Do You Need a Permit for a Shed in Snohomish or King County?
Short answer: usually not for a storage shed, and usually yes for anything you intend to sit in. The detail matters, because the rules change depending on which side of a city line you are on, whether you are inside an urban growth area, and whether the building will have power or heat. Here is what applies across our service area.
Last reviewed August 2026. This is general guidance to help you plan, not a substitute for confirming with your own city or county. Codes change and every parcel is different. We are happy to talk through your specific situation.
The rule that catches most people
Nearly every permit exemption in Washington applies to structures that are not used for human habitation and are unconditioned. A tool shed qualifies. A backyard office with insulation, a heater and a desk generally does not, even if it is the same size.
This is the single most common misunderstanding we encounter. People read “200 square feet, no permit required”, size their office at 190 square feet, and are surprised later. If you are planning a room you will occupy for hours at a time, budget for a permit from the start. It is not usually a large expense, and it is far cheaper than resolving it retroactively.
Washington state baseline
The Washington State Residential Code (WSRC R105.2, adopted under WAC 51-51) sets the statewide minimum exemption at a projected roof area of 120 square feet. Critically, the same statute lets cities and counties adopt a higher threshold without going through the usual amendment approval process, and most have raised theirs to 200 square feet. Seattle is the notable local exception and has stayed at 120.
Unincorporated Snohomish County
Snohomish County Code 30.50.103 governs work exempt from permit. For one-story detached accessory structures not used for human habitation:
- Inside an Urban Growth Area: up to 200 square feet, with sidewalls no more than 9 feet measured from grade average under the residential code.
- Outside an Urban Growth Area: up to 400 square feet, with sidewalls no more than 11 feet and a maximum stud height of 10 feet.
- Covered area counts. Any usable area under the horizontal projection of the roof is included in the floor area calculation, even where there are no walls. A covered porch counts against your total.
- Lofts are limited to one third of the footprint.
- Setbacks for exempt structures are 20 feet from other buildings, structures and property lines.
- Heating systems are not permitted in permit-exempt accessory structures.
That last point is the one worth reading twice. If you want heat in the building, you are outside the exemption in unincorporated Snohomish County regardless of size.
Unincorporated King County
King County exempts one-story detached storage sheds of 200 square feet or less accessory to a residential or agricultural use, under WSRC R105.2. The exemption requires unconditioned space with no plumbing, electrical or mechanical systems; each of those triggers a separate Title 16 permit.
Zoning still applies in full. Setbacks and lot coverage come from KCC Title 21A, and in most residential zones the side and rear setback is around 5 feet, though it varies by zone. Exempt sheds also need at least 5 feet of separation from other structures. You can check your parcel’s zoning on the King County Parcel Viewer, and the Department of Local Services Permitting team can be reached on 206-296-6600.
Seattle
Seattle is stricter and worth treating separately. SDCI exempts a shed from a permit only when all of the following are true:
- The roof footprint is 120 square feet or less
- It is a single-story building
- It sits on a simple concrete slab, pier blocks or soil
- It is not attached to a house or other building
- It is not in or near an environmentally critical area
- It is used only for storage, growing plants or similar unoccupied purposes
A backyard office fails the last condition, so it needs a permit in Seattle regardless of size. Most such projects qualify for a subject-to-field-inspection permit, which is the lighter-touch route. Seattle also caps shed height at 12 feet, limits combined lot coverage to roughly 50 to 60 percent in neighbourhood residential zones, and typically requires 5 feet from side property lines and 10 to 15 feet from the front.
Cities have their own rules
If your address is inside an incorporated city, the city’s code applies rather than the county’s. That covers Lynnwood, Edmonds, Mountlake Terrace, Bothell, Everett, Mill Creek, Shoreline, Kirkland, Redmond, Woodinville, Kenmore and Duvall. Most follow the 200 square foot exemption, but height limits, setbacks and lot coverage vary. Always check the city, not the county, for an in-city address.
Things that require a permit regardless of size
- Electrical wiring, which needs its own electrical permit
- Plumbing of any kind
- Mechanical or heating systems
- Any structure in or near a critical area: wetlands, streams, steep slopes, flood hazard areas or shoreline jurisdiction
- Anything intended as habitable or sleeping space, which becomes a detached accessory dwelling unit and follows an entirely different process
Setbacks apply even when permits do not
Being exempt from a building permit never exempts you from zoning. Setbacks from property lines, lot coverage limits, height limits and critical area rules apply to every structure. This trips people up more often than the permit question itself, because a shed that is perfectly legal in size can still be in the wrong place.
How we help
We have taken plenty of projects through permitting, including a build in Bothell where we secured a permit that another contractor had given up on, and a 410 square foot workshop designed alongside Housecall Architecture with permitting handled as part of the project. When a design is close to a threshold we will tell you, and we will tell you honestly when scaling down slightly is the cheaper path. One of our clients decided against permitting and scaled the building down instead, which was the right call for her budget.
Common Permit Questions
What size shed can I build without a permit in Snohomish County?
In unincorporated Snohomish County, a one-story detached accessory structure not used for human habitation is exempt up to 200 square feet inside an Urban Growth Area, or 400 square feet outside one, under SCC 30.50.103. Sidewall height is capped at 9 feet inside a UGA and 11 feet outside. Usable area under the roof counts toward the total even where there are no walls, and exempt structures must sit 20 feet from other buildings and property lines.
What size shed can I build without a permit in King County?
Unincorporated King County exempts one-story detached storage sheds of 200 square feet or less that are accessory to a residential or agricultural use, provided the space is unconditioned and has no plumbing, electrical or mechanical systems. Zoning setbacks and lot coverage under KCC Title 21A still apply, typically around 5 feet from side and rear property lines depending on your zone.
Do I need a permit for a backyard office?
In most cases yes. Permit exemptions across Washington apply to unconditioned structures not used for human habitation, and a backyard office is an occupied, conditioned space. Seattle makes this explicit by limiting its exemption to storage and similar unoccupied uses. Unincorporated Snohomish County additionally prohibits heating systems in permit-exempt accessory structures. Plan for a permit if you intend to work in the building.
Why is Seattle’s limit lower than everywhere else?
Washington’s statewide minimum exemption is a 120 square foot projected roof area, and the statute allows local jurisdictions to raise it. Most counties and cities in the region raised theirs to 200 square feet; Seattle has not. So a 150 square foot storage shed that needs no permit in Lynnwood does need one in Seattle.
Does adding electricity change anything?
Yes. Electrical work requires its own permit everywhere in Washington, independent of whether the structure itself needs a building permit. In King County, the presence of electrical systems also removes the building from the storage shed exemption entirely. Factor this in early, because it affects both cost and timeline.
What is an Urban Growth Area and how do I know if I am in one?
Urban Growth Areas are the boundaries Washington counties draw under the Growth Management Act to concentrate development. It matters in Snohomish County because the exemption is 200 square feet inside a UGA and 400 square feet outside. Snohomish County’s property information portal will tell you which applies to your parcel, and the county permitting office can confirm.
What happens if I build without a required permit?
Typically you will be asked to apply retroactively, which costs more than doing it upfront and may require opening up finished work for inspection. It can also surface during a sale, when an unpermitted structure becomes something you have to disclose and negotiate around. It is not worth the saving.
Not Sure Which Rules Apply to Your Lot?
Tell us your address and what you want to build. We will tell you what we think you are looking at.
