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Building Code Reference

Got a CBC 1004.5 correction?

Occupant load factor

For builders in California, Greater Seattle, the Las Vegas area, the Denver area and Kansas City · CrossBeam Permits

What this code requires, how to fix it, and how cities and counties review it

What this code requires

CBC 1004.5 is the California Building Code section that sets the occupant load calculation method for buildings and spaces. It requires designers to apply the area-per-occupant factors in Table 1004.5 to each space based on its use type, producing an occupant load number that determines how many exits are required and how wide they need to be. Commercial tenant improvements, assembly spaces, schools, and mixed-use projects are the most common permit types flagged on this section.

How to fix it

  1. List every distinct use area on the floor plan

    Go through the floor plan and identify every space that has a different use: office, reception, conference, storage, break room, restroom, retail floor, stockroom, etc. Each distinct use type from Table 1004.5 gets its own row in your occupant load table. Don't lump everything together under a single category — that's the fastest way to get a correction. If a room can serve multiple functions, use the one that produces the higher occupant load. The code is designed around worst-case occupancy.

  2. Determine gross vs. net area for each use

    Table 1004.5 specifies whether gross or net floor area applies for each use type. Gross area is measured within the inside perimeter of the exterior walls, without deducting corridors, stairways, closets, interior walls or columns. Net area is the actual occupied area, excluding unoccupied accessory areas such as corridors, stairways, toilet rooms, mechanical rooms and closets. Most business office uses take gross area. Assembly uses like concentrated seating (chairs only, no tables) take net area. Check each table entry carefully: every factor is marked gross or net, and that marking is not optional.

  3. Apply the correct Table 1004.5 factor to each space

    Divide each space's floor area by the occupant load factor from Table 1004.5 for that use. Common factors: business areas at 150 sq ft per occupant (gross); assembly with tables and chairs at 15 sq ft per occupant (net); assembly concentrated seating, chairs only, at 7 sq ft per occupant (net); mercantile sales floor at 60 sq ft per occupant (gross); storage at 300 sq ft per occupant (gross). Round up to the next whole number — the code does not allow rounding down on fractional occupants. If a use isn't listed, select the most similar use in the table and document your rationale in a code narrative.

  4. Build the occupant load table and show it on the drawings

    Create a table that shows: space name or number, use description per Table 1004.5, floor area (gross or net as applicable), the Table 1004.5 factor, and the calculated occupant load for each row. Sum the loads for the total occupant load of the suite or floor. Place this table on the code compliance sheet, the life safety plan, or directly on the floor plan. Plan-checkers need to trace the math without requesting additional information. A note that says 'occupant load calculated per code' with no table will be flagged every time.

  5. Verify exit count and egress width against the calculated load

    Once you have the total occupant load, check your exit configuration against CBC 1006 (number of exits required) and CBC 1005 (minimum egress width). For most occupancies, an occupant load of 49 or fewer can be served by one exit; 50 or more requires at least two. Some occupancies have lower thresholds, so check CBC 1006 for your specific occupancy type. Egress door and corridor widths are calculated at 0.2 inches per occupant for level egress components and 0.3 inches per occupant for stairways. If your corrected occupant load is higher than the original design assumed, you may need to add exits or widen corridors.

  6. Post the occupant load on the floor plan

    In addition to the calculation table, post the occupant load in a visible location on the floor plan — typically near the main entrance or the space it applies to. The posted load must match the calculation table exactly. Many plan-checkers and inspectors check the posted load against the egress design as a quick sanity check. A mismatch between the posted number and the egress design will produce a correction even if the underlying math is correct. CBC 1004.9 also requires a posted occupant load sign near the main exit of assembly, classroom, dining and drinking rooms with 50 or more occupants, so specify that in your construction notes.

  7. Update the calculation if the program changes during permit review

    If the tenant modifies the floor plan after you've submitted for permit — adds a break room, flips a storage room to a server room, expands the conference area — update the occupant load table and include a revision note. A program change that affects space use or area triggers a revised calculation. This applies even to changes that seem minor. A 200 sq ft room converted from storage (300 sq ft per occupant = less than 1 occupant) to a break room (15 sq ft per occupant net = 14 occupants, rounded up) can push the total above an egress threshold.

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Why you got flagged

Here's why plan-checkers flag CBC 1004.5 corrections: the occupant load calculation is the foundation of the entire egress design, and plan reviewers will stop the review entirely if it's missing or wrong.

The most common flag is a missing occupant load calculation table on the drawings. A lot of designers write "occupant load per CBC Table 1004.5" in a general note and leave it at that. That's not enough. The plan-checker needs to see each distinct space listed by use, its gross or net area, the applicable Table 1004.5 factor, and the resulting occupant count — all on the sheets.

