Why the joints matter
Block paving works as an interlocking surface. The blocks lock together through the sand in the joints, so when that sand washes out or is pulled out by a jet wash, the blocks start to rock, move and eventually sink or spread at the edges. Most block paving maintenance is really joint maintenance.
Cleaning without damaging it
Sweep regularly and deal with oil and leaf stains early. A pressure washer is effective but, used at close range, it blasts the jointing sand out and can scar the block face. Keep the lance at an angle and a sensible distance, and plan to re-sand straight afterwards. A rotary surface cleaner attachment is gentler and more even.
How to re-sand block paving
Wait for a dry spell; the blocks and joints must be completely dry. Use kiln-dried sand, which is fine and flows into narrow joints. Tip it onto the surface, sweep it diagonally across the joints with a soft brush until they are full, then leave it to settle. A plate compactor fitted with a rubber mat, run over the surface, vibrates the sand deep into the joints. Top up and sweep again, then brush off the excess.
Expect to top up the joints again after a few weeks as the sand settles, and after any heavy cleaning.
Does sealing help?
A block paving sealer, applied after cleaning and re-sanding, binds the top of the jointing sand, resists oil staining and can enhance or refresh the colour. It also discourages weeds rooting in the joints and ants moving the sand. Sealing is optional, not essential, and needs repeating every few years. Always test a small area first, because some sealers darken or add sheen.
Weeds and moss
Weeds in block paving grow from seeds landing in the joint sand, not up from beneath, if the base was built properly. Full joints, regular sweeping and sealing are the best prevention. Remove weeds with a knife or weed brush rather than digging, and treat moss in shady areas where it holds moisture.
Sunken or rocking blocks
A dip in the drive usually means the bedding or sub-base underneath has moved, often from a soft spot, a leaking drain or a vehicle wheel line. The fix is to lift the blocks in that area, correct and compact the sub-base and bedding layer, relay the same blocks and re-sand. Widespread sinking or spreading usually means the original base or edge restraints were inadequate, and that is a rebuild rather than a repair.
When to call someone in
Re-sanding and cleaning are good DIY jobs. Lifting and relaying, replacing edge courses and fixing drainage are better left to a groundworks team. Block-paved driveways, drainage and ground preparation are part of our hardscaping service, backed by more than 26 years' experience, FMB membership and full insurance. For choosing and installing a new drive, see the block paving driveway guide.
A simple yearly routine
For most drives and patios, a light routine through the year keeps block paving in good order. In spring, sweep off winter debris, pull any weeds and check joints. In early summer, clean stains and re-sand any low joints during a dry spell. In autumn, clear leaves promptly, as rotting leaves stain and feed moss. Through winter, avoid rock salt on sealed paving where you can, and brush snow rather than chipping ice with a spade.
Every few years, a deeper clean, full re-sand and optional re-seal brings the surface back close to how it looked when laid. Keeping gutters and downpipes clear so water does not pour straight onto one spot of the paving also helps prevent washout and sinking.
If you notice standing water after rain, it is worth finding out why before it softens the sub-base.
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Questions people ask
What sand should I use?
Kiln-dried sand. It is dry and fine enough to flow into narrow joints.
How often should block paving be re-sanded?
Whenever the joints look low, and always after pressure washing.
Should I seal my block paving?
It is optional. It helps with stains, weeds and colour but needs reapplying every few years.