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Why the sand in the joints matters as much as the clean itself.
Block paving cleaning removes the dirt, moss and weeds that build up on the surface and in the joints, and re-sanding refills those joints with fresh kiln-dried sand afterwards. The sand is what locks the blocks together, so replacing it is essential, not optional. A proper job cleans, re-sands and, ideally, seals the paving so it stays firm and tidy for years.
Block paving has a joint every few inches, and each of those joints is a little pocket where dirt, moss and windblown seeds collect. In our damp Irish climate those pockets stay moist, so weeds germinate and moss spreads across the whole surface. Add tyre marks, spilled oil and general grime on the blocks themselves and a paved driveway can look tired within a few years. The joints are the weak point, which is exactly why how you clean them matters so much.
The kiln-dried sand packed into the joints is not just cosmetic. It wedges the blocks tightly against each other so the whole surface behaves as one interlocking unit rather than loose individual bricks. When that sand is missing, the blocks can rock, shift and sink under the weight of a car, edges start to lift, and water gets underneath the paving where it can wash out the bedding layer. Refilling the joints with fresh kiln-dried sand after cleaning restores that interlock and stops the slow spread of movement and dips. Skipping the re-sanding is the single most common reason a cleaned driveway fails soon afterwards.
A hired power washer strips the joints out completely. The narrow jet blasts the kiln-dried sand clean out of every gap, and most people never replace it, so the blocks are left loose and unsupported. From there the surface only goes one way: blocks work free, edges lift, and puddles form in the dips. High pressure held too close can also chip the block faces and blow out the bedding sand beneath, which is far harder to put right. It looks impressive on the day, but a wash that removes the sand and never puts it back does more harm than good. Our driveway and patio cleaning service always finishes with re-sanding for exactly this reason.
Sealing is worth considering once the paving is clean and freshly sanded. A quality block paving sealer binds the joint sand in place so it does not wash out as easily, slows down weed and moss regrowth, and makes the surface easier to keep clean. It can also lift the colour of faded blocks. Sealing is not compulsory, and it needs to be done on a properly dried surface to work, but it noticeably extends the time between cleans. If you are weighing it up, our guide on whether driveway sealing is worth it goes through the trade-offs in plain terms.
Most block paving benefits from a proper clean and re-sand every couple of years, with a light maintenance wash in between if it sits under trees or in shade. Sealed paving tends to go longer between cleans. The right interval depends on how much sun the driveway gets, how much traffic it takes and whether it has been sealed, and our guide on how often to clean your driveway sets out a sensible schedule. If your paving is looking green, weedy or the blocks feel loose underfoot, get in touch for a free quote and we will tell you honestly what it needs.
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