Two phrases in San Francisco's regulatory vocabulary sound nearly identical and create genuine confusion for operators evaluating lease spaces: change of use and change of occupancy. They are not the same concept. "Change of use" is a Planning Code concept — moving between Planning use categories defined in §102 (e.g., General Retail to Restaurant, Office to Light Industrial). "Change of occupancy" is a Building Code concept tied to California Building Code Chapter 3 occupancy groups (e.g., Group M Mercantile to Group A-2 Assembly). They sometimes coincide. They often don't. The distinction matters because it determines which regulatory pathway your conversion takes, how many departments review your plans, whether your permit qualifies for the streamlined over-the-counter (OTC) track or the standard in-house review track, and consequently whether your project clears permits in days or weeks. For restaurant, retail, and small-commercial operators evaluating lease spaces in SF, this distinction is the single most consequential code concept to understand before signing — and it's almost never explained in the broker-tour conversation.
The two concepts in detail
Each concept is governed by a different code, evaluated by a different department, and triggers different review pathways.
- Change of use — SF Planning Code concept. Use categories are defined in §102 and govern what activities can legally happen at an address. Examples: General Retail (mercantile), Restaurant (limited or general), Bar, Office, Light Industrial, Residential, Self-Storage, Auto Repair. Moving between use categories is a Planning Department action. The Planning Department determines whether the new use is principally permitted under current zoning, conditionally permitted (requires a CUA hearing), or not permitted at all.
- Change of occupancy — California Building Code concept. Occupancy groups are defined in CBC Chapter 3 and govern the construction, fire protection, accessibility, and exit requirements that apply to a space. Examples: Group M (Mercantile / retail), Group A-2 (Assembly — food/drink consumption), Group B (Business / office), Group F (Factory / industrial), Group S (Storage), Group R (Residential), Group H (Hazardous). Changing occupancy groups triggers a Building Department review of the entire space against the new occupancy's code requirements.
Why the distinction controls your permit track
A change of use without a change of occupancy is procedurally lighter. The Planning Department processes the use change administratively (often through Prop H streamlined approval for eligible storefronts). The Building Department permits only the TI work itself, evaluating it against the existing permitted occupancy classification. If the TI scope is otherwise OTC-eligible — no Type-1 hood, no occupant-load increase, no §311 trigger — the building permit can clear in days.
A change of occupancy is procedurally heavy. The Building Department evaluates the entire space against the new occupancy's full code requirements: occupant-load recalculation, exit-capacity analysis, fire-rating upgrades, sprinkler coverage, ADA path-of-travel compliance across the entire premises (often including improvements at the public right-of-way approach to the front door), Title 24 energy compliance for the new occupancy type, and frequently new mechanical and plumbing requirements. This routes the building permit to in-house review with typical timelines of 8 to 14 weeks at minimum for SF projects.
When both apply — change of use AND change of occupancy — the timelines stack. The Planning side may go through Prop H administrative approval or full conditional use authorization (CUA), and the Building side goes through full in-house review with comprehensive code-compliance scope.
The four scenarios most operators encounter
Real situations from the broker-tour conversation, with how each plays out:
Scenario 1 — Clothing store to small café (≤750 sf assembly)
A clothing retailer is vacating, and an operator wants to put in a small café with seating. Crucial detail: the café's assembly seating area will be under 750 square feet, and the dining configuration will be under 50 occupants. Under CBC §303.1.2, a room or space used for assembly purposes that is less than 750 sf in area and accessory to another occupancy is classified as Group B (business) rather than Group A-2 (assembly). So the café remains in Group B or B/M mixed — same occupancy as the prior retail use.
Planning side: this is a change of use (General Retail to Restaurant). Planning evaluates zoning. If restaurant use is principally permitted in this zoning district, Prop H allows administrative OTC approval. Section 311 notification is generally eliminated under Prop H for storefront land-use changes citywide.
Building side: no change of occupancy. The Building Department permits only the TI work — finishes, partitions, kitchen equipment, plumbing fixtures — against the existing Group B/M classification. If the scope doesn't trigger SFFD (no Type-1 hood, no grease interceptor upsize, no hazardous materials), this clears over-the-counter.
Outcome: permit clears in days. This is the path operators should aim for whenever the lease economics work for a small footprint.
Scenario 2 — Clothing store to full-service restaurant
Same vacating retailer, but the operator's concept is a full-service restaurant: 80-seat dining room, 1,400 square feet of assembly area, Type-1 hood for a grill program, full kitchen. The assembly area exceeds 750 sf and the occupant load exceeds 50, so Group A-2 attaches under CBC Chapter 3.
Planning side: change of use (General Retail to Restaurant). Same Planning pathway as Scenario 1 — administrative or Prop H streamlined if zoning allows restaurant use.
Building side: change of occupancy from M to A-2. The Building Department evaluates the entire space against A-2 requirements: occupant-load calculations under CBC Chapter 10, exit-capacity review (number of exits, exit width, travel distance), sprinkler coverage upgrades if existing system isn't A-2 rated, ADA path-of-travel review from public right-of-way through the front door across all customer-accessible areas including restrooms, Title 24 compliance for the new occupancy type, fire-rated separation if mixed-use with adjacent tenants, and full SFFD plan check for Type-1 hood and suppression system.
Outcome: building permit routes to in-house review with typical timeline of 8 to 14 weeks, sometimes longer. Construction can begin sooner if the operator pursues a Site Permit + Addenda strategy under AB-032, but that's overkill for most restaurant projects of this scale.
