A cleanroom is a controlled environment engineered to keep airborne particles, temperature, humidity, and pressure within strict limits — classified by ISO 14644 — so that pharmaceutical, biotech, cosmetic, and medical-device products can be made without contamination. Paul Industries designs, builds, and validates modular and stick-built cleanrooms for manufacturing facilities across the United States, self-performing the HVAC, HEPA filtration, wall systems, and IQ/OQ/PQ under a single contract.
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How a cleanroom works
A cleanroom controls contamination by continuously supplying HEPA- or ULPA-filtered air, maintaining positive (or, for containment, negative) pressure relative to surrounding spaces, and using smooth, cleanable, non-shedding surfaces. Air changes per hour, airflow pattern (unidirectional/laminar vs. turbulent), and room pressurization are engineered to the ISO class the process requires. The cleaner the class, the more filtered air, the tighter the envelope, and the more rigorous the gowning and controls.
Paul Industries engineers the full system as one package: the HVAC and HEPA filtration that set the class, the wall, ceiling, and flooring systems that hold it, the pressure cascade between rooms, and the controls and monitoring that keep it in a validated state — then certifies performance against ISO 14644.
ISO 14644 cleanroom classifications
ISO 14644-1 classifies cleanrooms by the maximum allowable particle count per cubic meter. Choosing the right class is a balance of product risk and cost — over-classifying wastes capital and energy, under-classifying risks the product.
| ISO Class | Max particles ≥0.5 µm/m³ | ≈ FED STD 209E | Typical use |
|---|---|---|---|
| ISO 5 | 3,520 | Class 100 | Aseptic filling, sterile compounding |
| ISO 6 | 35,200 | Class 1,000 | Sterile prep, sensitive assembly |
| ISO 7 | 352,000 | Class 10,000 | Aseptic background, medical device |
| ISO 8 | 3,520,000 | Class 100,000 | General pharma / cosmetic packaging |
Modular vs. stick-built cleanrooms
Both approaches can meet any ISO class; the right choice depends on speed, flexibility, and your building.
| Modular (panel) | Stick-built | |
|---|---|---|
| Speed | Faster — prefabricated panels | Slower — built in place |
| Flexibility | Reconfigurable / relocatable | Permanent |
| Best for | Fast timelines, changing needs | Fixed, fully integrated suites |
| Finish | Cleanable panel systems | Custom architectural finishes |
Our cleanroom services
- Design & engineering — ISO-class selection, airflow and pressure-cascade design, HVAC and HEPA sizing.
- Construction — modular panel or stick-built walls, ceilings, cleanroom flooring, doors, and pass-throughs.
- HVAC & filtration — air handlers, HEPA/ULPA terminals, humidity and temperature control.
- Controls & monitoring — pressure, particle, and environmental monitoring for cGMP records.
- Certification & validation — ISO 14644 certification plus IQ/OQ/PQ.
- Process integration — high-purity water, process piping, and equipment tie-ins under one contract.
Industries we serve
We build cleanrooms for pharmaceutical and biotech manufacturing (aseptic filling, cell and gene therapy, WFI suites), sterile compounding pharmacies under USP <797>/<800>, medical-device assembly, and cosmetic and nutraceutical production where product protection and regulatory compliance matter.
Standards & compliance
- ISO 14644
- The international standard that classifies cleanrooms by airborne particle concentration and defines how performance is tested and certified.
- cGMP / 21 CFR 211
- FDA current Good Manufacturing Practice requirements that drive the environmental control, monitoring, and documentation a pharma cleanroom must maintain.
- USP <797> and <800>
- Standards governing sterile and hazardous-drug compounding environments, which set airflow, pressurization, and classification for compounding cleanrooms.
- IQ / OQ / PQ
- Installation, Operational, and Performance Qualification prove the cleanroom was built to design, operates within its parameters, and holds its class in production.
Why Paul Industries
Cleanrooms fail at the seams between trades — the mechanical contractor, the panel installer, the controls integrator, and the validation firm. Paul Industries self-performs across those trades, so one team owns the airflow, the envelope, the controls, and the certification, and there is a single point of accountability for the class you’re paying for. With 30+ years building process environments across the United States, every project is documented for cGMP traceability. Where client confidentiality limits public references, we provide capability statements and certification deliverables on request.
Frequently asked questions
What is a cleanroom used for?
