The shed kit is sitting in the driveway, half unboxed, when a neighbor leans over the fence: "You pull a permit for that?" For most backyard sheds in California, the honest answer is — you don't need one. The state's residential code draws a bright line at 120 square feet, and it draws similar lines for fences, decks, retaining walls and a surprising list of other weekend projects.
The list lives in § R105.2 of the 2025 California Residential Code: a one-story detached accessory structure needs no building permit if its floor area doesn't exceed 120 square feet. Fences are exempt up to 7 feet, retaining walls up to 4 feet (measured from the bottom of the footing, and only if they hold back nothing extra), and detached decks up to 200 square feet and 30 inches off the ground.
The permit-free list
| Project | No building permit needed when… |
|---|---|
| Shed / playhouse / accessory structure | One story, detached, floor area ≤ 120 sq ft |
| Fence | Not over 7 feet high |
| Retaining wall | Not over 4 feet (footing bottom to top) and not supporting a surcharge — extra load like a slope or driveway above |
| Deck | ≤ 200 sq ft, ≤ 30 inches above grade, detached from the dwelling, not serving the required exit door |
| Prefab swimming pool | Less than 24 inches deep |
| Water tank | On grade, ≤ 5,000 gallons, height ≤ 2× width |
| Sidewalks and driveways | Exempt as flatwork |
| Window awnings | Projecting ≤ 54 inches, supported by the wall |
| Paint, tile, carpet, cabinets, countertops | Finish work is exempt |
| Swings and playground equipment | Exempt |
Every row is from the Building list in § R105.2. Commercial and multifamily properties follow the Building Code's own version of this list at § 105.
What "exempt" doesn't mean
The section opens with the sentence people skip, so it's worth quoting:
"Exemption from permit requirements of this code shall not be deemed to grant authorization for any work to be done in any manner in violation" — § R105.2
No permit ≠ no rules. Three follow-on points matter for sheds specifically:
- Zoning still applies. Where the shed may sit — setbacks from lot lines, rear-yard coverage, height — is your city's zoning code, and it applies whether or not a building permit exists. A permit-exempt shed placed in a required side yard is still a violation. (Fire-safety rules also shape placement near property lines — see our guide to California's fire rules near the fence.)
- Wildfire-area rules still apply. § R105.2 says it outright: exempt accessory structures "still be regulated" by the state's Wildland-Urban Interface code. In fire-hazard areas, even a permit-free shed can carry material and siting requirements.
- Utilities are separate trades. The exemption covers the building. The electrical exemptions in the same section are tiny — plug-in decorative lighting, like-for-like breaker swaps, sub-25-volt gadgets — so running power, water or gas to the shed triggers its own permit even when the structure doesn't.
Just over the line? What a permit actually buys
If your plans say 12×12 (144 square feet), a loft, or wiring for a workshop, you're in permit territory — plans, fees and inspections. That's not purely friction: the inspection sequence exists to catch footing, framing and anchorage problems while they're still cheap to fix, and a permitted structure is one an appraiser, insurer or future buyer never argues with. Unpermitted structures, by contrast, have a way of surfacing during sales and claims.
One more local wrinkle: cities can amend the state code, and a few tighten or adjust these exemption thresholds. The 120-square-foot shed rule is the state baseline — a two-minute call to your building department ("is a 10-by-12 shed exempt here?") confirms your city hasn't moved the line.
