Working on a listed building is not the same as any other restoration project. The method must be agreed. The documentation is part of the job. We manage both.
There are around 500,000 listed buildings in England. London has an exceptional density of them — Georgian squares, Victorian civic buildings, Edwardian mansion blocks, medieval churches. Working on any of them requires consent, agreed methods, and documentation. This is not bureaucracy for its own sake: it's the legal framework that protects irreplaceable historic fabric from being damaged by well-intentioned but inappropriate intervention.
We work on listed buildings constantly. Our process is designed around the requirements: free site survey, method statement, conservation officer liaison, test clean, works, and completion records. All of this is included in our service. Clients aren't asked to handle the heritage side themselves.
Survey and specification. We visit the building, assess the stone or brick condition, identify soiling types, and prepare a written method statement. For listed buildings, this document is more detailed than a standard specification — it references the relevant heritage guidance, identifies the heritage significance of the building, and explains the rationale for every aspect of the proposed approach.
Conservation officer liaison. We submit the method statement to the local authority conservation officer and manage the approval process. We have working relationships with conservation officers across London boroughs and are familiar with the requirements of different local authorities.
Test clean. A test panel is agreed with the conservation officer before full works commence. This is standard practice and gives the officer the opportunity to assess the method's impact on the actual building before committing to the full programme. We carry out test cleans as part of our standard service.
Works. All cleaning is carried out to the agreed method, with no deviations without written approval. Heritage-approved methods only: DOFF steam cleaning, TORC, and poultice. No chemical washes or high-pressure systems.
Completion records. On completion, we provide a full written record of the works: method used, areas treated, before and after photography, and the conservation officer approval reference. This forms part of the building's record and is submitted to the local authority.
Conservation philosophy is grounded in minimum intervention: do only what is necessary, in the least invasive way, with methods that are reversible where possible. In cleaning practice, this means using the gentlest effective method; not over-cleaning; accepting that some soiling and patina is part of the building's character; and never risking the fabric to achieve a cosmetic result.
We approach every project this way, not just listed building work. But it's most critical on heritage assets where damage is both irreversible and legally consequential.
We use DOFF superheated steam cleaning, TORC vortex cleaning, and poultice drawing. These are the three methods you will see in Historic England guidance and in most conservation officer method statements. We do not use high-pressure water cleaning, acid cleaning, or abrasive techniques on any heritage building.
Usually yes. External cleaning of a listed building that changes its appearance requires listed building consent. The practical process is: we prepare the method statement, submit it alongside your consent application (or the conservation officer may approve the method statement directly), and obtain written approval before works begin. We handle this process for all our listed building projects.
Timescales vary by local authority. In our experience, straightforward cleaning projects in boroughs we work in regularly take four to eight weeks from submission to approval. Complex projects or those involving carved stonework in sensitive conservation areas may take longer. We can advise on realistic timescales for your borough once we've seen the building.
Minimum intervention is the founding principle of conservation philosophy: do only what is necessary to stabilise and preserve, in ways that cause the least possible change to the historic fabric. In cleaning terms, this means using the gentlest effective method, not cleaning beyond what is necessary for preservation, and leaving patina and character intact. We design every method statement around this principle.
Legally you can, but the risk to the building — and to you as the responsible party — is significant. Unlicensed intervention causing damage to a listed building can result in enforcement action, prosecution, and mandatory reinstatement at your cost. Using a contractor with documented experience of listed building work and a track record with conservation officers significantly reduces that risk.