The permit question gets answered wrong in both directions. Homeowners pull permits for countertops that never needed one, and skip them for the deck ledger that absolutely did. The actual rule fits on one page: IRC R105.1 makes a permit the default for essentially all work — construct, enlarge, alter, repair, demolish, or touch any electrical, gas, mechanical, or plumbing system — and R105.2 lists the exemptions. If your project is not on the list, it needs a permit. Here is the list, read closely, because the traps are all in the fine print.
The building exemptions — and their fine print
Sheds — 200 sq ft, one story, detached.The IRC exempts one-story detached accessory structures with a floor area of 200 sq ft or less (storm shelters excluded). Note what is not in that sentence: attached structures, two-story structures, and anything bigger than a 10×20. And the IBC — the code that governs everything that is not a house — sets its version at 120 sq ft, which is why your city's handout may say 120 while the IRC says 200. The local amendment wins.
Fences — 7 feet. Exempt at 7 ft or under. But a building-permit exemption is not a zoning pass: front-yard height limits and corner sight triangles are zoning rules, and they routinely cap front fences at a fraction of 7 ft. The 2024 IBC also carves swimming pool barriers out of its fence exemption — barrier rules are their own thing.
Retaining walls — 4 feet, measured wrong by almost everyone. The exemption is for walls not over 4 ft measured from the bottom of the footing to the top of the wall, and only where nothing surcharges the wall. A “3-foot” wall on an 18-inch footing measures 4½ ft the way the code measures it. A slope, driveway, or shed pushing on the backfill is a surcharge and kills the exemption at any height.
Decks — four conditions, all at once. Exempt only if the deck is 200 sq ft or less, not more than 30 inches above grade at any point, not attached to the dwelling, and not serving the required exit door. “At any point” is the sleeper — on a sloped yard you measure at the low corner, not at the door. Attached decks are never exempt, which is fitting, since a failed ledger connection is the classic deck collapse.
The rest of the building list: sidewalks and driveways; painting, papering, tiling, carpeting, cabinets, countertops and similar finish work; prefab pools under 24 inches deep; swings and playground equipment; window awnings projecting 54 inches or less on an exterior wall; and water tanks on grade up to 5,000 gallons.
The trade exemptions are narrower than people think
Electrical: swapping a breaker of the required capacity in the same location, low-voltage work under 25 V and 50 W, and minor repairs like replacing lamps. That's the list. A new outlet, a new circuit, anything at the panel — permit.
Plumbing: clearing stoppages and repairing leaks, provided nothing gets replaced or rearranged — and the code specifically blesses “the removal and reinstallation of water closets.” Pulling a toilet is officially not permit work. But the same section is blunt about hidden pipe: if concealed drain, water, or vent pipe is defective and has to be replaced with new material, the work “shall be considered as new work and a permit shall be obtained.”
Mechanical: portable equipment and minor parts. A window unit or space heater, fine. A furnace, condenser, or water heater swap is a permit — R105.1 says replace as plainly as it says install. For the Saturday-night water heater failure, R105.2.1 is the pressure valve: emergency replacements can proceed immediately as long as the application goes in the next working business day.
The “ordinary repairs” line
R105.2.2 waives the paperwork for ordinary repairs — and then defines the boundary by listing what ordinary repairs are not: cutting away any wall or partition, removing or cutting any structural beam or load-bearing support, changing any required means of egress, or adding or relocating any piping or wiring. Patching drywall and swapping shingles is ordinary repair. Opening up the living room wall — even a partition you are sure is non-bearing — is on the excluded list by name.
Exempt does not mean unregulated
The first sentence of R105.2 does more work than the whole list: exemption from a permit “shall not be deemed to grant authorization for any work to be done in any manner in violation of the provisions of this code.” Your permit-free fence still has to be a code-compliant fence. Zoning setbacks, HOA covenants, floodplain and historic overlays all apply regardless. The exemption removes one application, not the rulebook.
Notice the pattern in what made the list: paint, countertops, a low free-standing deck, a short fence, a kiddie pool — all things you can see and fix later. What is off the list gets buried: wiring behind drywall, pipe in the wall, footings under a tall wall, ledger bolts. Permits and inspections exist for the parts of a house nobody can check after the drywall goes up.
Verify your jurisdiction. These are the 2021/2024 IRC model-code thresholds — identical in both editions — but what your city adopted and amended governs, and shed thresholds in particular get amended down. For a specific project, take the 60-second version: the permit quiz walks your exact case through R105.2 and hands you the section to cite at the permit counter.