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Patio Black Spot Removal

Stubborn black spots draining your patio’s charm? We treat lichen at the root for a clean, lasting finish, not just a temporary fix.

Welcome to A&R Roof & Hard Surface Cleaning & Restoration, your local patio black spot removal company. We specialise in black spot patio removal, targeting the stubborn lichen that spoils the look of paving across natural stone, flagstone, and block paving surfaces, and restoring your patio’s appearance without damaging the surface underneath.

We provide patio black spot removal across Harpenden, St Albans, Rickmansworth, Milton Keynes, Dunstable, Radlett, Watford, Berkhamsted, Hemel Hempstead, Welwyn Garden City, and all nearby towns and villages. Every job starts with an assessment of the surface and the extent of growth, carried out by a team trained specifically in hard surface restoration rather than general pressure washing.

Why Black Spot Is So Difficult to Remove

Black spots on paving are usually lichen, part fungus, part algae that bonds tightly into the microscopic pores of the stone rather than simply sitting on the surface. This forms a protective biofilm that ordinary washing can’t penetrate, which is why so many DIY attempts remove the visible mark only for it to reappear within weeks.

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How Our Treatment Process Works

Our black spot patio removal process is built around treating the organism, not just the stain. A specialist biocide is applied directly to the affected areas and left to penetrate the surface, killing the lichen at the root before any washing takes place.

Our Process, Step by Step

  • Site assessment to confirm the type of growth and surface material
  • Targeted biocide treatment applied to affected areas
  • Dwell time to allow the treatment to penetrate and kill the root structure
  • Pressure or soft washing to lift the dead material away
  • A repeat application where growth is particularly established

For longer-lasting protection, we often recommend combining treatment with our patio sealing services, which help slow down future regrowth, particularly in shaded or damp areas of the garden.

Why Choose A&R as Your Patio Black Spot Removal Company

Choosing the right patio black spot removal company makes a real difference to how long the results last. We use professional-grade biocides that aren’t available in general retail products, along with the experience to judge dwell time and treatment strength correctly for different stone types; the details that typically separate a lasting result from one that needs repeating within a season.

Alongside black spot treatment, we also offer patio repointing and full patio cleaning services, giving you a complete solution for maintaining your outdoor space rather than treating black spot as an isolated problem.

What to Expect: Patio Black Spot Removal Checklist

  • Assessment of surface type and extent of lichen growth
  • Targeted biocide treatment, not high pressure alone
  • Correct dwell time before washing begins
    Full clean-up once dead growth has been removed
  • Advice on sealing to reduce the chance of regrowth
  • Follow-up treatment offered for particularly stubborn patches

Experience You Can Verify

A&R Roof & Hard Surface Cleaning & Restoration has provided patio black spot removal across Hertfordshire, Bedfordshire, and Buckinghamshire for a number of years, and we’re proud members of Checkatrade, TrustATrader, and Which? Trusted Traders. The process described on this page, assess, treat, dwell, wash is the same one our technicians follow on site, not generic guidance written without ever having treated a real patio.

Don't let stubborn black spots ruin your patio Call 01582 757304 or request a free quote today.

We provide Roof Cleaning & Moss Removal services in the following areas

Frequently asked questions - Patio Black Spot Removal

What are the black spots on my patio?
Those dark, often slightly raised spots are usually lichen, a slow-growing organism that’s part fungus, part algae. Unlike general grime or algae staining, lichen bonds tightly to the surface of the stone and can be genuinely difficult to shift with standard cleaning methods alone.
Lichen grows root structures into the microscopic pores of the stone, so blasting the surface with a jet washer often only removes the top layer while leaving the roots intact. Within a few weeks or months, the spots tend to reappear in the same places. Effective black spot patio removal usually needs a chemical treatment first to kill the organism before any pressure washing takes place.
No, though they’re often confused. Moss and green algae sit on the surface and are relatively easy to remove, whereas black spot lichen is embedded and far more stubborn. If your patio has a mix of green staining and dark, crusty spots, you’re likely dealing with more than one type of growth, which usually calls for a combined treatment approach.
Left untreated for long periods, lichen can gradually contribute to surface erosion on softer stones like sandstone, as its root structures work into the material. It’s not usually a structural concern for most patios, but the longer it’s left, the more ingrained and harder to remove, it becomes.
The process typically involves applying a specialist biocide or lichen treatment directly to the affected areas, allowing time for it to penetrate and kill the organism, then following up with pressure washing to lift the dead material away. Some particularly stubborn spots may need a repeat application.
They can, especially in shaded, damp areas where lichen spores are naturally present in the environment. Sealing the patio after treatment significantly reduces the chances of regrowth, and periodic maintenance cleans will catch any new spots early before they become established again.
This depends on how established the lichen is. Light spotting can often be treated and cleared in a single visit, while heavier, long-term buildup may need the treatment left to work for several days before the follow-up wash, plus a possible second treatment for the most stubborn patches.
Off-the-shelf products can help with light spotting, but they’re often weaker than the biocides used by a professional patio black spot removal company, and getting the dilution and dwell time right matters a great deal for results. For heavier infestations, professional-grade treatment tends to be both faster and more thorough.
Yes. Most black spot patio removal work can be scheduled around business hours, with the chemical treatment applied and left to work overnight or during a quieter period, followed by pressure washing. We always plan the visit to minimise disruption to footfall or outdoor seating areas.
Regular light cleaning, keeping the area free of leaf litter and shade-causing debris where possible, and sealing the patio all help slow down regrowth. Booking an annual check-up is usually the most reliable way to catch new spots before they spread.