CEQA §15303: what the Class 3 new construction exemption allows
Class 3 (CEQA Guidelines §15303) exempts a limited number of new small structures, small equipment in small structures, and conversions of small structures with only minor exterior changes. The limits are counted per legal parcel: one house, a building of up to four units, or a 2,500 sq ft store or office, with higher limits in urbanized areas.
The requirements, in order
Read §15303 together with the exceptions in §15300.2 and a Class 3 finding comes down to six questions:
- Is it the right kind of project? New construction of small structures, small new equipment installed in small structures, or converting a small structure to another use “where only minor modifications are made in the exterior.”
- Does it stay within the count? “The numbers of structures described in this section are the maximum allowable on any legal parcel.”
- Is the site in an urbanized area? Only then do the higher limits apply.
- For commercial buildings, no significant amounts of hazardous substances; for the larger urbanized tier, a site zoned for the use, all necessary public services and facilities available, and a surrounding area that is not environmentally sensitive.
- Does any exception apply? Class 3 is one of the five classes the location exception names, and the other exceptions apply too.
- Is there a discretionary approval at all? If the only approval is ministerial, CEQA doesn't apply and no exemption is needed.
Class 3 limits per legal parcel
| §15303 | Outside urbanized areas | In urbanized areas |
|---|---|---|
| (a) Houses | One single-family residence, or a second dwelling unit in a residential zone | Up to three single-family residences, constructed or converted |
| (b) Multifamily | A duplex or similar structure, no more than four dwelling units in total | Apartments, duplexes and similar structures designed for no more than six dwelling units |
| (c) Commercial | A store, motel, office, restaurant or similar structure up to 2,500 sq ft of floor area, without significant amounts of hazardous substances | Also up to four such commercial buildings “not exceeding 10,000 square feet in floor area,” on sites zoned for the use, with services available and a surrounding area that is not environmentally sensitive |
| (d) Utilities | Water main, sewer, electrical, gas and other utility extensions, including street improvements, “of reasonable length to serve such construction” | |
| (e) Accessory | Garages, carports, patios, swimming pools and fences | |
| (f) Sterilizer | A steam sterilization unit for medical waste at the generator's facility, run under the Medical Waste Management Act, accepting no offsite waste | |
The text of (c) doesn't say whether the 10,000 square feet applies to each of the four buildings or to all of them together. A finding that relies on the urbanized tier should say which reading it applies.
What counts as an urbanized area
Guidelines §15387 defines it as a central city or a group of contiguous cities with 50,000 or more people, together with adjacent densely populated areas of at least 1,000 persons per square mile. The lead agency decides, either by examining the area or by referring to a U.S. Census Bureau map that designates it as urbanized. A small town that isn't part of such an area gets the lower limits. The Class 32 infill exemption uses a different test, and a court has held the two are not the same.
No size cap on a house, but the exceptions still apply
Subdivision (a) counts houses; it sets no floor area for them. In Berkeley Hillside Preservation v. City of Berkeley (2015) 60 Cal.4th 1086, Berkeley used Class 3 and Class 32 to approve a 6,478 sq ft house with an attached 3,394 sq ft, 10-car garage on a lot with a slope of about 50 percent. The challengers conceded, for the appeal, that the project fit both classes, and argued the unusual circumstances exception instead.
The Supreme Court held that a reasonable possibility of a significant effect is not enough on its own: the effect has to be “due to unusual circumstances.” A challenger can show an unusual circumstance through “some feature that distinguishes it from others in the exempt class, such as its size or location,” and then needs only a reasonable possibility of a significant effect due to that feature; or it can show the project will have a significant effect. The court reversed and sent the case back.
Class 3 also carries the location exception in §15300.2(a): it doesn't apply where the project may impact “an environmental resource of hazardous or critical concern where designated, precisely mapped, and officially adopted pursuant to law.” Cumulative impact, state scenic highways, sites on the Government Code §65962.5 (Cortese) list and historical resources can bar it too; see the exceptions guide.
When CEQA doesn't apply at all: building permits and ADUs
CEQA doesn't apply to ministerial projects (Public Resources Code §21080(b)(1)), and Guidelines §15268(b) presumes a building permit is ministerial unless the ordinance gives the agency discretion. A house that needs only a building permit needs no exemption. Class 3 matters when local law adds a discretionary step, such as a use permit (as in Berkeley), design review or a hillside permit. If an approval mixes ministerial and discretionary elements, the whole project is treated as discretionary (§15268(d)).
Accessory dwelling units are the main case. Government Code §66317(a)(1) says an ADU permit application “shall be considered and approved ministerially without discretionary review or a hearing,” so CEQA doesn't reach the ADU permit. In the coastal zone the Coastal Act still applies (Gov. Code §66329), but the coastal development permit for an ADU must be decided within 60 days of a complete application, and no public hearing is required.
Worked examples
| Project on one legal parcel | Class 3? | Why |
|---|---|---|
| 2,400 sq ft house on a vacant residential lot, with design review, outside an urbanized area | Fits | One house under (a); then check the exceptions |
| Two new houses, outside an urbanized area | Doesn't fit | (a) allows one; inside an urbanized area, up to three |
| Six-unit apartment building in an urbanized area | Fits | (b) allows six in urbanized areas, four elsewhere |
| 3,000 sq ft café outside an urbanized area | Doesn't fit | Over 2,500 sq ft |
| The same café in an urbanized area, commercially zoned, services in place | Check | The (c) urbanized tier, if the surrounding area is not environmentally sensitive |
| Converting a 1,500 sq ft house to an office, new signs and paint only | Fits | Conversion with minor exterior changes; Class 1(n) also names it |
| Business that uses significant amounts of hazardous substances | Doesn't fit | (c) excludes them |
| House on a parcel on the Cortese list | Doesn't fit | §15300.2(e) |
| ADU behind an existing house | No CEQA | Ministerial under Gov. Code §66317 |
Getting the finding drafted
Once the lead agency approves a Class 3 project, it can file a Notice of Exemption, which starts a 35-day challenge period. ePlan's CEQA Exemption Finder lists Class 3 among its choices, checks the Cortese list, listed historical resources, state scenic highways and species records, and drafts a Notice of Exemption and an exemption memo. The draft is free to read and $49 to download as Word. It is an unsigned starting point, not legal advice: the parcel count, the urbanized-area call and any unusual circumstance are the agency's findings.
Sources
- CEQA Guidelines §15303, New Construction or Conversion of Small Structures (read November 13, 2026)
- AEP 2026 CEQA Statute and Guidelines, §§15268, 15300.2, 15303, 15387 (read November 13, 2026)
- CEQA Guidelines §15300.2, Exceptions (read November 13, 2026)
- CEQA Guidelines §15387, Urbanized area (read November 13, 2026)
- CEQA Guidelines §15268, Ministerial projects (read November 13, 2026)
- Public Resources Code §21080(b)(1) (read November 13, 2026)
- Government Code §66317 and §66329, ADU approvals (read November 13, 2026)
- Berkeley Hillside Preservation v. City of Berkeley (2015) 60 Cal.4th 1086, S201116 (read November 13, 2026)
- ePlan pricing and CEQA Exemption Finder page (read November 13, 2026)
About this guide
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