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Answers / Methods

Do terrazzo floors need to be sealed?

Yes, a cement-bound floor does, and the timing is measured in hours not weeks: the trade guidance is a penetrating sealer applied about 12 hours after installation, with two coats as standard. A resin-bound epoxy floor is a different case — it is non-porous, so it needs a sealer for stain resistance and UV protection rather than for permeability.
Six terrazzo processes, drawn to one scaleEach column shows the layers of one terrazzo process. Precast and cement-bound are thick; epoxy is thin; porcelain is a fired body. Dimensions are published ranges, not our measured figures.substratePrecast20 mmsubstrateCement-based12 mmsubstrateEpoxy5 mmsubstratePoured10 mmsubstrateLiquid3 mmsubstratePorcelain9 mmSections drawn to one scale from published ranges. Our measured figures are listed separately.
The six processes drawn to one scale. Layer thicknesses are published ranges.
Reference photograph of a terrazzo surface, s57. Not a photograph of our goods.
Fine quartz chip in a grey matrix. A dense, hard aggregate takes a sealer differently from a soft marble one.
Reference photograph of a terrazzo surface, s11. Not a photograph of our goods.
Dense angular aggregate. Chip size and shape are what a sealer has to bridge.
Reference photograph of a terrazzo surface, s66. Not a photograph of our goods.
Floor and wall in one material. A wet room is where sealing decisions are visible.
Reference photograph of a terrazzo surface, s00. Not a photograph of our goods.
A pale laid floor. The colour shows every mark a sealer failure would leave.

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

Item What the trade publishes Source
Cement-bound, first seal about 12 hours after installation NTMA trade guidance
Cement-bound, coats two or more NTMA trade guidance
Cement-bound, gloss sheen lasts 45 to 60 days before recoat NTMA trade guidance
Epoxy, first seal at least two coats after installation Published CSI specifications
Epoxy, porosity non-porous; sealer is for stain and UV, not permeability Published CSI specifications
Cleaner pH 7 to 10, neutral NTMA trade guidance
Sealer slip rating UL classified, minimum 0.5 NTMA trade guidance
Reseal, high traffic every 1 to 3 years Wayon commercial guide
Reseal, high traffic every 6 to 12 months Milestone commercial guide
Reseal, moderate traffic every 12 to 18 months Milestone commercial guide
Reseal, residential every 3 to 5 years D&G Flooring guide
Full re-grind to 800 grit roughly every 20 to 30 years D&G Flooring guide

Why the processes are not interchangeable

A cement matrix is porous; a resin matrix is not. That single difference decides whether sealing is about stopping water getting in or about stopping stains landing on the surface, and it is why the two answers are not variants of each other.

What these figures are, and what they are not

We have no measured figure of our own. Everything below is published guidance from the trade, and where two sources disagree we print both rather than choose. What we will do is quote you the sealer we supply, state its coverage rate, and put it in the contract.

Measured data sheets and test reports

If you are specifying this

We have not published products against this question yet. Send us the process, thickness and quantity and we will quote it against what we can actually form, rather than against a catalogue.

Send a specification Ask for a sample

Yes, a cement-bound floor does, and the timing is measured in hours not weeks: the trade guidance is a penetrating sealer applied about 12 hours after installation, with two coats as standard. A resin-bound epoxy floor is a different case — it is non-porous, so it needs a sealer for stain resistance and UV protection rather than for permeability.

A cement matrix is porous; a resin matrix is not. That single difference decides whether sealing is about stopping water getting in or about stopping stains landing on the surface, and it is why the two answers are not variants of each other.