What Do Professionals Use to Clean Patio Slabs?

Written by PureSeal Services on September 23, 2025. Posted in Blog, Pressure Washing

If you’ve ever admired a freshly cleaned patio and wondered how the professionals achieve such spotless results, you’re not alone. Patio slabs can quickly become dull and dirty thanks to the UK’s damp climate, fallen leaves, weeds, algae, moss, and everyday wear and tear. While DIY cleaning methods (like warm soapy water or vinegar) can help, professionals often use specialist tools and products to restore slabs to a nearly new finish.

In this guide, we’ll explore what professionals use to clean patio slabs, the methods behind their impressive results, and how you can decide whether to invest in similar products or hire an expert.

Why Hire a Professional?

Before diving into the kit itself, let’s look at why people often turn to a pro:

• Expertise: They know which products suit each type of stone (sandstone, limestone, concrete, porcelain, granite).

• Specialist equipment: Tools like commercial pressure washers and rotary surface cleaners are far more powerful than standard consumer versions.

• Time saving: A pro can complete a large patio in a fraction of the time.

• Long-lasting results: Professional-grade sealants and cleaners often give protection for months or even years.

• Less risk: Using the wrong cleaner on limestone, for example, can cause permanent damage.

The Professional Cleaning Arsenal

Professional patio cleaners don’t just show up with a power washer and soap. They use a carefully selected set of products and machines.

1. Commercial Pressure Washers

Unlike the consumer models sold in DIY shops, professionals often use heavy-duty pressure washers capable of 2,000–4,000 PSI (pounds per square inch). These machines deliver more consistent pressure and often connect to large water tanks for uninterrupted flow.

They also use rotary surface cleaners, which look like circular floor scrubbers. These allow even cleaning without striping or leaving patchy marks — a common problem when homeowners use a lance nozzle.

Why professionals like them:

• Deep cleans quickly.

• Even finish across slabs.

• Can be used on large areas efficiently.

Cost if you buy one: £400–£2,000 for professional-grade machines.

2. Specialist Patio Cleaners (Chemicals)

Pros often carry several different cleaning solutions tailored to specific jobs:

• Biocidal cleaners: These target organic growth such as algae, lichen, and moss. Unlike bleach, they don’t just remove surface colouration but kill spores, slowing regrowth.

• Alkaline degreasers: Used on greasy stains from barbecues or food spills.

• Acid-based cleaners: Sometimes used (with caution) on tough stains like rust or efflorescence. Not suitable for limestone or marble.

• Eco-friendly cleaners: Increasingly popular for clients worried about pets, plants, or runoff.

Cost if you buy: Around £15–£30 per 5 litres for professional-grade formulas.

3. Mechanical Scrubbing Tools

Sometimes pressure washing alone isn’t enough — especially on textured or porous stones. Professionals may use:

• Rotary scrubber machines (like those used on floors).

• Stiff brushes for working in cleaners.

• Wire brushes for weeds and stubborn lichen spots.

4. Weed Removal Tools

Weeds between patio slabs are a persistent issue. Professionals often:

• Use weed burners (flame or infrared heat tools) to kill weeds quickly.

• Apply a targeted herbicide to prevent regrowth.

• Refill joints with kiln-dried sand or resin-based jointing compound after cleaning.

5. Professional Sealants

After cleaning, many professionals recommend sealing the patio. Sealants provide:

• Protection against water penetration.

• Resistance to staining (oil, wine, barbecue grease).

• Reduced algae and moss regrowth.

• A refreshed colour and finish (either natural matte or “wet look” gloss).

Cost if you buy: £30–£60 for 5 litres, covering around 25–40 m².

Application usually requires specialist sprayers or rollers to achieve an even coat.

Comparison Table: Professional vs DIY Tools

Step-by-Step: How Professionals Clean Patio Slabs

Here’s the general process a professional will follow:

1. Inspection

   • Identify slab material (sandstone, concrete, porcelain, etc.).

   • Check for damage, stains, or fragile pointing.

2. Preparation

   • Remove furniture, pots, and obstacles.

   • Sweep away debris.

   • Apply weed killer if needed.

3. Pre-treatment

   • Apply biocidal cleaner to kill moss, algae, or lichen.

   • For stains, apply a targeted degreaser or rust remover.

4. Mechanical Cleaning

   • Use a rotary surface cleaner attached to a high-pressure washer.

   • Work systematically for even coverage.

5. Detailing

   • Tackle stubborn spots manually with brushes or a lance.

   • Clean joints, edges, and corners.

6. Rinsing

   • Thorough rinse with clean water to remove residues.

7. Joint Re-sanding (if needed)

   • Replace kiln-dried sand between slabs.

8. Sealing (optional but recommended)

   • Apply protective sealant for longer-lasting results.

What Does It Cost to Hire a Professional in the UK?

Prices vary by region, slab type, and patio size, but typical UK costs are:

For a 30 m² patio, a full clean and seal might cost around £240–£360.

Why Professionals Don’t Always Use Bleach or Vinegar

Many homeowners reach for bleach or vinegar when tackling patio stains. While these can be effective for light cleaning, professionals often avoid them:

• Bleach: Can discolour stone, harm plants, and damage soil.

