PermitNotebook / Guides
Do you need a building permit?
By Mario Bailey Last checked 2026-07-19
It depends on where you live and what you are building, and that is not a dodge: across the 668 local rules we have verified in 62 US localities, 52% of project scenarios require a permit outright, 43% depend on the project's size or scope, and only a small remainder are permit-free. The table below shows where each common project usually lands, and the threshold that most often decides it.
The short answer, by project type
Counted from every locality we cover. "Most common threshold" is the figure that appears most often in our verified rows; your locality can differ, so follow the link to its exact rule.
| Project | Across our localities | Most common threshold | Details |
|---|---|---|---|
| Bathroom Remodel | Depends on size or scope (0 of 16 outright) | No single number | By state |
| Deck | Varies widely (37 of 62 outright) | 200 sq ft (6 localities) | By state |
| Electrical | Usually required (55 of 62 outright) | No single number | By state |
| EV Charger | Usually required (12 of 16 outright) | No single number | By state |
| Fence | Depends on size or scope (9 of 62 outright) | 7 ft (9 localities) | By state |
| HVAC | Usually required (53 of 62 outright) | 5 tons (1 localities) | By state |
| Patio | Depends on size or scope (11 of 62 outright) | 200 sq ft (3 localities) | By state |
| Plumbing | Usually required (54 of 62 outright) | No single number | By state |
| Pool | Varies widely (33 of 62 outright) | 24 inches (10 localities) | By state |
| Roof Replacement | Depends on size or scope (16 of 62 outright) | 7500 USD (8 localities) | By state |
| Shed | Depends on size or scope (9 of 62 outright) | 200 sq ft (24 localities) | By state |
| Solar | Usually required (56 of 62 outright) | 3.5 lbs per sq ft (2 localities) | By state |
| Water Heater | Depends on size or scope (3 of 16 outright) | No single number | By state |
Why the answer is local
Building codes start from statewide or model codes, but the permit trigger, the exemption sizes, and the process belong to your county or city. The same backyard shed can be permit-free in one county and require a full application one county over. That is why every rule on this site is recorded per locality, with the official source it came from, instead of as one national answer.
Watch for two local wrinkles our data keeps turning up: a county rule often does not apply inside an incorporated city that runs its own building department, and some projects that skip the building permit still need a different approval, like a zoning review for a fence line or an electrical permit for the wiring inside an otherwise exempt project.
Thresholds: the numbers that decide it
Most "do I need a permit" answers are really threshold questions: a square footage, a height, or a depth on one side of which no permit is needed. The catch is that the popular number is not the universal number. Sheds are the classic case: our verified shed rows alone carry 9 different thresholds (100 sq ft, 12 ft, 120 sq ft, 150 sq ft, 200 sq ft, 256 sq ft, 36 sq ft, 400 sq ft, 50 sq ft). Fence rules spread the same way: we have verified 12 different fence height triggers (1 ft, 3 feet, 3 ft, 30 feet, 4 ft, 5 ft, 6 feet, 6 ft, 7 feet, 7 ft, 8 feet, 8 ft), so a fence that is exempt in one city needs a permit two towns over.
Every permit page on this site states its locality's threshold neutrally, with the official source, and the diagram on pages with a drawable threshold shows exactly what is being measured.
What happens if you skip the permit
Unpermitted work surfaces at the worst times: a sale, an insurance claim, a complaint, or a failed inspection on a later project. Consequences and the path back to compliance are set by state and local law, so we research them state by state, with statutes cited. If you are already in this situation, start with your state's guide:
More states are being researched; each page publishes only statute-cited facts.
Get your locality's answer in about two minutes
Pick your state and locality, check off what your project involves, and get the verified requirements, thresholds, fee notes, and office links for each item, assembled only from rules a person verified against official sources.