DIY GUIDE · CLEANING · CHECKED OCTOBER 2026
How to clean a patio yourself
A dry weekend day. £20–£70 in cleaner, a stiff brush and jointing sand.
Know the stone, weed and pre-treat, wash at the right pressure, refill the joints, keep it clean.
- Every step, start to finish
- Checked October 2026 — sources at the end
- Honest about when to call a pro
FIRST, THE HONEST ANSWER
Do it yourself, or get a cleaner?
Do it yourself if…
- You know what the slabs are — concrete, porcelain, sandstone, limestone, slate or granite — or can find out from the supplier
- The slabs are firmly bedded; none rock or sound hollow when you step on them
- You have a dry forecast for the day and the day after, so joints can be refilled on a dry surface
- Run-off can go to a lawn or a soakaway, not straight into a pond or watercourse
Get a pro if…
- Slabs are loose, cracked, sunken or rocking, or the pointing is crumbling — that is a repair and relay
- The patio is old, delicate natural stone or reclaimed York stone you do not want to risk
- There are deep oil or rust stains, or paint and cement splashes
- You want the patio cleaned and then sealed, which needs the stone completely dry and the right sealer
Safety first
- Use any mains-powered washer or tool outdoors through a 30 mA (or more sensitive) RCD, as HSE advises for wet or damp locations, and keep the plug and extension connection off the wet ground.
- Wear eye protection and closed shoes when pressure washing or using a wire brush; grit and moss fly back at your face.
- Never point a pressure washer jet at people, animals, plants or your own feet.
- Never mix patio cleaners, and keep bleach-based products off lawns, beds and away from ponds and drains.
- Wet algae and moss are very slippery. Work backwards off the area you have cleaned and keep children off it until it is dry.
- Wear gloves with patio cleaners and follow the label on dilution, contact time and the weather it can be used in.
| MATERIAL | COVERAGE | FOR THIS JOB |
|---|---|---|
| Patio cleaner or algae remover | Diluted as the label says; 2–5 minutes contact for one type | Per the label's coverage |
| Black spot remover (if needed) | Works over days or weeks on lichen | Only on the spotted slabs |
| Kiln-dried jointing sand | For sand-filled joints, brushed in dry | One bag for a small patio |
How much cleaner and sand
Cleaner = patio area in m² ÷ the coverage per litre of diluted cleaner on the label. A 5 × 4 m patio is 20 m²; at 10 m² per diluted litre that is 2 litres of mixed solution. For sand, measure the joint length: 20 m² of 600 mm slabs has about 70 m of joints, roughly one large bag of kiln-dried sand.
Mix only what you will use in one go. Diluted cleaners do not keep.
Concrete flags are uniform with a slightly sandy surface. Porcelain is smooth, thin and perfectly regular. Sandstone is layered and often riven, in buffs and greys; limestone is smoother and paler and fizzes with vinegar; slate is dark and splits in sheets; granite is very hard and speckled. If you have the supplier's name, look up its care advice.
A pressure washer can deliver up to 180 bar, and one washer maker says hard stones such as granite and basalt can take high pressure while softer natural stones should get only low pressure. A paving maker suggests 130 to 150 bar for patios and paths but low pressure for natural stone, sandstone and porcelain, which can erode. A rotary surface cleaner attachment spreads the force and keeps the nozzle a fixed distance from the slab.
Concentrated patio cleaners lift general grime and green algae; one washer maker gives them about 2 to 5 minutes to act before rinsing. Black spot removers work more slowly on lichen and often need repeat applications over weeks. Read the label for the stones it is safe on — acidic products etch limestone and marble.
One washer maker describes a bicarbonate of soda wash — between one and five tablespoons stirred into 10 litres, depending on the dirt — left for 15 to 20 minutes and scrubbed, or soap in warm water. Vinegar is acidic and should never go on limestone, marble or most sandstones. Test any of them on an offcut or a hidden slab first.
