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House Additions & Remodels

  • You need a construction permit to build an addition or to remodel your house.

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.

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.

Research the Code

Your new construction must comply with the current Seattle residential, building, zoning, electrical, 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 single-family 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.

What Do You Want To Do?


Still Need Help?


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