Block paving cleaning and re-sanding explained

Cleaning block paving and re-sanding it go hand in hand. Pressure washing lifts moss, algae and grime brilliantly, but it also blasts the kiln-dried sand out of the joints between the blocks. That sand is what locks the blocks together and helps keep weeds out, so brushing fresh kiln-dried sand back into the joints after cleaning is an essential final step, not an optional extra.

Why block paving needs cleaning

Block-paved driveways and patios collect moss, algae, dirt and weeds, especially in shaded or damp areas. Beyond looking tired, the growth makes the surface slippery. Pressure washing restores the colour and finish in a single visit, see our guide on removing moss and algae.

Why re-sanding matters so much

The sand in the joints does real structural work. It:

• Locks the blocks together so they do not shift or rock.
• Helps the surface shed water and stay stable.
• Fills the gaps that weeds would otherwise colonise.

Wash block paving without re-sanding and you will soon see blocks loosening and weeds returning through the empty joints. It is the single most common mistake in DIY block paving cleaning.

How the process works

1. Clear the surface and treat stubborn moss or weeds.
2. Pressure wash with a fan nozzle, working in even passes.
3. Let the paving dry thoroughly.
4. Brush kiln-dried sand into all the joints until full.
5. Optionally apply a sealant to protect and slow regrowth.

Keeping it looking its best

After cleaning and re-sanding, a sealant can help repel stains and slow weed and moss regrowth, keeping the surface cleaner for longer. Improving drainage and cutting back overhanging plants helps too. For a professional finish, our driveway and patio cleaning service cleans, re-sands and can seal block paving across Derby and the surrounding area. For pricing, see our driveway pressure washing cost guide.