How to Remove Moss from Block Paving

Lift moss

Brushing and pressure washing

Kill spores

Biocide treatment post-clean

Re-sand joints

Kiln-dried sand blocks regrowth

Why block paving mosses over

Sand joints hold moisture, low-traffic areas stay damp, and shaded spots never fully dry - all ideal conditions for moss colonisation.

Cleaning sequence

Stiff brush first to lift loose moss, then pressure wash on a wide fan setting to avoid blowing joint sand out and creating low spots.

Biocide application

Applied after cleaning, the biocide solution penetrates the cleaned joint sand and kills spores before they can germinate in spring.

Joint sand replacement

Kiln-dried sand brushed in dry, compacted with a plate or hand tamper, topped up, and reswept - fills the gaps moss needs to grow.

Sealing optional

Acrylic sealer over the top locks sand in place and slows moss return for 2-3 years - worth considering on driveways that moss over fast.

Seasonal timing

Late spring or early summer after the main spore release but before autumn leaf fall gives the best regrowth prevention window.

Frequently asked questions

Will pressure washing alone remove moss? It lifts the visible moss but does not kill spores - expect regrowth within 4-6 weeks without biocide treatment and joint re-sanding.

Can I use a wire brush on block paving? Wire brushes can scratch the surface of concrete blocks and lift the colour - use a stiff nylon brush instead for safer cleaning.

How often should I re-sand? Every 1-2 years for most driveways. Sooner if you see joint sand washing out after rain or settling below the block surface.

Related services and locations

Need help now, contact Jet Kings for advice and a free quote.

Need help applying this advice at your property? Call 07954 028819 or request a free quote.

Why Moss Loves Block Paving

Block paving is particularly vulnerable to moss for three reasons. First, the joints between blocks collect debris — dust, leaves, soil particles — that break down into a growing medium. Second, the sand in the joints holds moisture, creating the damp conditions moss needs. Third, block paving is often laid in shaded areas (alongside houses, under trees) where sunlight cannot dry the surface quickly.

In Leicester and the Midlands, the combination of regular rainfall, mild temperatures, and clay soils that hold moisture means block paving is a prime target for moss growth. Once moss establishes in the joints, it spreads across the blocks, creating slippery patches and making the whole driveway look neglected.

Step-by-Step Moss Removal

Clear the surface: Sweep or blow loose debris off the driveway so you can see the full extent of the moss.

Apply a moss killer: Use a biocide treatment formulated for exterior hard surfaces. Spray evenly over the affected areas and leave it to work — this usually takes 24-48 hours. The moss will turn brown or black as it dies.

Pressure wash: Once the moss is dead, pressure wash the driveway using a rotary surface cleaner attachment for even coverage. The dead moss lifts away along with surface dirt and debris from the joints.

Clear the joints thoroughly: The pressure washing will remove much of the old sand and debris from the joints. This is a good thing — that material was full of moss spores. Make sure the joints are cleaned out properly.

Re-sand the joints: This is the most important step for preventing moss returning. Brush kiln-dried sand into the joints until they are full. The sand locks the blocks, fills the gaps where moss would root, and helps keep the surface stable.

Optional: Apply sealant: A quality sealant reduces water absorption into the blocks and joints, making it harder for moss to establish. It also makes future cleaning easier.

Why Re-Sanding Matters

Many DIY driveway cleans fail because the joints are not re-sanded afterwards. Without sand in the joints, the blocks can shift, weeds and moss return quickly, and the driveway looks unfinished. Re-sanding is not optional — it is an essential part of the job. Use kiln-dried sand (not builders' sand, which holds too much moisture) and brush it in thoroughly until the joints will not take any more.

Preventing Moss Regrowth

You cannot permanently prevent moss — it is a natural part of the outdoor environment — but you can slow it down significantly:

Brush the driveway monthly to prevent debris accumulating in the joints

Trim overhanging branches to increase sunlight and airflow

Address any drainage issues that leave standing water on the surface

Apply a biocide treatment annually as a preventative measure

Re-sand joints every 2-3 years to keep them filled

Frequently Asked Questions

Will bleach kill moss on block paving?

Household bleach will kill surface moss but does not prevent regrowth, can discolour coloured blocks, and is harmful to plants and soil. Professional biocide treatments are specifically formulated for exterior surfaces, are more effective, and are safer for your garden.

How long after moss treatment can I use my driveway?

You can walk on it immediately after cleaning. We recommend keeping vehicles off for 2-4 hours to allow the surface to dry, especially if re-sanding has been done.

Is moss on block paving dangerous?

Yes. Moss becomes extremely slippery when wet, creating a slip hazard for you, your family and visitors. It also holds moisture against the blocks, which can lead to frost damage in winter. Regular removal is a safety measure as much as an aesthetic one.

Can I prevent moss without chemicals?

Regular brushing, good drainage, and keeping the surface dry and sun-exposed are the best chemical-free approaches. Re-sanding joints and sealing the surface also help. However, for established moss, a biocide treatment is the most effective solution.