Do I need
a permit
for that?
Most people find out the expensive way — at inspection, at resale, or when a neighbour calls it in.
Where is the work?
- Inside the houseWalls, kitchens and bathrooms, and the systems behind them
- On the houseThe roof, the windows, and anything bolted to the structure
- Out on the lotFences, sheds, driveways and anything standing on its own
What are you doing?
- Put up a fenceFences under 7 feet are typically exempt from a building permit — but height limits, corner-visibility rules and pool-barrier requirements are set locally and catch people constantly.
- Add a shed or small outbuildingOne-story detached sheds are typically exempt up to 200 square feet under the residential code — but the number people quote is 120, and both are right depending on which code your jurisdiction adopted.
- Build an ADU or convert a garageAlways requires permits, and this is the project where zoning approval — not the building permit — is usually the real obstacle.
- Pour or widen a drivewayFlatwork on your own lot is often exempt, but anything touching the street or the sidewalk needs a separate approval from the road authority.
- Put in a swimming poolDepth is what decides it, not whether the pool is in the ground: the residential code exempts only prefabricated pools less than 24 inches deep, and past that a pool brings a barrier requirement and electrical bonding with it.
- Install a hot tub or spaMost of the permit is electrical rather than structural — a portable spa is still a 240 volt appliance sitting in water — and a listed safety cover is what commonly relieves it of the pool barrier requirement.
- Build a fire pit or outdoor fireplaceA portable wood fire pit is generally not a building-permit item at all — it is governed by fire and open-burning rules instead. Plumb gas to it and the gas line is regulated work in nearly every jurisdiction.
- Put up a pergola or gazeboAttachment is what changes this: a freestanding pergola under the accessory-structure size ceiling is often exempt, while anything bolted to the house is an alteration to the dwelling and typically permitted.
- Build a retaining wallFour feet is the line in the model code, and it is measured from the bottom of the footing rather than from the ground you can see — so a wall that looks like three feet is often already past it.
- Take down a treeThis is not a building-code question at all — no building department issues a permit for it. It is decided by a local tree ordinance, and in the cities that have one the fines are unusually large.
- Install a standby generatorA permanently installed generator is two permitted trades at once — the electrical connection and the fuel supply — and the transfer switch is the part that is never optional.
- Replace a sewer or water lineClearing a blockage is exempt; replacing the pipe is not. And the line normally crosses into the public right-of-way, which is a second permit from a different authority.
Why nobody can just tell you
Permitting in the United States is run by thousands of separate authorities, and each one can amend the code it adopts. Any site giving you a confident yes or no for every address in the country is guessing, and you cannot tell which answers are the guesses.
22,662counties and incorporated places that could issue your permit
41%of Americans live where the state code does not settle it
30%of ZIP codes straddle a county line, so even the office is ambiguous
So this does not pretend. Each answer is the typical rule, where it comes from, and the thresholds that would flip it — plus a route to the office that actually decides. How this works.