Block Paving Maintenance: A Year-Round Guide

Block paving works as a flexible system: the load from a car spreads sideways through the blocks, and it can only do that if the joints between them are packed tight with kiln-dried sand. Empty joints mean the blocks can rock individually, edges chip, and water runs down into the laying course rather than across the surface.

Sand is lost to wind, rain and — most commonly — pressure washing. Every time a drive is jet washed, sand comes out. That is not an argument against cleaning, but it is a strong argument for re-sanding immediately afterwards while the surface is drying.

To re-sand, wait for a genuinely dry day, tip kiln-dried sand across the paving and sweep it in with a stiff broom, working in several directions. Then leave it. A light vibration with a plate compactor and a rubber mat helps on larger drives, but on a domestic driveway brushing and time will do it.

For general grime, a stiff brush and a bucket of warm water with a little washing-up liquid does more than people expect. Save the pressure washer for once every year or two rather than every spring.

If you do pressure wash, use a fan nozzle rather than a pencil jet, hold the lance at least 300mm from the surface, and keep it moving. A concentrated jet held close will strip the surface off a concrete block, leaving a lighter, rougher patch that never quite blends back in.

Green algae and black spot lichen respond much better to chemistry than to force. A dedicated patio and driveway cleaner applied on a dry, still day and left for the recommended dwell time will kill the growth, which then weathers off over the following weeks. Black spot in particular is a fungal deposit that bonds to the block and needs a specific treatment rather than brute pressure.

Weeds in block paving almost never grow up from the soil beneath — they germinate in organic debris that has collected in the joints. That means the real control measure is sweeping. A drive that gets brushed clear of leaves and grass clippings a few times a year develops far fewer weeds than one left to build up a layer of dirt.

Where weeds have taken hold, remove them by hand or with a wire joint scraper, then re-sand. A contact herbicide kills the visible growth but leaves the root and the debris that fed it. If moss is the problem, it is a sign the drive stays damp — check whether an overhanging shrub is keeping the sun off, and whether water is standing rather than running away.

Polymeric or resin jointing sand sets slightly firm and resists weeds better than kiln-dried sand. It is a reasonable upgrade on a drive that constantly seeds, though it is less forgiving of movement and needs a clean, dry, fully drained joint to install correctly.

Sealing a block driveway stabilises the jointing sand, deepens the colour and makes oil and tyre marks easier to lift. It is genuinely useful on a drive you want to look sharp with minimum effort.

The caveats are worth knowing. A sealed drive needs resealing every three to five years, the surface can look glossy if the wrong product is used, and sealing over damp or dirty paving traps the problem underneath. Sealer should only go on a thoroughly cleaned, fully dried, freshly re-sanded surface — which in the Essex climate realistically means a settled dry spell in late spring or early autumn.

New paving should be left to weather for two or three months before sealing so that efflorescence, the white salty bloom that comes out of new concrete blocks, has time to work its way to the surface and wash off.

A dip that forms where car wheels sit usually means the sub-base was not compacted adequately or was laid too thin. A localised dip near a manhole or a trench line points to backfill settling. Both are repairable: lift the blocks carefully, stack them in order, correct the base, re-lay and re-sand. Because the blocks are reused, the repair is largely a labour cost.

Spreading — where the outer rows of paving drift outwards and the joints open up — is an edge restraint failure. The perimeter blocks must be haunched in concrete on their outside face; if they are not, or if the concrete has cracked away, the whole field of paving slowly creeps. Rebuilding the edge is the only real fix, and it needs doing before the middle of the drive loses its interlock.

Sunken paving at the junction with a garage or house threshold is often a drainage issue rather than a base failure. Water tracking along that line washes fines out of the laying course. Solving the drainage first, then relaying, prevents a repeat.

In spring, brush the whole drive thoroughly, treat any algae or black spot, and top up the jointing sand once the surface is dry. In summer, pull any weeds while they are small and sweep away grass clippings. In autumn, clear leaves promptly — they are the single biggest source of the organic matter that weeds germinate in.

In winter, avoid rock salt where you can. Standard de-icing salt is hard on concrete blocks over time and can accelerate surface scaling. Grit or a proprietary paving-safe de-icer is a better choice on a drive you want to keep looking new.