Patio Cleaning in London: A Homeowner's Guide
9 July 2026 · 7 min read
How to clean a London patio safely — by surface type, with prices, moss control tips and when to call a specialist.
Most London patios spend half the year in shade and half under a slow drizzle of tree sap, algae spores and pollution grime. A yearly clean makes a bigger visual difference than almost any other garden job — and it's usually cheaper than people expect.
Know your patio surface
- Natural stone (sandstone, limestone, slate): pH-neutral cleaners only. Never acid — it etches.
- Porcelain: tough and non-porous; almost any cleaner works, but joint grout is fragile — pressure wash gently.
- Concrete slabs: tolerate strong cleaners and rotary surface cleaners.
- Block paving: as per our block paving guide — treat joint sand carefully.
The London method
- Apply a benzalkonium chloride algae killer 24–48 hours before cleaning.
- Sweep thoroughly.
- Apply pH-neutral patio cleaner, scrub in with a stiff (non-wire) brush.
- Pressure wash at 100–120 bar with a fan tip, or use a surface cleaner attachment for even results.
- Re-sand joints on block paving; re-grout any lifting slabs on stone patios.
Typical London patio prices
| Patio size | Typical cost |
|---|---|
| Small (up to 15 m²) | £90 – £160 |
| Medium (15–30 m²) | £140 – £260 |
| Large (30 m²+) | £4 – £7 per m² |
DIY vs professional: what it really costs
| DIY | Professional | |
|---|---|---|
| Up-front cost | £120–£250 pressure washer + £20–£40 chemicals | £90–£260 per clean, nothing to buy |
| Time (25 m² patio) | 4–6 hours plus drying | 1.5–3 hours |
| Risk | Striping, blown joints, etched sandstone or limestone | Insured, correct pressure and pH-neutral chemistry per material |
| Finish | Good on concrete and porcelain | Even finish on Indian sandstone, limestone and porcelain, with re-sanding or sealing available |
DIY makes sense on small concrete or porcelain patios you can clean yearly. For Indian sandstone, limestone or anything over ~25 m², a professional clean usually costs less than the tools and carries none of the etching risk.
Sealing
Sealing natural stone and concrete extends the clean by 2–3 years and locks out red wine, barbecue grease and bird droppings. Budget £150–£250 on a typical London patio.
Preventing regrowth
Shady, north-facing patios re-green fastest. A residual algae treatment in September dramatically slows the winter build-up.