Codes, Standards, and Plan Review
Know the document stack
NFPA 13 is the design and installation standard for commercial and industrial sprinkler systems. NFPA 13R covers residential occupancies up to and including four stories and 30 ft in height; NFPA 13D covers one- and two-family dwellings and manufactured homes. Around them sit NFPA 14 (standpipes), NFPA 20 (fire pumps), NFPA 24 (private service mains), NFPA 25 (inspection, testing, maintenance), and NFPA 72 (detection and alarm). The edition in force is whatever the authority having jurisdiction adopted, so the first move on any question is to fix the edition year and the occupancy.
Two classification systems
Occupancy classification (building/fire code) and hazard classification (NFPA 13 light, ordinary Group 1 or 2, extra Group 1 or 2) are not the same thing, and storage commodity classification is a third axis. Questions often describe an occupancy and ask for a density - you must translate to hazard first, and for storage go to the commodity and storage-height tables instead.
What plan review actually checks
A submittal is complete only when it contains signed working plans, hydraulic calculations, manufacturer's data sheets, water supply information, and the required certificates. Reviewers check code compliance, hydraulic adequacy against the supply curve, coordination with structure and other trades, and constructability.
Traps: annex material is explanatory ("should"), not enforceable ("shall"); 13R cannot be stretched past its scope; a remodeled space can change hazard class and void the existing density.
Rule of thumb: if the building exceeds four stories or 30 ft, a residential occupancy needs full NFPA 13, not 13R.