Buyer guide
How to choose a cleanroom contractor: questions and evidence
Choose the contractor that can show, in documents, how it will meet your room specification and how it will prove the result at handover. Ask for evidence on scope, design basis, factory control, testing and site support, and treat a supplier's country as one more risk to check, not as a reason to accept or reject.
By ZY Cleanroom · Updated · Sources at the end of the page
Start with your own room list
ISO 14644-4:2022 sets out a process from requirements through design, construction and start-up, for new, refurbished and modified cleanrooms. Use that order. Write the requirements first, then compare bids.
Send every bidder the same room list: class and occupancy state, floor area, pressure plan, temperature and humidity, utilities, and who supplies what. Bids built on different assumptions cannot be compared.
Questions to ask and evidence to demand
Ask each question in writing. Keep the answers with the bid.
| Topic | Ask | Evidence to request |
|---|---|---|
| Scope | Who designs, supplies, installs and tests? What is excluded, for example air handler, ducting, utilities, controls? | A scope matrix marking each item as supplier, owner or third party |
| Design basis | Which standards does the design follow? | Design basis document, drawings and room data sheets |
| Past work | Which projects did the bidder's own team build, and which came through partners? | Reference contacts you can call, and project records for a similar class and sector |
| Panels and doors | Who makes them? | Test reports that name the core, thickness and facings you will buy |
| Testing | Which tests at handover, by whom, with what instruments? | A draft test protocol and calibration certificates |
| Site team | Who supervises installation, and in which language? | Named supervisor and a site plan |
| After handover | What happens when a test fails or a part breaks? | Written warranty terms and a spare-parts list |
What a certificate shows
ISO 9001 and similar certificates can be searched in IAF CertSearch. A record lists the standard, scope, status, certification body and accreditation body. Read the scope: it may cover only part of the business. If nothing appears, ask the certification body.
A management-system certificate shows that a process exists. It does not show that your room will pass. Class is shown by particle counts in the agreed state, measured with the test methods in ISO 14644-1 and ISO 14644-3.
Buying from a Chinese supplier: fair checks
Apply the same evidence list to every supplier. The extra checks below concern distance, paperwork and the rules of your market.
Name the standard. China's GB 50073-2013 covers cleanroom design and GB 50591-2010 covers construction and acceptance of new and reconstructed cleanrooms. If your market follows EU, US or other rules, write them into the contract.
Check fire and panel reports. The EU route for sandwich panels uses a harmonised standard and factory production control (Efectis). Ask for the report for the exact panel, and for the fire class your building code needs.
Fix the trade term. Each Incoterms 2020 rule sets the delivery point, the point where risk passes, and the split of costs (ICC). Name the rule and the named place.
Plan for distance. Agree who is on site, who commissions, how fast a defect gets a response, and how a video audit of the factory will work. Tie payment steps to inspection or test results.
Red flags
Watch for a bidder who will not list exclusions, cannot say who made the panels, shows a test report for a different panel, offers no handover test plan, or promises a class without naming the state and the test.
Who approves the room
Your regulator or customer auditor judges the facility, not the contractor. The contractor builds to your room list and supplies test data. The owner keeps the responsibility. To have a room list reviewed, send it to ZY Cleanroom, a cleanroom design-and-build contractor in Tianjin, China.
Questions
Common questions
Should I choose a local or an overseas contractor?
Neither location decides. A local firm is easier to visit and may know local codes better. An overseas firm needs more planning for site support and paperwork. Ask both for the same evidence.
Does ISO 9001 prove a contractor can build to ISO 14644?
No. It shows a management system is in place. Class is proved by testing the finished room.
What should the contract say about testing?
Name the class, the occupancy state, the test methods, who tests, and what happens if the room fails.
Can a contractor promise a cleanroom class?
Only subject to a test. The class applies to a stated state and is confirmed by measured particle counts.
What makes a cleanroom manufacturer stand out?
Evidence tied to your project, not general claims. Look for test reports on the finished product at your size or thickness, factory production control records, and a test plan that matches your room list. Ask to see a real handover document set with client details removed.
What is a turnkey cleanroom?
It is one contract that covers design, supply, installation and handover testing, so one firm answers for the joins between trades. The word has no fixed meaning, so ask for a scope matrix naming who supplies the air handler, power, utilities and validation. A regulator approves the owner's facility, not the contractor, so those duties stay with the owner.
Related guides
- The Cleanroom Project Lifecycle
- Cleanroom cost per m²: published ranges by ISO class
- Building a cleanroom inside an existing building
- What a cleanroom costs to run: energy, filters and testing
- Turnkey cleanroom contractor
- Room list builder
Sources
- ISO 14644-4:2022, Cleanrooms and associated controlled environments, Part 4: Design, construction and start-up (ISO catalogue entry; checked 31 October 2026)
- ISO 14644-1:2015, Cleanrooms and associated controlled environments, Part 1: Classification of air cleanliness by particle concentration (published 9 December 2015; checked 31 October 2026)
- ISO 14644-3:2019, Cleanrooms and associated controlled environments, Part 3: Test methods (published August 2019; contents list; checked 31 October 2026)
- IAF CertSearch, General FAQ (support pages; checked 31 October 2026)
- GB 50073-2013, Code for design of clean room (issued 28 January 2013, in force 1 September 2013; catalogue page with contents list; checked 31 October 2026)
- GB 50591-2010, Code for Construction and Acceptance of Cleanroom (issued 15 July 2010, in force 1 February 2011; clause 1.0.2; catalogue page; checked 31 October 2026)
- Efectis, CE certification process of sandwich panels (undated web page; checked 31 October 2026)
- ICC Academy, Insider thoughts: Bob Ronai on Incoterms 2020 rules (26 March 2020; checked 31 October 2026)
Project enquiry
Send what you have
A room list, a floor plan or only the floor area is enough to start. After you submit, send drawings by email or WhatsApp.
We reply by email within one working day. We can sign an NDA before you send drawings.
WhatsApp +44 7962 561184 is our UK number for export enquiries. The factory is in Tianjin, China.
Email: [email protected]
WhatsApp: +44 7962 561184