Heritage stone, soft brick and sensitive masonry don’t respond well to high pressure or harsh chemicals. Too much force strips the surface and the wrong solvent stains it.
That’s why so many London building owners use the DOFF system — a low-pressure, high-temperature steam clean that kills biological growth and lifts atmospheric soiling without abrading the substrate underneath.
At RAIL, we combine DOFF with IRATA-certified rope access to deliver gentle, effective cleaning on listed buildings, heritage façades and modern stone elevations at any height.
What DOFF cleaning is — and why it works
DOFF is a specialist superheated water and steam system that operates at temperatures up to around 150°C but at very low pressure. Heat does the work, not force.
It kills algae, moss, lichen and bacteria at the root, melts ingrained pollution and lifts paint, gum and biological staining without saturating the wall or driving water into joints and mortar.
Once the surface dries (usually within minutes) the building can be inspected, pointed or coated straight away.
Why rope access is the ideal pairing for DOFF
Most of the surfaces that need DOFF cleaning are high up and architecturally sensitive: parapets, cornices, ornamental stonework, dormers, chimney stacks and statuary.
Scaffolding wraps the whole elevation just to reach a few details, while cherry pickers can’t fit on a typical London street.
Rope access lets our DOFF technicians descend directly to the cornice, the parapet or the carved stone, treat it precisely and move on. The result is faster work, lower access costs and a much smaller impact on residents and pedestrians below.
Where DOFF cleaning works best
RAIL’s rope access DOFF teams routinely clean:
- Listed and heritage façades: Portland stone, Bath stone, Yorkstone, soft red brick and terracotta.
- Ornamental stonework: carved heads, finials, balustrades, statuary and detailed cornices.
- Painted masonry: gentle paint removal where chemical strippers are too aggressive.
- Algae, lichen and moss: full biological kill on parapets, copings and north-facing elevations.
- Chewing gum and grease: quick removal from porous surfaces without staining.
For harder, more modern substrates we usually recommend high-pressure cleaning instead, and for delicate brick we’ll often pair DOFF with brick and masonry cleaning chemistry to handle deeper staining.
