By the end of a North East winter, most patios have picked up a slippery green-black film of algae, along with rust rings from furniture legs and general grime worked into the joints between paving. None of it is permanent, but it does need the right approach to bring the patio back without damaging the surface.
This guide covers how to safely remove the algae film that builds up over winter, deal with furniture marks and staining, and what a professional patio revival typically costs.
Why Patios Get So Bad Over Winter
Cold, damp, low-light conditions are exactly what algae thrives in, and a patio that sits shaded or under trees for much of the day barely dries out between rain showers all winter, giving algae months of uninterrupted growth. By spring it has usually formed a slick film that is genuinely dangerous underfoot, not just unsightly.
Natural stone and block paving are more prone to this than smooth poured concrete, since their texture and joints hold moisture longer, but any patio surface left untouched over a wet North East winter will show some build-up. Areas under trees or close to fences that block sunlight are usually the worst affected, and often stay damp long after the rest of the patio has dried.
Removing the Algae Film Safely
Pressure washing lifts algae effectively, but the pressure and nozzle need matching to the surface; natural stone, in particular, can be etched or have its surface pattern damaged by excessive pressure held too close for too long. A wider fan nozzle at a sensible working distance, moved steadily rather than held in one spot, gets a clean result without scarring the stone.
For heavier growth, an algaecide or patio cleaning solution applied first and left to work loosens the film before pressure washing, which reduces the risk of needing excessive pressure to shift stubborn patches.
Furniture Marks and Other Staining
Rust rings from metal furniture legs need a specific rust-removing treatment rather than general pressure washing, since pressure alone will not touch a genuine rust stain worked into porous stone. Similarly, any oil or barbecue grease spots from the previous summer benefit from a degreasing pre-treatment before the general clean.
Once clean, using furniture pads or coasters under table and chair legs, and moving furniture periodically, helps avoid the same rust rings forming again through the following winter. Storing metal furniture under cover or indoors over winter, rather than leaving it out on the patio, is the single most effective way to avoid rust marks reappearing each spring.
Typical Costs
Patio cleaning is typically priced per square metre, around £3 to £6, so a small to medium patio often comes in somewhere between £100 and £250 total. Heavier algae build-up or stubborn staining like rust rings can push the price toward the upper end of that range or slightly beyond, given the extra time involved.
A sealant applied after cleaning, while an additional cost, can noticeably slow how quickly algae returns and makes the next clean easier, which is worth considering for patios that suffer badly year after year.
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