Suspended ceiling glossary
The words you will see on ceiling quotes, datasheets and drawings, explained in a sentence or two.
- Suspended ceiling
- A secondary ceiling hung below the structural soffit on wires or rods, usually a metal grid filled with lay-in tiles.
- Soffit
- The underside of the structure above, such as a concrete slab or steel deck, which the ceiling hangs from.
- Ceiling void
- The space between the suspended ceiling and the soffit, used for ductwork, cabling, pipework and sprinklers. Also called the plenum.
- Main tee
- The long load-carrying grid members, hung from the soffit, usually running at 1200mm centres.
- Cross tee
- Shorter grid members that clip between main tees to form the 600 × 600 or 1200 × 600 modules.
- Wall angle
- The L-shaped trim fixed around the room perimeter that supports the grid and cut tiles at the walls.
- Hanger
- The wire or rod that suspends the grid from the soffit.
- Module
- The size of each grid opening, most commonly 600 × 600mm or 1200 × 600mm in the UK.
- Margin
- The row of cut tiles at the room edge. Good setting out keeps margins roughly equal on opposite walls.
- Setting out
- Planning where the grid lines fall in a room so margins are balanced and fittings sit to the grid.
- Reflected ceiling plan (RCP)
- A drawing of the ceiling as if reflected in a mirror on the floor, showing the grid, lights and services.
- Square edge
- A tile edge that sits flush with the face of the grid.
- Tegular edge
- A stepped tile edge that drops below the grid face, giving a shadow line.
- Microlook
- A fine tegular edge used with a narrow 15mm grid for a more refined look.
- Exposed grid
- A ceiling where the grid face is visible between the tiles.
- Concealed grid
- A system where the supporting grid is hidden, as in clip-in metal or MF plasterboard ceilings.
- MF ceiling
- A concealed steel framework of primary channels and furring sections lined with plasterboard.
- Bulkhead
- A boxed-down section of ceiling that hides beams, services or a change of level.
- Shadow gap
- A recessed joint where a ceiling meets a wall or bulkhead, giving a crisp line.
- Sound absorption class
- A grade from A (best) to E under BS EN ISO 11654, describing how much sound a ceiling absorbs within a room.
- αw (alpha w)
- The weighted sound absorption coefficient used to set the A–E class. 1.0 means all incident sound is absorbed.
- NRC
- Noise Reduction Coefficient, an American average of sound absorption sometimes shown on datasheets.
- Dn,f,w
- Room-to-room sound attenuation through the ceiling void, in decibels. Higher is better for privacy.
- Reaction to fire
- How a material behaves when exposed to fire, classed under BS EN 13501-1 (for example A1, A2-s1,d0).
- Fire resistance
- How long a complete, tested construction resists fire, classed under BS EN 13501-2 (for example 30 or 60 minutes).
- Hold-down clip
- A clip that stops tiles lifting from air pressure, required in some fire-rated and hygiene ceilings.
- Access panel
- A hinged or removable panel in a plasterboard ceiling that lets you reach services above.
- Deflection head
- A slotted head track that lets the structure above move without cracking a partition.
- Raft
- A flat sound-absorbing panel hung below an exposed soffit.
- Baffle
- A vertical sound-absorbing blade hung in rows below a soffit.