Building Codes, Regulations, and Statutory Requirements
Core concepts
Know the hierarchy of codes (national building code, seismic provisions, material codes), occupancy classifications, allowable height and area limits, egress requirements (travel distance, exit width, dead-end corridors), fire-resistance ratings, and accessibility requirements. Understand the permit and inspection process and the roles of the authority having jurisdiction (AHJ).
Common traps
- Occupancy classification: mixed occupancies may require separation or the more restrictive provisions.
- Egress: travel distance and exit width are separate checks; both must pass.
- Fire-resistance: ratings depend on construction type and occupancy, and are not interchangeable.
- Code edition: the governing edition is the one adopted by the AHJ, not necessarily the latest.
Worked rule of thumb
Egress width is based on occupant load times a unit width per occupant, and the number of exits depends on occupant load thresholds. A common check: if occupant load exceeds a threshold, a second exit is required, and travel distance to an exit is limited by occupancy and sprinkler status. Always confirm whether sprinklers are present - they often relax both travel distance and area limits.
Remember that codes set minimums; a design that meets the letter but not the intent may still be rejected by the AHJ.