LICT-Interior key terms

The category assigned to a building or space based on how it is used, such as business, mercantile, or assembly. The category sets allowable area, height, and fire-protection requirements for interior work.

The calculated number of people a space is designed to hold, derived from floor area divided by a use-based factor. It drives egress width, exit count, and plumbing fixture counts.

A building classification based on the fire resistance of structural elements, ranging from noncombustible protected to combustible. It limits how much interior finish and what structural protection is permitted.

The time in hours a building assembly resists fire under standardized test conditions. Ratings apply to walls, floors, shafts, and doors, and interior details must preserve them.

A fire-resistance-rated wall or floor assembly that restricts fire spread and must be continuous from the floor through the roof or to a rated horizontal assembly. Penetrations and joints require listed protection.

A rated interior wall with a lower fire-resistance rating than a fire barrier, typically used to separate dwelling units, guest rooms, or corridors. Openings must use appropriately rated door assemblies.

A door, frame, hardware, and closing device tested and labeled together to resist fire for a stated period. Labels, clearances, and self-closing or automatic operation must remain intact after interior alterations.

A tested combination of materials used to seal openings where pipes, cables, or ducts pass through rated assemblies. The system must match the listed assembly for the penetrating item and wall type.

An opening made through a rated wall or floor to accommodate a pipe, conduit, cable, or duct. Each penetration must be protected by a listed firestop system appropriate to the item and assembly.

A breach of only the finished surface layer of a rated assembly, such as a recessed electrical box in a rated wall. Protection rules are less stringent than for full through-penetrations but still apply.

The continuous and unobstructed path from any point in a building to a public way, comprising exit access, the exit, and exit discharge. Interior layouts must keep this path clear and protected.

The measured distance a occupant travels from the most remote point in a space to the nearest exit. Limits vary by occupancy and whether the building is sprinklered.

The portion of exit access travel before a occupant reaches a point with two independent ways out. Long common paths may require additional exits or sprinkler protection.

The clear width of a corridor, stair, or door serving an exit path, calculated from occupant load and a per-person factor. Width must not be reduced by projections, furniture, or finish build-up.

The final portion of a means of egress leading from the exit to the public way. It must remain unobstructed and may require rated enclosure where it passes through the building.

The fire-resistance-rated construction surrounding an interior exit stairway or ramp. Interior finishes inside the enclosure are restricted, and openings are limited to rated doors.

A continuous path connecting accessible elements and spaces that meets width, slope, and surface requirements. It must be provided from arrival points to all accessible features in the project.

The minimum unobstructed area required for a single wheelchair, typically 30 by 48 inches, positioned for forward or side approach to an element. Finishes and casework must not encroach on it.

A circular or T-shaped clear area allowing a wheelchair to reverse direction, commonly 60 inches in diameter. It is required in accessible rooms and at dead ends of accessible routes.

The height band within which operable controls and dispensers must be located for use from a wheelchair, generally 15 to 48 inches. Obstruction depth can reduce the high reach.

The rating of wall and ceiling finishes by flame spread and smoke-developed index, expressed as Class A, B, or C. The permitted class depends on occupancy, location, and sprinkler protection.

A numerical result from a standardized surface-burning test describing how quickly flame travels across a material. It is used with smoke ratings to assign a finish class.

A numerical result from the same surface-burning test describing how much smoke a material produces. High values can disqualify a finish in egress corridors or other regulated locations.

A rating of floor covering based on critical radiant flux testing, applied in corridors and exits of certain occupancies. It is separate from wall and ceiling finish classes.

The minimum radiant energy at which a floor finish sustains flame spread in a standardized test, reported in watts per square centimeter. Higher values indicate better performance.

A drywall system of panels, framing, fasteners, and joint treatment whose fire or acoustic performance depends on the exact listed combination. Substitutions in thickness or fastener spacing can void the rating.

A rated enclosure around an elevator, mechanical, or other vertical shaft. It must be continuous and protected from the lowest to the highest level, with rated doors and firestopped penetrations.

The reduction of airborne sound between rooms achieved through assembly mass, resilient connections, insulation, and sealed perimeter joints. Field performance depends on workmanship as much as the design.

A single-number laboratory rating of how well a partition blocks airborne sound. Higher numbers mean better isolation, and field-tested values are usually lower than laboratory values.

A flexible, non-hardening compound used to close gaps at perimeters, outlets, and penetrations in a sound-rated assembly. Unsealed gaps sharply reduce the achieved acoustic separation.

Product data, shop drawings, samples, or mockups submitted by the contractor for the designer's review before installation. Review confirms compliance with the specification but does not relieve the contractor of responsibility.

A full-size sample of a construction assembly built on site to verify appearance, workmanship, and performance. Approval of the mockup can establish the standard for all subsequent work.

A formal written question from the contractor asking the design team to clarify or resolve a conflict in the documents. The response becomes part of the contract record and may trigger a change order.

A site visit by the design professional to compare installed work with the contract documents. Observations are not a guarantee of compliance and do not replace contractor quality control.

A written inventory of incomplete or defective work identified near project completion. Items must be corrected before final acceptance and final payment.

The stage when the work is sufficiently complete for the owner to use it for its intended purpose. It starts warranty periods and allows the remaining work to be finished through a punch list.

Records proving that specified products and installation practices meet a green building program's criteria, such as recycled content or low emissions. These records are submitted for credit verification and closeout.

Maximum allowed emissions from paints, adhesives, sealants, and flooring under air-quality rules or green programs. Compliance is shown by product data and certification submitted before installation.