A stiff synthetic yard brush for scrubbing, a narrow joint brush or weeding knife for the gaps, and a wire brush only on hard stone and concrete. Wire bristles leave rust marks and scratches on soft stone and porcelain.
Sand-filled joints lose sand in any wet clean. Kiln-dried sand brushes back into dry joints. Mortar or resin joints need checking for cracks rather than refilling with sand.
THE PART THAT DECIDES THE FINISH
Preparing the patio — by what it is made of
Find your paving below and do its prep before the cleaner or the hose comes out.
Concrete flags and slabs
The most common patio.
- Concrete is absorbent, so the washer maker advises cleaning it with a small amount of water
- Treat oil and grease marks first with a concrete or stone cleaner, as soon as you can
- Check older flags for a crumbly surface — they get only a low-pressure rinse and a brush
- Clear weeds from the joints before washing
Sandstone and limestone
Natural stone, often riven or tumbled.
- Do not use acid cleaners or vinegar on limestone; test any product on sandstone
- Plan to clean by hand with a pH-neutral cleaner and a stiff brush, or at low pressure only
- Soak green areas with an algae cleaner and let it work rather than blasting it
- Expect natural colour variation; black lichen spots need a dedicated treatment and patience
Porcelain
Smooth, thin, uniform outdoor tiles.
- Use low pressure only, as the paving maker advises, or a brush and a cleaner
- Avoid wire brushes, which leave metal marks on the surface
- Check grout or jointing compound for cracks before washing
- Remove cement or grout haze with a cleaner made for porcelain, not general acid
Granite, basalt and slate
Very hard natural stone.
- Granite and basalt can take higher pressure, the washer maker says
- Slate is hard but layered — use moderate pressure and keep the jet off the edges
- Rinse thoroughly after any cleaner so the surface does not dull
- Check that slabs are firmly bedded before washing
Block paving areas round the patio
Small blocks with sand joints.
- Keep the jet angled across the surface, never down into the joints
- Plan on re-sanding before the area is used heavily again
- Pull weeds out by the root first
- Leave any sunken areas for a repair
Grease, rust, paint and cement stains
Spot problems on any stone.
- Blot or scrape off fresh spills at once — porous stone soaks them up
- Use a stain remover made for the stain and the stone, tested first
- Do not pressure wash a grease stain; it spreads it
- Rust and paint on natural stone are best left to a specialist
THE JOB
How to clean a patio, in order
Identify the stone and test
15 minWork out what your paving is from the section above. Test your cleaner and your method on one hidden slab or an offcut: apply, wait the label's time, scrub and rinse, then let it dry and look at it in daylight. Check also that every slab is firmly bedded — tap with a broom handle and listen for hollow sounds.
- Test on a dry day; wet stone hides marks
- Mark any rocking slab with chalk and avoid washing it
- Note where the patio drains to
Mistake to avoid: Skipping the test on natural stone. An etched or bleached slab is permanent.
Clear and sweep
20 minMove furniture, pots and the barbecue off. Sweep thoroughly with a stiff brush to remove leaves, soil and loose debris, working towards the edge. Cover nearby plants, a pond or a lawn edge with sheets if you are using a cleaner.
- Clear the drains and gullies so the water can get away
- Lift pot feet — the rings underneath are often the worst
- Close windows and doors near the patio
Mistake to avoid: Washing over loose debris. It turns into mud and is pushed into the joints.
Weed and rake out the joints
45 minRun a weeding knife or joint brush along every joint to pull out moss, weeds and loose sand. Pull weeds out by the root where you can. Collect it all for the garden waste.
- A narrow knife lifts moss out in strips
- Remove only loose sand, not firm jointing
- Note any joint where the mortar is crumbling
Mistake to avoid: Leaving weeds to be blasted out by the washer. The jet tears the joint apart to get at them.
Treat stains and algae
30 minTreat grease and oil marks with a stone or concrete cleaner applied straight to the mark. Dilute the patio or algae cleaner exactly as the label says and apply it evenly with a watering can or sprayer to the whole surface. Leave it for the contact time — one washer maker gives 2 to 5 minutes for its type. Do not let it dry on.
