own review time.
On the Auburn job, the before photos are from July 2024 and the finished photos from November 26, 2024. The project page gives no start or finish date for the build itself.
How much does it cost to build a carport?
We publish no separate carport line. Our patio page lists our Auburn carport under covered patios. A covered patio starts at $45,000+ with an open beam pergola and $70,000+ with a solid roof tied to the house. Our Auburn gable roof carport cost about $75,000 in 2024.
| Option | Starting at, or project price | Includes, among other items |
|---|---|---|
| Covered patio, Basic | $45,000+ | Patio surface, open beam pergola, footings and posts, permit and inspections managed |
| Covered patio, Mid-Range | $70,000+ | Everything in Basic, a solid roof tied to the house, gutters and downspouts, recessed lights and fan, an outlet |
| Covered patio, Luxury | $110,000+ | Everything in Mid-Range, infrared heaters, a fireplace or fire table, a stone surface, full design drawings |
| Gable roof carport, Auburn, 2024 | About $75,000 | Old panel carport replaced: wood posts and beams, open trusses, shingle gable roof, skylights |
Starting prices from our patio page, read October 2026; typical size 200 to 500 sq ft under cover. Not included: drainage beyond the patio area, retaining walls, tree removal, gas lines and permit fees. The Auburn price is from its project page, in 2024 dollars.
How does Volcano Builders build a carport in the Greater Seattle Area?
It starts at your house. We measure the space, talk through the roof style and finishes, and send a written, itemized price before work starts. We manage the permit and the inspections. Our patio work carries a 2-year workmanship warranty, extendable to 5 years.
See Patio Contractors Across the Greater Seattle Area for the full service. For the city where our carport example stands, see Home Remodeling Contractors in Auburn, WA.
Frequently Asked Questions
Can I build a carport myself?
The permit rule is the same whoever builds it. Section R105.1 of the 2021 Seattle Residential Code requires a permit before erecting a structure, and adds: "All work shall comply with this code, even where no permit is required." The 12 inch footing depth, the 20 psf snow load and the 98 mph wind speed apply to a carport you build yourself.
Is a metal carport kit exempt from a permit?
Not by name. No item in the R105.2 exempt list names carports or kits, so a kit goes through the same permit check as a built carport. Confirm it with your city before you order one.
Can I enclose my carport later?
Yes, with a permit, and it then counts as a garage. Under Section R309.2 of the 2021 Seattle Residential Code, a carport not open on two or more sides is treated as a garage and has to meet the garage rules. Enclosing it is an alteration, which needs a permit under R105.1.
How close to the property line can a carport go?
Setbacks come from your city's zoning code, and walls or roof edges near a lot line also fall under the fire rules in Section R302.1 of the residential code. We check both for your lot before the design is drawn.
