What Is the Best Thing to Clean Paving Slabs?
Table of Contents
What You'll Need Before You Start
The Best Approach to Clean Paving Slabs by Surface Type
Indian Sandstone and Natural Stone
Block Paving, Concrete and Porcelain
Biocidal Pretreatment for Patios: Why It Comes First
Black Spot Removal from Indian Sandstone
Block Paving Re-Sanding After Cleaning
Patio Repointing Services: When Cleaning Reveals Failed Joints
Common Mistakes to Avoid When Cleaning Paving
Frequently Asked Questions
Last Updated: September 26, 2026
What You'll Need Before You Start
The best thing to use to clean paving slabs is not one single product. It is the right method for your surface, applied in the right order. At SavingPaving, we have cleaned and restored driveways and patios across South Croydon and Bromley since 2001, and the honest answer is that technique matters more than any bottle on the shelf.
Get these basics ready before you begin:
A stiff broom and a soft brush
A pump sprayer for biocidal treatment
A suitable paving cleaner for your surface type
A pressure washer with a rotary surface cleaner, used with care
Kiln-dried jointing sand for block paving
Gloves, eye protection and old clothes
Most homeowners reach straight for the pressure washer. That is the first mistake.
Watch Out Blasting a patio at full pressure on a narrow jet can strip pointing, remove jointing sand and leave stripe marks. Once the surface is marked, correcting it may need more than cleaning.
The Best Approach to Clean Paving Slabs by Surface Type
Every paving surface responds differently, so match your method to the material. Cleaning a porcelain patio like a concrete one, or a sandstone patio like block paving, is how surfaces get damaged. Here is how the main types compare.
Surface | Best Cleaning Method | Key Risk | Jointing Approach |
Indian sandstone | Biocide first, then low-pressure clean | Stripping the surface face | Repoint or resin joint |
Natural stone | Gentle clean, suitable cleaner | Acid damage, scratching | Repoint where suitable |
Block paving | Clean, then re-sand joints | Losing jointing sand | Kiln-dried sand |
Concrete slabs | Standard clean, spot treat stains | Surface marking | Repoint where suitable |
Porcelain | Soft wash, mild cleaner | Harsh chemicals | Resin joint where suitable |
Crazy paving | Careful clean, assess joints | Loose pieces | Repoint or resin joint |
Indian Sandstone and Natural Stone
Indian sandstone and natural stone need a gentle hand. These surfaces are porous and can be marked by harsh chemicals or too much pressure.
Start with a biocidal treatment rather than the pressure washer. Let it work, then clean at low pressure. A common mistake is attacking black spot with brute force, which can pit the stone without removing the growth.
Block Paving, Concrete and Porcelain
Block paving, concrete and porcelain are tougher, but each has its own needs. Block paving needs its joints re-sanded after cleaning. Porcelain is dense and usually cleans easily, though it can be slippery when wet.
For all three, work in sections and rinse as you go. Never let cleaning solution dry on the surface.
Biocidal Pretreatment for Patios: Why It Comes First
Biocidal pretreatment for patios is the step most homeowners skip, and it is the one that decides how well the rest of the job goes. The treatment helps to break down moss, algae and lichen before any cleaning starts.
Why does order matter? If you clean first, you remove the growth but leave the spores behind. It returns quickly. A biocide applied first, with suitable dwell time, breaks the growth down so cleaning lifts it away.
At SavingPaving, we pretreat, allow the product time to work, then clean. It takes longer, but the finish can be more effective than cleaning alone.
Black Spot Removal from Indian Sandstone
Black spot removal from Indian sandstone is one of the most common jobs we are asked to do. Black spot is a lichen that colonises suitable stone. It is not caused by failed joints, and it may not shift with ordinary soap and water.
The right approach is a specialist treatment that targets the lichen, followed by cleaning once the growth has died back. Patience matters here. Trying to scrub it off in one go rarely works and can damage the stone.
