How To Clean Block Paving

Knowing how to clean block paving properly is the difference between a driveway that looks smart for twenty years and one that turns green, weedy and tired within five. Block paving is one of the most popular hard surfaces in the UK, and for good reason. It is hard wearing, easy to repair and it copes well with our unpredictable weather. But it does need regular attention. Left alone, the sand joints wash out, moss colonises the surface and oil stains bed in permanently.

This article draws on hands on trade experience to walk you through cleaning block paving the right way. I will cover the tools, the correct method, the products worth using, realistic costs, and the mistakes that damage the surface rather than restore it.

Why Block Paving Needs Regular Cleaning

Block paving is made from individual concrete or clay units laid over a compacted sub base and a bedding layer of sharp sand. The joints between the blocks are filled with kiln dried sand. That sand is doing a structural job. It locks the blocks together and stops them shifting under load.

Over time, three things happen. Rain and foot traffic wash the jointing sand out. Airborne spores settle in the damp gaps and grow into moss, algae and weeds. And oil, tyre marks and organic debris stain the surface. Each of these problems compounds the others.

Cleaning is not just cosmetic. When you keep the surface clear and the joints topped up, you protect the whole structure. A neglected driveway that loses its jointing sand starts to rock, dip and pool water, which then accelerates the decay.

When Should You Clean Block Paving?

For most UK homes, a proper clean once a year is enough, ideally in late spring or early autumn. Spring clears the winter build up of moss and algae. Autumn clears leaf debris before it rots into the joints over winter.

Between these deep cleans, a quick brush every few weeks and prompt removal of leaves and spills keeps problems from taking hold. Shady, north facing driveways under trees will need more frequent attention because they stay damp and encourage moss growth.

Avoid pressure washing in freezing conditions. Water forced into the joints and blocks can freeze, expand and cause spalling on the surface of concrete blocks.

Tools And Materials You Will Need

You do not need a huge kit to clean block paving well. Here is a realistic list.

• A stiff bristled outdoor broom or a wire brush for stubborn joints
• A pressure washer, ideally with a rotating patio cleaner attachment
• A garden hose with a decent nozzle
• Block paving cleaner or a general purpose patio cleaner
• A dedicated moss and algae treatment or biocide
• Kiln dried jointing sand for refilling
• A plastic weeding knife or joint scraper
• Protective gloves, safety goggles and sturdy footwear
• A watering can or garden sprayer for applying treatments

A patio cleaner attachment for your pressure washer is a worthwhile investment. It has two enclosed rotating jets that clean evenly, avoid the harsh striping you get from a single lance, and dramatically reduce splashback onto walls and windows.

How To Clean Block Paving Step By Step

Follow this sequence and you will get a professional result. Rushing or skipping steps is where most DIY jobs go wrong.

Step 1: Clear the surface

Sweep the whole area thoroughly to remove loose grit, leaves and debris. Move any vehicles, pots and furniture off the driveway. You want unobstructed access to every block.

Step 2: Remove weeds and moss

Pull or scrape out visible weeds and dig moss out of the joints with your weeding knife. Getting the roots out now saves you scrubbing them off dead later. For widespread growth, apply a biocidal moss and algae killer and leave it to work according to the product instructions, often 24 to 48 hours.

Step 3: Apply cleaning solution

Wet the surface, then apply your block paving cleaner. Work in manageable sections. Let the product dwell for the time stated on the label, usually 10 to 15 minutes, so it can break down grime and organic staining. Do not let it dry out on the surface.

Step 4: Agitate stubborn areas

Scrub heavily soiled patches, oil marks and stained joints with a stiff brush. This mechanical action lifts what the chemicals have loosened and gives a far better finish than jetting alone.

Step 5: Pressure wash

Work the pressure washer methodically across the surface, keeping the nozzle at a consistent height and angle. Hold a single lance around 30cm from the blocks. Too close, or held at a steep angle, and you will blast out the jointing sand and etch the block face. Work in straight, overlapping passes so you do not miss strips or create uneven cleaning.

Step 6: Rinse and let dry

Rinse away all the dislodged dirt and spent cleaning product. Then leave the paving to dry completely. This is essential before the next step. Dry blocks are usually needed for a full day of dry weather, so plan around the forecast.

Step 7: Re-sand the joints

This is the step most people skip, and it matters most. Pressure washing removes jointing sand, so you must replace it. Pour kiln dried sand over the dry surface and sweep it into the joints with a broom, working in different directions until every gap is filled to just below the chamfer of the blocks. Compact it gently by walking over the area or using a vibrating plate on larger driveways, then top up any joints that have settled.

