A second ceiling hung from the structural one on droppers, creating a service plenum above it and, below, a continuous or panelled surface. It absorbs noise, hides and gives access to the services, integrates lighting and diffusers, and can give the floor fire resistance. It is the element that «finishes» and equips rooms, from offices to public spaces.
Technical section of the system, from inside (left) to outside (right).
A second ceiling hung from the structural one on droppers, creating a service plenum above it and, below, a continuous or panelled surface. It absorbs noise, hides and gives access to the services, integrates lighting and diffusers, and can give the floor fire resistance. It is the element that «finishes» and equips rooms, from offices to public spaces.
The suspended ceiling is a secondary hung ceiling, fixed to the floor on adjustable droppers that carry a metal grid; to this are fixed panels (mineral fibre, metal, wood) or continuous boards (plasterboard). Between the two ceilings a plenum remains, the service space where pipes, ducts and cables run. It is an entirely dry system.
Unlike a wall, the ceiling works mainly by absorption: sound-absorbing panels (mineral fibre, wool, perforated metal with felt) capture the sound energy that strikes them, cutting the reverberation and background noise of the room. It is the key to acoustic comfort in offices, schools, restaurants and public spaces, where the problem is not (only) to insulate but to make speech intelligible.
The space above the ceiling houses lighting, ventilation, sprinklers, cables and ducts, keeping them hidden but reachable: modular panels lift out for maintenance, continuous boards have access hatches. The plenum sets the clear height and must be sized with the services; at the walls the ceiling can stop or continue over, according to the acoustic and fire needs.
The ceiling can contribute to the floor's fire resistance (a protective membrane) or, conversely, form a hidden path for smoke and flames in the plenum: so, where needed, it is compartmented and certified panels and grids are used. Droppers, grid and edges must be fixed to resist suction too and, in seismic areas, the horizontal actions.
A bare slab is hard and reflects sound: voices and footfall bounce around and the room becomes noisy and echoing. A suspended ceiling of porous or perforated panels does the opposite — the sound waves enter the open structure of the material and are turned into a little heat by friction in the fibres, instead of being reflected. Less reflected energy means a shorter reverberation time and a quieter, more intelligible room; the plenum above also helps absorb the low frequencies and hides the services that feed the space.
A hanger fixed to the structural slab carries the main tee of the grid; an adjuster on it sets the exact level and takes up the slab’s tolerances. In the plenum above run the services — ducts, trays, cables — which are supported independently, not from the ceiling.
At the wall the ceiling ends on a perimeter angle or a shadow-gap trim; a movement gap lets it expand without buckling. Where fire resistance is asked of the ceiling, the membrane is turned up the wall to close the line and keep the compartment continuous.
Informational links to the regulatory framework. Always verify the current text on the official source.
A ready-to-edit DOCX from this system’s data — build-up, performance, and cited regulations with their current in-force status. Courtesy draft, free.