Pro Tip Treat black spot in mild, damp conditions rather than hot sun. The treatment stays active on the surface for longer and works more thoroughly.
Block Paving Re-Sanding After Cleaning
Block paving re-sanding is essential after any deep clean. Cleaning lifts dirt from the joints, but it also washes out the jointing sand that keeps the blocks stable and tidy.
Once the paving and joints are suitably dry, we brush kiln-dried jointing sand into the joints and compact it. This is not the same as repointing. Block paving is re-sanded, not repointed with mortar.
Skipping this step may leave joints open, collecting debris and supporting weeds.
Patio Repointing Services: When Cleaning Reveals Failed Joints
Patio repointing services are often needed once cleaning exposes what was hidden. You may know this as "patio regrouting", but repointing or jointing is the correct term in the UK. Grout is generally associated with tiles, not paving.
Cleaning strips away dirt and old growth, and failed pointing becomes obvious. If joints are crumbling or missing, repointing restores them. For suitable stable paving, a two-part resin joint may be an option.
Watch Out Repointing does not fix loose or rocking slabs. If paving is moving, the bedding underneath needs assessing first. Jointing alone will not hold a slab that is not properly bedded.
Common Mistakes to Avoid When Cleaning Paving
Much of the paving damage we see can come from cleaning, rather than from dirt. Avoid these errors and your surfaces will last far better.
Using full pressure on a narrow jet, which strips joints and marks stone
Skipping biocidal pretreatment, so growth returns within weeks
Cleaning block paving and forgetting to re-sand the joints
Using harsh acids on sandstone or natural stone
Sealing before the paving is fully dry
Treating black spot as a joint problem when it is a surface growth
If your paving is loose, sunken or badly stained, a professional assessment is worth having. SavingPaving offers free site surveys and detailed quotations, so you know exactly what your patio needs before committing. Our uniformed, fully insured team works across South Croydon, Bromley and nearby areas such as Purley and West Wickham.
Cleaning paving slabs well comes down to method, not muscle. Use the right approach for your surface, pretreat before you clean, and repair joints or bedding where needed. If your driveway or patio needs more than a quick wash, SavingPaving can help. We offer professional cleaning, black spot removal, repointing, re-sanding, sealing and six-monthly maintenance, all with no hidden costs. Get started with SavingPaving and restore your paving to its former glory with a free site survey and detailed quotation.
Frequently Asked Questions
What is the safest way to clean natural stone paving?
Natural stone such as Indian sandstone is porous and can be marked by harsh acids or high-pressure washing. The safest approach is a professional clean using methods suited to the stone, often after a biocidal pretreatment to loosen organic growth. Cleaning pressure and any treatments should be chosen according to the paving and its condition. For black spot and lichen, a suitable specialist treatment applied with care works better than scrubbing, which can damage the surface.
Can I use household bleach to clean my patio slabs?
Household bleach is not a good choice for paving. It can discolour some stones, harm nearby plants and may not effectively address black spot or lichen. A biocidal pretreatment for patios, applied correctly, is more effective and can be used with care around planting. If you are unsure which product suits your paving, a free site survey can identify the surface and recommend the right approach.
Is it better to use a pressure washer or manual cleaning for paving slabs?
It depends on the surface and its condition. A pressure washer can strip jointing sand from block paving and mark some natural stone if used at the wrong pressure or angle. Manual cleaning with the right solutions is gentler but slower. Professional cleaning uses equipment and pressure settings matched to the paving, which reduces the risk of stripes or damage while still removing ingrained dirt and organic growth.
How often should I have my patio professionally cleaned?
There is no fixed schedule, as it depends on shade, moisture and how much organic growth the paving attracts. Many homeowners choose a professional clean every year or two, with routine maintenance in between. A six-monthly maintenance visit that sweeps debris and reapplies a suitable biocidal treatment can help keep regrowth in check and reduce the build-up of moss, algae, lichen and weeds.
Request a free site survey and no-obligation detailed quotation