OBC Complex Buildings flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Accessory occupancy limit

An occupancy is accessory when it is subordinate to the main use and typically occupies less than 10 percent of the floor area; larger areas require a full mixed-occupancy analysis.

High-rise threshold

A building is generally classified as a high-rise when its occupied floor exceeds 75 feet above the lowest fire-department vehicle access level, triggering additional fire-protection systems.

Occupant load factor

A code-specified area per person used to compute occupant load for a given use; dividing floor area by the factor yields the number of occupants used for egress and fixtures.

Separated occupancies

A mixed-occupancy design approach in which fire barriers with specified ratings separate different occupancy groups, allowing each to be evaluated under its own height and area limits.

Change of occupancy

A change in a building's use that can trigger code upgrades to structural, egress, and fire-protection systems, with the extent based on comparing the hazard of old and new uses.

Incidental use areas

Small rooms such as mechanical, storage, or boiler rooms that are regulated by a separate table of incidental-use requirements rather than treated as full occupancies.

Automatic sprinkler requirement

Sprinklers are generally mandated in high-rise buildings, large assembly occupancies, and buildings exceeding allowable height or area limits, providing both life safety and allowable increases.

Standpipe classes

Class I provides 2.5-inch connections for fire-department use; Class II provides 1.5-inch connections for occupant use; Class III combines both in a single system.

Stairwell pressurization

A smoke control strategy that maintains positive pressure in exit stairs during a fire to keep them tenable and free of smoke for occupant evacuation.

Fire damper location

A listed device installed where ducts penetrate fire-resistance-rated assemblies to maintain the assembly's integrity, unless an approved code exception applies to the configuration.

Visible alarm notification

Strobes or other visible signals required in public and common areas and in accessible spaces to alert occupants who are deaf or hard of hearing during a fire emergency.

Exit illumination duration

Emergency lighting along egress paths must provide the required illumination for a minimum duration, commonly 90 minutes, so occupants can exit during a power loss.

Seismic Design Category

A classification (A through F) based on seismic hazard and building risk that determines required seismic-force-resisting systems and detailing; higher categories demand ductile systems.

Construction type limits

Construction Types I through V set allowable building height and area based on fire resistance; Type I-A permits the greatest limits and Type V-B the least.

Structural fireproofing

Protection applied to structural members (spray fireproofing, intumescent coatings, encasement) so their fire resistance matches the required construction type rating.

Continuous air barrier

A sealed envelope layer that limits uncontrolled air leakage through walls, roofs, and joints; continuity at transitions and penetrations is essential to performance.

Thermal bridging

A path of high heat conductance through the envelope, such as a structural penetration, that reduces effective insulation and must be addressed in complex geometry.

Snow drift load

An additional roof load caused by snow accumulation against parapets or higher roof sections; it is often governing on complex or stepped roofs.

Means of egress parts

The three components of egress: exit access (path to the exit), the exit itself, and exit discharge (path from exit to public way).

Exit remoteness rule

Two required exits must be separated by at least one-half the diagonal of the area served, ensuring that a single fire event does not block both escape routes.

Egress width calculation

Required egress width equals occupant load multiplied by a capacity factor (e.g., 0.2 in/person on level floors, 0.15 in/person on stairs), subject to minimum widths.

Travel distance limit

The maximum permitted distance from the most remote point to an exit, varying by occupancy and sprinkler status, commonly 150 to 400 feet depending on conditions.

Accessible means of egress

A continuous accessible path out of a building, including compliant doors, ramps, and in high-rise buildings an area of refuge or accessible elevator.

Door swing direction

Egress doors must swing in the direction of travel when serving large occupant loads, so occupants can exit without the door blocking the path.

Plumbing fixture ratios

Code tables that set the number of water closets, lavatories, and drinking fountains based on occupant load and use, with accessible fixtures required for each type.

Outdoor air ventilation

Mechanical systems must supply outdoor air at rates based on occupants and use, with higher rates for spaces such as assembly areas and lower rates for storage.

Life-safety power branch

An emergency power branch dedicated to loads such as egress lighting, fire alarm, and fire pumps, separated from optional standby loads and tested regularly.

Elevator standby power

In high-rise buildings, at least one elevator must be connected to standby power so it remains usable for firefighter operations and accessible egress during outages.

Plenum coordination

Ducts, sprinklers, and lighting sharing a ceiling plenum must maintain clearances so sprinkler spray patterns and exit signage are not obstructed.

Permit before construction

A permit must be obtained before construction, alteration, or change of use; work without one can trigger stop-work orders and additional inspections.

Special inspections

Inspections mandated by code for items such as structural welding, high-strength bolting, and post-installed anchors, performed by approved agencies and documented.

Certificate of occupancy

A document issued after final inspections confirm the building complies with approved plans and applicable codes and is safe for its intended use.