Softwall cleanrooms:
when are they the right fit?

A softwall cleanroom is often considered when a process needs a defined particle-controlled zone inside an existing building, without the weight and complexity of a conventional room. It can be a practical answer. It can also be a false economy if the project actually needs a sealed pressure cascade, close temperature and humidity control, robust containment or frequent washdown.

What is a softwall cleanroom?

A typical system has a rigid frame and ceiling grid carrying fan filter units, lights and controls. Clear flexible curtains form the sides. Filtered air moves down through the work zone and leaves through gaps at low level or around the curtain edges. The precise airflow arrangement varies, so it should be described by the supplier rather than assumed from a product photograph.

Softwall systems may be fixed, freestanding or designed so that they can be relocated. The terms portable and mobile are not universal technical definitions. A frame may be moveable only when shut down, emptied and requalified. Ask how relocation affects power, stability, classification and any validation records. Our broader portable clean room guide compares the main enclosure formats.

Where a softwall cleanroom can work well

The strongest application is a stable process or item of equipment that needs cleaner air than the surrounding room can provide. Examples may include inspection, assembly, packaging or sensitive laboratory work, subject to the product risk assessment and sector requirements. The host building still matters: dust, temperature swings, draughts and busy traffic outside the enclosure can affect performance and operating cost.

A modular frame can also suit a project that must be installed with limited building work or may need to change size later. Curtain access can simplify movement of large components. Those benefits depend on the actual design. Wheel kits, removable bays and unrestricted curtain openings can all change structural stability and airflow behaviour.

Do not select the enclosure first and try to make the process fit it. Record the critical activity, people and material movements, equipment heat load, cleaning method, operating hours and contamination risks. That information shows whether flexible walls are compatible with routine work.

Softwall versus hardwall cleanrooms

Pressure and airflow

A softwall enclosure normally relies on a downward supply of filtered air and outward leakage. It can maintain a cleaner local zone, but flexible boundaries do not behave like sealed partitions and doors. A hardwall room is usually the firmer starting point where the design depends on defined room-to-room pressure differentials, controlled airlocks or containment.

Temperature, humidity and services

Many softwall systems recirculate or draw air from the host room. If the process needs a narrow temperature or relative-humidity range, the surrounding HVAC system and the heat released by equipment and fan filters must be assessed. Hardwall construction makes it easier to create a dedicated conditioned volume and integrate extract, gases, utilities and building controls, although the engineering requirement remains project-specific.

Access, cleaning and durability

Curtains offer simple access, but every opening disturbs airflow. Overlaps, folds and floor clearances need to be compatible with the cleaning regime and transfer method. Check curtain material, thickness, replacement method and resistance to the approved cleaning agents. A hardwall enclosure may be better for frequent impact, secure access, acoustic separation or a finish that must tolerate intensive cleaning.

Can a softwall cleanroom achieve an ISO class?

Yes, a correctly designed and operated softwall cleanroom can be classified by airborne particle concentration. ISO 14644-1:2015 sets the method for assigning an ISO cleanliness class. The class applies to the tested space under a defined occupancy state; it is not a permanent rating attached to the frame or filter unit.

The specification should say whether acceptance is required as built, at rest or operational. It should also define the classification boundary and the equipment and occupancy present during testing. People, product movement and obstructions can change particle levels and airflow, so a result from an empty enclosure may not represent routine production.

There is no single fan-filter coverage or air-change rate that makes every enclosure ISO 7 or ISO 8. Filter performance, air quantity, ceiling layout, internal loads, curtain leakage and the cleanliness of incoming items all contribute. ISO 14644-4:2022 covers cleanroom design, construction and start-up, while ISO 14644-2:2015 addresses the monitoring plan used to provide evidence of continued performance related to particle concentration.

Consider the regulated context

An ISO classification alone does not demonstrate that an enclosure is suitable for a regulated manufacturing process. For sterile medicinal products, the European Commission's EU GMP Annex 1 places cleanroom design within a contamination control strategy and sets expectations for premises, airflow, transfers, environmental monitoring and qualification. Its requirements need to be assessed with the organisation's quality and regulatory specialists.

Flexible curtains are neither automatically compliant nor automatically unsuitable. The decision depends on the operation, product exposure, required grade, cleaning, transfer controls and evidence needed for the qualified state. Where aseptic processing, hazardous materials or containment are involved, seek competent design and regulatory input before choosing an enclosure type.

What determines softwall cleanroom cost?

Published kit prices rarely describe the same finished scope. Compare total installed and qualified cost against a controlled requirement. The main drivers include:

• internal footprint, clear height and frame arrangement;
• target ISO class, operating state and fan-filter capacity;
• existing room cleanliness, temperature, humidity and electrical supply;
• lighting, controls, alarms and environmental monitoring;
• curtain specification, access openings and any moveable structure;
• process extract, equipment interfaces and additional utilities;
• delivery route, site preparation and installation constraints; and
• commissioning, classification, training and handover records.

Energy and maintenance also belong in the comparison. More fan filter units increase power use and filter replacement obligations. Curtains are consumable components, while controls and sensors need calibration or verification. Ask each bidder to state assumptions, exclusions, recommended spares and the conditions on which the quoted performance depends.

A supplier-ready softwall cleanroom brief

1. Describe the process, product and reason airborne-particle control is needed.
2. State the required ISO class and occupancy condition.
3. Give the usable dimensions, equipment layout and clearances.
4. Map operator, material and waste movements, including large-item access.
5. List temperature, humidity, pressure, extract and utility requirements.
6. Provide host-room conditions, working hours and expected occupancy.
7. Define cleaning agents, frequency and material compatibility needs.
8. Identify applicable quality, safety, fire and regulatory requirements.
9. Set out testing, monitoring, qualification and documentation deliverables.
10. Ask for installed price, programme, energy data, maintenance and exclusions.

Use the same brief for every bidder. It makes proposed airflow, enclosure construction and commercial scope easier to compare, and exposes any design assumptions before they become variations. The cleanroom classification guide can help project teams define the required class and test state; the environment control guide covers monitoring and alarm requirements in more detail.