ICC 21 key terms

The appointed authority responsible for enforcing the code, reviewing submittals, issuing permits, conducting inspections, and approving or disapproving work under the adopted code.

Written authorization from the code official allowing specified construction, alteration, or repair work to proceed, subject to plan review, inspections, and code compliance.

A local body authorized to hear appeals of code official decisions and grant limited interpretations or variances allowed by the adopted administrative provisions.

A document issued by the code official confirming that a building or portion has been inspected and meets code requirements for the stated occupancy before use or occupancy.

The vertical distance measured from the grade plane to the average height of the highest roof surface, used with occupancy and construction type to regulate allowable size.

A reference plane representing the average finished ground level adjoining the building at exterior walls, used for measuring building height and story count.

The distance measured horizontally from the building exterior wall to the lot line, centerline of a street, or other building on the same lot, used to limit exterior fire spread.

The maximum floor area permitted for a building or story based on occupancy, construction type, sprinkler protection, and frontage, as determined by code area tables and adjustments.

The category assigned to a building or space according to its use, such as assembly, business, educational, factory, mercantile, residential, storage, or utility, which sets applicable code requirements.

An occupancy used for gathering people for civic, social, religious, recreational, or similar purposes, where occupant load and egress features receive particular attention.

The most fire-resistive construction type, with structural elements generally of noncombustible materials and high fire-resistance ratings intended for tall or large buildings.

A building containing two or more occupancy classifications, where separations or other protections may be required and allowable area is determined by code rules.

The time in hours or minutes a building element resists fire exposure under standardized test conditions, as required by code tables and used to protect structural frames, walls, and openings.

A fire-resistance-rated wall or assembly designed to restrict fire spread, often required to be continuous from foundation to roof or floor, with protected openings and smoke sealing where specified.

A fire-resistance-rated wall assembly used to separate dwelling units, guest rooms, or corridors, generally with lower continuity requirements than a fire barrier.

A continuous membrane, wall, or assembly designed to resist the movement of smoke, often used to protect exits, corridors, or areas of refuge.

A fire-rated assembly such as a door, shutter, window, or fire damper installed in an opening to maintain the fire-resistance rating of the surrounding wall or floor.

A continuous and unobstructed path of travel from any point in a building to a public way, consisting of exit access, exit, and exit discharge.

The portion of a means of egress that leads from the occupied space to an exit, including aisles, corridors, and intervening rooms, but not the exit itself.

The portion of a means of egress separated from other spaces by fire-resistance-rated construction, such as an exit stairway or exit passageway, that provides protected travel to the exit discharge.

The portion of a means of egress between the termination of an exit and a public way, such as an exterior door, yard, or walkway.

The measured distance along the path of egress travel from the most remote point in a space or story to an exit or other permitted point, limited by occupancy and construction.

The permanent vertical load from the weight of building materials, fixed equipment, and other permanently installed components that remain in place throughout the structure's life.

The variable load produced by occupants, furniture, movable equipment, and similar temporary uses, determined from code load tables for the occupancy or function.

The lateral force from wind pressure on a structure's surfaces and components, determined using code criteria that account for wind speed, exposure, height, and building shape.

The structural system that transfers building loads to the supporting soil or rock, including footings, piles, piers, and slabs, designed to limit settlement and provide stability.

The widened base of a foundation element that distributes concentrated building loads over a larger soil area to keep bearing pressures within allowable limits.

The maximum allowable pressure that soil can support beneath a foundation without excessive settlement or shear failure, determined by testing or code-prescribed values.

The exterior enclosure of a building, including walls, roof, windows, doors, and foundation walls, that separates conditioned interior space from the outdoors and controls heat, air, and moisture flow.

A material or assembly behind exterior cladding that resists water penetration into wall assemblies while allowing drainage and, when required, vapor movement.

A material or layer installed to limit diffusion of water vapor through building assemblies, helping control condensation and moisture accumulation within walls, roofs, or floors.

The building envelope elements that enclose conditioned space, including insulation, windows, doors, and air sealing, and that are regulated for energy efficiency.

A measure of thermal resistance; higher values indicate greater resistance to heat flow and are used to specify insulation and assembly performance in energy code compliance.

The overall coefficient of heat transfer through an assembly, expressed in Btu/(h·ft²·°F); lower values indicate better thermal performance.

A receptacle or device that receives water, waste, or both and discharges into a drainage system, such as a sink, water closet, or floor drain.

The water retained in a plumbing trap that prevents sewer gas from entering a building while permitting wastewater to flow through the drainage system.

Air supplied to fuel-burning appliances for proper combustion and venting, required to be provided in adequate quantity and from permitted sources.