Concrete Cleaning Cardiff

Why concrete stains so easily

Unsealed concrete looks solid and behaves like a sponge. The surface is full of open capillaries, so oil, grease, chewing gum, chemical spills, tyre marking and mould soak in rather than sitting on top. In Cardiff the bigger culprit is usually biological. A shaded, north-facing yard behind a terrace in Roath or Canton grows a black and green film within two winters, and that film holds water against the slab, which feeds more growth the following year.

That depth of contamination is why concrete defeats most people who try it themselves. A hire shop washer running 100 to 130 bar at around 8 litres a minute lifts the loose dirt and leaves the ingrained staining exactly where it was. Flow matters as much as pressure. Professional machines move far more water, and it is volume, not the bar figure printed on the box, that carries broken-down dirt out of the pores and off the slab.

We work with hot water on most concrete. Heat softens oil and fat so it releases from the pores instead of being driven deeper, and it kills surface growth as it passes. It reduces how much chemical a job needs without replacing it. Oil still wants a degreaser, rust still wants an acid based remover, and heavy algae still wants a biocide to kill what the water only knocks off. We use the mildest product that will do the job, dilute it properly and rinse it out.

Concrete Cleaning expertise across Cardiff and South Wales

• Concrete paths, side passages and rear lanes, including the shaded strip down the side of a terrace that never sees sun.
• Steps, thresholds and ramps, where the nosings and the back of each tread hold the worst of the growth.
• Garage floors, including power-floated slabs carrying years of oil drip and tyre marking.
• Yards, hardstanding and parking bays behind houses, flats, shops and workshops.
• Exposed aggregate, where the pebbles sit proud of a thin cement matrix.
• Imprinted concrete drives, the pattern-stamped surfaces laid all over Cardiff in the 2000s.
• Concrete driveways, aprons, dropped kerb crossings and bin stores.
• Factory floors, loading bays and commercial hardstanding, cleaned outside your trading hours.

Imprinted concrete and exposed aggregate need a lighter touch

Imprinted concrete is not solid colour all the way through. The colour sits in the top few millimetres, under a sealer that usually needs redoing every three to five years and starts looking patchy and grey well before that. Hit it with a turbo nozzle held close and you strip the colour off in arcs that cannot be put back. We clean it with a rotary head at reduced pressure to lift the dead sealer, the algae and the joint growth, then recommend a fresh seal to bring the colour back up.

Exposed aggregate fails the opposite way. The stones are held by a thin cement matrix, and too much pressure in one place washes that matrix out and drops the pebbles, leaving a pitted patch that only spreads. Constant movement and a fixed distance are the whole job here. If your aggregate is already shedding stones, we will tell you, because cleaning shows that up rather than hides it.

Rotary cleaning for an even finish with no lance stripes

Most of the bad concrete cleaning you see around Cardiff was done with a lance on its own. A lance concentrates everything into a narrow band, so the finish depends on how steady the operator's arm was. You get zebra striping: clean arcs, dirty arcs, and a slab that reads worse than before because now the dirt has a pattern.

A rotary surface cleaner solves that mechanically. Jets spin under a shrouded head that rides at a set height, so every square metre gets the same distance, angle and dwell time. The shroud also contains the splash, which matters in a yard hemmed in by walls, windows and a neighbour's washing. The lance comes out only where the rotary cannot reach: edges, kerb lines, step nosings, corners and gullies.

Oil, rust and paint stains

Oil is not a surface mark on concrete. It has wicked down into the pores and has to be drawn back up. We apply a degreaser, let it dwell until it emulsifies the oil, then flush it out with hot water. Recent drips normally come out completely. A patch that has been feeding into a garage floor for ten years will lighten a long way and may still leave a shadow, and we would rather say that at the quote than afterwards.

Rust behaves differently again. It comes off garden furniture feet, wheelie bin frames, fertiliser granules or reinforcement sitting too close to the surface, and blasting at it just erodes the concrete around the stain while the orange stays put. It needs an oxalic acid based remover, given time to work and then rinsed off thoroughly. Paint is judged case by case. Emulsion often lifts with heat and a rotary pass, while a two-pack floor paint usually needs a stripper and a second visit.

Anti-slip is the part people forget

A clean slab is normally a safer slab. The slippery layer on a Cardiff path or yard is almost always biofilm, and taking it off gives back the grip the concrete had when it was laid. Two exceptions are worth knowing about.

The first is a power-floated garage or workshop floor. That finish is deliberately smooth, and once it is clean and wet it can be genuinely slick. If you want it sealed, ask for an anti-slip additive in the coat rather than a straight gloss.

The second is steps and slopes. Sealer on a step nosing or a driveway ramp can cut grip in the rain, so we either leave those areas unsealed or use a grit-loaded finish. Tell us if anyone in the house is unsteady on their feet and we will treat the steps accordingly.

A considered concrete cleaning process, start to finish

1. Quote. We look at the slab in person wherever we can. Area in square metres, surface type, stain history and water access all move the price. Quotes are free.
2. Set up and protect. We move or cover what needs it, tape off airbricks where splash could get in, check the gullies are running and keep wash water off planted beds.
3. Pre-treat the stains. Degreaser on oil, rust remover on rust, biocide on heavy algae and lichen. Each is given time to work instead of being rinsed straight back off.
4. Rotary clean. The surface cleaner goes on in overlapping passes at a set walking speed, hot where the job needs it. It is deliberately the slowest part of the day.
5. Detail and rinse. Lance work around edges, steps, kerbs and gullies, then the whole area is rinsed and the slurry flushed to a drain rather than left to dry into a grey film.
6. Walk it, and seal if you want it. We go over the finished surface with you while it is still damp, so you see the true colour. Sealing is a separate visit once the slab has dried right through, at least 48 hours later and longer after a wet week.

How long a clean concrete surface stays clean

On an open, sunny drive in somewhere like Lisvane or Radyr, two years is realistic. On a shaded yard behind a Grangetown or Splott terrace, with a north-facing wall and a gutter that drips, twelve months is nearer the mark. Sunlight and drainage decide it. Clearing your gutters and cutting back whatever overhangs the slab buys more time than any product will. A breathable sealer stretches the interval further and makes the next clean quicker, because the dirt then sits on the sealer instead of down in the concrete.

Concrete cleaning in Cardiff and across South Wales

We cover the whole of Cardiff, including Roath, Penylan, Cyncoed, Lisvane, Llanishen, Whitchurch, Rhiwbina, Radyr, Llandaff, Canton, Pontcanna, Grangetown, Splott, Rumney, Llanrumney and Cathays, and we work out across South Wales to Barry, Newport and beyond. Concrete is often booked alongside driveway or patio cleaning, or with gutter cleaning, since a leaking gutter is usually what put the green stripe down the path in the first place.

Ready when you are: arrange your concrete cleaning quote

We have been cleaning exterior surfaces around Cardiff since 2019, and our Google rating is 5.0 from five reviews. Call or text 07576 128903, or email Liamdunn2406@outlook.com with a photo and a rough size and we will come back with a price. We are based in Cardiff and answer seven days a week, 7:00 to 21:30. If a slab is past saving we will say so rather than take the job.