Pressure washing guide
Surfaces that can safely be pressure washed
Not every surface can handle the force of a pressure washer. Using too much pressure on the wrong material causes damage that is often expensive and sometimes irreversible. This guide covers what is safe, what needs care and what to avoid entirely.
Pressure washing is one of the most effective ways to restore the appearance of exterior surfaces, but only when the right pressure is used on the right material. Applied incorrectly, a pressure washer can strip coatings, erode mortar, crack tiles and force water deep into porous materials, causing structural damage that is not always immediately visible. Understanding which surfaces are safe matters before any cleaning begins.
1,500+
PSI needed to clean concrete effectively without surface damage
500
PSI maximum recommended for delicate stone and natural paving materials
0
PSI recommended for roof tiles. Soft washing only — pressure washing risks cracking and water ingress
Surfaces that pressure washing works well on
The following surfaces are hard, dense and durable enough to withstand high-pressure water without the risk of surface erosion or structural damage, provided the correct nozzle and distance are used.
Concrete driveways and paths
Dense and hard-wearing. Handles 2,500 to 3,000 PSI effectively. Removes oil stains, moss and embedded grime.
Block paving
Responds well to medium pressure. Removes algae and staining from between joints. Re-sand joints after cleaning.
Tarmac and asphalt
Light to medium pressure only. Cleans surface grime and oil but avoid high PSI which can displace aggregate.
Granite and porcelain paving
Very dense, non-porous materials. Handle pressure well. Effective for removing surface algae and grime.
Commercial forecourts
Heavy concrete and tarmac designed for vehicle traffic. Responds well to high-pressure commercial equipment.
Brick walls (modern, dense)
Dense, newer brickwork in good condition with sound cement mortar. Low to medium pressure only.
Surfaces that need a careful, lower-pressure approach
These surfaces can be cleaned with pressure but only with reduced PSI settings, appropriate nozzles and correct technique. Getting it wrong causes damage that often cannot be undone.
Sandstone and limestone paving
Soft and porous. Requires low PSI with wide fan nozzle. High pressure strips the natural surface layer permanently.
Victorian and Edwardian brickwork
Porous with lime mortar joints. Soft washing is strongly preferred. If pressure is used, it must be very low.
Wooden decking and fencing
Must be cleaned along the grain at low pressure. High PSI raises grain, causes splintering and strips protective coatings.
Painted or sealed surfaces
High pressure strips paint and sealant. Once removed the surface is exposed to moisture and requires recoating.
Surfaces that should never be pressure washed
For these surfaces, pressure washing causes more damage than the problem it is trying to solve. Soft washing or specialist steam cleaning is the correct approach.
Roof tiles and slates
Pressure dislodges fixings, cracks tiles and forces water beneath the roof structure. Soft washing only.
Render and pebble dash
Pressure washing blasts off render and leaves the underlying wall exposed to damp. Cannot be repaired without significant cost.
Listed or heritage buildings
Heritage brickwork, lime mortar and original stonework require specialist conservation-grade cleaning methods only.
Vehicles and wrapped surfaces
Pressure washing at close range or high PSI damages vehicle paintwork, vinyl wraps and window seals.
Professional pressure washing London
Let Cloud Nine assess and clean your surfaces correctly
Cloud Nine carries out a surface assessment before every clean. We match the method and pressure settings to the material, whether that is a concrete driveway needing full pressure or a Victorian wall that requires a specialist soft wash approach.
Part of our guide
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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