Decks and Patios in Seattle, WA
A new composite deck in Seattle costs $65 to $115 per square foot and a cedar deck $50 to $80, with elevated decks on steep lots costing considerably more. Seattle outdoor projects are shaped by small yards, steep grades and old houses: front porch rebuilds and compact rear decks are as common here as large backyard platforms.
Seattle deck and patio costs
| Project | Typical Seattle range | Seattle factors |
|---|---|---|
| Compact rear deck, 120 – 250 sq ft, composite | $12,000 – $28,000 | Tight access, short stairs |
| Elevated deck on a steep lot | $90 – $180 per sq ft | Tall posts, engineering, geotech in hazard areas |
| Craftsman front porch rebuild | $25,000 – $70,000 | Columns, railings, period details |
| Townhouse roof deck | $60 – $140 per sq ft | Membrane protection, pedestals, guards |
| Paver patio, small yard | $28 – $58 per sq ft | Hand excavation where equipment cannot reach |
Seattle yards and outdoor projects
Small flat yards in Ballard, Wallingford and Columbia City favor ground-level patios and low decks that step down from the back door, sometimes with a pergola for definition.
Steep lots in Magnolia, Queen Anne, West Seattle and Madrona put the main floor a story above the yard. Elevated decks there need engineered footings and bracing, and may sit in environmentally critical areas.
Front porches on Craftsman houses are part of the house's character. Rebuilding them with matching columns, rail profiles and rot-resistant hidden framing is a common Seattle project.
Roof decks on townhouses and modern infill sit on pedestals over the roof membrane and must be detailed so the membrane can be inspected and repaired.
Seattle deck rules and permits
Decks more than 30 inches above grade, attached decks, larger decks and roofed structures need permits through SDCI. Porches in historic districts need review. Seattle's tree protection rules can decide where footings go near large trees, and decks in critical areas get extra review.
Seattle access and materials
Narrow side yards often mean materials are carried by hand from the street or alley. Ask builders how they plan delivery and whether a street-use permit is needed for a dumpster or material drop. On shaded Seattle lots, capped composite or PVC usually outlasts cedar on low decks.
Seattle deck and patio questions
Can I rebuild my porch to look original?
Yes, with matching profiles in rot-resistant materials. In historic districts the review usually welcomes it.
Does my steep-lot deck need a geotechnical report?
If it sits in a mapped steep-slope or landslide-prone area, SDCI may require one.
Are roof decks allowed on my house?
On many infill houses and townhouses, yes, within height limits and with proper guards.
What deck surface works in a shady Seattle yard?
Capped composite or PVC, with airflow under the deck.