Multiple-family dwelling; single interior exit stairway; requirements.

Sec. 4j. Subject to section 4k, a multiple-family dwelling that has not more than 4 levels above grade plane may have a single interior exit stairway if all of the following conditions are met: (a) The dwelling has not more than 4 units on each level. (b) The net floor area of each level of the dwelling is not more than 4,000 square feet. (c) The exit access travel distance is not more than 125 feet measured from the most remote point within a level of the dwelling along the natural and unobstructed path of egress travel. (d) Openings to the interior exit stairway enclosure are limited to all of the following openings: (i) Openings required for exit access into the enclosure from normally occupied spaces. (ii) Openings required for egress from the enclosure. (iii) Openings to the exterior. (e) An elevator does not open into the interior exit stairway enclosure. (f) The dwelling has a manual fire alarm system and an automatic smoke detection system that activates an occupant notification system. The manual fire alarm system, automatic smoke detection system, and occupant notification system all must be installed in accordance with the building code. (g) Smoke detectors are located in common spaces outside of the dwelling units, including, but not limited to, all of the following areas: (i) Gathering areas. (ii) Laundry rooms. (iii) Mechanical equipment rooms. (iv) Storage rooms. (v) Interior corridors. (vi) Interior exit stairways. (vii) Exit passageways. (h) Regardless of the stairway construction type in the dwelling, automatic sprinkler locations in the interior exit stairway comply with the requirements for combustible stairways under the "Standard for the Installation of Sprinkler Systems", as adopted by the director as part of the code, developed by the National Fire Protection Association. If a standard described in this subdivision is revised after the effective date of the amendatory act that added this section, the department shall take notice of the revision and the department shall promulgate rules to incorporate the revision by reference. (i) An electrical receptacle is not located in an interior exit stairway. (j) The interior exit stairway is not less than 48 inches wide.