Polished concrete is a trade where the finish reveals every shortcut for the next 20 years. Choose the wrong installer and you'll see swirl marks, dull patches and premature wear — usually just after the warranty runs out. Here's what to ask before you hire, from a Sunshine Coast crew that does this every day.
1. Local coastal-slab experience
Sunshine Coast slabs behave differently. Humidity keeps moisture rising through concrete for months longer than an inland pour, and salt air introduces contaminants you can't see. An installer who's only worked in Brisbane or inland regions may miss it.
Ask how many coastal jobs they've done and how they moisture-test before quoting.
2. Their full grit sequence
A proper mechanical polish moves through 30 → 80 → 200 → 400 → 800 → 1500 → 3000 grit. Cheaper installers skip grits (usually 200 or 400) to save a day. The floor looks fine for six months, then dulls unevenly.
Red flag: any installer who won't tell you their exact grit sequence.
3. What densifier they use
Lithium silicate is the modern standard — it reacts inside the surface, hardens the slab and helps the polish take a deeper sheen. Sodium densifiers are older, cheaper and can leave residue. Ask which one, and ask why.
4. A real sample on your slab
Aggregate exposure, sheen level and tone are all decisions that should be made on your actual slab in your actual light — not from an Instagram post. A good installer will grind a small test patch or show you finished floors nearby before you commit.
5. A quote you can actually read
- Line-itemed square metres, not a lump sum
- Named grit sequence and densifier product
- Crack chase and joint fill approach
- What sealer (if any) sits on top
- Clean-up, mobilisation and site protection included or excluded
6. QBCC licence and insurance
Any concrete polishing job over the QBCC threshold in Queensland needs a licensed contractor. Ask for the licence number and check it on the QBCC register. Public liability insurance should be $10M+.
7. Warranty in writing
A proper warranty covers the polish and the seal, spells out what's included, and lasts more than 12 months. Verbal warranties don't exist.
8. Recent local reviews with photos
Look for Google reviews with photos on the Sunshine Coast — not stock photos, not Brisbane jobs from 2019. If the reviews are all five stars with no photos and generic wording, be careful.
9. They pick up the phone
This trade lives or dies on communication — moisture readings, sheen decisions, aggregate exposure, timing around trades. If they're hard to reach at the quote stage, they'll be worse once your slab is torn up.
Ready to talk about your slab?
A local Sunshine Coast crew, specialist polished-concrete finishers, and a written quote after every site visit.
Frequently asked
- How do I check a QBCC licence? +
- Search the licence number on the QBCC's online register at qbcc.qld.gov.au — it takes about 30 seconds and shows current status plus any complaints.
- Do all polished concrete installers use the same machines? +
- No. There's a big spread between commercial-grade planetary grinders and small propane burnishers. Ask what machines and diamond tooling they'll bring to your job.
