The word concrete covers at least three different things once it comes indoors, and the gap between them is where most disappointing projects begin. A poured floor, a three-millimetre coating and a bolted-on panel produce a similar photograph and an entirely different building site, budget and set of consequences.
Before you commit
- Cast in place gives the truest result and is the only option that raises real structural questions.
- Microcement delivers the look over existing floors and walls at a fraction of the weight, and depends entirely on the substrate underneath.
- Concrete is porous. Sealing is not a finishing touch, it is what decides whether the surface survives a kitchen.
- Fine surface cracking is a property of the material, not a defect. Anyone promising you a crack-free result is selling something else.
Concrete indoors is three different techniques
Each of the three routes below produces a grey mineral surface. That is where the resemblance ends, and choosing between them is the first conversation to have with a contractor rather than the last.
Cast in place
A slab or screed poured on site, then ground and polished to the level of sheen you want. It is the only technique that gives genuine depth, because the aggregate and the surface are the same material rather than a coating over something else. It is also the heaviest, the slowest to cure and the least forgiving: once it is down, changes mean demolition. For floors this typically means a screed of several centimetres, and the weight it adds is the reason an upper floor cannot simply be assumed to take it.
Microcement
A polymer-modified cement coating applied in thin layers, usually two to three millimetres in total, over an existing floor, wall or worktop. It is the technique that has driven most of the growth in domestic concrete finishes, because it adds negligible weight, needs no demolition and can be laid over tile, screed or plasterboard. Its weakness is inherited: microcement moves with whatever is underneath it, so a substrate that flexes or a joint that is not properly bridged will show through within a season.
Precast panels and large-format tiles
Factory-made panels, or porcelain tiles printed and textured to read as concrete, fixed to a prepared surface. The finish is consistent because it was made under controlled conditions rather than in a cold room in February, and the installation is dry, quick and reversible. The compromise is legibility: panels have joints, and the eye finds them.
Where concrete belongs, room by room
Living rooms and hallways
These are the rooms where a concrete floor performs best, because the traffic is high, the spills are rare and the surface can run continuously through several spaces. Continuity is most of the effect: a poured floor that carries from a hall through to a living area makes a modest footprint read as generous. The failure mode here is acoustic rather than visual, which we come back to below.
Kitchens and worktops
A concrete worktop is the most demanding application in the house and the one most often regretted. Concrete is alkaline and porous, and common kitchen acids, lemon juice, vinegar and wine, will etch an inadequately sealed surface within minutes. It can be done well, with a high-performance sealer and an owner who accepts that patina is part of the deal. It suits people who like a surface that records use, and frustrates everyone else.
Bathrooms
Seamlessness is the real argument for concrete in a bathroom, since a microcement shower enclosure removes the grout lines that collect everything. The waterproofing membrane underneath does the actual work, and it must be specified and installed as a system with the coating rather than assumed. This is not a surface to attempt as a first project.
Vertical surfaces and furniture
Walls, fireplace surrounds, a bench, a basin. These are the low-risk applications, because a vertical surface takes no traffic and a piece of furniture can be replaced. They are also the sensible way to test whether you actually like living with the material before committing a whole floor to it. A concrete wall paired with timber shelving, the combination at the centre of most raw material interiors, is a weekend’s work rather than a renovation.
The four things showrooms leave out
- Weight. Structural concrete runs at roughly 2,300 to 2,400 kilograms per cubic metre, so even a modest screed adds a couple of hundred kilograms to every square metre of an upper floor. On a ground-floor slab this is irrelevant. On a timber-framed first floor it is the whole question.
- Cracking. Cement-based surfaces shrink as they cure and move with temperature. Fine hairline cracking is normal and, in a polished floor, usually reads as character. Structural cracking is a different matter, which is why movement joints belong in the design and not in the repair.
- Sealing and staining. Unsealed concrete absorbs oil, wine and grease permanently. A penetrating sealer, reapplied on the schedule the manufacturer specifies rather than when a stain appears, is the single maintenance task that matters.
- Temperature and sound. Concrete is cold underfoot and reflects sound hard. Underfloor heating solves the first and pairs unusually well with the material’s thermal mass. The second needs textiles, soft furniture and something absorbent on the ceiling, planned in from the start.
The checks to make before anything is poured
Interior finishes rarely trigger planning formalities, but concrete is the exception often enough to be worth checking properly. Two questions decide it.
The first is structural. Any added floor weight on a suspended floor, and any opening or alteration to a load-bearing element, needs a qualified structural engineer’s assessment before work starts. This is not a formality that varies much between countries: the engineer’s sign-off is what an insurer will ask for if something moves later.
The second is regulatory, and it does vary. Most jurisdictions distinguish work needing no formality, work needing a prior declaration, and work needing full permission, with additional obligations once a building is listed, in a protected area, or old enough to raise asbestos and lead questions during demolition. Check which category your project falls into with the local authority before ordering materials, because the answer changes the programme rather than just the paperwork.
Choosing between the three
Set against the constraints of a real room, the decision usually makes itself.
| Technique | Added thickness | Disruption | Choose it when |
|---|---|---|---|
| Cast in place | Several centimetres | High. Curing time, dust, room out of use | Ground floor, new build or full renovation, and the depth matters to you |
| Microcement | Two to three millimetres | Moderate. No demolition, several drying stages | Upper floors, refurbishment, wet rooms, seamless surfaces |
| Panels and tiles | Depends on the fixing | Low. Dry installation, reversible | Rented spaces, tight programmes, or a predictable result matters more than depth |
Whichever route you take, the same rule applies to the palette around it. Concrete is a background material, and it reads as deliberate only when something warm sits against it. Timber, wool, aged leather and brass all do that job, and the pairing of mineral and metal we cover in our piece on combining wood and metal is the shortest route to a room that looks composed rather than unfinished.
Straight answers
Can microcement go over existing tiles?
Usually yes, provided the tiles are sound, well bonded and properly primed, and the joints are bridged as the system specifies. Loose or hollow-sounding tiles have to come up first, because the coating will follow whatever the substrate does.
How often does a concrete surface need resealing?
It depends on the sealer and the traffic, so follow the manufacturer’s interval rather than a general rule. A worktop needs attention considerably more often than a hallway floor, and waiting for a stain to appear means the sealer failed some time ago.
Is concrete a sustainable choice indoors?
Cement production carries a significant carbon cost, which is the honest starting point. Against that, a poured floor can last the life of the building and needs no replacement cycle, and recycled aggregates and lower-clinker binders are increasingly available. The environmental case rests on longevity rather than on the material itself.
Wondering where else concrete earns its place?
Our piece on concrete features in home design looks at the applications beyond floors and walls, from worktops to built-in furniture.
