Before committing to polished concrete floors, there's one question to answer first: is the underlying concrete actually suitable to be polished? Getting this wrong is the single most common cause of blown budgets and delayed renovations in concrete flooring projects.

What a Genuine Burnished Concrete Floor Looks Like

• Burnished concrete is a polished concrete floor finish where there is no aggregate exposed.
• Highly sought after in today's concrete flooring landscape.
• Can only be achieved with a new concrete pour, or a topping slab.

What Makes Concrete Polishable

Concrete specified for polishing is usually 40 MPa, sometimes 32 MPa — concrete under 32 MPa is generally considered too soft to hone or polish well. Most ground-level homes without polishing in the original spec are built on a 25 MPa slab. A skilled polisher can still get reasonable results on 25 MPa concrete by densifying the surface during the polishing process, but it's a harder starting point.

Signs Your Slab May Not Be Polishable

Older buildings — particularly inner-suburb properties — often have softer concrete due to age, placement, curing and finishing factors, and can show spalling, curling, or an uneven level across the building. These typically need repair, patching and levelling before polishing is even an option. Buildings that have been extended or renovated multiple times often carry additional complications from the join between original and newer slabs.

What Non-Polishable Concrete Looks Like

Grinding back and polishing this type of concrete floor can reveal undesirable imperfections — concreters' rubbish, cigarette butts, fallen leaves, footprints, all trowelled over and concealed when the slab was originally poured. Nobody can control where these will appear.

What Removing Your Old Flooring Can Reveal

Grinding back and polishing an existing slab exposes whatever got trowelled into the surface when it was poured — and once concrete is polished, none of it can be hidden again.

Tiles

Removing tiles can chip the concrete surface underneath from the removal process; a good polisher can patch and blend most of this. Tile ghosting — a faint outline of the old tile grid left in the surface — is harder to fully remove, regardless of skill.

Timber

Pulling up timber flooring commonly reveals a levelling compound underneath (timber needs a flat substrate), plus a regular pattern of bolt holes from the fixing points. These can be patched but usually remain faintly visible.

Carpet

Removing carpet leaves chip holes around room perimeters from the carpet gripper strips, and depending on the property's age, old stains that have penetrated into the concrete and won't lift out during polishing.

What to Check Before You Commit

Where possible, have a tradesperson pull up a section of the existing floor covering to inspect the concrete underneath — straightforward with carpet, harder with tiles, and laminate is usually glued but manageable with the right tools. Look for: stains, cracks, a soft or chalky surface, existing levelling or patching compound, an uneven level, slab extensions or adjoining substrates, and holes or fixings left in the surface.

The Alternative: A MicroConcrete Overlay

Where the existing slab isn't a good polishing candidate, a cement-based resurfacing system is an alternative that keeps the genuine concrete look without depending on what's underneath being flawless. It can go over repaired concrete, directly over tiles, or onto new structures, in a range of colours and finishes. Read how this played out for one Melbourne renovation.

Do What Mel Zammit and 100s of Others Have Done

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FAQ

Can a 25 MPa concrete slab be polished?
Yes, though results are less predictable than 32–40 MPa slabs — a skilled polisher can improve outcomes by densifying the surface during the process, but this is a harder starting point.

What is "tile ghosting" on a polished concrete floor?
It's a faint outline of the old tile grid left visible in the concrete after tiles are removed and the floor is polished — it's very difficult to fully remove regardless of the installer's skill.

What can I do if my existing slab isn't suitable for polishing?
A cement-based MicroConcrete overlay achieves a genuine concrete look without requiring the original slab to be flawless, and can be applied over repaired concrete or directly over tiles.