Scenario 3 — Office to retail
An office space (Group B) is vacating and the new tenant is a small retailer. Surface read: this looks like a simple change of use, similar to Scenario 1.
Planning side: change of use from Office to General Retail. Planning evaluates zoning. Retail is principally permitted in most NC (Neighborhood Commercial) and downtown zones.
Building side: this IS a change of occupancy. Group B (Business) to Group M (Mercantile). Even though both are non-residential and both are commercial-tier occupancies, they have different code requirements: M occupancies have different egress widths (typically higher because retail attracts more occupants per square foot than office), different storefront accessibility requirements at the public entry, different signage regulations, often different mechanical ventilation requirements, and different fire alarm system requirements.
Outcome: routes to in-house review, though typically lighter than a restaurant conversion because most of the code-compliance scope is documentation rather than physical retrofit. Plan check typically 6 to 10 weeks. Operators often underestimate this scenario at the lease stage, expecting it to be quick. It isn't — but it's predictable.
Scenario 4 — Industrial to mixed-use
A vacant warehouse or light-industrial building is being converted to ground-floor restaurant or retail with upper-floor residential or office. Both change of use AND change of occupancy apply at significant scale.
Planning side: substantial change of use, often requiring conditional use authorization (CUA) — a public hearing process at the Planning Commission. CUA adds 3 to 6 months minimum, sometimes longer with continuances or appeal. Mixed-use projects in housing-sensitive zones may also fall under SB 423 ministerial coverage (SF subject to SB 423 as of June 28, 2024) for code-complying mixed-income housing — a different track entirely.
Building side: multiple changes of occupancy stacked. Industrial (Group F) to Mercantile or Assembly (M / A-2) at ground level, and to Residential (Group R) or Business (B) above. Mixed-occupancy buildings require separated construction with fire-rated horizontal and vertical separation per CBC Chapter 5, independent egress for each occupancy, often new shaft and stair construction, full seismic retrofit to current code, and frequently environmental remediation (Phase I / II assessment, mitigation) given prior industrial use.
Outcome: routes to Site Permit + Addenda under AB-032 as a substantial project. Total timeline from feasibility to certificate of occupancy is typically 18 to 36 months. These projects are the most rewarding adaptive reuse work but the least amenable to streamlined review pathways.
The design decisions that keep you on the lighter track
Knowing the distinction is one thing. Designing your project to land on the lighter track is the other. Decisions an architect can make that meaningfully shape the regulatory pathway:
- Keep assembly area under 750 square feet. The §303.1.2 carve-out keeps a small dining program in Group B accessory rather than Group A-2 — a fundamentally different regulatory tier. For first-time restaurant operators with a small concept, this is the single most consequential design decision.
- Keep occupant load under 50 in dining configuration. The 50-occupant threshold is the Planning Code reference for many small-business streamlining provisions. Combined with §303.1.2, staying under both keeps the project in the streamlined lane.
- Lease a space with existing matching occupancy. The cleanest path is no change of occupancy at all. A former restaurant space already in Group A-2 can host a new restaurant tenant without the building-code review that an office-to-restaurant conversion triggers. Verify the existing permitted occupancy with DBI permit history before signing.
- Avoid changes that trigger fire-rating differences. Conversions between occupancies with similar fire-rating requirements (e.g., B to M) are lighter than conversions between occupancies with materially different requirements (e.g., S to A-2, F to R).
- Don't expand the building envelope. Vertical or horizontal additions trigger §311 / §312 notification in residential zones, and even where allowed, add review complexity that an interior-only conversion avoids.
- Confirm zoning permits the use principally. Conditional use authorization adds months. A use principally permitted under zoning skips the CUA pathway entirely.
What this looks like at the broker-tour stage
The right time to ask the change-of-use / change-of-occupancy question is when you're walking the space with the broker — before the letter of intent is countersigned. The four diagnostic questions:
- 1. What was the most recent permitted occupancy classification of this space? Pull the DBI permit history for the address; don't rely on visual inspection or the broker's description.
- 2. What is the zoning district, and is my intended use principally permitted, conditionally permitted, or not permitted? Check the SF Property Information Map (PIM) for zoning, then cross-reference Planning Code §102 use definitions for your specific use.
- 3. Will my dining/assembly configuration cross the 750 sf or 50-occupant threshold? If yes, plan for A-2 occupancy attachment and the heavier code path. If no, plan for the §303.1.2 accessory-assembly carve-out and the lighter path.
- 4. Are there any Section 311 / 312 triggers in my scope? Exterior envelope changes, storefront modifications visible from the public way, occupant-load increases in residential zones. If yes, plan for 30-day notification windows and Discretionary Review exposure.
These four questions take 15 minutes to answer with the help of an architect. They save weeks of misalignment between lease economics and actual permit reality.
Common misconceptions
Three patterns we correct often with first-time operators:
- "It was a restaurant before, so I can put a restaurant in." Not necessarily. Permitted occupancy expires if a space has been vacant for an extended period or used for a different occupancy in the interim. Verify the current permitted occupancy via DBI permit history, not via the broker's description or the prior signage.
- "The change of use is just paperwork." If a change of occupancy also applies (which it often does), the building-side review is substantial code work — not paperwork. Operators who underestimate this find out at plan check, not at lease signing.
- "My contractor will handle the permit." Contractors handle construction permits. Change of use applications, occupancy reclassification analysis, and CBC code-path analysis are architectural work, not construction work. The architect's involvement before the LOI is countersigned is where the biggest timeline and budget risks get caught.