What makes a cleanroom different from a normal clean space?
What are the main components of a cleanroom?
What ISO classes do cleanrooms come in?
How does a cleanroom keep particles out?
Why is positive pressure important in a cleanroom?
What is an air change rate and why does it matter?
Do cleanrooms control temperature and humidity too?
What industries rely on cleanrooms?
Pharmaceutical and biotechnology manufacturing above all, where classified space is a regulatory requirement rather than a preference. Then medical devices and diagnostics, semiconductor and electronics assembly, aerospace optics, and some cosmetics and food operations where the customer rather than the regulator demands it. A large share of what gets called cleanroom work is actually laboratory and quality control space that needs contamination control without any formal ISO classification, and building that as classified space is the common waste.
How do people enter a cleanroom without contaminating it?
What is the difference between a cleanroom and a containment room?
How is a cleanroom certified?
Can a cleanroom be built inside an existing building?
How is a cleanroom kept clean over time?
By monitoring and by discipline, not by the construction. Classification has to be reverified on a schedule, typically annually and twice yearly for ISO 5 and cleaner. Between those, routine particle and microbial monitoring runs to a plan, filters are integrity tested on schedule, pressure differentials are logged and trended, and gowning practice is audited because it is the largest single variable a building cannot control. Recovery time lengthening is usually the first sign of envelope or filter degradation.
Can Paul Industries build a cleanroom anywhere in the US?
Yes, nationwide from Kilmarnock, Virginia as planned projects with dates confirmed at quotation. On cleanroom work the constraints that actually govern are air handling equipment lead time at the front and commissioning and qualification at the back, and neither changes with contractor location. Where a project sits on a federal or federally adjacent site, personnel screening can add weeks to mobilization, which is worth raising at enquiry rather than after award.
How do I decide what cleanroom I need?
What ISO class cleanroom do I need?
Is a modular or stick-built cleanroom better?
How long does cleanroom construction take?
Do you handle the HVAC and HEPA filtration?
Yes, and on a cleanroom that is the substance of the job rather than an add-on. Air change rate, filter selection and placement, pressure cascade across the suite and the balancing that delivers it are what determine whether the room classifies. The envelope is the easy part. Where this goes wrong is a project that buys panels from one party and air handling from another with nobody owning the cascade across the whole suite, so rooms pass individually and the suite does not behave.
Do you certify and validate the cleanroom?
Yes, through classification testing to ISO 14644 and support for your qualification. Certification covers particle counts in the specified occupancy state, airflow velocity and volume, pressure differentials against the design cascade, installed filter leakage testing, and recovery testing. Qualification against your approved protocols, with your acceptance criteria and change control, remains your quality unit responsibility, and we produce the objective evidence it rests on rather than substituting for it.
Do you build cleanrooms nationwide?
Yes, all 50 states, mobilizing for planned work rather than operating regional branches. Crews stay through balancing and certification rather than handing those to a third party who was not involved in the installation, which matters because the people who built the envelope are best placed to find where it leaks. Long-lead air handling equipment is coordinated before mobilization, since that is normally what sets the schedule.
Get a cleanroom project quote
Tell us about your facility, product, and target ISO class — a Paul Industries engineer will follow up to discuss scope, standards, and timeline.
Request a Project Quote or call 201-450-8280How long does it take to install a modular cleanroom?
The panel installation itself takes days. The project takes months. Softwall assembly can be a few hours, a rigidwall room a few days to a few weeks, and a standard ISO 7 or ISO 8 room can go from site entry to handover in as little as seven days. But the complete project – design, approvals, manufacture, delivery, installation and qualification – runs two to twelve months.
Both figures are true and they answer different questions. The seven-day number describes the crew being on site. It is the number most often advertised, and it is not the number to plan a production start against.
