A ceiling system consisting of T-framed members as hung from the structure with wires to carry ceiling tile, light fixtures, diffusers, drywall etc. threshold limit values TLV's, the exposure limit workers are allowed to be exposed to a substance within a 8-hour period during a 40- hour work week as set forth by ACGIH and as policed by OSHA.

A ceiling, not being part of the structural framework of a building, installed below the level of the underside of the floor above or of the roof. Commonly used to provide space for services eg. cables, recessed lighting and piping; to reduce the cost of heating in a room; to improve the acoustics; or to produce more aesthetically pleasing proportions.

Same philosophy as in "raised floor" but usually houses lighting, A/C blowers for VRV and sound speakers.

Flat ceiling, of lightweight panels, which is built lower than the original ceiling by being supported by metal framework and suspended by wires from the ceiling joists.

ceiling hung from floor or loot above it.