TITLE 39

HEALTH AND SAFETY

CHAPTER 41

IDAHO BUILDING CODE ACT

39-4109C.  single stairway building exceptions. (1) Notwithstanding a local government’s adoption of the International Building Code or any other provision of law to the contrary, local governments may allow residential group R-2 apartment buildings to be served by one (1) single stairway under the following conditions:

(a)  The building has no more than six (6) stories above grade plane without an occupiable roof, or has no more than five (5) stories above grade plane with an occupiable roof and no more than one (1) basement level;

(b)  The building has no more than four (4) dwelling units on any floor with a maximum gross floor area not exceeding six thousand (6,000) square feet for each story;

(c)  The building is of type I, II, III, IV, or V construction;

(d)  An automatic sprinkler system shall be provided throughout the building in accordance with section 903.3.1.1 of the national fire protection association’s standard, NFPA 13;

(e)  An interior stairway is provided and doors in the stairway swing into the interior stairway regardless of the occupant load served, provided that doors from the interior exit stairway to the building exterior are permitted to swing in the direction of exit travel;

(f)  Openings into the interior exit stairway shall be ninety (90) minute fire protection rated with self-closers and no hold-open devices, unless they are interconnected with the fire alarm system to release upon activation of the occupant notification system and openings are limited to those required for exit access into the enclosure from normally occupied spaces, openings required for egress from the stairway, and openings to the exterior. Elevators shall not open into the interior exit stairway;

(g)  The interior exit stairway and elevator shaft shall have a fire resistance rating of not less than two (2) hours regardless of the number of stories connected;

(h)  The width of the exit stairway shall not be less than forty-eight (48) inches;

(i)  A minimum one (1) hour fire resistance rated corridor separates each dwelling unit entry and exit door from the door to an interior exit stairway, including any related exit passageway, on each floor;

(j)  Dwelling unit doors shall not open directly into an interior exit stairway;

(k)  No more than twenty (20) feet of travel distance shall exist between the exit stairway and the entry and exit door of any dwelling unit;

(l)  Exit access travel distance shall not exceed one hundred twenty-five (125) feet;

(m)  An exit serving the group R-2 occupancy as defined in the International Building Code shall not discharge through any other occupancy, including an accessory parking garage;

(n)  An exit shall not terminate in an egress court where the court depth exceeds the court width unless it is possible to exit in either direction to the public way;

(o)  Exterior wall openings shall be three-fourths (3/4) hour fire protection rated when located within ten (10) feet of the exit discharge door or other unprotected exterior wall openings into the interior exit stairway;

(p)  Emergency escape and rescue openings shall comply with the requirements of the International Building Code on all floors served by the single exit;

(q)  No electrical receptacles shall be installed in an interior exit stairway. Any electrical receptacles in a common corridor or lobby shall have lockable outlet covers, accessible by maintenance personnel;

(r)  An automatic smoke and fire detection system that activates the occupant notification system in accordance with the requirements of the International Building Code shall be installed in the building;

(s)  An approved sign mounted adjacent to the fire alarm control panel shall be provided stating "THIS BUILDING CONTAINS ONLY ONE STAIR";

(t)  There shall be no more than two (2) buildings, or two (2) areas in a single building, each provided with a single exit, per lot. Where there are two (2) buildings on the same lot, exception 1 of section 705.3 of the International Building Code shall not be allowed; and

(u)  The building shall meet all other applicable provisions of the adopted local building codes.

(2)  A manual fire alarm system and automatic smoke detection system that activates the occupant notification system in accordance with the requirements of the International Building Code shall be installed in single stairway apartment buildings provided for in this section in the following locations:

(a)  Common spaces outside of dwelling units;

(b)  Laundry rooms, mechanical equipment rooms, and storage rooms;

(c)  Interior corridors serving dwelling units; and

(d)  Interior corridors, interior exit stairways, and exit passageways.

History:

[39-4109C, added 2026, ch. 320, sec. 1, p. 1282.]