How do you clean block paving?

Block paving cleans up well, but the commonest mistake — aggressive pressure washing — strips the joints and damages the surface. Work from gentle to strong.

Routine cleaning first

Most block paving stays presentable with simple, regular care rather than occasional heavy cleaning. Sweeping removes the grit, leaves and organic debris that feed moss and weeds, so doing it regularly prevents a lot of build-up. Pulling or treating weeds as they appear stops them establishing in the joints. For general grime, a wash with warm water, a little washing-up liquid or a mild paving detergent, and a stiff brush lifts surface dirt without any risk to the surface or joints. This low-effort routine, done a few times a year, keeps most drives and patios looking tidy and reduces the need for the more aggressive methods that can do harm.

Moss, algae and stains

For green moss and algae — common on shaded, damp UK paving — a dedicated paving cleaner or biocidal (algae and moss) treatment is more effective and gentler than blasting. These are brushed or sprayed on, left to work, then rinsed; they kill the growth and slow its return. Different stains call for different approaches:

• Oil and grease: act fast. Cover fresh spills with an absorbent (cat litter, sand) to soak up the oil, then treat the stain with a paving degreaser before it penetrates the porous block. Old, soaked-in oil is much harder to shift.
• Rust (from metal furniture or fertiliser): needs a specific rust remover suitable for paving; general cleaners will not touch it.
• Tyre marks and rubber: a degreaser and stiff brush, repeated as needed.
• Efflorescence (white salt bloom on new blocks): usually weathers off naturally over time, or can be treated with a proprietary efflorescence remover — avoid harsh acids that can etch the blocks.

As a rule, avoid neat bleach and strong acids: they can discolour or damage concrete blocks, harm nearby planting, and run off into drains.

Pressure washing without wrecking the joints

A pressure washer is the tool people reach for, and it can restore a tired-looking drive — but it is also the commonest way to damage block paving. The risk is twofold. First, the jet readily blasts the kiln-dried sand out of the joints; once the joints are empty, the blocks lose their interlock and weeds and ants move in, so a vigorous clean can leave the paving in worse shape than before. Second, holding the lance too close or using a narrow, high-pressure nozzle can erode and pit the surface of the blocks, prematurely ageing them and creating a rougher surface that traps dirt faster afterwards.

If you do pressure wash, do it carefully. Use a lower pressure setting and a wider fan nozzle rather than a pin-point jet; keep the lance at a shallow angle and a sensible distance from the surface; and work methodically along the joints rather than straight down into them, so you are lifting dirt off the block faces, not excavating the sand. Accept that some joint sand will inevitably come out. The crucial final step — whatever cleaning method you used — is to let the paving dry, then re-sand the joints with fresh kiln-dried sand, brushing it in and vibrating or settling it down so the joints are full again. Skipping this leaves the paving vulnerable, which is why so many people find weeds explode in the season after a power-wash. For heavily soiled or large areas, a careful clean with the right chemical treatment and a stiff brush often gives a better, longer-lasting result than reaching straight for maximum pressure.

A simple cleaning routine through the year

Block paving stays at its best with a light, seasonal rhythm rather than one big annual battle, and a simple routine keeps the harsher methods unnecessary. Through spring and summer, sweep regularly to clear grit, dust and debris, deal with weeds in the joints as they appear, and give the surface an occasional wash with warm water, a mild paving detergent and a stiff brush. This is enough to keep most drives and patios looking tidy. In autumn, the priority is clearing fallen leaves promptly — left to lie and rot, they stain the blocks with tannins and feed moss, so regular sweeping during leaf-fall saves a lot of cleaning later. Heading into and through winter, shaded, damp paving is prone to green algae and moss, so a biocidal paving treatment applied in autumn or early winter slows that growth and keeps surfaces less slippery in the cold, wet months.

A few habits make the routine more effective. Act on spills quickly — fresh oil, fuel or food lifted before it soaks into the porous block is far easier than a set-in stain. Keep the joints full of kiln-dried sand, topping them up after any wash, because full joints shed water and resist weeds and so reduce the cleaning needed in the first place. Reach for the gentlest method that works, escalating only when needed: sweep, then wash, then a targeted treatment for moss or stains, and only then careful pressure washing. And avoid harsh chemistry — neat bleach, strong acids and salt can discolour blocks, harm nearby planting and run off into drains. Kept to this light-touch routine, block paving rarely needs the aggressive, joint-stripping cleans that cause as many problems as they solve, and a quick wash and re-sand once or twice a year keeps it looking cared-for for decades. The pattern worth remembering is that cleaning and maintenance are linked: the same full joints and regular sweeping that keep weeds and moss at bay also keep the surface clean, so good routine care steadily reduces how much active cleaning the paving ever needs. Time spent on prevention is repaid in far less time spent scrubbing, blasting and repairing later. It is also worth matching the effort to the surface: a shaded, north-facing patio under trees will green over faster and need treating more often than an open, sunny drive, so let the paving's own conditions set how frequently you sweep, wash and treat rather than following a fixed calendar.

Frequently asked questions

Sources & further reading

• Pavingexpert — cleaning and maintaining paving
• Marshalls — how to clean block paving
• HomeOwners Alliance — driveway maintenance advice

Figures on this page are typical UK ranges drawn from published sources and depend on your specific site. They are guidance, not a quotation.