BOABC Level 2 key terms

The weight of people, furniture, stored goods, and other movable items a floor or roof must support. Building codes set minimum values for different occupancies.

The permanent, stationary weight of a structure itself, including walls, floors, roofs, and fixed equipment. It stays constant throughout the building's life.

The category assigned to a building based on how it is used, such as residential, mercantile, or assembly. The category determines which code requirements apply.

The continuous, unobstructed path people use to leave a building during an emergency, including exit access, the exit itself, and exit discharge to a public way.

The portion of the escape route that leads from any point in a building to an exit. It includes aisles, corridors, and intervening rooms.

The clear, usable dimension of a corridor, stair, or doorway that allows occupants to pass during evacuation. Codes set minimum widths based on occupant load.

The total number of people a space is calculated to hold, based on floor area and use. It drives requirements for exits, stairs, and plumbing fixtures.

The time in hours a building assembly can withstand fire exposure while maintaining its structural function. Ratings are shown in hours, such as one or two.

A wall, floor, or assembly that resists the spread of fire between areas of a building. Its required rating depends on occupancy and construction type.

A classification, usually numbered I through V, describing how fire-resistant a building's structural elements are. Higher types permit less combustible material.

The clear horizontal distance a beam, joist, or other structural member must bridge between supports. Span controls the required member size and depth.

A horizontal structural member placed over an opening such as a door or window to carry the loads above it and transfer them to adjacent framing.

A wall that supports weight from floors, roofs, or other walls above it. It cannot be removed or altered without providing alternate structural support.

The widened base of a foundation that spreads building loads over a larger soil area. Footing size and depth depend on soil conditions and frost depth.

The depth to which soil freezes in winter at a given location. Footings must extend below this depth to prevent frost heave from lifting the structure.

A perforated pipe or drainage system placed around or beneath a foundation to remove groundwater. It protects the basement or crawl space from water intrusion.

A vertical framing member in a wall, typically spaced at regular intervals, that supports wall finishes and transfers loads to horizontal framing.

A sloping structural member that supports roof sheathing and spans from the ridge or a ridge beam down to the wall top plate.

The slope of a roof expressed as a ratio of vertical rise to horizontal run. Pitch affects drainage, material choice, and snow shedding.

Sheet metal or other material installed to shed water at joints and penetrations, such as roof valleys, chimneys, and wall intersections. It prevents leakage.

A small opening left in a wall, veneer, or masonry assembly that lets trapped moisture drain out. It helps prevent water damage behind cladding.

A window in a sleeping room that is large enough and low enough to allow escape in an emergency. Codes specify minimum opening size and sill height.

The horizontal bottom member of a window frame. Its height above the floor matters for egress requirements and fall protection.

A barrier installed along open edges of floors, balconies, stairs, and landings to prevent falls. Codes set minimum heights and limit opening sizes.

The vertical height of a single stair step, measured from one tread surface to the next. Consistent rise is required for safe stair use.

A graspable rail along a stairway or ramp that gives users support and stability. Codes specify its height, continuity, and clearance from the wall.

The number of plumbing fixtures such as toilets, sinks, and lavatories required for a building. It is calculated from occupant load and use.

A toilet fixture that receives human waste and discharges it into the drainage system through a trap. Codes set its water use and clearance requirements.

A U-shaped fitting that holds a water seal to block sewer gases from entering a building. Every fixture connection generally requires one.

A pipe that allows air to enter the drainage system and lets sewer gases escape above the roof. It protects trap seals from siphonage.

The network of pipes that carries sewage and gray water away while admitting air to keep pressures balanced. It includes drains, waste lines, and vents.

An accessible fitting with a removable cap that lets maintenance workers clear blockages in a drain line. Codes specify where cleanouts must be installed.

A device that stops contaminated water from flowing backward into a potable water supply. It protects drinking water from cross-connections.

Any actual or potential link between a potable water system and a source of contamination. Cross-connections must be eliminated or protected against.

A pipe that carries potable water under pressure from the main to fixtures and appliances. Sizing must maintain adequate pressure at the farthest outlet.

An appliance that heats and stores potable water for domestic use. Installation rules cover temperature relief, venting, and seismic strapping.

A safety device on a water heater that opens to release excess pressure or temperature. It must discharge to a safe location through a proper pipe.

The downward fall of a horizontal drain pipe, expressed as a ratio or percent, that lets wastewater flow by gravity. Too little slope causes clogs.

The section of pipe between a fixture trap and the main drain line. Its length and slope are limited so the trap seal is not lost.