Can you polish an existing concrete slab? What to expect in a renovation

Pulling up tiles or carpet and finding a concrete slab underneath is how a lot of polished floors start. Many old slabs polish well. Some do not, and it is better to know which before you commit.

What can be under the covering

• Tile adhesive and carpet glue, which has to be ground off before anything else.
• Levelling compound or screed, which is not concrete and does not polish.
• Patches where walls, plumbing or old fittings were moved, usually in a different colour.
• Cracks, some old and stable, some not.
• Paint, sealers or old coatings.
• Stains from water, rust, oil or timber that have soaked in deeply.

How we find out

Send photos of the slab and what is on it now, and the age of the house if you know it. Then we grind a test area in a spot that will be hidden or forgiving. That shows what the concrete is like under the surface and how much stone is there. It is the only reliable way to know.

What finish suits an old slab

• Minimal exposure, a light scatter of stone, is the most forgiving choice. It takes off the least and hides more of the slab's history.
• Honed and sealed, a matte finish, is kinder to an uneven slab than high gloss, which shows every wave.
• Grind and seal, where the sheen comes from a coating, suits slabs that are too patched or too weak to polish.
• Full stone exposure on an old slab is a gamble. The stone is wherever it settled decades ago.

What changes the price

Removing glue, coatings and screed is extra grinding and is quoted separately. So are crack repairs and patching. We show you the floor after the first pass, before going further, so the plan can change while it still can.

Be ready for character

An old slab will never look like a new one poured for polishing. Patches, old wall lines and colour shifts are part of what you get. Many people like that history in the floor. If you need a uniform look, a new topping slab or a coating may suit you better, and we will say so.