Do you need antistatic terrazzo, and what resistance should it have?

Only in specific buildings: operating theatres, electronics assembly, pharmaceutical clean rooms, and some data centres. Where it is required, GB 50944-2013 sets the surface resistance of an antistatic cement-based floor, which is what antistatic terrazzo is, at between 1.0 x 10^4 and 1.0 x 10^9 ohms. Below that band is conductive, above it is dissipative.

Reference photograph of a terrazzo surface, s77. Not a photograph of our goods. — Teal resin floor with a floral inlay

Reference photographs. They show the material and the finish; they are not photographs of goods we made, and the colour on screen is not a colour-match.

The figures, and where each one comes from

Floor type	Surface resistance, ohms
Antistatic cement-based floor, including antistatic terrazzo	1.0 x 10^4 to 1.0 x 10^9
Conductive antistatic panel floor	1.0 x 10^4 to 1.0 x 10^6
Dissipative antistatic panel floor	1.0 x 10^6 to 1.0 x 10^9
Antistatic resin coating floor	5.0 x 10^4 to 1.0 x 10^9
Antistatic wall and ceiling	not more than 1.0 x 10^10

Why the processes are not interchangeable

Two things make this specification harder than it looks. The first is that the code requires the substrate to be below 8% moisture content before the resistance test is done, so the floor cannot be tested on a wet screed and left to dry afterwards. The second is that the divider strips must be isolated from the conductive mesh beneath them, which is why the code requires a gap of 3 to 5 millimetres between adjacent strips and forbids them touching the mesh. Get either of those wrong and the floor fails its test while looking perfectly correct.

What these figures are, and what they are not

The resistance band is table 14.5.1 of GB 50944-2013, in force since 1 June 2014, whose clause 4.1.1 covers antistatic terrazzo floors. The moisture limit is clause 4.5.1 and the strip isolation detail is clause 4.4.4. ⛔ TWO WARNINGS. GB 12158 is not the right standard: it is now General requirements for preventing electrostatic accidents, GB 12158-2024, and it replaced GB 12158-2006 and GB 13348-2009. And JC/T 507-2022 clause 6.5.4 refers to SJ/T 31469 for antistatic performance, while several industry sources report that document as withdrawn in 2017 — a conflict we are reporting rather than resolving. Confirm the current position with the authority before you specify against it. We hold no antistatic test report.

Measured data sheets and test reports

If you are specifying this

These are the forms we actually supply for this question, with production photographs where we have them:

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