If your patio has gone green and turns slippery after rain, you're not alone, and it's worth sorting before winter. That green film is algae, and on a cold, wet day it's genuinely dangerous underfoot. Here's why it happens, why it keeps coming back, and how to fix it properly.
What the green actually is
The green is algae, with moss usually getting a hold in the joints alongside it. It thrives anywhere that stays damp and shaded, which is why north-facing patios, spots under trees and areas near a fence or wall go over fastest. It feeds on the film of dirt and organic matter that settles on the surface.
Why it's a slip hazard
Wet algae is like a thin layer of grease on the paving. It's the most common cause of slips on patios and paths, and it gets worse through autumn and winter exactly when the ground is wet and icy. Clearing it isn't just about looks, it's about not going over on the way to the bins in January.
Why a quick rinse doesn't last
A hose or a light once-over rinses the top but leaves the algae film and the moss roots down in the joints, so it's green again within weeks. To fix it properly you have to lift the growth out of the joints as well as off the surface. We clean with water alone at a pressure matched to your paving, working the moss and algae out of the joints so it stays clean far longer than a quick rinse, and it's safe for your plants and pets.
Keeping it clean
Once it's properly clean, keeping leaves and debris cleared, especially in autumn, slows the green from coming back. When it does need doing, a photo on WhatsApp is enough for Mark to give you a fixed price the same day.
Want a fixed price for yours?
Send a photo of your driveway or patio and your postcode on WhatsApp, and Mark will send you a fixed price the same day.
Common questions
Why is my patio so slippery?
It's almost certainly algae - the green film that builds up on damp, shaded paving. Wet algae is very slippery and is the most common cause of slips on patios in winter.
Why does my patio go green again so quickly after I clean it?
Because a surface rinse leaves the algae film and moss roots down in the joints. We lift the growth out of the joints as well as off the surface, so it stays clean far longer.
Do you use chemicals to remove the green?
No, we clean with water alone. It lifts the algae and moss out of the joints and off the surface, and it's safe for your plants, pets and children.