• Vinegar: Acidic, which can etch and damage limestone or marble.

Instead, pros use specially formulated cleaners that are safer for stone and often biodegradable, giving better long-term results.

Eco-Friendly Options Used by Professionals

As more clients request environmentally responsible cleaning, professionals now offer eco-friendly services:

• Biodegradable detergents: Break down naturally without harming lawns or flowerbeds.

• Hot water pressure washing: Uses heat instead of chemicals to lift stains.

• Low-pressure steam cleaning: Gentle but effective on delicate stone.

• Organic herbicides: Plant-safe weed killers for joints.

How Professionals Handle Different Patio Materials

Pros always test cleaners in a small area first to avoid damage.

Tools Professionals Use That You Can Too

If you’re inspired to tackle your own patio, here are some pro-level tools worth investing in:

• Rotary surface cleaner attachment (£50–£150 for domestic use).

• Mid-range pressure washer (~£200–£300, 1800–2200 PSI).

• Biocidal patio cleaner (£15–£20 for 5 litres).

• Pump sprayer (£10–£20).

• Stiff broom + wire brush (£10–£15).

This setup could cost around £250–£350 — about the same as one professional deep clean for a medium patio, but reusable year after year.

Mistakes Professionals Avoid (But Homeowners Often Make)

• Using too much pressure: Can damage slabs or pointing.

• Choosing the wrong chemical: Acid on limestone is a costly error.

• Skipping pre-treatment: Washing alone won’t kill spores; growth comes back quickly.

• Failing to rinse thoroughly: Leaves residue that attracts dirt.

• Not sealing: Without sealing, slabs get dirty again much faster.

Long-Term Benefits of Professional Cleaning

Hiring a professional isn’t just about instant results. It also helps:

• Extend the lifespan of your slabs.

• Reduce slipping hazards from algae and moss.

• Improve kerb appeal and property value.

• Lower future cleaning costs (since sealed surfaces resist dirt).

Steam Cleaning vs Pressure Washing

Some professionals use steam cleaning instead of (or alongside) pressure washing. This method uses superheated water vapour at relatively low pressure.

Advantages:

• Gentle on delicate stone like limestone and sandstone.

• Kills moss, algae, and lichen spores without chemicals.

• Less risk of damaging pointing or mortar.

Disadvantages:

• Slower and more expensive.

• Requires specialised machines costing thousands of pounds.

Steam cleaning is often used for heritage sites or period properties where preservation is key.

Training and Safety Standards Professionals Follow

Cleaning patios may sound straightforward, but professionals follow strict safety practices:

• COSHH compliance: Correct handling of chemicals under UK law.

• Protective equipment: Goggles, gloves, ear defenders, and steel-toe boots.

• Surface testing: Spot-testing cleaners on a hidden slab before full application.

• Water run-off management: Preventing chemical flow into drains or flowerbeds.

Hiring a professional means peace of mind that safety and regulations are being respected — something DIY jobs sometimes overlook.

The Role of Sealants in Professional Work

For many professionals, cleaning is only half the job. Sealing is what makes results last:

• Penetrating sealers: Soak into the stone, protecting it from within. Best for natural stone.

• Topical sealers: Form a surface coating, enhancing colour and gloss. Better for concrete or porcelain.

• Breathable sealants: Allow moisture to escape while still protecting against stains.

Most sealants last 2–5 years, depending on foot traffic and exposure. Pros often recommend reapplication every 3 years for best results.

Cost-Saving Tips if You Want Professional Results

Hiring a professional isn’t the only way to achieve high standards. You can save money by:

• Hiring equipment: Rotary cleaners and pressure washers can be rented for £40–£60 per day.

• Buying pro-grade cleaners: Many suppliers sell to homeowners online.

• Doing prep yourself: Move furniture, sweep, and pull weeds before the professional arrives to save time (and labour charges).

• Sealing yourself: Ask the pro to just clean, then apply the sealant DIY with a roller.

This hybrid approach can cut bills by 20–40%.

Questions to Ask Before Hiring a Professional

If you decide to bring in a pro, it pays to ask a few key questions:

1. What equipment do you use? (Look for rotary cleaners, not just lance washing.)

2. Which cleaning solutions do you use, and are they safe for pets/plants?

3. Do you offer sealing after cleaning?

4. Can I see before-and-after photos of previous jobs?

5. Are you insured? (Public liability insurance is essential.)

This ensures you’re choosing a reputable provider rather than a “cowboy cleaner” with just a cheap pressure washer.

Final Thoughts

So, what do professionals use to clean patio slabs? In short: commercial pressure washers, rotary surface cleaners, targeted chemical treatments, and high-quality sealants. These tools and products deliver results that last far longer than DIY methods — which is why patios look nearly new again after a professional visit.

If your patio is small and only lightly soiled, DIY methods might be enough. But for larger areas, stubborn stains, or delicate stone, investing in professional help (or professional-grade products) is usually the best way to restore your patio to its former glory.

Tags: Driveway cleaning, Exterior cleaning, gutter cleaning, Patio cleaning, pressure washing, Roof Cleaning, window cleaning