How to stop a patio being slippery in winter

A patio gets slippery in winter because algae, moss and rotting leaves form a slimy layer on the surface, and the damp weather keeps it wet. The fix is to remove that layer, either with a stiff brush on small areas or a proper pressure wash, then keep leaves swept off and let the surface dry out as much as possible. Washing on a dry, mild day rather than a frosty one matters too.

Below is why it happens, what you can do yourself, and how we clean patios and paths without damaging them.

Why paving turns green

The green film on paving is mostly algae. It grows anywhere that stays damp and shaded for long periods. In South Devon that is a lot of places from October to March:

• North-facing patios and paths that rarely get sun in winter
• Paving under trees, where leaves sit and rot on the surface
• Areas next to walls, fences and hedges that block the light
• Porous stone such as sandstone, which soaks up water and stays wet
• Low spots where water puddles after rain

Many gardens in Torbay are on a slope, with steps and paths leading down from the road. Those steps are often the worst, because they sit in the shade of the house and get used every day.

What you can do yourself

• Sweep leaves off regularly. A layer of wet leaves is slippery on its own and feeds the algae underneath.
• Scrub small areas, such as a doorstep or the top of the steps, with a stiff brush and water.
• Cut back overhanging plants so light and air can reach the paving.
• Clear blocked drains and gullies so water runs off rather than sitting on the surface.
• Put grit or salt down on icy mornings where people walk, as a short term measure.

Be wary of strong chemical cleaners. Some can mark natural stone or harm plants and pets, so read the label and test a hidden corner first.

When a pressure wash makes sense

Once the green has properly taken hold, especially on block paving and textured slabs, scrubbing by hand does not get into the surface. That is where a pressure wash earns its keep. Done properly it brings the paving back to its original colour and takes off the slippery layer.

How it is done matters as much as doing it:

• A rotary surface cleaner over open areas gives an even finish without the stripes a lance can leave
• The pressure is set to suit the surface. Softer sandstone and older concrete get gentler treatment
• Steps, edges and corners are done with the lance
• Block paving has kiln-dried sand brushed back into the joints afterwards, because washing takes some of it out

Avoid washing on frosty days

If the forecast says frost, leave it for another day. Water left on the surface and in the joints after a wash can freeze overnight, which is the opposite of what you are trying to achieve. Re-sanding block paving also needs the surface to be dry, and that can be hard to find in midwinter. A mild, dry spell is ideal. In practice that means many people book in late autumn, before the coldest weeks, or in early spring.

Sealing after cleaning

Sealing is optional. On porous sandstone and block paving it can slow the green coming back and makes the next clean easier. It is not essential on every surface, and it has to go on a clean, dry patio, so it is usually a spring or summer job rather than one for November.

Keeping the whole outside in step

Green paving often sits next to green walls, because both are caused by the same shade and damp. If your render or cladding has gone the same way, our guide on getting green algae off render and cladding explains how we deal with walls without high pressure.

Patio and driveway cleaning in South Devon

AbraClean pressure washes patios, paths, steps and drives across Torbay, South Devon and Exeter. See our driveway and patio cleaning service and our render and cladding cleaning. Areas include Paignton, Totnes and Newton Abbot. Call or text Mark on 07901 563000 for a free quote.