A mild, damp climate is perfect growing weather for moss, algae and lichen, which is why even a newish driveway here can turn green within a couple of winters. Cleaned properly, most driveways come back remarkably well. Cleaned badly, they can be left worse than before. This guide covers what good driveway cleaning involves.
Why driveways green over so quickly here
Moss and algae need moisture, shade and a surface to grip. Block paving offers thousands of joints holding damp sand, north-facing drives stay shaded for months, and our rainfall keeps everything topped up. Left alone, moss roots into the jointing sand, weeds follow, and the surface becomes slippery underfoot, especially on a frosty morning.
What pressure washing fixes, honestly
A proper clean lifts moss, algae, dirt crust and most organic staining, and the colour change is usually dramatic. What it cannot always remove are deep oil stains that have soaked into concrete or old lichen spotting, which etches into the surface; these may fade rather than vanish. A trustworthy quote will tell you which category your staining falls into before any work starts.
Technique matters more than raw pressure. Blasting block paving at maximum power strips the jointing sand, scars the block faces and can force water under the surface. Surface-appropriate pressure, the right nozzle and a methodical pass protect the driveway while still getting it clean.
Re-sanding: the step people skip
The sand between paving blocks is structural; it locks the blocks against each other. Cleaning inevitably flushes some of it out, so a proper block paving job finishes with kiln-dried sand brushed back into the joints once the surface is dry. Skipping it leaves blocks free to rock and shift, and gives weeds an open invitation.
Keeping it clean for longer
After a full clean, an annual maintenance wash keeps growth from re-establishing, and trimming back overhanging shrubs reduces both shade and leaf litter. Some customers choose a sealant after cleaning and re-sanding, which slows moss regrowth and makes future cleans easier, though it is an optional extra rather than a necessity.