| Phase | Typical duration | Who owns it | Can it overlap? |
|---|---|---|---|
| Requirements and classification decision | 1-4 weeks | You, with the contractor | No – everything downstream depends on it |
| Design and engineering | 2-8 weeks | Contractor | Partly, with long-lead ordering |
| Building permits | 2-6 months, depending entirely on the local planning office | You and the contractor | Yes – and this is the single biggest schedule lever |
| Manufacture of panels and components | 4-12 weeks | Manufacturer | Yes, alongside site preparation |
| Long-lead items – air handling, controls | Often the binding constraint | Manufacturer | Order early or it sets your date |
| Site preparation – floor, services, structure | 1-4 weeks | Contractor | Yes, during manufacture |
| Panel installation | Hours to a few weeks | Contractor | No |
| Mechanical and electrical connection | 1-3 weeks | Contractor | Partly |
| Balancing and commissioning | 1-3 weeks | Contractor | No |
| Certification and qualification | 1-4 weeks, and it is not in most quoted timelines | Independent certifier plus contractor | No |
The two things that turn a seven-day install into a nine-month project
Permits. Two to six months is not unusual, it varies entirely by jurisdiction, and it is almost never included in a manufacturer’s timeline because it is outside their control. Start the permit conversation before the design is finalized, not after.
Qualification. This is the one we see missed most often. A room that is built is not a room that is usable. It must be certified against its classification – airflow, HEPA integrity scan, particle counts in the defined occupancy state, pressure differentials, recovery time – and for a cGMP facility it must then be qualified through IQ, OQ and PQ. None of that appears in an installation quotation, and a production date set from the install figure will be missed by weeks.
Differences between modular and traditional cleanrooms
| Modular | Traditional stick-built | |
|---|---|---|
| Construction | Prefabricated panels assembled on site | Built in place from studwork, board and finishes |
| Speed on site | Much faster – days rather than weeks | Slower, sequential trades |
| Disruption | Lower – most fabrication happens off site | Higher – extended trade presence in the building |
| Reconfigurability | Panels can be moved, extended or relocated | Changes mean demolition and rebuild |
| Depreciation treatment | Often treated as equipment rather than building | Typically a building improvement |
| Finish and cleanability | Purpose-made cleanroom surfaces, flush details | Depends entirely on workmanship |
| Fit to odd spaces | Constrained by panel modules | Adapts to any geometry |
| Integration with existing structure | Freestanding or wall-supported | Fully integrated |
| Cost profile | Higher material cost, lower labor | Lower material cost, higher labor |
| Best suited to | Speed, future change, leased premises | Permanent facilities, awkward geometry, full integration |
The reconfigurability point is the one that most often decides it, and it is a commercial argument rather than a technical one. If the process is likely to change, or the building is leased, a room you can dismantle and re-erect is worth more than the panel cost difference. If the facility is permanent and the geometry is awkward, stick-built usually wins.
Either way the constraints from installing into an existing building still apply – ceiling height, air handling capacity, pressure cascade and structural loading – and our air change calculator checks whether the filters physically fit the ceiling you have.
How long does it take to install a modular cleanroom?
The panel installation takes days; the project takes months. Softwall assembly can be a few hours, a rigidwall room a few days to a few weeks, and a standard ISO 7 or ISO 8 room can go from site entry to handover in as little as seven days. The complete project – requirements, design, permits, manufacture, delivery, installation, commissioning and qualification – runs two to twelve months. Permits alone are commonly two to six months depending on the local planning office.
What is a modular cleanroom and what is it used for?
A cleanroom built from prefabricated wall, ceiling and door components assembled on site rather than constructed in place from studwork and board. It is used wherever a controlled environment is needed quickly, may need to change later, or sits in leased premises – pharmaceutical and biotech production, medical device manufacture, compounding, electronics, laboratories and research. The panels can be moved, extended or relocated, which is the main reason it is chosen over stick-built.
What are the differences between modular and traditional cleanrooms?
Modular rooms are prefabricated and assembled on site, so they go up in days rather than weeks, cause less disruption, and can be reconfigured, extended or relocated later. Traditional stick-built rooms are constructed in place, adapt to awkward geometry, and integrate fully with the building – but changing one means demolition and rebuild. Modular carries higher material cost and lower labor; stick-built the reverse. If the process may change or the premises are leased, modular usually wins.
How do you choose a modular cleanroom system for pharmaceutical use?
Decide the classification and the occupancy state it must hold first, because everything else follows from it. Then confirm the ceiling height available slab to slab, the air handling capacity and where a dedicated unit would sit, the pressure cascade across every adjacent space, and the structural loading for equipment. For cGMP use, confirm the wall and ceiling surfaces withstand the disinfectants you will actually apply, including sporicidal agents, and that certification and qualification are in the scope rather than assumed.
Does the quoted installation time include certification and qualification?
