Pressure washing guide
How to pressure wash block paving
Block paving looks stunning when clean but is easily damaged by the wrong technique. The joints hold the whole structure together and must always be re-sanded after every pressure wash. Here is how to do the job correctly.
Block paving is one of the most popular driveway and patio surfaces in London. It responds well to pressure washing, which can remove years of algae, black spot, weed growth and surface staining and restore the paving to near-original condition. However, it requires a more careful approach than a standard concrete surface because the structure of block paving depends on kiln-dried sand packed between the joints, and pressure washing removes that sand. Replacing it after every clean is not optional.
Always
re-sand block paving joints after every pressure wash. Without this the blocks become unstable and weeds return quickly
Diagonal
always clean across the joints at a diagonal, never directly along them, to protect the joint structure
Surface cleaner
attachment is the professional choice for block paving — even coverage, no stripes, faster results
How to pressure wash block paving: the correct process
Step 1: Clear and sweep
Remove all vehicles and items from the area. Sweep thoroughly to remove loose grit, leaves and debris that the pressure washer could pick up and fling.
Step 2: Pre-treat weeds and oil stains
Apply a weed killer to any established weed growth in the joints at least 24 hours before cleaning. Pre-treat any oil stains with a degreaser and leave for 20 minutes before washing.
Step 3: Pressure wash diagonally across the joints
Use a 25 or 40-degree fan nozzle or a surface cleaner attachment at medium pressure. Work in diagonal passes across the joints rather than along them. Keep the nozzle at 30 to 40 cm from the surface and keep moving.
Step 4: Final rinse
Rinse the entire surface thoroughly to clear dirty water and any cleaning solution residue. Direct the rinse water towards the drain to prevent it pooling and redepositing on cleaned areas.
Step 5: Allow to dry fully
Allow the block paving to dry completely before re-sanding. Applying sand to a damp surface results in clumping and poor sand distribution in the joints.
Step 6: Re-sand the joints
Brush kiln-dried jointing sand across the surface using a stiff broom, working it into the joints from multiple directions. This is the most important step and should never be skipped. Allow traffic to bed the sand in over the following days.
What to avoid when pressure washing block paving
Washing directly along joints
This blasts sand out aggressively, collapses joint structure and loosens blocks. Always work diagonally.
Skipping re-sanding
Without sand in the joints, blocks shift under vehicle or foot traffic and weeds establish very quickly in the open gaps.
Using too high a pressure
Very high PSI damages the surface of the blocks over time, eroding the top layer and accelerating future staining.
Washing in winter
Do not seal after washing in winter. Damp blocks retain moisture that prevents sealant from bonding correctly, wasting the cost of the product.
Professional pressure washing London
Block paving cleaned and re-sanded by Cloud Nine
Cloud Nine pressure washes block paving driveways and patios across London using commercial equipment and the correct technique. Re-sanding is included in every block paving clean we carry out. Contact us for a free quote.
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Pressure washing help and guidance
Everything you need to know about pressure washing for London homes and businesses, from surface types to costs and what to expect from a professional clean.
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