- Damp the slabs first if the label says so
- Work in sections in hot weather
- Keep cleaner off the lawn and beds
Mistake to avoid: Leaving a strong cleaner far longer than the label says. Some bleach the colour out of the stone unevenly.
Scrub
45 minScrub each section with a stiff brush, working in one direction and then across. Pay most attention to the shaded, green areas and to the slab edges. On soft natural stone this is the main cleaning step, so take your time with it.
- Change direction to get into the riven texture
- Synthetic bristles on soft stone and porcelain
- Scrub before the cleaner dries
Mistake to avoid: Using a wire brush on sandstone or porcelain. It scratches and leaves rust marks.
Rinse or pressure wash
1 hrOn soft stone and porcelain, rinse with a hose or a pressure washer at its lowest setting, from well back. On concrete, granite and hard stone, wash at moderate to high pressure with a rotary surface cleaner, or with the lance held at a shallow angle — the washer maker suggests keeping the rotating jet about 15 cm from the ground and moving it slowly. Work with the fall so dirty water runs onto uncleaned areas, and keep the jet off the joints.
- Overlap each pass to avoid stripes
- Never hold the jet still on one spot
- Angle across the joints, not into them
Mistake to avoid: Holding the nozzle close to a soft slab. It etches tracks into the surface that are visible forever.
Inspect and repeat where needed
20 minLet the patio dry for an hour and look at it from a standing height in daylight. Re-treat any green or dark patches. Black lichen spots usually need a dedicated remover and several weeks; do not try to blast them off.
- Dry patio shows the true result
- Mark patches with chalk for a second treatment
- Black spots fade slowly — patience, not pressure
Mistake to avoid: Blasting lichen spots at close range. The stone around them erodes and the spots remain.
Let it dry completely
OvernightLeave the patio to dry thoroughly before refilling joints. Kiln-dried sand will not run into damp joints and clumps on a wet surface.
- A breezy dry day speeds it up
- Keep people and pets off while it is slippery
- Check the forecast for the joint-filling day
Mistake to avoid: Sanding on a damp patio. The sand sticks to the surface and stains it, and the joints stay half empty.
Refill the joints
45 minPour kiln-dried sand over a dry patio and brush it diagonally across the joints with a soft broom until they are full. Sweep the excess off the slabs. For block paving round the patio, the paving maker says the sand must go back before heavy traffic, because it binds the blocks together.
- Brush diagonally so the sand drops into the joints
- Top up again after the first rain settles it
- Leave mortar joints alone — repair cracks with mortar, not sand
Mistake to avoid: Skipping the re-sanding. Weeds root into the empty joints within weeks and blocks start to move.
Protect and maintain
15 minSweep the patio weekly in autumn so leaves do not sit and stain. Apply a diluted algae treatment once or twice a year on shaded patios. If the stone was sealed before, reseal with a product suitable for it once it is fully dry, following its label.
- Leaves left in piles stain light stone
- Lift pots on feet so water does not sit under them
- Reseal only a clean, completely dry patio
Mistake to avoid: Sealing over a damp or dirty patio. Moisture is trapped under the sealer and it clouds or flakes.
