The Short Answer: It Depends on Three Things
Whether your backyard shed needs a permit almost never comes down to a single national rule. It depends on three things: the shed's floor area, whether it's attached to utilities or a permanent foundation, and your specific city or county's local code. Two neighbors in different towns can build the exact same 10x12 shed and get completely different answers from their building department.
That said, there is a common baseline worth knowing before you call anyone. Many municipal codes exempt one-story, detached accessory structures — sheds included — from a building permit when the floor area is 200 square feet or less. That's the rule you'll see repeated most often in general shed-building guides. But it is a baseline, not a guarantee, and plenty of cities set their own, stricter number.
Why the Square-Footage Cutoff Varies So Much
In practice, permit-exempt sizes for sheds range anywhere from about 100 to 200 square feet depending on where you live. Some cities, including Chicago and San Francisco, use a lower 100-square-foot exemption threshold. Others, like Austin and Denver, allow up to 200 square feet without a permit. A handful of smaller or more rural jurisdictions have no separate shed rule at all and default straight to the state building code.
This wide range exists because permitting is set locally, not federally. Your city or county building department writes its own accessory-structure rules on top of whatever base code (often the International Residential Code) it has adopted, and they're free to tighten or loosen the exemption as they see fit. That's exactly why "my cousin didn't need a permit for his shed" isn't a reliable answer for your own build — his cousin's shed was permitted under different local rules.
Things That Trigger a Permit Even on a "Small" Shed
Square footage is the headline number, but it isn't the only trigger. Several other factors can push even a modest shed into permit territory:
- Running electricity or plumbing to it. The moment a shed gets wired for outlets or lighting, or gets water or drain lines run to it, most jurisdictions require an electrical or plumbing permit regardless of the shed's size. This is one of the most commonly missed triggers, since people assume the size exemption covers everything.
- Height. Even a shed well under the square-footage cutoff can require a permit if it's taller than your area's height cap — commonly somewhere around 15 feet to the peak, though this also varies by city.
- A permanent foundation. A shed set on skids or paving blocks is usually treated as more temporary and easier to exempt. Pouring a permanent concrete slab or footings can reclassify the structure and bring it under full building-permit review in some areas.
- Setback and lot-coverage rules. These are separate from the permit-or-not question and apply to almost every structure on your property, permitted or not. How close a shed can sit to your property line, a fence, or an easement is governed by zoning rules, and violating them can mean a forced relocation or teardown even if you never needed a building permit in the first place.
- HOA rules. If you're in a neighborhood with a homeowners association, its architectural review requirements are entirely separate from — and often stricter than — your city's permit rules. Clearing the city doesn't mean you've cleared your HOA.
What Actually Happens If You Skip a Required Permit
Building without a permit you actually needed isn't just a theoretical risk. The most common real-world consequences are:
- Stop-work orders and after-the-fact permitting if a neighbor complains or an inspector notices, which often costs more than pulling the permit up front would have.
- Insurance complications. Some homeowners insurance policies exclude coverage for unpermitted structures, which can matter a lot if the shed is damaged by a storm, fire, or theft.
- Problems at resale. A home inspection or the closing process on a future sale can surface an unpermitted structure, occasionally requiring it to be brought up to code, removed, or disclosed in a way that spooks buyers.
None of this means every shed needs a permit — most small, unpowered, skid-mounted sheds genuinely don't. It just means "probably fine" isn't the same as "confirmed fine," and the downside of guessing wrong is bigger than the five minutes it takes to check.
How to Actually Find Out for Your Specific Shed
The reliable way to answer this for your own project is to check with your local authority directly, since online rules of thumb can be outdated or simply wrong for your specific address:
- Call or check the website of your city or county building/permitting department and ask specifically about "accessory structures" or "detached accessory buildings," not just "sheds" — that's often the exact code term they use.
- Ask how they measure floor area. Some jurisdictions measure exterior wall to exterior wall, others measure the interior footprint, and a shed that's exempt by one measurement method can require a permit by the other.
- Ask about setback distances from property lines, fences, and easements separately from the permit question, since those rules apply either way.
- If you're planning to run power or water, ask about electrical and plumbing permits specifically — these are frequently handled by a different department or form than the general building permit.
- If you're in an HOA, check the covenants or ask the board before you check with the city, since HOA approval can take longer and sometimes needs to happen first.
A Faster Way to Get a Straight Answer
Calling a building department and getting a clear, complete answer on the first try isn't always easy — hours are limited, and answers can vary depending on who picks up. If you'd rather get a municipality-specific rundown of what your shed project actually needs before you pick up the phone, a tool like PermitPal generates a permit checklist and rough project-cost estimate for your specific location in under a minute, so you walk into that call (or skip needing one) already knowing what to ask about.