Guides / Ceiling Systems
An open cell ceiling is an aluminium grid, mesh or woven-strip system that leaves the space above visible so air and services can pass through it. Free area runs from 50 to 90 per cent depending on the cell type. This guide sets out what an open cell ceiling is, what free area does for a room, and how to write the specification so the supplier quotes the same ceiling you drew.
An open cell ceiling is an aluminium grid or mesh that keeps the void above reachable instead of hiding it behind a solid face. The ceiling is a lattice, not a sheet: air moves through it, and the services above stay visible and reachable from below. The three forms are expanded mesh, interwoven aluminium strip and an assembled grid of open cells.
Free area is the number that defines the system. Across the range we quote, woven strip runs 50 to 70 per cent, expanded mesh 60 to 80, and assembled grid cells 70 to 90. The figure you need is set by the mechanical and fire consultants on the project, not picked from a catalogue — the higher the free area, the less the ceiling restricts airflow and the easier sprinklers and smoke detectors can see through it.
An open cell ceiling is a metal ceiling with openings large enough to see and reach through. It is the opposite of a solid panel ceiling: there is no continuous face, so the plenum above stays part of the room rather than being boxed in behind a sheet.
Three forms cover most enquiries. Expanded mesh is a single sheet of aluminium slit and stretched into a lattice. Woven strip interlaces aluminium blades into a fabric-like grid. An assembled grid cell is built from aluminium U-sections locked into a honeycomb of open cells. The open cell ceiling page lists all three with their free-area ranges and access methods.
It is easy to confuse an open cell ceiling with a perforated panel. A perforated panel is a solid sheet with holes punched in it, and its open area is far lower. An open cell ceiling has no panel face to punch; the grid or mesh is the ceiling. The perforated panel guide keeps the two apart in more detail.
Free area is the percentage of the ceiling plane that is open. It is the most important line on an open-cell specification, because it decides how much air moves through and how much access the services keep.
| Type | Structure | Free area | Services access | Typical use |
|---|---|---|---|---|
| Expanded mesh | Single-piece expanded aluminium | 60–80% | Whole panel lifts out | Plant rooms, car parks |
| Woven strip | Interwoven aluminium strip | 50–70% | Whole panel lifts out | Data centres, back-of-house |
| Grid cell | Assembled aluminium grid | 70–90% | Individual cells removed | Laboratories, clean rooms, atria |
The ranges and access methods are the ones on our open cell ceiling page. The higher the free area, the less metal in the ceiling and the more open it reads.
Free area governs airflow first. A ceiling at 90 per cent open area barely restricts the air passing through it; one at 50 per cent begins to act as a partial barrier. Return-air paths in plant rooms and data centres depend on this number, which is why it is fixed by the mechanical design rather than picked from a catalogue.
It governs fire and smoke as well. Sprinklers and smoke detectors are often mounted in the void, and an open grid lets them see the occupied space below. The free area required for that comes from the fire engineering on the project, and the build-up is tested for reaction to fire against EN 13501-1. The ceiling itself is a suspended metal ceiling, so it also carries the requirements of EN 13964.
The practical rule is to state the free area you need in the enquiry and let the supplier confirm the cell size and spacing that reaches it. Two ceilings that both look like grids can differ by twenty points of free area, and the quotes are not comparable until that number is fixed.
Free area is the first line, not the whole list. The grid has a cell or blade size, a sheet thickness, an edge height and a finish, and each of them appears on the quotation.
| What you specify | Common range | Why it matters |
|---|---|---|
| Blade / cell width | 100 / 150 / 200 / 300 mm | Narrow blades read as a fine line; 300 mm reads as a plank |
| Aluminium thickness | 0.6 – 3.0 mm | Priced on a sliding scale per 0.1 mm step |
| Edge height | 20 / 24 / 28 / 30 mm | Sets the carrier and the clip |
| Standard length | to order | Set by the runs on your drawing |
| Finish | Powder coat / PVDF / anodized / wood-grain / stone-grain | Finish tier adds a per m² premium |
| Accessories | Carrier, clips, trim | Quoted separately unless included |
These values are the production specification on the open cell ceiling page. Send the drawing and the sizes are confirmed against it before quotation.
The system earns its keep where air and services have to move through the ceiling. Plant rooms, data centres, clean rooms, laboratories, car parks and industrial interiors are the standard list — any space that would suffer if the plenum were sealed off.
It is not the system for a quiet office or a corridor, where a flat panel or a linear plank gives the cleaner line and the better acoustic surface. That choice is set out in the linear, baffle or cell comparison, which places open cell against the other two families.
Put the fields below on one sheet and send it to every supplier, so each quote describes the same ceiling:
Weight follows from the same fields: a mesh or grid removes metal, so it weighs less than a solid sheet of the same thickness. The weight per m² guide sets out how that load reaches the hangers. Installation cost is a separate question, covered on the metal ceiling installation page.
It is an aluminium ceiling that leaves the void above visible and reachable. Instead of a solid panel face it is built as a grid, mesh or woven strip, so air moves through the ceiling and services stay accessible from below. The three forms are expanded mesh, interwoven strip and assembled grid cell.
Free area depends on the cell type: typically 50-70% for woven strip, 60-80% for expanded mesh and 70-90% for assembled grid cells.
Plant rooms, data centres, clean rooms, laboratories, car parks and industrial interiors - any space where air and services need to move through the ceiling.
No. A perforated ceiling is a solid panel with holes punched in it, so its open area is much lower. An open cell ceiling has no panel face; the grid or mesh is the ceiling, and its free area is far higher.
Standards are cited for the definitions and methods they contain. The free area for a project comes from the mechanical and fire design, agreed with the supplier, not from this page.