House Additions & Remodels
See also: Garages, Mother-in-Law Units
What Is It?
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.
- Tip 101, Getting a Single Family Building Permit from SDCI
- Tip 303, Applicant Responsibilities and Plan Requirements for Single Family and Two-Unit Dwellings
- Tip 316, Subject-to-Field-Inspection Permits
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).
- Tip 103, Site Plan Requirements
- Tip 106, General Standards for Plans and Drawings
- Tip 220, Lot Coverage, Height and Yard Standards for Homes in Neighborhood Residential Zones
- Tip 303A, Common Seattle Residential Code Requirements
- Tip 312, Decks, Fences and Arbors for Single Family Homes in Seattle
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.