PDFWAC 51-50-1604

Section 1604General design requirements.

Table 1604.5
Risk Category of Buildings and Other Structures
RISK CATEGORY
NATURE OF OCCUPANCY
I
Buildings and other structures that represent a low hazard to human life in the event of failure including, but not limited to:
 
 
• Agricultural facilities.
 
 
• Certain temporary facilities.
 
 
• Minor storage facilities.
II
Buildings and other structures except those listed in Risk Categories I, III, and IV.
III
Buildings and other structures that represent a substantial hazard to human life in the event of failure including, but not limited to:
 
 
• Buildings and other structures whose primary occupancy is public assembly with an occupant load greater than 300.
 
 
• Buildings and other structures containing Group E or Group I-4 occupancies with an occupant load greater than 250.
 
 
• Buildings and other structures containing educational occupancies for students above the 12th grade with an occupant load greater than 500.
 
 
• Group I-2 occupancies with an occupant load of 50 or more resident care recipients but not having surgery or emergency treatment facilities.
 
 
• Group I-3 occupancies.
 
 
• Any other occupancy with an occupant load greater than 5,000.a
 
 
• Power-generating stations, water treatment facilities for potable water, wastewater treatment facilities and other public utility facilities not included in Risk Category IV.
 
 
• Buildings and other structures not included in Risk Category IV containing quantities of toxic or explosive materials that:
 
 
 
Exceed maximum allowable quantities per control area as given in Table 307.1(1) or 307.1(2) or per outdoor control area in accordance with the International Fire Code; and
 
 
 
Are sufficient to pose a threat to the public if released.b
IV
Buildings and other structures designated as essential facilities including, but not limited to:
 
 
• Group I-2 occupancies having surgery or emergency treatment facilities.
 
 
• Structures that house private emergency power generation, medical gas systems, HVAC systems or related infrastructure systems that support emergency surgery or emergency treatment.
 
 
• Fire, rescue, ambulance and police stations, and emergency vehicle garages.
 
 
• Designated earthquake, hurricane, or other emergency shelters.
 
 
• Designated emergency preparedness, communications and operations centers, and other facilities required for emergency response.
 
 
• Power-generating stations and other public utility facilities required as emergency backup facilities for Risk Category IV structures.
 
 
• Buildings and other structures containing quantities of highly toxic materials that:
 
 
 
Exceed maximum allowable quantities per control area as given in Table 307.1(2) or per outdoor control area in accordance with the International Fire Code; and
 
 
 
Are sufficient to pose a threat to the public if released.b
 
 
• Aviation control towers, air traffic control centers, and emergency aircraft hangars.
 
 
• Buildings and other structures having critical national defense functions.
 
 
• Water storage facilities and pump structures required to maintain water pressure for fire suppression.
a
For purposes of occupant load calculation, occupancies required by Table 1004.1.2 to use gross floor area calculations shall be permitted to use net floor areas to determine the total occupant load.
b
Where approved by the building official, the classification of buildings and other structures as Risk Category III or IV based on their quantities of toxic, highly toxic or explosive materials is permitted to be reduced to Risk Category II, provided it can be demonstrated by a hazard assessment in accordance with Section 1.5.3 of ASCE 7 that a release of the toxic, highly toxic or explosive materials is not sufficient to pose a threat to the public.
[Statutory Authority: RCW 19.27.031 and 19.27.074. WSR 20-01-090, § 51-50-1604, filed 12/12/19, effective 7/1/20; WSR 19-02-038, § 51-50-1604, filed 12/26/18, effective 7/1/19.]