Seamless floors compared

At a glance

Thicknesses: terrazzo from the US National Terrazzo & Mosaic Association (converted to mm, as on our terrazzo sheet); resin from FeRFA; microcement and polished concrete from makers. Base figures are the makers’ for their own systems. Read 7 Nov 2026.

Five systems, and who writes the specification

‘Seamless’ describes a look, not a material. Five systems can give a floor with no tile or board joints, and they behave differently under the same slab.

• In situ terrazzo is chips in a matrix, laid wet and ground flat on site. The matrix is cement or resin. Our terrazzo page says both cement and resin surfaces can be reground and repolished in place. The detail is on the terrazzo specification sheet.
• Resin flooring is a liquid binder that cures by a chemical reaction. FeRFA, the UK resin flooring trade association, sorts it into eight types by thickness and duty, from a floor seal of about 150 µm to a heavy-duty trowelled floor of over 6 mm.
• Microcement is a cement-based overlay in very thin layers, usually sealed. It is a surface finish, not a floor build-up.
• Polished concrete is the structural or screed concrete itself, mechanically ground in stages and densified.

Who writes the technical specification. Each of these is a specialist trade, and the makers and installers publish their own system data. The sources we read all put the substrate preparation and the system build-up in the specialist’s hands, and one even says that a floor counts as that maker’s process only if its own equipment and a certified contractor are used. Our reading: the designer writes the result wanted (colour, sheen, texture, joint pattern, slip, cleaning) and asks the partner to name the system, the installer and the evidence; the specialist writes the system specification. The studio coordinates this through partner workshops and does not lay these floors itself.

Thickness, and what the slab must provide

The drawing puts the surfaces on one scale. The thicknesses are not equivalent: a 13 mm terrazzo topping, a 3 mm microcement and a ground polished concrete slab ask very different things of the floor beneath them and of the floor build-up height.

• Cement terrazzo. The US trade body’s nominal thicknesses are 13 mm for monolithic and 10 mm for epoxy; bonded and sand cushion types are thicker (see the terrazzo sheet). These are US figures: UK build-ups come from BS 8204-4 and the terrazzo contractor.
• Resin. FeRFA’s classification gives type 05 flow-applied flooring at 2 to 3 mm and type 06 resin screed at over 4 mm. Its higher types go to over 6 mm, trowelled and aggregate filled, and described as effectively impervious through the thickness.
• Microcement. One maker’s data sheet gives a coating of 1 to 3 mm and recommends a total of 3 mm, with no layer over 1 mm. Another asks the specifier to allow 3 to 4 mm of height for the finished system.
• Polished concrete. Nothing is added. The equipment maker’s specification removes no more than 1.5 mm for a fine, sand-aggregate finish, and more where the aggregate is to show.

Then what the slab must provide. The figures below are the makers’, for their own systems, and are not UK standard values.

Different methods are used to measure these, and the maker gives each method for its own product. Do not compare a resin’s relative humidity limit with a microcement’s moisture percentage: ask the partner to state the test and the limit for the chosen system.

Joints and cracks

A seamless surface does not make a seamless floor. The slab beneath it moves, shrinks and is cut by joints, and a thin bonded layer follows it. The first decision is where the joints in the slab fall, and the second is what the surface does when it reaches one.

• Terrazzo. The US trade body says strips set over joints in the slab do the work of a joint for the systems that bond to the slab, and that strips elsewhere are decorative. So the strip layout starts from the slab joints and the pattern fits it (see the terrazzo sheet).
• Microcement. One maker says movement in subfloors can crack microcement along joints: it is an overlay and does not hold up under significant movement despite its flexibility. It asks for slabs poured in a single pour with expansion and control joints where needed, and, where joints exist, for a threshold with the microcement stopped to it on each side. Another maker’s sheet says the coating should be continuous but always respect expansion joints. A third says to follow the architect’s or engineer’s specified expansion joints and not fill them completely.
• Resin. The sources we could read do not give joint rules, and the FeRFA guide and BS 8204-6 were not read. The resin maker, or the specialist, will say how it treats slab joints and cracks. A resin screed is far thicker than a coating and a different case from a seal.
• Polished concrete. The concrete is the finish, so its joints, hairline cracks and pores are the floor. The equipment maker asks for curing methods that minimise shrinkage, cracks and pores, and fills pin holes and micro cracks with a grout before the final stages.

For the line where a seamless floor meets another floor, see floor transitions and movement joints. For build-up height, see floor build-up heights.

