How to Clean a Very Dirty Patio?

Written by PureSeal Services on October 1, 2025. Posted in Blog, Pressure Washing

Patios are one of the most used outdoor spaces in UK homes. Whether you enjoy summer barbecues, family gatherings, or simply relaxing with a book, the patio is a central feature. Over time, though, patios can become very dirty — covered in moss, algae, lichen, stains, and layers of dirt that sweeping alone won’t fix.

Cleaning a heavily soiled patio might seem daunting, but with the right approach, tools, and products, you can restore it to a like-new condition. In this comprehensive guide, we’ll explore the best methods, costs, and practical steps for cleaning a very dirty patio, as well as how to keep it looking good for longer.

1. Why Do Patios Get So Dirty?

Several factors contribute to a patio becoming heavily soiled:

• Weather exposure: Constant rain, frost, and UV sunlight weaken surfaces.

• Algae and moss growth: Thrive in damp, shaded conditions, making surfaces slippery.

• Lichen and black spots: Hard-to-remove organisms that bond into the stone.

• Organic debris: Leaves, soil, and pollen create stains and encourage growth.

• General use: Barbecue grease, drinks spills, and foot traffic all leave marks.

Understanding the cause of the dirt helps you choose the best cleaning method.

2. First Steps: Preparing to Clean

Before diving into the cleaning itself, preparation is essential:

1. Clear the patio – Remove furniture, pots, planters, and decorations.

2. Sweep thoroughly – Get rid of loose debris such as leaves and soil.

3. Protect surroundings – Cover nearby plants and walls if using chemicals.

4. Safety gear – Wear gloves, boots, and safety goggles if using pressure washers or strong cleaners.

3. Cleaning Methods for a Very Dirty Patio

There’s no single best way — the right approach depends on how dirty the patio is, the material it’s made from, and your budget.

Option A: Jet Washing (High-Pressure Cleaning)

Jet washing is the fastest and most dramatic method.

Pros:

• Immediate results

• Removes moss, algae, dirt, and stains

• Can make an old patio look new

Cons:

• Risk of damaging soft stone or grout

• High water usage (400–500 litres per hour)

• Weeds and moss may regrow if not treated afterwards

Cost of Jet Washing

Option B: Scrubbing by Hand

The traditional method — scrubbing with a stiff broom or wire brush plus detergent.

Pros:

• Very safe for all surfaces

• Cheap, only requires detergent and elbow grease

• Good for small patios

Cons:

• Very labour-intensive

• Less effective on ingrained black spots and lichen

Costs of Scrubbing by Hand

Option C: Chemical Patio Cleaners

Patio cleaners and biocides are specially formulated to remove moss, algae, and black lichen.

Pros:

• Targets biological growth

• Long-lasting results (slows regrowth)

• Requires less scrubbing effort

Cons:

• Some products contain bleach or acids (risk to plants/colour)

• Not instant — can take days or weeks to fully work

Typical UK Patio Cleaner Costs

Option D: Natural Cleaning Methods

Eco-friendly solutions such as vinegar, baking soda, and boiling water can be effective for mild dirt.

Pros:

• Cheap and safe for plants

• No harsh chemicals

• Easy to apply

Cons:

• Less effective on very dirty patios

• Requires repeated applications

• Won’t tackle heavy black spots

Option E: Steam Cleaning

A specialist option that uses hot steam at low pressure.

Pros:

• Eco-friendly, no chemicals

• Kills moss and algae spores

• Safe for delicate stone surfaces

Cons:

• Expensive equipment hire (£80–£150 per day)

• Not widely available compared to jet washing

4. Step-by-Step Guide: Deep Cleaning a Very Dirty Patio

Here’s a practical cleaning routine that combines methods for best results:

1. Sweep and remove debris
   Clear away soil, moss, and leaves.

2. Apply a patio cleaner or biocide

   • For algae and moss: use a biocide.

   • For black spots: use sodium hypochlorite or specialised lichen remover.

   • Allow product to dwell (follow manufacturer’s instructions).

