Cleanroom construction is far stricter than ordinary factory building works. Even millimeter-level errors may cause non-compliant cleanliness, failed acceptance and millions of renovation losses. Based on GB/T 50591-2010 and decades of practical experience, we sort out 10 key construction points for owners, supervisors and construction teams.

Point 1: Pre-construction Preparation – Control Benchmarks to Avoid Inherent Defects

Insufficient preparation leads to tilted walls, uneven floors and incompatible systems.

Case: A medical workshop skipped elevation inspection. The 8mm elevation gap caused pressure below the required 10Pa and cracked epoxy flooring. Renovation cost: $120,000+, project delayed by 1 month. Tip: Hold technical briefing in advance to coordinate HVAC, electric and fire protection works.

Point 2: Envelope Construction – Sealing & Flatness for Dust Prevention

Envelope systems (walls, ceilings, doors & windows) form the primary dust barrier. Gaps and rough surfaces cause dust accumulation and air leakage.

• Sandwich panel joint gap ≤0.5mm with continuous sealant; wall verticality ≤2mm, ceiling flatness ≤3mm.
• Cleanroom steel door gap ≤1mm, air leakage ≤0.1m³/(m²·h). Double-layer observation windows must be airtight.
• Wall-floor arc radius ≥50mm. Pipe penetrations sealed with sealant and fire blocking.

Case: A food cleanroom had poor sealant works and 2.5mm door gaps. High air leakage failed QS certification. Renovation cost: $45,000, production stopped for 20 days.

Point 3: Flooring Construction – Precision, Wear Resistance & Anti-static Performance

Cleanroom floors must be flat, wear-resistant and anti-static according to industrial requirements.

• Epoxy self-leveling (ISO 5–7): Base moisture ≤8%, thickness 2–3mm, flatness ≤0.2mm/m. Anti-static resistance: 10⁶–10⁹Ω, curing ≥72h.
• Anti-static PVC (ISO7–8): Base flatness ≤0.3mm/m, hot weld 10–15mm, resistance 10⁶–10⁹Ω.
• Wall-floor arc ≥50mm. Construction temperature:15–25℃, humidity ≤70%. 24h water test after completion.

Case: A laboratory constructed epoxy floor on 12% moisture base. Severe cracking. Renovation cost: $63,000, delayed 15 days.

Point 4: Ductwork Construction – Cleanliness, Sealing & Smooth Airflow

Ductwork circulates clean air. Dirty inner surfaces and leaking joints ruin cleanliness.

• Galvanized steel ≥0.8mm, polished inner surface, cleaned with alcohol before installation.
• Flange sealing; joint leakage ≤0.02m³/(m²·h). Elbow radius ≥1.5 × pipe diameter to reduce resistance.
• Air purging ≥20m/s for minimum 30 mins per duct section. Particle test required before filter installation.

Case: A bio-lab duct was unpolished and uncleaned. High airflow resistance and excessive particle count. Reconstruction cost: $39,000, delayed 10 days.

Point 5: Filter System Installation – Standard Operation & Leak Test

Primary, medium and HEPA filters are the core purification components. Wrong sequence or missing leak test leads to purification failure.

Case: A medical workshop fitted HEPA filters too early without PAO test. 0.08% leakage caused GMP rejection. Replacement cost: $27,000, delayed 7 days.

Point 6: HVAC Installation – Level & Stability for Reliable Operation

Misaligned air handlers and fans trigger vibration, noise and unstable temperature & humidity.

• Level deviation ≤0.5mm/m; vertical deviation ≤1mm/m. 5–10mm vibration pads, fan vibration ≤4.5mm/s.
• Flexible pipe connection. Hydraulic test at 1.5×design pressure, hold 30 mins without leakage.
• Commissioning: Airflow tolerance ≤10%, temp & humidity accuracy ±1.5℃ / ±8%RH.

Case: A lab fan had no vibration pad, noise hit 72dB exceeding limits. Noise control renovation cost: $17,000.

Point 7: Pressure & Airflow Commissioning – Prevent Cross Contamination

Pressure gradient and uniform airflow prevent reverse contamination.

• Pressure difference ≥5Pa between different clean classes; ≥10Pa between ISO5 core area and buffer / non-clean zone, tolerance ±1Pa, monitored for 24h continuously.
• Air velocity for unidirectional flow:0.36–0.54m/s. Air change rate: ISO6 ≥100/h, ISO7 50–60/h, ISO8 20–30/h.
• Weighing rooms keep negative pressure vs clean corridor. Record data hourly over 24h.

Case: A medical workshop only maintained 6Pa pressure and suffered microbial cross-contamination. Recommissioning cost: $36,000, delayed 8 days.

Point 8: Temperature, Humidity & Anti-static Commissioning

Poor control causes product scrap and equipment damage.

• Temp & humidity: Semiconductor:22±1℃, RH45–55%; Pharma:18–26℃, RH45–65%; Food:20–24℃, RH40–60%.
• Anti-static: Floor & wall resistance 10⁶–10⁹Ω; ionizer static elimination ≤±100V.
• Joint commissioning for purification, humidity and anti-static systems.

Case: An SMT workshop skipped anti-static commissioning. High resistance caused 4.8% defect rate. Renovation cost: $54,000, defect rate reduced to 0.8%.

Point 9: Auxiliary Systems – Coordination & Compliance

Electrical, monitoring, fire, sterilization and airlock systems must coordinate with main construction to meet regulatory requirements.

• Electric: IP65 LED panels ≥500lux; sealed cable routing.
• Monitoring: Particle, pressure, T&H sensors; data stored ≥1 year with alarm.
• Fire protection: FM200 for electronic cleanrooms; pre-action sprinkler for pharma.
• Sterilization: VHP sterilization for pharma aseptic areas; interlocked passbox response ≤0.5s.

Case: A medical cleanroom had conflicts between electric and HVAC works, failing GMP inspection. Retrofit cost: $87,000, delayed 18 days.

Point10: Final Acceptance – Thorough Inspection to Eliminate Hidden Risks

Acceptance covers visual check, parameter test, document audit and full cleaning.

• Visual: No cracks on envelope and doors; smooth arc transitions.
• Parameter: Third-party test for cleanliness, pressure and airflow complying with GB/T50591 & ISO standards.
• Documents: Drawings, material certificates, PAO reports and validation records fully traceable.
• Recheck particle level after deep cleaning.

Case: An eco-lab applied for acceptance without full cleaning. Particle overload caused rejection. Cleaning & repair cost: $21,000, delayed 6 days.

Summary

Cleanroom construction wins by details. There is no "almost qualified", only pass or fail. Tiny gaps or pressure deviations can lead to huge losses. Standardized full-process control helps achieve one-time acceptance and cut future renovation costs.