For most small backyard sheds in Washington, the honest answer is: maybe not a building permit — but it depends on which size rule your county uses, and that is exactly where people get tripped up. Some Washington sources exempt detached accessory buildings under 200 square feet of floor area; others work from a 120-square-foot threshold measured by roof area. Both numbers are real, they come from different rules, and your county is the only one who can tell you which one governs your lot.
This post lays out both thresholds plainly, the rules that apply even when a building permit does not, and the questions to ask your county before your shed is delivered.
Why do you see both 120 and 200 square feet?
Because two different measurements are in play. One line of rules looks at the building’s floor area and exempts small detached accessory structures up to 200 sq ft. Another looks at roof area and uses 120 sq ft. A 10×16 shed is 160 sq ft of floor — exempt under one reading, over the line under the other. That is not a loophole to exploit; it is a sign to make one phone call to your county planning or building department and ask which standard they enforce, before you order.
What rules apply even if no building permit is required?
Permit-exempt is not rule-exempt. Even where a small shed needs no building permit, you still have to respect:
- Setbacks — how close the building can sit to property lines, fences, and other structures (typically 3–5 ft in many Washington jurisdictions; some cities require more).
- Height limits — a lofted model sits taller than a utility model, and height caps vary by zone.
- Critical areas — wetlands, shorelines, slopes, and septic systems can restrict placement regardless of the shed’s size.
- HOA and easement rules — private rules can be stricter than the county’s.
Do you need a permit for electrical or plumbing in a shed?
Yes — separately. Even when the shed itself is permit-exempt, adding electrical wiring or plumbing generally requires its own permits and inspections. If your long-term plan is a workshop with power or a cabin you might finish out later, price that permit path in now instead of discovering it after delivery. A storage shed is also not a legal dwelling as-is: living in one full-time means meeting dwelling code through your county’s ADU or tiny-home path.
What size shed keeps you under the most thresholds?
Smaller footprints clear more hurdles in more places: an 8×12 is 96 sq ft of floor, and a 10×12 is 120 sq ft. Popular mid-sizes like 10×16 (160 sq ft) sit between the two thresholds — which is precisely why the county call matters for them. Browse sizes and Washington monthlies here: https://nocredsheds.com/sheds/ — for example, the 8×12 Utility Shed is $4,145 list, $178.40/mo, and the 10×16 Lofted Barn is $6,395 list, $255.54/mo, each figured as (((list − 15%) + $150 + $750 delivery) × 1.089 tax) ÷ 27, and that result is the 60-month rent-to-own payment with the Washington delivery fee already included.
FAQ
Do you need a permit for a shed in Washington? Small detached sheds are often building-permit-exempt, but Washington sources conflict — 200 sq ft of floor area in some rules, 120 sq ft of roof area in others. Confirm with your county before you buy.
How close to the fence can I put a shed in Washington? Setback rules vary by county and city; 3–5 ft from property lines is typical, and some cities require more. Your county’s current setback table is the final word.
Can I run power to my shed without a permit? Generally no — electrical work normally needs its own permit and inspection even when the shed itself is exempt.
What happens if I skip checking? You can be required to move or remove a non-complying building. One call before delivery is far cheaper than moving a shed after it.
Check first, then pick your size
Call your county, get your number, then Call/Text 360-968-4503 and we will match the size to your lot and confirm your exact monthly. No credit check to apply; approval is not guaranteed. Average delivery is 4–6 weeks, Washington statewide — Neah Bay is home turf. Rent-to-own details: https://nocredsheds.com/rent-to-own/ — lay your shed out first in the builder: https://nocredsheds.com/build-your-shed/
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