Diagnostic stone cleaning for period facades across London. Portland stone, Bath stone, limestone, sandstone. The correct method depends on the stone, the soiling, and the building's history — not the day rate.
Every stone cleaning enquiry we receive starts the same way: a building with visible soiling and an owner who wants it clean. What they often don't know is that the right answer depends on five or six variables that can't be assessed from the street.
The stone type matters. Portland stone tolerates DOFF steam cleaning exceptionally well. Softer limestones and sandstones require lower pressures and sometimes poultice drawing instead of steam. Bath stone, often found on Georgian properties in central London, is porous and delicate — it responds badly to anything vigorous.
The soiling type matters too. Atmospheric carbon pollution, the sulphur-based black crust that forms on sheltered surfaces, biological growth, paint, and mineral staining all require different approaches. Using the same method on all of them is the most common mistake in the industry.
Then there's the building's status. Listed buildings have an agreed method. Conservation areas have guidelines. Both require documentation. We handle this as part of our standard process.
DOFF steam cleaning is our most commonly specified method for ornate carved stonework and listed buildings. It uses superheated low-pressure steam at up to 150°C — hot enough to kill biological matter and lift pollution without introducing significant water into the substrate. Minimal chemical use. No abrasion. The default specification from most conservation officers.
TORC cleaning introduces a fine swirling aggregate into the steam flow, increasing the mechanical action for stone with heavy carbonation or surfaces that DOFF alone won't shift. We use TORC on robust Portland stone in areas of heavy atmospheric soiling, and on flat carved surfaces where biological crust has calcified.
Poultice cleaning works by drawing staining out of the stone rather than removing it mechanically. Applied as a paste to the surface, left for a controlled period, then carefully removed. Appropriate for localised mineral staining and for surfaces where steam or aggregate would cause damage.
We do not use high-pressure water cleaning, acid cleaning, or abrasive techniques on period stonework. The damage from these methods shows up immediately in friable surfaces, lost arrises, and etched tooling — or sometimes not for years, by which time the water ingress has done its work internally.
London's period building stock is predominantly Portland stone — the oolitic limestone quarried from Dorset that clads everything from St Paul's Cathedral to the terrace houses of Belgravia. It's durable, takes a clean well, and rewards careful method selection. We work with Portland stone constantly.
London stock brick is sometimes categorised as brickwork rather than stonework, but it deserves equal care. The yellow-grey brick produced from Thames valley clay is softer than modern brick, acid-vulnerable, and routinely damaged by contractors who don't know its properties. We've cleaned thousands of square metres of London stock and we treat it with the same diagnostic care as carved stonework.
We also regularly work with Bath stone (on Georgian Bloomsbury and Mayfair properties), sandstone (Scottish baronial and commercial Victorian), limestone in various forms, and terracotta facades from the late Victorian and Edwardian periods.
Our site visits are free. We come to the building, assess the stone condition, identify the soiling types, check access requirements, and note any areas of existing damage or fragility. This takes around an hour for a typical terrace.
Within 48 hours we provide a written specification: the method proposed, the areas to be treated, the access required, the programme, and the cost. No vague estimates. A document that forms the basis of the contract.
For listed buildings, we also prepare the method statement required by the conservation officer — this is part of our standard service, not an add-on.
We work across London and the South East, with particular density in Westminster, Islington, Kensington & Chelsea, the City of London, Camden, and Wandsworth. For buildings in Surrey and Kent, we cover the commuter belt regularly.
Costs vary significantly by stone type, soiling level, access requirements, and building complexity. A small Victorian terrace facade might start from £800–£1,500. A commercial Portland stone facade will be priced per square metre after survey. We provide written specifications with costs within 48 hours of a site visit.
For a typical period terrace, a full facade clean takes one to three days once scaffolding is in place. Larger commercial buildings or those requiring TORC for heavy soiling may take longer. We'll give you a realistic programme as part of our written quote.
DOFF superheated steam cleaning is the most commonly specified method for Grade I and Grade II listed buildings, as it uses minimal water and no chemicals. The method is always agreed with the relevant conservation officer before works commence. We handle this process as part of our service.
For low-level work and smaller properties, we use access towers or MEWP platforms. Full scaffolding is required for multi-storey facades and is typically arranged by us or coordinated with the main contractor.
Stone cleaning removes soiling from the surface — atmospheric pollution, biological growth, paint, mineral staining. Stone restoration goes further: filling voids, replacing damaged sections, consolidating friable material. Most projects involve both, and we quote for the full scope after survey.