Buyer guide
Cleanroom wall and ceiling finishes: coving, sealants, joints and stainless steel
Cleanroom walls and ceilings must be smooth, impervious and unbroken, with no recesses that are hard to clean. The corners, joints and penetrations decide whether they are, so specify each junction in writing.
By ZY Cleanroom · Updated · Sources at the end of the page
What the rules say
| Source | Requirement |
|---|---|
| Annex 1, para 4.5 | Exposed surfaces smooth, impervious and unbroken, to limit shedding and build-up of particles and micro-organisms |
| Annex 1, para 4.6 | No recesses that are hard to clean. Ledges, shelves and cupboards kept to a minimum. Sliding doors may be undesirable |
| Annex 1, para 4.7 | Materials limit particles and allow repeated cleaning with disinfectant and sporicidal agents |
| Annex 1, para 4.8 | Ceilings designed and sealed to stop contamination from the space above |
| FDA, 2004 | Seamless, rounded floor-to-wall junctions and accessible corners. Smooth, hard surfaces that clean easily |
| Welsh HBN 00-10 Part B, 2014 (healthcare) | Walls free from fissures, open joints and crevices. Penetrations sealed tightly. Finishes do not promote microbial growth and withstand wall expansion and contraction (paras 2.10 to 2.13) |
Coving and corners
Coving is a rounded, continuous profile at a junction, so a sharp corner cannot trap dust. FDA asks for rounded floor-to-wall junctions. The same logic suits wall-to-wall and wall-to-ceiling corners.
Neither Annex 1 nor FDA gives a radius. Write the radius and profile into your specification, and ask the supplier for the profile drawing. Keep the profile flush with the wall face so no ledge forms.
Joints, sealants and penetrations
A sealed joint must stay sealed through wall movement and repeated cleaning. Ask the sealant supplier for test data against your own cleaning agents, its movement capability and the repair method.
| Junction | What to specify |
|---|---|
| Panel to panel | Flush face, continuous seal, no open joint |
| Wall to floor, wall to ceiling | Continuous rounded profile, sealed at both edges |
| Pipe, duct or conduit through a wall | Sealed tightly around the penetration |
| Door frame and window to panel | Flush with the panel face, no recess (Annex 1, para 4.6) |
| Ceiling to terminal filter housing | Sealed so air cannot bypass, and arranged so the filter and seals can be tested (HTM 03-01, para 8.102) |
Stainless steel
A 2023 trade article from IMOA, the molybdenum industry association, says Type 316 stainless steel contains 2% molybdenum and resists repeated chemical cleaning. It says lower-alloyed grades can develop crevices and pits from repeated cleaning, and bacteria can hide in them.
IMOA adds that stainless steel can be polished very smooth, which leaves fewer peaks and valleys where cleaning chemicals can remain. This is dated trade comment from a body with an interest in 316, not a standard, so check the grade against your own disinfectant list.
Match the finish to the cleaning regime
Annex 1 (paras 4.33 and 4.34) asks for more than one type of disinfectant and a periodic sporicidal agent. It also asks for validation on the surface material or a representative one. Ask the finish supplier for samples to test with your agents.
Where vapour-phase hydrogen peroxide is used, Annex 1 (para 4.36) asks that the agent and its dispersion are understood and validated.
Put these in the room data sheet
State the panel facing and joint type. State the cove radius and profile. State the sealant type, its movement capability and cleaning-agent test data. State the penetration seal method, and the stainless grade and finish where used. List the cleaning and sporicidal agents the surfaces must tolerate.
Who approves the room
Your regulator or customer auditor judges the facility, not the contractor. The contractor builds to your room data sheet and supplies test data. To have a room list reviewed, send it to ZY Cleanroom, a cleanroom design-and-build contractor.
Questions
Common questions
What is coving in a cleanroom?
A rounded, continuous profile at the junction of two surfaces, such as floor and wall. It removes the sharp corner that traps dust. FDA (2004) asks for rounded floor-to-wall junctions.
What radius should coving have?
Neither Annex 1 nor FDA gives a value. Set the radius in your own specification.
Does a cleanroom need stainless steel walls?
Annex 1 does not require it. It asks for smooth, impervious, unbroken surfaces that tolerate repeated cleaning and sporicidal agents (paras 4.5 and 4.7). Choose the material by your cleaning agents.
Which sealant should I choose?
None of the sources here ranks sealants. Choose by movement capability, resistance to your cleaning agents and the supplier's test data.
Related guides
- How to audit a cleanroom panel factory, on site or by video
- Cleanroom flooring options: epoxy, vinyl, raised and static control
- Cleanroom doors: hinged, sliding and hermetic selection
- Modular vs conventional cleanroom: how to choose
- Turnkey cleanroom contractor
- Room list builder
Sources
- EudraLex Volume 4, Annex 1: Manufacture of Sterile Medicinal Products (published 25 August 2022, applied from 25 August 2023; checked 31 October 2026)
- FDA, Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing, Current Good Manufacturing Practice (September 2004, nonbinding; checked 31 October 2026)
- NHS Wales Shared Services Partnership, Welsh Health Building Note 00-10 Part B: Walls and ceilings (2014; healthcare guidance, used here for general finish principles; checked 31 October 2026)
- NHS England, Health Technical Memorandum 03-01, Specialised ventilation for healthcare premises, Part A (published 22 June 2021; checked 31 October 2026)
- International Molybdenum Association, MolyReview issue 1/2023, Sterile stainless steel serves cleanrooms (2023 trade article, excerpt; dated, and the publisher has a commercial interest; 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.
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