Life Safety Code / NFPA 101
NFPA's consensus standard covering egress and fire/life safety in buildings, widely adopted by reference into state and local building codes, and separately required for accreditation by healthcare, assisted-living, and other institutional bodies regardless of what the local building code otherwise requires.
Why it matters
A building can meet its local building code and still fail an NFPA 101 survey, because an accrediting body's own life-safety inspection applies the code's more detailed occupancy-specific chapters, healthcare in particular, that a general building permit review doesn't always dig into as deeply.
On a real project
A hospital renovation gets a building permit under the general building code, but still has to separately satisfy NFPA 101's healthcare occupancy chapter before its accrediting body will sign off, a stricter, more detailed set of requirements layered on top of the permit.
Who this matters most to
A Permit Expediter working on institutional projects has to track both the building department's requirements and NFPA 101's own occupancy-specific rules, since satisfying one doesn't guarantee satisfying the other.
Where this goes wrong
A hospital renovation team designs to the general building code alone, assuming that covers life safety, and only discovers NFPA 101's stricter healthcare occupancy requirements during the accreditation survey, well after construction is finished, forcing costly rework to correct.