Building Construction Chapter 5

Fire Behavior and Ratings

• Burn rate is significantly influenced by the material’s composition, structure, and environmental conditions.
• Surface burning characteristics can be evaluated and predicted in degrees using the material's flashpoint and ignition temperature.
• A common type of fire-retardant coating is intumescent paint, which expands when exposed to heat.
• The ASTM E-84 standard test measures the surface burning characteristics of building materials, specifically their flame spread and smoke development.

Structural Fire Resistance

• Fire-retardant coatings alone do not provide adequate fire resistance to structural members or assemblies due to their limited protective duration and dependency on the material underneath.
• A flame spread rating over 200 indicates a higher potential for rapid flame spread, which is significant in occupancy classifications because it can elevate the risk of fire hazards and evacuation concerns.

Smoke and Fire Partitions

• The smoke developed rating measures the amount of smoke generated in relation to flame spread, affecting visibility during a fire event.
• Fire partitions are used to limit the spread of fire and smoke between different areas of a building, contributing to occupant safety.

Construction Considerations

• Tying walls in steel frame or concrete construction buildings provides structural integrity and helps resist lateral forces from wind or seismic activity.
• In certain facilities like warehouses or industrial buildings, fire walls may not be necessary due to low occupancy risk or unoccupied spaces.
• Code determines the range for parapet height above a combustible roof, typically between 30 inches to 42 inches.

Fire Ratings and Walls

• The International Code Council allows fire walls to have fire-resistive ratings of 1-hour to 4-hours, depending on structural requirements and occupancy classifications.
• 4-hour fire walls must be constructed of non-combustible materials such as concrete or masonry.
• Stairwell enclosures in buildings with 4 stories or fewer require a 1-hour enclosure rating for safety.

Fire Door Regulations

• Fire door openings in vertical shafts and 2-hour partitions are designated with letter designations such as "D" for doors.
• Gravity-operated doors close when a fusible link melts or a smoke detector activates, ensuring closure during fire conditions.
• Glazing may be used in fire-rated assemblies where visibility is crucial, provided it complies with specific fire-resistance ratings.

Enclosure Ratings

• Openings in exterior walls subject to moderate or light exposure require a 1-hour enclosure rating to inhibit fire spread.
• Openings in fire walls with greater than a 2-hour rating demand a minimum 2-hour enclosure rating to maintain fire safety.
• For rooms and corridors with resistance ratings of less than 1 hour, openings require a 30-minute enclosure rating.

Fire Door Testing Conditions

• Permissible surface temperature rise on the unexposed side of most fire doors is limited to 250°F above ambient temperature.
• 1/3 hour rated doors may not be subjected to a hose test if installed in low-risk areas without high exposure possibilities.
• After 30 minutes during the flame test, fire doors may demonstrate a slight temperature rise, provided it remains within acceptable limits for safety.