monobloc or modular cleanroom: how to choose.

A monobloc cleanroom is built as a single unit. Walls, ceiling, filtration and usually the floor are assembled in a factory, tested there, and delivered as one block that requires little more than a power supply and a connection to the building. Nothing is cut or fitted on site.

That is the advantage, and it is also the limit. A unit that arrives finished has to pass along the route it travels: the road, the yard, the doorway and, in most buildings, the lift. Its geometry is fixed on the day it leaves the factory, so a column, a low beam or a service duct in the target room becomes something to design around rather than build around.

Monobloc is one of three ways to obtain a controlled environment. The second is a modular panel system, assembled from wall and ceiling elements inside the existing room. The third is a mobile laminar flow unit, which delivers clean air over a defined workspace instead of enclosing a classified room.

The useful comparison is not which method is better in general, but which constraint the project is actually working against. Where the binding constraint is access to the site, the monobloc has the advantage: no assembly crew ever enters the building. Where the binding constraint is the building itself, the modular system has it, because the room is fitted to the space rather than the space being cleared for the room.

Our own range covers the second and third of these. Cleanroom kits are made from aluminium system profiles with modular wall and ceiling elements, and arrive with the fan filter unit and ceiling light already built in. Self-build cabins take the same principle further: the wall elements are delivered pre-assembled and fixed in place by your own people, which removes travel and assembly cost from the project. Mobile laminar flow units answer a different requirement again, a clean workspace rather than a clean room, and are supplied with a HEPA filter, lighting, antistatic curtains and castors.

A monobloc is the stronger answer where several identical rooms are required and the process is validated once and then repeated, where the site cannot accommodate an assembly crew or the schedule cannot accommodate one, and where the unit will stand on a slab at ground level with a clear delivery route.

A modular system is the stronger answer where the space already exists and contains columns, beams, sloped soffits or building services, where the classification is likely to change or one zone will need a different class from the next, where the room sits above the ground floor and the way in is an ordinary doorway and an ordinary lift, and where the room will be reconfigured, extended or moved.

A mobile laminar flow unit is the stronger answer where the clean requirement covers a process, a bench or an instrument rather than a room, and where the need is temporary or the location changes between jobs.

ISO 14644-1 classifies a cleanroom by the concentration of airborne particles, on a scale from ISO Class 1, the most stringent, to ISO Class 9. Industrial and laboratory work usually requires a class between ISO 5 and ISO 8; ISO 5 corresponds to the former Class 100.

No wall panel has a class of its own. The class is produced by the whole system: air changes, filter grade, the pressure cascade between zones, the airlocks, and the gowning discipline of the people who work inside. What the construction method decides is whether that system can be kept tight and kept clean. Smooth, jointless surfaces with rounded transitions leave particles nowhere to settle, and both a monobloc and a well detailed modular system deliver them.

The two differ at the seams and the openings. Every door, hatch and airlock is a point at which a pressure cascade is either held or lost. Our pass-through hatches, used to move documents and materials between zones of different class, are rated for cleanroom classes up to ISO 4 and GMP classes A to D.

Silicone migrates. It travels along surfaces, transfers on contact, and is difficult to remove once it has spread. In two of the industries that build cleanrooms this is a defect rather than an inconvenience: it interferes with bonding, coating and painting in electronics, and it is a contaminant that has to be accounted for in pharmaceutical production.

This is why silicone free materials are named in the specification of our self build cabins and cleanroom kits rather than left as a footnote. When a monobloc quotation is compared with a modular one, the same question is worth putting to both.

Will this room still be in this place in five years?

Where the answer is yes and the process will not change, the fixed geometry of a monobloc costs nothing. Where the answer is no, or where the honest answer is that the line is under review, the room is better built from parts that can be taken apart again. A modular cleanroom is set up, extended, reconfigured and relocated using the same elements it was built from, and that difference appears years after the quotation, not during it.

If a monobloc turns out to be the right answer for a given project, the criteria above should make that clear. Our range covers modular cleanroom systems: wall and ceiling elements in aluminium system profiles, cleanroom kits with the fan filter unit and lighting built in, self build cabins with pre-assembled walls, pass-through hatches rated to ISO 4 and GMP A to D, and mobile laminar flow units.