Cleanroom ceiling systems: walkable, non-walkable, grids and loads

By ZY Cleanroom · Updated 2026-11-01 · Sources at the end of the page

Walkable or non-walkable

Decide who must reach what, and from where. Welsh Health Building Note 00-10 Part B says access through the ceiling should be avoided in operating theatres, aseptic suites and laboratories, and asks for a local risk assessment (para 3.24).

A walkable ceiling moves service access above the room. Weigh that against the advice to avoid access through the ceiling in the rooms named above. The table sets out what the texts say on each point.

Grids and ceiling modules

An FFU is typically the same size as a ceiling grid module (LBNL-49106, 2001). Match the grid module, the FFU size and the luminaire size before you order. A mismatch leaves a cut panel or a gap to seal.

GB 50591-2010 lists supply air terminal installation (clause 5.6) and purification device installation (clause 11.2) as separate items. Decide who fits the grid, the filters and the fixtures.

Each module edge needs a seal to the frame. USP <797> asks for inlaid panels to be caulked around each panel.

Loads: state them as numbers

None of the texts checked sets a walking load for a cleanroom ceiling. State the loads yourself: the fixed load of filters, lights and trays, and the walking load of people and tools above.

Ask the supplier for a test report that names the test method, the span, the point load, the distributed load in N or kg, and the safety factor.

Worked example: fixed load per module

Assumed values: an FFU of 25 kg sits in a 1,200 × 600 mm module of 0.72 m². Load per module is 25 × 9.81 = 245 N. Per square metre of ceiling it is 25 ÷ 0.72 = 34.7 kg. Add the luminaire, the cable tray and the walking load on top.

Fire and materials

WHBN 00-10 Part B says demountable ceilings must not be required to provide or contribute to fire resistance or fire containment, because the access they allow may be incompatible with it (para 3.10).

ANSI/FM 4910-2013 tests cleanroom materials for fire spread and smoke. Materials thinner than 6 mm go to a parallel panel test instead. Ask which test the ceiling material passed. A material test is not a test of the whole ceiling.

Put these in the data sheet

State the ceiling type, the module size, the load rating with its test report, the seal at each edge, the fixture list with weights, the access points, and the fire and material test evidence. Say who supplies the hangers and the structure above.

Who approves the room

Your regulator or customer auditor judges the facility. The contractor builds to your room data sheet and supplies test results. The owner keeps the responsibility. To have a room list reviewed, send it to ZY Cleanroom, a cleanroom design-and-build contractor with its own panel factory in Tianjin, China.

Paper honeycomb ceiling panel: moisture, load and fire checks

A paper honeycomb ceiling panel is a sandwich panel with a paper core. We found no standard or published test series that rates paper honeycomb for cleanroom ceilings, so ask for the supplier's own evidence on each point in the table.

A ceiling faces the void above it. A review inside a 2020 paper on paper cell cores (Materials, Basel, 13(9):2058) reports that compressive strength in humid conditions can be as low as 25% of the dry value. Ask what humidity the void will reach, and how every cut edge around lights, filters and sprinklers is sealed.

For fire, a 2010 cone calorimeter study in the Journal of the Korean Institute of Fire Science and Engineering found impregnation with flame retardant the best of four treatments of honeycomb paper. Its flame-resistant film delayed ignition but worsened heat and smoke release. Those were laboratory samples, not ceiling panels.

Related guides

• The Cleanroom Project Lifecycle
• Cleanroom cost per m²: published ranges by ISO class
• Writing a cleanroom URS: contents and testable wording
• What a cleanroom costs to run: energy, filters and testing
• 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 1 November 2026)
• Washington State Department of Health, Pharmacy Self-Inspection Worksheet, 2026 USP 797 Sterile Compounding Addendum, DOH 690-296 (January 2026), which reproduces USP <797> text by section; checked 1 November 2026
• NHS Wales Shared Services Partnership, Welsh Health Building Note 00-10 Part B: Walls and ceilings (2014; healthcare guidance; checked 1 November 2026)
• EN 13964:2014, Suspended ceilings, Requirements and test methods (scope exclusions as listed on the Estonian Centre for Standardisation page; checked 1 November 2026)
• FM Approvals, ANSI/FM 4910-2013 (2021), American National Standard for Cleanroom Materials Flammability Test Protocol, sections 2.2, 2.4, 2.5 and 6 (reaffirmed 29 November 2021; checked 1 November 2026)
• Tengfang Xu and William Tschudi, Energy Performance of Cleanroom Environmental Systems, LBNL-49106 (November 2001; checked 1 November 2026)
• GB 50591-2010, Code for Construction and Acceptance of Cleanroom (issued 15 July 2010, in force 1 February 2011; contents list, chapter 4 and Appendices E and G; checked 1 November 2026)