A second common scenario is applying the wrong area type. Table 1004.5 specifies whether gross or net floor area applies for each use. Business office space uses gross area; concentrated assembly uses net area. Mixing these up produces an occupant load that's too low, which means the egress calculation is under-designed. Plan-checkers know the difference and will flag it.

A third scenario comes up on mixed-use spaces or multi-function rooms. Conference rooms that double as training spaces, restaurants with a bar area, or retail with a storage back room all have distinct uses within the same suite. Each zone gets its own factor from Table 1004.5, and the totals are summed for the suite-level occupant load. Designers who apply a single factor to the whole floor get a correction every time.

Finally, tenant improvements in existing buildings frequently miss a recalculation. When a space changes use — say a storage room converted to office — the occupant load changes and so does the egress requirement. If the drawings don't include a revised occupant load analysis reflecting the new use, expect a correction on CBC 1004.5.

The official code

California Building Code Section 1004.5 — Occupant Load Factor (Title 24, Part 2)

Read the source →

Common questions

What is the occupant load factor for office space under CBC 1004.5?
Business office space uses 150 square feet gross floor area per occupant under Table 1004.5 of the California Building Code. Gross area is measured within the inside perimeter of the exterior walls, with no deduction for hallways, partitions, and built-in features within the suite. To calculate: divide the total gross square footage by 150 and round up to the next whole number. A 2,500 sq ft office suite would have an occupant load of 17. Keep in mind that conference rooms within the suite may use a different factor if they're set up as assembly space — in that case, pull the conference room area out and calculate it separately using the assembly factor, then add it back to the office total.
Does CBC 1004.5 apply to tenant improvements in existing buildings?
Yes. Any tenant improvement that changes the use of a space, adds square footage, or reconfigures the floor plan requires a fresh occupant load calculation under CBC 1004.5. Even if the space was previously permitted and had an occupant load posted on the wall, the new TI permit needs a current calculation based on the proposed layout and uses. This is one of the most common corrections on TI projects. Designers often assume the existing load still applies and skip the calculation table. If the use hasn't changed and the layout is identical, you can reference the prior permit's occupant load and note it explicitly — but you still need to show the table.
What's the difference between gross and net area in Table 1004.5?
Gross floor area is measured within the inside perimeter of the exterior walls. It includes interior partitions, columns, corridors, closets, and built-in cabinets within the measured area. Net floor area is the actual occupied area, excluding unoccupied accessory areas such as corridors, stairways, toilet rooms, mechanical rooms and closets. Table 1004.5 specifies which type applies to each use, and the footnotes are part of the requirement. Business and mercantile uses typically use gross area. Assembly uses — concentrated seating, standing room, and similar — use net area. Using gross area when the table calls for net gives you a lower occupant load than the code requires, which means your egress design is under-built. Plan-checkers are trained to spot this discrepancy.
How does the occupant load from CBC 1004.5 affect the number of exits required?
The occupant load from CBC 1004.5 feeds directly into CBC 1006, which sets the minimum number of exits. For most occupancies, spaces with 49 or fewer occupants can use a single exit; 50 or more requires at least two exits. Some occupancy groups have lower thresholds, so check Table 1006.2.1 for your specific use. Egress door and corridor widths are calculated from the occupant load using the factors in CBC 1005: 0.2 inches per occupant for level egress components like corridors and doorways, and 0.3 inches per occupant for stairways. Minimum widths still apply regardless of the calculated load, such as 32 inches clear at doors under CBC 1010.1.1. If your corrected occupant load pushes you above an exit threshold, the fix isn't just updating the table — the floor plan may need a second egress path.
What if my space has multiple uses -- do I need separate calculations for each?
Yes. Each distinct use area within a space or suite gets its own row in the occupant load table, with its own Table 1004.5 factor applied to its specific area. A restaurant with a dining area, a bar, and a kitchen would have three separate calculations — one for each zone — then the totals are added together for the suite-level occupant load. Don't apply a single blended factor to the whole floor. The uses often have very different factors: business areas at 150 sq ft per occupant versus assembly concentrated seating at 7 sq ft per occupant. Using the wrong factor for even one zone can significantly under-count the occupant load and trigger a full egress redesign.
Can I use a lower occupant load than what Table 1004.5 calculates?
You can propose a lower occupant load, but it takes explicit approval from the building department and you need solid justification. The plan-checker has discretion to reject it. A lower load only makes sense when the actual use is demonstrably more restricted than the table use — for example, a dedicated server room that nobody occupies except for maintenance. You cannot propose a lower load just to reduce the exit count without a documented program basis. Conversely, if the actual planned occupancy is higher than the table calculation — like a venue with fixed seating that exceeds the area-based result — you must use the actual count. The code always takes the higher of the table calculation or the actual design occupancy.

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