Cleanroom Design & Construction: ISO Classifications & Cost Guide

Cleanrooms are controlled environments where airborne particulate contamination is minimized through HEPA filtration, pressurization, and strict protocols. They’re essential for semiconductor manufacturing, pharmaceutical production, biotech research, medical device assembly, and many other industries.

Designing and building a cleanroom is a significant investment. This guide covers ISO classifications, design principles, construction methods, and costs to help you plan your project. For detailed cost information, see our prefabricated cleanroom cost guide.

ISO Cleanroom Classifications

ISO 14644-1 defines cleanroom classes based on the maximum allowable number of particles per cubic meter:

ISO Class	Particles ≥0.5µm per m³	Equivalent FED STD 209E	Typical Applications
ISO 5	3,520	Class 100	Semiconductor fab, sterile compounding
ISO 6	35,200	Class 1,000	Optical manufacturing, biotech
ISO 7	352,000	Class 10,000	Pharmaceutical, medical device, biotech
ISO 8	3,520,000	Class 100,000	General controlled environment, packaging

For reference, typical indoor air has 10–35 million particles per cubic meter — roughly ISO 9.

Key Design Elements

HVAC & Filtration

The HVAC system is the heart of any cleanroom. HEPA filters (99.97% efficient at 0.3µm) or ULPA filters (99.999%) remove airborne particles. Air change rates range from 15–25 per hour for ISO 8 to 300–600 per hour for ISO 5.

Pressurization

Cleanrooms maintain positive pressure relative to surrounding areas (typically 0.02–0.05 inches WG). This ensures that when doors open, air flows OUT of the cleanroom rather than dirty air flowing in. Cascade pressurization creates pressure differentials between zones of different classes.

Materials & Surfaces

All surfaces inside a cleanroom must be smooth, non-porous, non-shedding, and easy to clean. Common materials include painted steel, aluminum, polypropylene, and stainless steel panels. Seamless vinyl or epoxy flooring. Flush-mounted lights and sealed utility penetrations.

Gowning & Airlocks

Personnel are the biggest source of contamination. Gowning rooms with air showers, sticky mats, and step-over benches separate the dirty outside from the clean inside.

Modular vs. Stick-Built Construction

Factor	Modular (Prefab)	Stick-Built
Construction time	4–12 weeks	3–9 months
Cost per sq ft	$150–$400	$300–$600+
Expandable/relocatable	Yes	No
Customization	Good	Unlimited
Quality consistency	Factory-controlled	Site-dependent

Cleanroom Cost Factors

• ISO class: Stricter classes cost more (more filtration, higher air changes)
• Size: Larger cleanrooms cost less per square foot
• HVAC complexity: Temperature/humidity control adds 20–40% to HVAC costs
• Utilities: Process gases, DI water, vacuum, compressed air add to cost
• Monitoring: Particle counters, differential pressure monitors, environmental monitoring systems

Frequently Asked Questions

How much does a cleanroom cost per square foot?

ISO 8: $150–$250/sq ft. ISO 7: $200–$400/sq ft. ISO 6: $300–$500/sq ft. ISO 5: $400–$600+/sq ft. These are fully installed costs including HVAC, filtration, and controls.

Can I convert an existing room into a cleanroom?

Yes. Modular cleanroom panels can be installed inside existing buildings. Ceiling-mounted fan filter units (FFUs) provide filtration without major HVAC modifications. This is often the most cost-effective approach.

What furniture goes in a cleanroom?

Cleanroom-compatible laboratory furniture including stainless steel or phenolic casework, cleanroom-rated seating, and stainless steel shelving. All furniture must be non-shedding and easy to wipe down.

Start Your Cleanroom Project

From initial concept to final certification, our team handles complete cleanroom design and construction. Free initial consultations and budget estimates.

Request a free cleanroom consultation → or call (801) 999-8277.