Renovation Triggers a Change of Major Occupancy in a Two-Storey Wood-Frame Building
A developer buys a 60-year-old, two-storey wood-frame building of 1,180 m² gross area. The ground floor was a retail store (Group E) and the upper floor was a dance studio (Group A, Division 2). The new owner wants to convert the ground floor into a restaurant (Group A, Division 2) seating 140 people and keep the upper floor as a fitness studio (Group A, Division 2). The building is not sprinklered, has a single open stair connecting floors, and the existing exit is one 1,050 mm door at the front. The building official notes the renovation exceeds 50% of the building's value. The owner argues that because both occupancies become Group A, Division 2, nothing about fire protection or egress needs upgrading. The designer must determine the practical consequences before submitting drawings.
1. Evaluate the owner's claim that no upgrade is needed because the resulting occupancy is uniform. What classification and fire-protection issues actually arise?
Read the worked answer
The owner's claim is wrong on two counts. First, changing from Group E to Group A, Division 2 is a change of major occupancy, and the code requires that the new occupancy comply with the requirements for that occupancy as if it were new construction, including fire separations, exits, and fire-resistance ratings. Second, the building is two storeys and unsprinklered, so the allowable area and construction requirements for Group A, Division 2 must be checked against the building's actual construction (combustible wood frame). Group A, Division 2 is typically limited in unsprinklered combustible buildings, and the permitted area for a two-storey building may be exceeded at 1,180 m². The designer should calculate the permitted area using the applicable area and height provisions, confirm whether sprinklering is required or is the practical route to compliance, and verify that the floor assemblies and supporting structure achieve the required fire-resistance rating. The single open stair and single exit also fail the means-of-egress requirements for an assembly occupancy of this occupant load, so the owner's position cannot be sustained.
2. The restaurant will seat 140 and the fitness studio has a calculated occupant load of 90. Assess the exiting problem and recommend a compliant approach.
Read the worked answer
The combined occupant load is 230, with 140 on the ground floor and 90 above. For a Group A, Division 2 occupancy, at least two exits are required once the occupant load exceeds the small-occupancy threshold, and the two exits must be remote from each other. A single 1,050 mm door provides roughly 1,050/5 = 210 persons of egress width under the typical 5 mm per person rule, which is close to but below the combined load, and in any event a single exit is not permitted for this load and occupancy. The open stair connecting the floors is a concern because it does not provide a protected path; the upper floor's occupants must have access to at least two independent exits, and one of them should not pass through the ground-floor assembly space. A practical solution is to add a second exit from the upper floor, either an exterior stair or an enclosed interior stair separated from the ground floor by a fire separation, and to provide a second means of egress at grade from the restaurant. The designer should also confirm exit signage, emergency lighting, and that exit widths and travel distances comply after the reconfiguration.