Understanding the International Building Code (IBC) is essential for anyone who works in the construction and architecture industry. The IBC is a set of guidelines and regulations that determine how buildings must be constructed to ensure safety and accessibility for occupants. In this blog post, we will discuss some of the key provisions of the IBC related to egress and exits, including occupant load, egress width, stairway rise and run, common path of egress travel, intervening rooms, exit separation, corridors, and single-exit buildings.
Occupant Load per IBC Section 1004.1.2
The IBC uses both gross and net floor areas to calculate the number of occupants that a building can safely accommodate. Gross floor area includes everything inside the building’s exterior walls, with the exception of vent shafts and courts. To determine net floor area, unoccupied accessory areas such as corridors, stairways, closets, and toilet rooms are excluded. This ensures that the number of occupants in a building does not exceed the safe capacity for that space.
Egress Width per IBC Section 1005
Egress width is the width of the stairway or other egress component that is required to safely accommodate the number of occupants in a building. For most occupancies, the stairway width is 0.3 inches times the number of occupants. For other egress components, the width is 0.2 inches times the number of occupants. However, the IBC allows for reduced width in buildings with sprinklers. In buildings with sprinklers, the stairway width factor is 0.2 inches, and the factor for other egress components is 0.15 inches.
Stairway Rise and Run per IBC Section 1009.3
Stairways are an essential component of egress in any building, and the IBC has specific regulations for the rise and run of stairways to ensure they are safe and accessible for occupants. According to the IBC, stairways are required to have risers that are no more than 7 inches high, and treads that are no more than 11 inches deep.
Common Path of Egress Travel per IBC Section 1013.3
The common path of egress travel is defined as the portion of the exit access that occupants are required to traverse before two separate and distinct paths of egress travel are available. Paths that merge are considered common paths of travel. The IBC limits the common path of egress travel to 75 feet in most occupancies or 100 feet in occupancies with sprinklers. This is to limit the possibility that a single fire could make both exits unusable.
Intervening Rooms per IBC Section 1013.2
The IBC provides fewer restrictions on an egress path passing through intervening rooms as long as the rooms are accessory to the area served by the egress path, there is a discernible path of travel to an exit, and the common path of travel provisions are satisfied.
Exit Separation per IBC Section 1014
The IBC requires that the doors to exits are separated by one-half the diagonal distance of the building served. This ensures that the occupants can quickly and easily access an exit in the event of an emergency. The IBC also reduces the minimum separation to one-third the diagonal distance in buildings with sprinklers, and does not require a minimum separation between walls of different exit enclosures.
Corridors per IBC Section 1016
Corridors are another essential component of egress in a building, and the IBC returns to the use of occupant load to determine whether fire-resistance-rating is required for a corridor. However, except in H and R and some I occupancies, rated corridor construction is not required if the building has sprinklers. The concept of “hallway” as an intervening room does not appear in the IBC.
Single-exit Buildings per IBC Section 1018
The IBC allows buildings to have a single exit, provided they comply with limitations on number of stories, number of occupants, and travel distance. Table 1018.2 lays out these limitations, ensuring that even buildings with a single exit can be safely occupied.
In conclusion, the IBC provides a comprehensive set of guidelines and regulations that ensure the safety and accessibility of buildings for occupants. Understanding these provisions is essential for anyone working in the construction and architecture industry. It’s important to comply with the IBC to guarantee the safety and well-being of the people that will occupy the building.