If the work is structural, electrical, plumbing, mechanical, or changes the building in any real way, assume you need a permit until your local building department tells you otherwise. Cosmetic like-for-like work (paint, flooring, swapping a faucet) usually does not. The catch is that permits are a local decision, not a national one, so the only answer that actually protects you is the one your city or county building department gives for your specific job. When in doubt, one phone call to them beats a tear-out later.
Permits are local, and so is "the code"
There is no national building permit and no single national code. Your jurisdiction (the city or county building department, known as the Authority Having Jurisdiction, or AHJ) adopts a version of the model codes, the IRC and IBC for buildings, the NEC for electrical, the IPC for plumbing, and the IECC for energy, and then amends them locally.
The part that trips people up: your AHJ is often enforcing an older edition of those codes, plus local amendments, not the newest one published. So "what does the code say" is really "what edition did my jurisdiction adopt, and what did they change." Never assume the latest book, and never assume the town next door is the same.
What usually needs one (check locally)
As a general rule, permits are required for:
- New structures, additions, and demolition
- Structural changes: removing or altering load-bearing walls, framing, footings, decks
- New or altered electrical, plumbing, HVAC, gas, and reroofing
- Anything that changes the building's footprint, use, or occupancy
And usually not required for genuinely cosmetic, like-for-like work: painting, trim, flooring, cabinet swaps, minor repairs. But "minor" is defined by your AHJ, not by you, so verify anything you are unsure about.
How the process actually runs
- Apply to the building department with your plans and scope.
- Plan review, where they check it against the adopted code.
- Permit issued, and you post it on site.
- Do the work, and stop at the required stages.
- Inspections at set points, typically a rough-in inspection before you cover anything up (drywall, backfill, slab), and a final inspection at the end.
- Sign-off, and for bigger jobs a certificate of occupancy.
The golden rule of inspections: do not cover work that has not been inspected. Closing up a wall or backfilling a trench before the rough-in inspection is how you end up opening finished work back up at your own cost.
Why skipping it lands on you
Working without a required permit is not a shortcut, it is a liability transfer onto yourself:
- Stop-work orders and fines, often double fees to permit it after the fact.
- Tear-out. They can make you open up finished work to prove it was done right.
- You own the defect. Unpermitted, uninspected work that fails later is squarely your problem, and it can void the homeowner's insurance.
- It surfaces at resale. Unpermitted work shows up in inspections and appraisals and can kill a sale or force retroactive permitting.
And a warning: be the one who pulls the permit for work you are doing. If a homeowner pulls an owner-builder permit to save a few dollars, they take on responsibilities they do not understand, and it is a classic sign of a contractor cutting a corner. Whoever pulls it is on the hook for it.
The move
Before you bid, and definitely before you start, call the local building department, describe the exact job, and ask two things: does this need a permit, and which code edition and amendments apply. Get the answer for that jurisdiction, because the one down the road may differ. The Permit and Code Lookup tool and Working in Your State point you to the right department and what they have adopted.
Common questions
Do I need a permit to replace a water heater?
In most places, yes. A like-for-like water heater swap involves gas, water, and often electrical connections, so most building departments require a permit and an inspection even when the new unit sits where the old one did. A few jurisdictions treat a straight replacement as minor repair, but do not assume it, because the ones that require a permit take it seriously. Call your building department, describe the exact swap, and confirm before you pull the old tank.
Can I get a permit after the work is already done?
Usually yes, through an after-the-fact or retroactive permit, but it costs more and it is more painful than doing it up front. You typically pay the normal fee plus a penalty, and you may have to open up finished work so the inspector can see what got covered. The work also has to meet the code in force now, not the code from when it was built. Get the exact process from your building department.
How long does it take to get a permit?
It depends entirely on the jurisdiction and the job, from same-day over-the-counter permits for simple work to weeks of plan review for anything structural or complex. There is no national timeline, so build the real number into your schedule before you promise a homeowner a start date. Ask your building department for their current plan-review turnaround, and factor in that inspections usually need a day or two of lead time to book.
Who is supposed to pull the permit, me or the homeowner?
As the contractor doing the work, you should pull it yourself, under your own license. Letting the homeowner pull an owner-builder permit to save money puts the legal responsibility on someone who does not understand it, and in many states it is illegal for a licensed contractor to work under an owner-builder permit. Whoever pulls the permit owns the code compliance, so it should be you.
The honest bit
- Every code number that matters (frost depth, stair geometry, egress sizes, load tables) depends on the edition your AHJ adopted and any local amendments, and some were renumbered between editions. This national guide deliberately does not print those. Get them from the Permit and Code Lookup tool and confirm with your AHJ.
- Permit thresholds and fees are set locally and change. Verify with your building department.
- This is general guidance, not code interpretation or legal advice. The AHJ has the final say, always.
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