Driveway and Sidewalk Moss Removal in Nanaimo

Most of the moss work we do is about protecting a building. This page is about the people walking around it. A concrete driveway, a paver path or a run of front steps can grow a thin film of moss and green algae that hardly shows when dry, then turns slick the moment it rains. In Nanaimo it rains a lot from October through March, so that film is wet for months on end. We clear it from concrete, pavers and exposed aggregate across Nanaimo and the surrounding towns, and this is the job where higher pressure sometimes earns its place.

Why a green surface is slippery

Concrete holds a shoe because its surface is rough at a fine scale. A broom finish or the tops of the stones in an aggregate slab give the sole something to bite into. Moss and algae fill that roughness with a soft, waterlogged layer, so your foot lands on the growth rather than on the concrete. Once wet, that layer behaves more like a polished floor than a path.

The danger is easy to miss. A driveway can still look grey from the house while the texture underneath has gone. Most homeowners only notice when somebody slides, usually on a morning when the surface is wet with dew and the light is poor.

Where people slip

Nanaimo is built on hills, and that shapes where the hard surfaces are. Plenty of houses above Departure Bay or on the lower slopes of Mount Benson sit above or below the street, with a steep driveway and a flight of concrete steps between the car and the door. Those are the surfaces that worry us most.

• Steps. The front edge of each tread is where weight lands, and it is often the greenest part, because water sits along the nosing.
• Sloped driveways. A slope turns a slip into a slide. Wheels spin on them too, especially at the bottom where water collects.
• Shaded side paths. The narrow strip between the house and the fence, where bins and the recycling go out, rarely sees sun and almost never dries.
• Under trees. This coast sits in the Coastal Douglas-fir zone. Fir, western red cedar and bigleaf maple drop needles and leaves that mat down on paving and hold water against it.
• Low spots and joints. Any dip that holds a puddle, and every expansion crack and paver joint, stays damp longer than the slab beside it.

Flat, open driveways in the newer subdivisions of the north end tend to stay cleaner, though their shaded edges and the walk along the north wall usually do not.

Low pressure first, more only where it is needed

On a roof we never put high pressure on shingles, and our roof demossing page explains how we work up there instead. Our washing is low pressure by default, on the ground as well, and a soft wash lifts most of the film from a path or patio. Higher pressure is kept for the tasks that need it, such as a concrete driveway or walkway with growth worked deep into the finish. Concrete has no granule coat to strip off, so it can take that. Even then each kind of surface needs its own setting.

Plain concrete. Durable, but older or softer slabs etch. Hold a narrow jet in one place and it leaves a pale stripe that stays for years. We use a wider fan, keep the wand moving, and work in even, overlapping passes so the finish comes out uniform.

Exposed aggregate. This is common on driveways around the city. The stones are held in a cement binder, and it is the binder that fails first. Push too hard and stones come loose, and they do not go back. Patience and distance do the work here, not force.

Pavers. The units are tough. What sits between them is the issue, as the next section explains.