Hardwall cleanrooms:
what should buyers specify?

A hardwall cleanroom is usually selected when a project needs more enclosure integrity than flexible curtains can provide. It may be modular and freestanding or integrated into the surrounding building. Either way, the term describes the boundary construction, not a guaranteed cleanliness class or regulatory status.

What is a hardwall cleanroom?

A hardwall cleanroom uses rigid wall panels, doors and a ceiling system to form a defined controlled space. The panels may have coated steel, aluminium, high-pressure laminate or another cleanable facing around a suitable core. Joints, coving, glazing and service penetrations are detailed to reduce particle traps and uncontrolled leakage.

Many systems are modular: panels and framing are manufactured in repeatable sizes, then assembled on site. Modular does not mean temporary or lightly engineered. A hardwall room may still need structural support, fire-stopping, dedicated air handling, process extract and utilities.

The enclosure is only one part of the cleanroom. Airborne cleanliness depends on filtered air supply, airflow distribution, room pressure, internal contamination sources, cleaning and operator behaviour. ISO 14644-1:2015 classifies air cleanliness by particle concentration at designated sampling locations; it does not certify a particular panel system.

When is a hardwall cleanroom the better option?

Hardwall construction is a strong starting point when rooms need defined pressure differentials, interlocked doors or controlled transfer routes. Rigid boundaries make leakage more predictable and create proper junctions for airlocks, pass-through hatches and service penetrations.

It also suits facilities that need close temperature or humidity control, substantial process services, secure access or finishes that tolerate repeated cleaning. The enclosure can be designed around equipment loads and maintenance access instead of relying on the host room.

A hardwall system is not automatically the best value for every local clean zone. Where the principal objective is particle control around a stable process inside a suitable host room, a flexible enclosure may be simpler. The softwall cleanroom selection guide explains that alternative. Compare both against the process risk, not against purchase price alone.

Specify the enclosure as a coordinated system

Select wall panels for cleanability, chemical resistance, impact risk, fire strategy and structural loads. State the facing, core, thickness, joint treatment and permitted sealants. Identify wall-mounted equipment and fixing locations before manufacture.

For ceilings, define whether they are walk-on, how filters and lights are supported, what access is required above and how the perimeter is sealed. Maintenance access must not damage the clean boundary.

Doors, glazing, coving and penetrations often expose gaps between suppliers. Agree door type, opening direction, closer, interlock, access control, vision-panel detail and threshold. Map every cable, pipe, duct and equipment connection through the panels. The cleanroom construction details guide covers the drawing information needed at these interfaces.

Fire performance cannot be inferred from the words “cleanroom panel”. The project team must coordinate the wall and ceiling construction with the building fire strategy, compartmentation, detection, suppression and escape requirements. Approved Document B provides statutory guidance for fire safety under the Building Regulations in England; the applicable requirements and professional advice depend on the building and jurisdiction.

Coordinate the hardwall room with HVAC and process equipment

Define the target cleanliness class, occupancy state, room pressure, temperature, humidity, recovery expectations and operating hours before selecting fan capacity. Equipment heat gains, extract air, door openings and the number of operators affect the final duty. A standard air-change figure is not a substitute for a design calculation.

Filter positions and air returns should support the intended airflow pattern around equipment and work zones. Tall machinery, storage and solid benches can create stagnant areas or short-circuit supply air. Review the layout with the HVAC design rather than treating terminal filters as evenly spaced ceiling components.

Controls need a written sequence covering alarm limits, sensor locations, trends, user permissions and building-management links. If the room uses occupied and setback modes, define the conditions required before work resumes. Our guide to cleanroom environmental control gives a practical monitoring checklist.

Classification and compliance are project-specific

ISO 14644-4:2022 sets out the process for taking a cleanroom from requirements through design, construction and start-up. It applies to new, refurbished and modified installations and includes life-cycle and energy considerations. It does not prescribe one construction technology, so “built to ISO 14644” needs a defined scope and evidence.

For sterile medicinal manufacturing, EU GMP Annex 1 expects exposed surfaces in cleanrooms to be smooth, impervious and unbroken, with materials able to withstand repeated cleaning and disinfection. It also addresses transfers, airflow, qualification and the contamination control strategy. Those are specific requirements for sterile medicinal products, not a universal definition of every hardwall cleanroom.

Set the inspection, commissioning and qualification plan during design. It may include envelope checks, airflow balancing, filter leakage testing, pressure verification, recovery testing and particle classification. Select tests from the user requirement, sector and risk assessment. The cleanroom validation guide explains what each stage should establish.

What drives hardwall cleanroom cost?

Floor area matters, but it does not explain the whole quotation. Two rooms of the same size can have very different cost and programme because of classification, heat load, extract, pressure cascade, panel specification, ceiling support, utilities and testing. Compare the completed facility scope, not the wall kit.

• Footprint, clear height, number of rooms and airlocks
• Target class, occupancy state and required environmental limits
• Panel facings, cores, ceiling loading and fire requirements
• Doors, glazing, pass-throughs and access-control integration
• HVAC plant, HEPA filtration, extract and energy-control strategy
• Power, gases, water, drainage and process-equipment connections
• Building alterations, delivery access and shutdown constraints
• Commissioning, qualification, training and handover records

Ask bidders to state assumptions about the host building, incoming utilities, working hours and validation scope. Separate provisional items from fixed prices. A lower figure may simply exclude controls integration, fire-stopping, builders' work or the testing needed before the room can be released.

A supplier-ready hardwall cleanroom brief

1. Describe the process, exposed product and contamination risks.
2. State the required classification, occupancy state and regulatory framework.
3. Provide the room layout, equipment dimensions, heat loads and access routes.
4. Define pressure, temperature, humidity, airflow and extract requirements.
5. Specify panel, ceiling, floor, door and glazing performance.
6. Map utilities, penetrations, controls and building-service interfaces.
7. Identify cleaning agents, impact risks and maintenance-access needs.
8. Set the fire, structural, electrical and health-and-safety responsibilities.
9. List commissioning, qualification and document deliverables.
10. Request programme, energy data, maintenance obligations and exclusions.

Issue the same requirement to each bidder and ask them to return a room-by-room scope. This gives the design team a clearer basis for technical review and makes commercial differences easier to explain. The broader modular cleanroom systems page describes how Cleanrooms Direct matches projects with suitable UK specialists.