Kiln dried sand must go down bone dry. If it is damp it clumps and will not flow into the joints. Buy it in sealed bags and keep it dry until you use it.

Dealing With Specific Stains

Different stains need different approaches. Generic cleaning will not shift everything.

Oil and grease

Fresh oil should be soaked up immediately with cat litter, sand or a proprietary absorbent granule. For set in stains, use a dedicated oil and grease remover for block paving. Domestic degreasers can help but rarely match the specialist products. Deep, old stains sometimes never fully disappear and may need the affected blocks lifting and turning or replacing.

Rust

Rust from metal furniture, fertiliser or car parts needs an oxalic or phosphoric acid based rust remover. Never use a wire brush on rust as it can spread iron particles and make it worse.

Moss and algae

A biocide is far more effective than physical removal alone because it kills the spores. Regular application, once or twice a year, keeps regrowth slow.

Tyre marks and rubber

These respond to warm water, a degreaser and firm scrubbing. Turning tight in the same spot repeatedly is the usual cause, so vary your parking where you can.

Cost Breakdown: DIY Versus Professional Cleaning

Cleaning block paving yourself is affordable if you already own or hire the kit. Hiring a professional saves time and gives a reliable result, especially on large or badly neglected drives. Here is a realistic UK cost comparison for 2026.

Option	Typical Cost	What It Covers
DIY, own equipment	£20 to £60	Cleaner, biocide and a bag or two of kiln dried sand
DIY, hiring a pressure washer	£40 to £90	Daily hire plus consumables
Professional clean, small drive	£150 to £300	Clean, weed treatment and re-sanding of a single car drive
Professional clean, large drive	£300 to £600	Clean and re-sand of a double or larger driveway
Clean plus sealing	£400 to £900	Full clean, re-sand and application of a protective sealant

Prices vary by region and by the condition of the paving. Heavily moss covered or oil stained drives take longer and cost more. Always get more than one quote and confirm whether re-sanding is included, because a cheap clean that leaves empty joints is a false economy.

If your paving is beyond restoration and you are weighing up a replacement, our article on How Much Does It Cost to Install a New Driveway in the UK in 2026? Block Paving vs Resin vs Tarmac Prices Compared sets out realistic figures for every option.

Should You Seal Block Paving After Cleaning?

Sealing is optional but increasingly popular. A quality block paving sealer stabilises the jointing sand, reduces weed and moss growth, makes future cleaning easier and can enhance the colour of the blocks.

Sealers fall broadly into two types. Water based sealers give a natural, matt finish. Solvent based sealers tend to give a wet look or gloss and deeper colour enhancement. Both need applying to clean, completely dry paving, ideally in mild, settled weather.

Expect a sealer to last three to five years before it needs reapplying. It is not a one off job. Never seal damp paving or paving that still has active moss, because you will trap the problem underneath.

Common Mistakes To Avoid

Most block paving damage I am called out to fix is self inflicted. Here are the errors that cause the most trouble.

• Pressure washing too close. Holding the lance right against the blocks strips the surface and blasts out all the jointing sand. Keep your distance and let the cleaner do the work.
• Skipping the re-sand. This is the single biggest mistake. Empty joints let blocks shift, water pool and weeds return faster. Always re-sand after cleaning.
• Using the wrong sand. Building sand or damp sand will not flow into joints. Only kiln dried jointing sand does the job.
• Cleaning in frost. Trapped water freezes, expands and spalls the block faces. Wait for milder, drier spells.
• Using strong acid or bleach carelessly. Household bleach can discolour blocks and kill nearby plants. Strong acids can etch the surface. Use products designed for paving and follow the dilution rates.
• Ignoring drainage. Water that will not drain points to a blocked channel or a failing sub base, and cleaning alone will not fix it.
• Letting run off pollute drains. Oily or chemical laden run off should not enter surface water drains. Contain and dispose of it responsibly.

Drainage, Regulations And Run Off

If you are cleaning an existing driveway, you do not need planning permission. But it is worth understanding the rules that apply if you ever alter or replace it.

Since 2008, homeowners in England and Wales have needed planning permission to lay an impermeable driveway over five square metres that drains onto the road, under permitted development rules. Permeable surfaces, or those that drain to a lawn or soakaway, are generally exempt. The government guidance on this is set out clearly on the GOV.UK planning permission pages.

If you want to understand how drainage friendly paving works and where it is required, our article on Permeable Paving Explained for Homeowners Drainage Rules Materials and Best Uses explains the materials and rules in detail.

