House Additions & Remodels

See also: GaragesMother-in-Law Units

What Is It?

A white man with a grey beard thinking about putting an addition on his house.A house addition or remodel is an extension or modification to an existing house. This may include a second-story addition, dormer, footprint expansion, interior reconfiguration, or house lift.

What Permits Do You Need?

You need a construction addition / alteration permit to build an addition or remodel. If the size of the addition or remodel is small, you may qualify for a subject-to-field inspection permit.

You may also need to apply for electrical service changes or new services from Seattle City Light.

A permit is not required to paint your house, repoint your chimney, or replace your roofing and siding if no structural changes are made. See Do I Need a Permit for a list of projects that do not require a permit. See Seattle Residential Code R105.2 for more information.

Research the Code

Your new construction must comply with the current Seattle residential, building, zoning, electrical, land use, environmental, shoreline, and mechanical codes. You do not need to upgrade existing portions of your house that are not being remodeled to the current codes. However, any structural impacts from your addition or remodel will need to be accounted for in the design and permit submittal. For example, if you are adding a second-story addition, your existing house may need structural upgrades to support the new construction.

Our Seattle Municipal Code (SMC) limits the size and location of your addition. The combined footprint of all structures (including the new addition), covered areas, and decks 36 inches or more above the ground cannot exceed a certain percentage of your lot size. That percentage varies by zoning. For neighborhood residential zones, the total coverage is limited to 35 percent of the lot (on lots 5,000 square feet or larger) or 1,000 square feet plus 15 percent of the lot area (on lots smaller than 5,000 square feet).

Should You Hire a Professional?

House drawings rarely require a professional stamp indicating they were created by an architect or engineer. You may prepare the drawings yourself or hire a professional.

Construction and Inspections

Nathan Torgelson, Director
Address: 700 5th Ave, Suite 2000, Seattle, WA, 98104
Mailing Address: P.O. Box 34019, Seattle, WA, 98124-4019
Phone: (206) 684-8600
Phone Alt: Violation Complaint Line: (206) 615-0808
Contact Us

Newsletter Updates


Sign up for the latest updates from Construction and Inspections

SDCI issues land use, construction, and trade permits, conducts construction and housing-related inspections, ensures compliance with our codes, and regulates rental rules. SDCI is committed to an antiracist workplace and to addressing racism through our work in the community.