Block Paving Cleaning

Block paving is everywhere in the region's public realm — the precinct regenerations of the last thirty years, retail park forecourts, supermarket entrances, housing development parking courts. It looks smart when it's laid and it ages badly when it isn't maintained, which is why we clean a great deal of it.

It's also a surface where the cleaning itself can cause the damage. Block paving isn't a solid slab; it's thousands of individual units held in place by the sand between them. Blast that sand out with a jet lance and the blocks lose their interlock, start to rock under traffic and eventually settle unevenly. Plenty of the sunken, wandering paving we're asked to look at was made worse by an over-enthusiastic clean.

The joints are the job

Everything that goes wrong with block paving happens in the joints. They're narrow, they hold moisture, they collect wind-blown soil, and that combination is a perfect seed bed. Moss establishes first, then grasses, then anything else that lands there.

The paving system depends on those joints being full. Kiln-dried sand between the blocks transfers load sideways from one unit to the next — that interlock is what lets a flexible pavement carry vehicles at all. Empty joints mean each block works alone, and they begin to move.

So a proper block paving clean is a three-part job: clear the growth out of the joints, clean the block faces, then re-sand the joints and vibrate or brush the sand home. A quote that omits the re-sanding is quoting for a surface that will look excellent for a fortnight and be back to weeds by the summer.

How we clean it

The rotary head matters more here than almost anywhere else. A hand lance across a large paved area leaves stripes — the operative's arc and stand-off vary constantly, and every variation shows once the surface dries. A shrouded rotary cleaner holds a constant height and speed, so the result is genuinely even across the whole area.

• Clear the joints — remove weeds, moss and accumulated soil, mechanically or by hand where needed
• Rotary jetting with a shrouded flat-surface cleaner for even, stripe-free coverage
• Detail work around kerbs, edges, gullies, tree pits and street furniture with a hand lance
• Spot treatment for oil, gum and any stubborn staining, using the appropriate method
• Residual weed treatment so the joints don't re-colonise within weeks
• Re-sand and settle the joints with kiln-dried sand to restore the interlock

Gum, oil and the specific stains

General cleaning gets the surface back. The individual marks usually need individual attention.

Chewing gum is the classic precinct problem — thousands of black discs that most people stop noticing until the paving around them is clean and they stand out. Steam handles gum better than anything else and needs no chemistry, which is why our gum removal is usually a steam job.

Oil and diesel on parking bays and forecourts has soaked into the blocks and won't jet out. That's a degreaser and, where it's long-established, a poultice — and sometimes a shadow remains. Where a single bay is badly contaminated, lifting and replacing a handful of blocks can genuinely be the cheaper answer, and we'll say so.

White bloom on newer paving is usually efflorescence — salts brought out of the concrete blocks as they cure. It typically weathers off within a year or so, and treating it is possible but rarely urgent.

Colour, wear and honest expectations

Concrete block paving gets its colour from pigment concentrated in a thin facing layer on the top of each block. Years of traffic wear that layer, and aggressive cleaning wears it faster. Blocks that have already lost their facing will come up clean but noticeably paler than sheltered blocks under a canopy or against a wall — that isn't a cleaning failure, it's the wear becoming visible now the dirt is gone.

Similarly, blocks replaced at different times will still look different once everything is clean, and heavily trafficked entrance bays will read differently from quiet corners. We flag this at survey where we can see it coming, because the surprise is much less welcome at handover.

Keeping it on a cycle

Block paving responds better to routine cleaning than almost any surface we work on. Growth in the joints is seasonal and predictable, so a spring visit before the growing season and an autumn visit after leaf fall keeps most sites permanently presentable — and each visit is quick because nothing has had time to establish.

The alternative pattern — leaving it three or four years until it's visibly bad, then paying for an intensive clean, full weed clearance and a complete re-sand — costs more overall and means the site looks poor for most of that period. For retail parks, town centre schemes and managed estates a planned cycle is almost always the better value, and it's much easier to budget.