Codes, Standards, and Regulations
Occupancy and construction type
The building code classifies every space by occupancy group (Assembly A, Business B, Educational E, Factory F, High-Hazard H, Institutional I, Mercantile M, Residential R, Storage S, Utility U) and by construction type (I–V with A/B subtypes). Together with sprinkler status, these determine allowable height and area and the required fire-resistance of structural elements.
Egress
Egress has three parts: exit access (travel to the exit), the exit itself, and exit discharge. Compute occupant load by dividing floor area by the code load factor for the use; verify number of exits, remoteness of exits, common path and dead-end limits, travel distance, corridor width, door clear width, and swing direction. Doors serving 50 or more occupants must swing in the direction of travel, and hardware must allow single-motion release without a key or special knowledge.
Fire and finishes
Interior finishes are limited by flame spread and smoke-developed index, typically Class A in corridors and exit enclosures with some Class B or C permitted in rooms depending on sprinklers. Upholstered furniture and textiles may be regulated in certain occupancies.
Accessibility
Accessible routes must be 36" clear, doors 32" clear, with 30" × 48" clear floor space and a 60" turning circle. Reach ranges are roughly 15"–48" above the floor, with tighter limits for side reach over obstructions. Ramps cap at 1:12 with landings.
Traps
Load factors are gross versus net area; using the wrong one skews everything downstream. Remoteness, common path, and travel distance are frequently confused with each other.
Rule of thumb
A 10,000 sf business area at 150 gross sf per occupant gives 67 occupants; egress width at 0.2 in per occupant is about 14", and two exits are required - two 36" doors comply comfortably.