On the environmental side, the run off from cleaning chemicals and oil should never be washed into a road gully or surface water drain. Guidance from the Environment Agency is clear that pollutants entering surface water drains can end up directly in rivers. Use biodegradable products where possible and sweep, rather than flush, contaminated residue for proper disposal.

Cleaning Checklist

Use this quick checklist before, during and after the job.

• Check the weather forecast for at least two dry days
• Clear vehicles, pots and furniture off the paving
• Sweep the whole surface
• Remove weeds and dig out moss
• Apply biocide and allow it to work
• Apply block paving cleaner and let it dwell
• Scrub stubborn stains by hand
• Pressure wash in even, overlapping passes
• Rinse thoroughly and let the paving dry completely
• Re-sand the joints with dry kiln dried sand
• Compact and top up the joints
• Consider sealing once fully dry

Maintaining Block Paving Between Cleans

The less you let build up, the easier each annual clean becomes. Sweep regularly to stop debris rotting into the joints. Clear leaves promptly in autumn. Deal with spills straight away rather than letting them soak in.

Keep an eye on the jointing sand and top it up if you notice gaps opening. A quick biocide spray once or twice a year keeps moss and algae at bay far more effectively than a big scrub once problems have taken hold.

While you are outside caring for your driveway, it pays to keep the rest of your property in check too. Our guide with Expert Tips on Maintaining Your Roof and Gutters is a useful companion for seasonal home upkeep.

If your paving problems are more about failing joints and stubborn weeds on a patio rather than a driveway, the principles overlap with our article on How to Repoint Patio Slabs and Stop Weeds Coming Back.

How Long Does Cleaning Block Paving Take?

For a typical single car driveway of around 30 to 40 square metres, allow half a day for cleaning and re-sanding if you are working alone. A double driveway can easily fill a full day, particularly if the moss and staining are heavy.

Sealing, if you choose to do it, adds another half day plus drying time, and must happen on a separate dry day once the paving is fully dry. Do not try to compress the whole job into one afternoon after rain. Patience with drying times is what separates a lasting result from a disappointing one.

Frequently Asked Questions

Can I clean block paving without a pressure washer?

Yes, though it takes more effort. A stiff brush, a good block paving cleaner and a biocide will clean the surface effectively by hand. This gentler method is actually kinder to the jointing sand and the block faces. It suits smaller areas and lightly soiled paving well. For large or heavily neglected driveways, a pressure washer saves considerable time, but the hand method remains a valid choice, especially where you want to avoid disturbing the joints.

Will pressure washing damage my block paving?

It can if done incorrectly. The main risks are stripping out jointing sand, etching the surface of the blocks and, in cold weather, causing spalling from trapped water freezing. Keep the lance at least 30cm from the surface, use a patio cleaner attachment where possible, avoid steep angles, and never wash in frosty conditions. Provided you re-sand the joints afterwards, sensible pressure washing does no lasting harm.

How often should I re-sand the joints?

Re-sand every time you pressure wash, because the process removes sand from the joints. Beyond that, inspect the joints once or twice a year and top up any that have washed out or settled. Well maintained joints keep the blocks locked together, prevent weeds and stop water pooling, so this small task protects the entire driveway structure.

What is the best product for killing moss on block paving?

A dedicated biocidal path and patio cleaner is the most effective option, because it kills the spores rather than just removing surface growth. Products containing benzalkonium chloride are widely used and effective. Apply according to the instructions, allow the stated dwell time, and repeat once or twice a year. Avoid household bleach, which can discolour blocks and harm surrounding plants.

Should I clean block paving before or after sealing?

Always clean first and seal afterwards. Sealing traps whatever is on the surface, so any dirt, moss or oil left in place will be locked in permanently. Clean the paving thoroughly, re-sand the joints, allow everything to dry completely over at least a full dry day, then apply the sealer in mild, settled weather. Sealing damp or dirty paving is one of the most common and costly mistakes.

Final Thoughts

Cleaning block paving is a straightforward job that rewards a methodical approach. Clear the surface, treat the moss, apply a proper cleaner, wash carefully and, above all, re-sand the joints. Get those steps right and your driveway will look smart and perform well for decades. Cut corners, and you will be back out there far sooner than you would like.

If the paving has sunk, lost large areas of jointing sand or shows signs of a failing sub base, that goes beyond cleaning and needs a professional assessment. The same applies if oil staining runs deep or drainage has stopped working.

If you would rather hand the work to an expert, or you need repairs alongside a clean, you can post a job on BookaBuilderUK and get free quotes from vetted local tradespeople in your area.