Almost never, and this is the most common scheduling error. A room that is built is not a room that is usable. It must be certified against its classification – airflow, HEPA integrity scan, particle counts in the defined occupancy state, pressure differentials and recovery time – and for a cGMP facility qualified through IQ, OQ and PQ. That is typically one to four further weeks and it does not appear in an installation quotation.
What is the biggest cause of delay on a modular cleanroom project?
Building permits, which commonly add two to six months and vary entirely by jurisdiction. They are rarely in a manufacturer timeline because they are outside the manufacturer control. The second is long-lead equipment, particularly air handling units and controls, which frequently sets the date regardless of how fast the panels go up. Start the permit conversation before the design is finalized and order long-lead items early.
Who offers turnkey modular cleanroom solutions?
Providers range from panel manufacturers who supply and erect the enclosure to turnkey contractors who also deliver the air handling, utilities, controls, commissioning and qualification. The distinction matters because the enclosure is the straightforward part – the air handling, pressure cascade and qualification are what determine whether the room performs. Paul Industries delivers cleanrooms as a turnkey scope nationwide, including the mechanical services and the qualification.
How much does a 500 square foot modular cleanroom cost?
Cost is driven far more by classification, air handling and finishes than by floor area, so a per-square-foot figure taken from a general source will mislead at either end of the range. An ISO 8 room with modest air changes and a lower-grade air handling unit is a different purchase from an ISO 5 room needing high ceiling coverage and a dedicated unit at the same footprint. Our cleanroom cost guide sets out what actually drives the number.
See our cleanroom cost guide for what drives the number, and cleanroom design and construction for how a project runs.
How much does a cleanroom cost per square foot to build, and per square foot per year to keep certified?
Cleanroom budgets are usually built on installed cost per square foot, which is the right starting point but only half the picture. The classification you choose sets the build cost once and the operating cost every year afterwards, because cleaner rooms move more air, change more filters and require more frequent testing. Both halves are below.
| ISO class (and Federal Standard 209E equivalent) | Typical installed cost | What drives the number at this class |
|---|---|---|
| ISO 8 (Class 100,000) | $150 to $300 per sq ft | Modest air change rate; often achievable within an existing shell |
| ISO 7 (Class 10,000) | $250 to $500 per sq ft | Higher air change rate, real pressure cascade, gowning airlock |
| ISO 6 (Class 1,000) | $400 to $750 per sq ft | Substantial ceiling filter coverage; air handling starts to dominate |
| ISO 5 (Class 100) | $700 to $1,500 per sq ft | Near-full filter ceiling, unidirectional flow, tight envelope construction |
| Aseptic fill suite with barrier system or isolator | $1,500 to $3,000+ per sq ft | Barrier equipment, decontamination systems and qualification dominate |
The recurring side is the number that gets left out of the business case, and over a ten year life it routinely exceeds the original build cost.
| Annual line item | Typical annual cost | Comment |
|---|---|---|
| Classification and recertification testing | $3 to $12 per sq ft | Twice yearly for ISO 5 and cleaner, yearly for ISO 6 and dirtier |
| HEPA and ULPA filter replacement | $4 to $15 per sq ft | Driven by ceiling filter coverage, so it rises steeply with class |
| Conditioned air and fan energy | $8 to $30 per sq ft | Air change rate is the single biggest lever on running cost |
| Gowning consumables and cleaning supplies | $5 to $25 per sq ft | Scales with headcount and entries per day, not with floor area |
| Environmental monitoring program | $3 to $18 per sq ft | Sample point count and test frequency; highest in aseptic areas |
This is why barrier systems and isolators are often the cheaper answer over a plant lifetime. Enclosing the process in a small ISO 5 envelope and letting the surrounding room sit at ISO 7 or ISO 8 cuts the conditioned air volume, the filter count and the monitoring burden all at once, even though the barrier equipment costs more on day one.
Certification, failure and classification questions buyers ask before choosing a class
How often does a cleanroom need to be recertified?
What happens if a cleanroom fails particle count testing?
What does ISO 14644-1 Class 7 mean in particle counts?
What are the alternatives to a hardwall cleanroom?
Who are the best cleanroom installation companies?
If you are comparing builders rather than specifying a room, how to evaluate cleanroom companies covers what separates a turnkey contractor from a panel supplier, and which of the two your project actually needs.