State Building Code.
The State Building Code (SBC) provides a set of minimum statewide standards and requirements for buildings.  The SBC is comprised of several different codes.  Most of these codes are international model codes that the Legislature has adopted by reference in statute, including the International Building Code (IBC), the International Residential Code (IRC), the International Mechanical Code, the International Fire Code, portions of the International Wildland Urban Interface Code, and the Uniform Plumbing Code.  The SBC also includes certain state-created standards for making buildings accessible to individuals with disabilities or elderly persons, and the State Energy Code.
 
The State Building Code Council (Council) is responsible for adopting, amending, and maintaining the SBC through the rulemaking process under the Administrative Procedure Act.  Amendments to the SBC adopted by the Council are codified in the Washington Administrative Code.  The Council periodically reviews updated editions of the model codes for potential adoption in the SBC.  For example, the 2018 model codes, with state amendments, are currently in effect.  After a multiyear review and rulemaking process, the 2021 model codes, with state amendments, are set to take effect July 1, 2023.
 
Local Amendments to the State Building Code.
The governing body of each county or city is authorized to amend the SBC as it applies within the local jurisdiction.  However, the local amendments must not result in code requirements that are less than the minimum SBC standards, with certain exceptions.  For example, a county or city may adopt amendments that eliminate or reduce minimum gross floor area requirements for single-family detached dwellings.  The Council must review and approve or deny all proposed local amendments that apply to single-family or multifamily residential buildings, with certain exceptions.
 
International Residential Code.
The IRC was created to serve as a comprehensive code regulating the construction of single-family houses, two-family houses, and townhouses.  The IRC does not include occupancy classifications.  All buildings within the scope of the IRC are limited to three stories above grade plane.  For example, a four-story single-family house would fall outside the scope of the IRC and into the scope of the IBC.  Detached one- and two-family dwellings and townhouses that are not more than three stories above grade plane have the option of complying with either the IBC or the IRC.  
 
International Building Code.
The IBC establishes minimum standards and requirements for construction of all buildings, except for detached one- and two-family dwellings and townhouses that are not more than three stories above grade plane.  The IBC classifies buildings into use groups and occupancies based on the primary purpose of the building and the nature of the hazards and risks to building occupants generally associated with the intended purpose of the building.  Throughout the IBC, occupancy classification is important for establishing construction requirements, occupant safety requirements, means of egress, fire protection systems, and interior finishes.  Under the IBC, the residential group R-2 occupancy classification applies to buildings containing sleeping units or more than two dwelling units where the occupants are primarily permanent in nature, such as apartments and certain congregate living facilities. 
 
International Building Code Criteria for Means of Egress.
The IBC provides general criteria for designing the means of egress or exit from a building.  The means of egress from a building is the primary method for protection of people in the building by allowing timely relocation or evacuation of building occupants.  The IBC egress requirements provide an approach for determining a safe exiting system for all occupancies that works in coordination with other sections of the IBC that have an impact on life safety, such as the requirements for protection of vertical openings, interior finishes, and fire suppression and detection systems. 
 
Under the IBC requirements for single exits that apply to residential group R-2 occupancies, a single exit or access to a single exit is permitted from the basement, first, second, or third story above grade plane where the maximum number of dwelling units per story is four, and the maximum common path of egress travel distance is 125 feet.  A single exit is not permitted for the fourth story above grade plane and higher.  Additionally, buildings classified as group R-2 occupancies must be equipped throughout with an automatic sprinkler system and emergency escape and rescue openings in accordance with other IBC requirements.

Until July 1, 2026, the legislative body of a county or city may exercise its authority to amend the SBC by adopting local amendments to the IRC that allow for up to five stories of group R-2 occupancy to be served by a single exit under the following conditions:

• The building does not have more than six stories above grade plane.
• The building does not contain a boarding house.
• The building does not contain certain state facilities licensed by the Department of Health or the Department of Social and Health Services that must obtain approval from construction review services before licensure activity.
• The building does not have more than four dwellings on any floor.
• The building is constructed with not less than one-hour fire-resistive construction and is also equipped throughout with an automatic sprinkler system in accordance with certain IBC provisions.  Residential-type sprinklers must be used in all habitable spaces in each dwelling unit. 
• There are not more than two single-exit stairway conditions on the same property for buildings four stories or higher.
• An exterior stairway or an interior exit stairway is provided.  The interior exit stairway must meet certain IBC pressurization requirements and have doors that swing into the stairway.  However, the door that connects the interior exit stairway to the building exterior is permitted to swing in the direction of exit travel.
• A corridor separates each dwelling unit entry/exit door from the interior stairway exit door on each floor.  Dwelling unit doors must not open directly into an interior exit stairway but are permitted to open directly into an exterior stairway.
• There are not more than 20 feet of travel to the exit stairway from the entry/exit door of any dwelling unit.
• The travel distance measured in accordance with the IBC section related to exit access travel distance does not exceed 125 feet.
• The exit does 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.
• Elevators are pressurized in accordance with certain IBC provisions or open into elevator lobbies that comply with certain other IBC provisions.  If approved by the building official, natural ventilation is permitted to be substituted for pressurization where the ventilation would prevent the accumulation of smoke or toxic gases.
• Other occupancies are permitted in the same building if they comply with all the same conditions.  These other occupancies must not communicate with the group R occupancy portion of the building or with the single-exit stairway, except that parking garages and occupied roofs accessory to the group R occupancy are permitted to communicate with the exit stairway.
• The exit serving the group R occupancy does not discharge through any other occupancy, including an accessory parking garage.
• There are no openings within 10 feet of unprotected openings into the stairway other than required exit doors that have a one-hour fire-resistance rating.

 
A city that intends to adopt these local amendments must meet the following criteria before adoption:

• The city is served by a municipal fire department or fire district.
• The city does not have a current restriction on development due to lack of fire flow capacity as set forth in the Department of Health rules related to water demand design criteria.  Minimum fire flow capacity must be at least 750 gallons per minute for 60 minutes, as set forth in the Department of Health rules related to minimum standards for fire flow.

 
Nothing prevents a city from determining that it does not have appropriate fire apparatus or hydrant networks to serve single stairwell buildings.
 
All of the provisions related to local amendments that allow a single exit for buildings with up to five stories of group R-2 occupancy expire July 1, 2026. 
 
By July 1, 2026, the Council must adopt, by rule, standards to allow for up to five stories of group R-2 occupancy to be served by a single exit and make them available for local adoption.