Residential Property (RP)
The Residential Property (RP) domain tests NFPA 101 residential occupancy requirements for one- and two-family dwellings, lodging and rooming houses, hotels and dormitories, and apartment buildings. Enforcement centers on features that give occupants early warning and a viable escape path: smoke alarms, carbon monoxide alarms, emergency escape openings, separation, and exit access.
Core rules
- Smoke alarms: Provide alarms in each sleeping room, outside each separate sleeping area, on each story, and in basements. Alarms must be interconnected so activation of one sounds all, and they must be audible in sleeping areas.
- Carbon monoxide alarms: Required where fuel-fired appliances are installed or where an attached garage creates a CO exposure. Follow the alarm placement and mounting instructions.
- Emergency escape and rescue openings: Each sleeping room needs at least one operable window or door with a clear opening of at least 5.7 ft², minimum clear width 20 in, minimum clear height 24 in, and sill height not more than 44 in above the floor. It must open without keys, tools, or special knowledge.
- Means of egress: Apartment buildings generally require two exits. Single-exit allowances are narrow and depend on factors such as sprinkler protection, number of stories, and travel distance; confirm the edition-specific limits.
- Separation: Dwelling units are separated from each other and from corridors by fire-resistance-rated construction, commonly 1-hour rated. Do not accept unprotected openings that defeat the separation.
Worked example
A new apartment bedroom has a sliding window whose clear opening is 22 in wide by 28 in high. The area is 22 × 28 = 616 in², or 616 ÷ 144 = 4.28 ft². Although each dimension exceeds the 20-in and 24-in minimums, the opening fails the 5.7 ft² minimum. If the sill is also 48 in above the floor, it fails the 44-in sill limit. The inspector should require a compliant egress window or an approved alternative, not merely note that the window opens.
Traps that cost marks
Measuring the rough opening or window frame instead of the clear opening; forgetting the smoke alarm outside the sleeping area; treating a smoke detector as equivalent to a smoke alarm; overlooking CO alarm requirements; and applying a single-exit allowance without verifying sprinkler protection, height, and travel-distance limits.