3. Scrub with a stiff brush
   Work the cleaner into the surface.

4. Jet wash the surface
   Rinse thoroughly with medium pressure. Start at one end and move systematically.

5. Tackle stubborn stains
   Reapply cleaner on black spots or grease patches.

6. Rinse again
   Flush away all detergent and debris.

7. Allow to dry
   Check the condition of joints and re-sand if needed (for block paving).

8. Seal the patio (optional but recommended)
   Apply a sealer to protect from stains and slow moss regrowth.

5. Comparing Methods

6. How Much Does It Cost to Clean a Patio in the UK?

If you’re hiring professionals, the cost depends on patio size and condition.

DIY methods are cheaper but require time and effort. Professional services may include sealing, which extends the life of the clean.

7. Maintenance Tips to Keep Your Patio Clean

Once you’ve restored your patio, you’ll want to keep it that way:

• Sweep weekly – Prevent debris buildup.

• Treat annually – Use a biocide once a year to kill spores.

• Seal the patio – Reduces staining and makes cleaning easier.

• Remove spills quickly – Oil or grease should be tackled immediately.

• Trim back plants – Less shade = less moss growth.

8. Safety and Environmental Considerations

Cleaning patios isn’t just about looks; safety and sustainability matter too.

• Slippery algae: A dirty patio can be a major slip hazard.

• Chemicals: Always follow instructions and avoid letting runoff reach drains.

• Water use: Jet washing consumes a lot of water — consider using rainwater if possible.

• Protect wildlife: Avoid harsh bleach near ponds or flowerbeds.

9. Should You Hire a Professional?

Hiring a professional makes sense if:

• The patio is very large.

• You don’t own a jet washer.

• The patio has delicate stonework (requiring specialist care).

• You want sealing included.

Professionals have stronger equipment and specialist cleaners, meaning faster and often better results.

10. Conclusion

Cleaning a very dirty patio may seem like a big job, but with the right tools and methods, it’s entirely possible to restore it to near-new condition.

• Jet washing offers the fastest transformation, but comes with water usage and potential damage risks.

• Scrubbing is cheap and safe but labour-intensive.

• Chemical cleaners are essential for lichen and black spots.

• Eco methods are kinder to plants but less powerful.

For most UK homeowners, a combined approach works best: apply a patio cleaner, scrub, and then rinse with a jet washer. Follow up with sealing to extend the results.

Keeping on top of maintenance afterwards ensures you won’t have to tackle such a dirty patio again anytime soon.

11. Tackling Specific Patio Stains

Even after a deep clean, some stains are particularly stubborn. Here’s how to deal with them:

12. Tools and Equipment Checklist

A very dirty patio requires more than just a bucket of water. Having the right kit makes the job far easier:

13. Common Mistakes to Avoid

Many homeowners unintentionally damage their patio during cleaning. Avoid these pitfalls:

1. Using too much pressure – Can strip grout, erode sandstone, or damage surfaces.

2. Not pre-treating stains – Jet washing alone won’t remove lichen or oil.

3. Skipping safety gear – Flying debris and harsh cleaners can cause injury.

4. Forgetting to re-sand joints – On block paving, this weakens the structure and encourages weed regrowth.

5. Cleaning unevenly – Overlapping strokes prevent “tiger stripes” on the patio.

6. Not sealing afterwards – Means dirt, algae, and stains return far quicker.

14. Seasonal Patio Care Plan

A very dirty patio usually means years of neglect. To prevent it happening again, follow a seasonal care routine:

By tackling small jobs regularly, you won’t need another heavy restoration for years.

15. Final Verdict – The Best Way to Clean a Very Dirty Patio

After exploring all the methods, tools, and costs, what’s the best approach?

• For instant results: Jet washing combined with detergent.

• For long-lasting cleanliness: Use a biocide treatment after cleaning and apply a patio sealer.

• For delicate surfaces: Opt for soft washing or steam cleaning.

• For budget-friendly cleaning: Hand scrubbing with a stiff brush and vinegar/baking soda for stains.

Bottom line: The best method for cleaning a very dirty patio is usually a multi-step approach:

1. Pre-treat with a patio cleaner.

2. Scrub stubborn stains.

3. Jet wash thoroughly.

4. Re-sand/seal for protection.

This way, you achieve both an immediate transformation and lasting results.

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