Slip, sealing, care and repair

• Slip. None of these has a slip value that belongs to the material: it belongs to the finished surface, with its sealer, wet or dry. HSE says slipperiness can change with installation, cleaning and wear, so test the finished sample wet, as the floor will be used. See slip resistance for floors. A maker’s sealer or grit can change the result, so approve the sample, not the system name.
• Sealing and stains. Microcement is sealed once hardened, and one maker sets a moisture limit of 5% before sealing and uses a water-based varnish. The polished concrete maker says stain protection is not compulsory but strongly recommended, since otherwise there is a high risk of permanent stains. Cement terrazzo is sealed and cleaned with a neutral cleaner, and resin terrazzo is effectively non-porous (our terrazzo page).
• Maintenance and repair. The sources give no re-seal interval or repair method that we can state. Ask the partner for the written regime for the chosen system, who carries it out, what is re-applied and when. See handover and O&M pack.
• Where water is present. Microcement makers ask for the absence of water ingress during the work, and one says the product should not make up for a wet-area failure. For wet rooms see stone and timber in wet areas and ask the specialist to name the membrane system.
• Underfloor heating. No source read here covers heating under these systems. Ask the system maker for its heating guidance before you rely on it.

What to put in the brief

Put these in the brief before you ask for a price, so the partner is quoting the same thing from every source:

1. The result: colour and chip scale, sheen (matt, honed or polished), texture, and slip class to the pendulum method.
2. The base: what the slab or screed is, its age and dryness, the joints already designed, and who confirms it is ready.
3. The joint pattern: where slab joints fall, and whether the design shows them with strips, a trim or a threshold.
4. The build-up: total height from the slab to the finished floor, and the levels at each door.
5. A mock-up on site: at least one panel at full thickness, finished and sealed, approved by name before the floor starts.
6. The care regime and warranty wording, in writing, from the system maker and the installer.

Seamless floor to [room or area]: [in situ cement terrazzo / resin terrazzo / resin flooring FeRFA type [ ] / microcement / polished concrete], total thickness [ ] mm, colour and chip or aggregate [reference] to the approved sample panel. System, installer and system maker to be named by the partner before order, with the maker’s data sheet for the system and the base it requires.

The partner shall confirm in writing that the base is [concrete / screed to [reference]], at [ ]% moisture by the method the system maker requires, with strength not below the system maker’s figure of [ ] N/mm². Joints in the base at the positions on drawing [ ] shall be carried through the finished surface at the same positions with [strip / flexible joint / trim], and shall not be bridged.

A mock-up panel of [ ] m x [ ] m at full thickness, finished and sealed, shall be approved by [designer] before the floor starts. Slip resistance of the finished, sealed sample to be tested wet by the pendulum method [BS EN 16165] and the result issued before approval.

The partner shall issue a written care regime for the finished floor (products, methods, re-sealing interval [ ], who carries it out) and the system maker’s and installer’s warranty terms [ ].

Standards and sources

• FeRFA, Resin Flooring Classification System (eight types): classification page read 7 Nov 2026; the FeRFA guide itself (behind a form) not read.
• BS 8204-6:2008+A1:2010 and BS 8204-2:2003+A2:2011 (both Current per BSI Knowledge, 7 Nov 2026); BS 8204-1 and -4 (Current per listings read earlier this week): named, not read.
• Makers’ microcement and polished concrete documents: read 7 Nov 2026; makers are named in the notes file, not on the page.

Questions we are asked

Which seamless floor is best for a hotel?

None is best in itself. In situ terrazzo (cement or resin) is a thick, ground floor that can be reground, according to our terrazzo page; resin flooring is a family from a thin seal to a heavy-duty screed; microcement is a 1 to 3 mm overlay that follows the slab and does not hide movement; polished concrete is only as good as the slab. Choose by the base, the joints, the slip test on the finished sample and the care regime the operator will keep to.

Is microcement the same as a resin floor?

No. The makers we read describe microcement as a thin cement-based overlay with resins and additives, applied in layers about 1 mm thick and sealed. FeRFA’s resin flooring is a liquid resin binder cured by a chemical reaction. They share a trowelled look, not a chemistry or a standard.

Will a seamless floor crack?

It can follow cracks in the slab beneath. One microcement maker says movement in subfloors can crack microcement along joints; the terrazzo trade body says strips over slab joints do the work of a joint for bonded systems. Plan the joints in the slab first, and carry them through the surface.

Does a seamless floor need movement joints?

Where the slab has joints, the sources agree that the surface should respect them, at the same positions, or stop at a trim. UK joint spacing for each system comes from the relevant part of BS 8204 and the system maker; we did not read those texts, so the sheet gives no spacing.

Can I put underfloor heating under a seamless floor?

The documents we read do not cover it. Ask the system maker for heating guidance in writing, including heating up and cooling down limits, before you specify it.

Who writes the specification for a resin or microcement floor?

The specialist installer and the system maker write the system specification. The designer writes the result wanted and approves a mock-up. The studio coordinates this through partner workshops.