Pressure washing guide
Is pressure washing safe for brickwork and stone properties?
The answer depends heavily on the age, type and condition of the brickwork or stone. For many of London's older properties, high-pressure washing is the wrong choice. Here is what you need to know before any cleaning begins.
Brickwork and natural stone are among the most common exterior surfaces on London properties, and also among the most misunderstood when it comes to cleaning. Both materials can be cleaned safely when the right method and pressure are used. But both are also easily damaged when they are not. Given that over 60% of London's housing stock was built before 1945, this matters more here than in most UK cities.
60%+
of London homes pre-1945 with porous brick and lime mortar that cannot handle high pressure
3 to 5
years between recommended cleans for most brickwork when the correct method is used
150°C
temperature of DOFF steam cleaning, the specialist system for delicate and heritage brickwork
Can brickwork be pressure washed?
The short answer is yes, in some cases, but with significant caveats. Modern, dense, high-fired bricks in good condition with sound cement mortar joints can handle a carefully controlled low to medium pressure wash. However, older Victorian and Edwardian brickwork uses softer bricks and lime-based mortar that is far more vulnerable to water penetration and physical erosion. High-pressure water forced into these materials washes out the mortar, erodes the face of the brick and creates channels for water ingress that lead to damp problems internally. This damage often does not show immediately, which is why it is frequently underestimated.
Stone surfacesIs pressure washing safe for natural stone?
Natural stone varies significantly in density and porosity. Granite and porcelain are dense and non-porous, making them suitable for pressure washing. Sandstone and limestone are soft and highly porous. High-pressure water on these surfaces strips the natural protective surface layer, causes efflorescence (white salt deposits), and accelerates deterioration. Once the patina of natural stone is damaged by incorrect cleaning, it cannot be restored. For sandstone and limestone patios and path surfaces, soft washing is the appropriate method regardless of how dirty the surface appears.
Safe to pressure wash
Granite, porcelain, slate (with care), dense concrete pavers, engineering brick, modern block paving
Soft wash or specialist clean only
Sandstone, limestone, travertine, York stone, Victorian brick, heritage stonework, render
Signs that brickwork needs assessing before cleaning
Before any cleaning takes place, brickwork and stone should be checked for existing vulnerabilities. Cleaning a surface with pre-existing damage makes that damage worse, not better.
Cracked or eroded mortar joints
Damaged mortar allows water to penetrate during cleaning. Repointing should happen before any cleaning takes place.
Existing staining or efflorescence
White salt deposits on brickwork indicate that water is already getting into the masonry. Pressure washing will accelerate this process.
Spalling or surface flaking
Brick faces that are breaking away indicate previous water damage or freeze-thaw deterioration. High pressure will worsen this immediately.
Lime mortar visible between joints
Soft lime mortar is a clear indicator of older brickwork. It cannot withstand pressure washing and will be washed out, requiring costly repointing.
Professional pressure washing London
Expert brickwork and stone cleaning across London
Cloud Nine assesses brickwork and stone before every clean. We identify the material type, check for vulnerabilities and select the correct cleaning method to restore the surface without causing damage. We serve residential and commercial properties across all London boroughs.
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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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