Short answer
Once block paving has been cleaned, the joints need refilling with kiln-dried sand. Wait until the blocks and joints are completely dry, spread the sand over the surface, brush it diagonally into the joints until they are full, then sweep off the excess. Kiln-dried sand is used because it is dry and fine enough to flow right down into narrow gaps.
Why the joints matter
Block paving is a flexible surface. The blocks sit on a compacted base and are held against each other by the sand packed into the joints. That sand spreads the load when a car drives over, stops individual blocks shifting, and leaves less room for weeds to establish.
Rain, frost, weeding and cleaning all take sand out over time. Pressure washing removes the most, which is why re-sanding is best seen as the second half of a clean rather than an optional extra. If you have not cleaned yet, start with our guide on how to clean block paving.
Why kiln-dried sand?
Kiln-dried sand has been dried right out and is fine and free-flowing, so it pours into joints rather than clumping on top of them. Building sand and sharp sand are damp and coarser; they tend to bridge across narrow gaps, leave voids underneath and can stain the blocks.
Bags sold for this purpose are available from builders' merchants and garden centres, and some are labelled as jointing sand. Choose a colour that suits your blocks, and buy a little more than you think you need. It is easier to keep a bag for topping up later than to run out halfway across the drive.
Wait until everything is dry
This is the step most people rush. Sand will not flow into damp joints; it sticks to the sides and forms a crust near the top that washes out at the next downpour. The face of the blocks can look dry long before the joints are, so give it time and choose a dry, settled spell. A breezy, warm day helps.
A simple check is to brush a little sand across a few joints. If it slides in freely, you are ready. If it clings to the surface or the edges of the blocks, wait longer.
How to re-sand block paving
- Sweep the cleaned paving so it is free of grit, leaves and any debris left from cleaning.
- Pour the sand in small heaps across one section of the surface. On a windy day, work a small area at a time.
- With a soft brush, sweep the sand diagonally across the joints. Brushing at an angle fills the gaps better than brushing along them.
- Keep brushing back and forth until the joints are full to just below the top edge of the blocks.
- If you have a plate compactor fitted with a protective mat, run it over the paving to settle the sand, then brush in more. Without one, walking over the area and brushing again a little later helps the sand settle.
- Sweep the remaining loose sand off the surface and keep it for topping up.
After re-sanding
Expect the sand level to drop slightly as it settles, especially after the first heavy rain. Topping up is quick and far easier than dealing with loose blocks later. Avoid pressure washing the area again until the sand has bedded in.
If you are planning to seal the paving, the sand needs to be fully settled and dry first, as most sealers help bind the top of the joints. Whether sealing is right for you is a separate decision, covered in our guide on sealing block paving. If weeds keep reappearing in the joints even after re-sanding, our guide to weeds and moss in block paving explains why.
When to call a professional
Re-sanding is a manageable job on a small path or patio. Call a professional if the drive is large, if many joints are empty to some depth, or if blocks are already rocking or sinking; in that case the base may need attention from a paving contractor before any sand will help.
When we clean block paving, re-filling the joints with kiln-dried sand is part of the job, and we will discuss sealing on site if you are interested.
Rather have it done for you?
Block paving jet washed, weeds and moss cleared from the joints, with re-sanding discussed on site. Family-run by Jason and Lucas Prior, covering south Essex.
Frequently asked questions
Can I use building sand instead of kiln-dried sand?
It is not recommended. Building sand is damp and coarse, so it does not flow into narrow joints and can leave gaps underneath or stain the blocks. Kiln-dried sand is made for this job.
How do I know when the joints are dry enough?
Brush a little sand across a few joints. If it slides in freely, the joints are dry. If it sticks to the edges or the surface, give it longer.
Does re-sanding stop weeds?
Full joints leave less room for weeds to take hold, but seeds can still land and grow in the top of the sand. Regular sweeping and pulling seedlings early make the biggest difference.
Related guides
- How to clean block paving: step-by-step cleaning for block-paved drives and paths, including how to pressure wash without blowing out the joints.
- Should you seal block paving?: an honest look at what a sealer can and cannot do, how to prepare for it and when sealing is better left alone.
- How to remove weeds and moss from block paving: why weeds and moss take hold in the joints, how to get them out roots and all, and how to slow them coming back.
- What affects the cost of driveway and patio cleaning: the factors that change a driveway, patio or jet washing quote, including surface type, condition, re-sanding and sealing, and how to compare quotes.