Office-to-Restaurant Change of Occupancy in a 1908 Masonry-and-Timber Building
A 1908 three-story building has 11,400-square-foot floor plates, 12-inch masonry exterior bearing walls, heavy timber columns and beams, and wood-joist floor construction rated 1 hour by a fire-resistance evaluation. It has been Group B office since a 1998 renovation and has been protected throughout by an NFPA 13 sprinkler system since then. The owner now proposes to convert the entire first floor into a Group A-2 restaurant and bar with a calculated occupant load of 480. Floors 2 and 3 remain Group B office at 114 occupants each. The first floor is served by two exits: a 44-inch-wide enclosed interior stair at the center of the plate and a 44-inch-wide open steel stair at the rear added in the 1998 work. The two are 210 feet apart on a plate whose diagonal is 330 feet. Construction cost is $1.9 million. The owner's accessibility statement reads "no restroom upgrades - building is historic," and nothing in the submittal establishes a historic designation. No fire-resistance analysis of the existing stair enclosure was submitted.
1. Check the means of egress for the proposed 480-occupant restaurant. Include the number of exits, capacity, and remoteness, and identify anything the submittal leaves out.
Read the worked answer
Number of exits. A Group A-2 story with 480 occupants requires at least two exits, and two exist. The one-exit allowance is irrelevant at this occupant load. So the count passes; capacity does not.
Capacity. In a sprinklered building, stairways are sized at 0.20 inch per occupant (Table 1005.3.2). 480 × 0.20 = 96 inches of required stair width. Available: 44 + 44 = 88 inches. The design is 8 inches short. This is a real deficiency, not a rounding issue - under crowd loading at a bar closing, 88 inches cannot clear the floor.
Remedies. Widen one stair by at least 8 inches (usually painful in masonry), add an exit, or reduce the calculated occupant load. Reducing load means changing the plan: fixed seating instead of loose tables, deleting the standing bar area, or cutting the dining area. A posted occupant load lower than the design load is not an acceptable remedy unless the layout physically enforces it.
Remoteness. Two exits must be separated by at least half the diagonal of the floor area (Section 1007.1.1): half of 330 = 165 feet, and the actual separation is 210 feet. That check passes.
Omissions. The 44-inch rear stair is an exterior exit stairway and must be evaluated against the exterior stairway provisions, including its distance to the property line and its protection from openings in the building wall. The interior stair is an exit enclosure; Section 1023.2 sets the required rating by building height and story count, and the submittal contains no rating analysis. The 1998 sprinkler system must also be shown to meet current NFPA 13 and be under a current inspection contract.
2. The owner refuses restroom accessibility upgrades on the grounds that the building is historic. Evaluate that position under the existing building provisions.
Read the worked answer
The obligation exists and is triggered. A change of occupancy that affects the usability of a space triggers path-of-travel obligations. The applicable existing-building provisions require the path of travel serving the altered or newly occupied area - including at least one accessible restroom where restrooms are provided - to be upgraded to the current accessibility requirements, but only up to 20 percent of the cost of the alteration. That cap is a ceiling on the obligation, not a discretionary budget.
Apply the numbers. 20 percent of $1.9 million is $380,000. There is a large funding envelope here; a restroom conversion in an 11,400-square-foot floor plate is unlikely to approach it. The "we cannot afford it" argument is not available on these figures.
The historic argument. A historic designation does not waive accessibility. It permits documented alternatives or, only with a formal building-official determination, relief where compliance would threaten or destroy the historic significance of a qualified historic building. Two things must exist before that discussion starts: (1) the building must actually be a qualified historic building under the code definition - listed on the National Register, listed on a state or local register, or formally determined eligible by the state historic preservation officer; and (2) the applicant must submit a written finding of the specific threat, not a sentence in a cover memo. The owner's assertion establishes neither.
Action. Reject the statement as unsupported, require the path-of-travel analysis with the 20 percent calculation, and tell the applicant what documentation would be required to pursue the historic alternative.
3. Beyond egress and accessibility, what analysis does a Group B to Group A-2 change of occupancy require in this specific building? Identify the items the submittal is missing.
Read the worked answer
Framework. A change of occupancy classification is not approved by simply carrying forward the existing-building approvals for the old occupancy. The applicable existing-building chapter for change of occupancy requires an evaluation that answers two questions: is the new occupancy a higher hazard than the old one, and does the building comply with the code requirements that attach to the new occupancy?
Hazard comparison. The office-to-restaurant change is a move to an assembly occupancy with a late-night, alcohol-serving, unfamiliar-occupant profile. Even if the structural hazard scoring comes out close, the egress, fire protection, and interior finish requirements for Group A-2 attach in full and are not grandfathered.
Missing item one - structural. This is the easy one to miss. The floor is 1908 wood joists under a heavy timber frame. Office live load is 50 psf; assembly live load is 100 psf. A bar with a packed dance floor and long span joists is a completely different loading case. The submittal contains no structural evaluation of the existing floor system for assembly loading, and none should be accepted.
Missing item two - interior finish and fire protection. Group A-2 brings Class A or B interior finish limits, stricter than the existing office finishes, plus requirements for the bar area, drapery, and decorative materials that a restaurant remodel introduces.
Missing item three - weather protection at the exterior stair and the exit discharge. Confirm both exits discharge to a public way and that the rear exterior stair is not blocked or compromised.
Action. Withhold approval pending a change-of-occupancy evaluation covering hazard comparison, structural capacity for 100 psf assembly loading, egress capacity as computed above, interior finish, and accessibility.