Home Remodeling Contractors in Seattle, WA

Seattle building permits come from the Seattle Department of Construction and Inspections (SDCI), and applications are filed online through the Seattle Services Portal.

Smaller jobs such as converting a basement to living space, building a deck, remodeling part of a house or adding a small single-story addition may qualify for a subject-to-field-inspection permit, where the inspector checks code on site. Adding a story, adding a dwelling unit or changing how a building is used needs a regular building permit.

For a regular permit, SDCI aims to finish its first review of simple applications in 2 to 3 weeks and complex ones in 8 weeks. SDCI publishes its current review times; we schedule around the published figures, not the goal. Once issued, a permit is valid for 18 months.

The rules sit in Seattle Municipal Code chapter 25.09. They cover landslide-prone, liquefaction-prone and peat-settlement-prone ground, steep slope erosion hazard areas, flood-prone areas, wetlands, fish and wildlife habitat (including Haller Lake, Bitter Lake and the land within 100 feet of a stream) and abandoned landfills.

The city describes most of its ECA maps as advisory, so SDCI can ask for a topographic survey or a wetland report to confirm what is on a lot. Disturbing any ground on a lot with a mapped critical area (other than a wetland, riparian or habitat area), or more than 750 square feet on any other lot, also means a site visit by SDCI before the application is accepted.

Land within 200 feet of Puget Sound and Elliott Bay, the Duwamish River, the Ship Canal, Lake Union and Portage Bay, Lake Washington and Green Lake is in the Shoreline District, governed by the Shoreline Master Program in SMC 23.60A.

Many projects there need a shoreline substantial development permit. Some qualify for an exemption instead, requested through the Seattle Services Portal, but exempt work still has to meet the shoreline rules, and an ADU inside the district must comply with SMC 23.60A as well.

Since June 30, 2025, a Seattle lot with a house can have up to two accessory dwelling units, attached, detached or one of each. The standards are in SMC 23.42.022, added by Ordinance 127211, the city's HB 1337 compliance bill.

Each ADU can have up to 1,000 square feet of gross floor area, heights of up to 32 feet are allowed in most Neighborhood Residential zones, and ADUs are exempt from street improvement requirements. A new ADU needs a regular building permit; SDCI tracks detached units built from pre-approved ADUniverse plans as a category of their own.

The median Seattle housing unit was built in 1981, according to the 2024 American Community Survey, but about 87,000 units, roughly one in five, date from 1939 or earlier, and around 36 percent were built before 1960.

In a house that age, the surprises are behind the plaster: wiring, plumbing and framing that were never built to current code. We allow for that when pricing a remodel instead of discovering it halfway through.