The mistakes that damage patios
- High pressure on sandstone, limestone, porcelain or old concrete
- Aiming the jet into the joints, then not re-sanding
- Acid cleaners or vinegar on limestone and marble
- Mixing cleaners, or letting bleach products run onto the lawn and into ponds
Stop here and get a patio cleaner
- Slabs are loose, cracked, sunken or rocking, or the pointing is breaking up
- The stone is delicate, reclaimed or valuable and you are not sure what it will take
- There are deep oil, rust, paint or cement stains
- You want it cleaned and professionally sealed
| WHAT YOU SEE | WHY, AND THE FIX |
|---|---|
| Stripes or swirl marks after pressure washing | The jet was held too close or passes did not overlap. Re-wash evenly with a rotary surface cleaner at a lower setting; marks etched into soft stone will weather in slowly. |
| Green comes back within weeks | Shade and damp. Apply an algae treatment once or twice a year and keep the surface swept of leaves. |
| Black spots will not shift | These are lichens. A dedicated black spot remover over several weeks works; pressure washing does not. |
| The slabs look patchy or bleached | A cleaner was too strong, left too long or uneven. Rinse well; mild patches usually even out with weathering. |
| The joints are empty and weeds are back | Sand was washed out and not replaced. Weed, let it dry and brush in kiln-dried sand. |
| A slab now rocks | The jet washed out bedding or jointing. Do not walk on it; it needs lifting and rebedding. |
| White salt marks on new slabs | Efflorescence from the stone or mortar. Brush it off dry; it usually stops on its own. Washing makes it reappear. |
| Oil stain has spread into a halo | It was washed rather than treated. Apply a degreaser or poultice made for the stone and give it time. |
WHAT YOU SAVE
What it costs to do it yourself
| Patio cleaner or algae remover | £11–£36.95 |
|---|---|
| Stiff patio brush or weed brush | £5.79–£14.99 |
| Kiln-dried jointing sand | £7.95–£17.99 |
| Plug-in RCD adaptor | £9.94–£21.82 |
| Total | £20–£70 |
| DIY total | £20–£70 |
Guide prices compiled by the Locufy team from published Irish and UK provider price lists and 2026/27 cost guides. Updated 2026.
If you own a pressure washer, the cleaner and sand are the only real costs. A professional clean often includes re-sanding and sometimes sealing.
RATHER NOT?
Patio cleaners near you, with prices shown
The ones who cover your area, nearest first, with one score from every review. No account needed to look.
Or post the job free and let them come to you.
Top up the sand after the first heavy rain, when it settles.
Weeds, moss and leaves go in your council's garden waste collection or to the household waste recycling centre. Leftover concentrated cleaner stays in its own container; unwanted cleaners go to the recycling centre's hazardous waste point, not down a drain.
Rinse brushes and the sprayer, and drain the pressure washer hose before winter frost.
Sweep in autumn, treat for algae once or twice a year, and do a full clean only when it is needed.
Cleaning a patio: questions people ask
Identify the stone, sweep and weed the joints, apply a suitable patio cleaner for the time on the label, scrub with a stiff brush, then rinse — at low pressure for soft stone and porcelain, higher for concrete and granite — and refill the joints when dry.
Concrete, granite and other hard stone, yes, ideally with a rotary surface cleaner. Sandstone, limestone and porcelain need low pressure only, as paving and washer makers advise, or a brush and cleaner instead.
They are lichens. Use a dedicated black spot remover and give it weeks rather than days; pressure washing removes the stone around them faster than the spots.
If the joints are sand, yes. Brush kiln-dried sand into the dry joints; empty joints let weeds back and let slabs or blocks move.
The Locufy UK price guide puts patio cleaning at £75–£400 per job, typically £150. Large areas, delicate stone and sealing push it up.
Many patio cleaners already contain it, so never add your own or mix products. Keep bleach-based cleaners off lawns, beds and away from ponds, and do not use them on stone the label excludes.
MORE GUIDES
More DIY guides
Sources — checked October 2026
- Kärcher — cleaning patio slabs: contact times, bicarbonate solution, pressure by stone
- Kärcher — how to clean pavers: distance, joints and wide joints
- Marshalls — how to pressure wash your patio, decking and driveway
- HSE — electrical safety FAQs: RCDs in wet or damp locations, 30 mA
- HSE — safe use of cleaning substances (CAIS22): never mix
- GOV.UK — dispose of garden waste
- B&Q — price check: patio cleaners, October 2026
- B&Q — price check: patio brushes, October 2026
- B&Q — price check: kiln-dried sand, October 2026
- B&Q — price check: RCD adaptors, October 2026