How long does stone cleaning take?

The two things people usually mean by "how long"

There is a useful distinction between the time the work itself takes on site and the total project timeline from enquiry to completion. For a straightforward terrace house with no listing complications, these can be close together — a few weeks from first contact to works complete. For a listed building in a conservation area with complex soiling, the total timeline can be six months or more, even if the on-site works take only three or four days.

Understanding both is important for planning purposes, especially if there are events, sales, or tenancy changes tied to the project.

On-site cleaning time by project type

The following are honest estimates based on typical projects. They assume good access conditions and a single soiling type. Projects with complex or mixed soiling, or requiring additional works alongside cleaning, will take longer.

What the total project timeline looks like

Phase 1: enquiry and site visit

A site visit is the starting point for any project. We walk the building, identify the substrate and soiling type, and assess any complicating factors — previous treatments, friable areas, defective pointing that should be addressed before cleaning. The visit produces a written method statement and quotation, usually within a week of the visit itself. There is no charge for the visit or the quote.

Phase 2: trial panel (all projects)

Before any full cleaning proceeds, a trial panel is required. This is carried out in a representative 1m² area, assessed after 48–72 hours of drying, and used to confirm the method and temperature specification for the full works. For unlisted buildings, the trial is typically done on the same day as the pre-works survey, with assessment the following week. For listed buildings, the trial panel is part of the consent application.

Phase 3: consent (listed buildings only)

Listed Building Consent is required before cleaning works commence on any listed building. The application is submitted to the local planning authority with the method statement and trial panel documentation. Consent decisions typically take six to eight weeks from submission, though complex applications or those in sensitive conservation areas can take longer. The consent process is the single largest variable in a listed building project timeline.

Phase 4: access setup

For projects requiring scaffold, the scaffold contractor's programme has to be factored in. Scaffold erection typically takes one to two days for a terrace frontage and two to three days for larger buildings. Mobile elevated work platforms (MEWPs) have no setup lead time and can begin cleaning the day of arrival.

Phase 5: cleaning works

The actual cleaning. Duration as described above, subject to weather. DOFF cleaning is carried out in dry conditions — rain during works does not damage the cleaning process, but wet stone makes it difficult to assess the result in real time. Works are paused in frost or temperatures below 4°C.

Phase 6: assessment and completion

After cleaning, the surface is allowed to dry fully — 24–72 hours depending on conditions — before a final assessment. If additional mortar repair or repointing was included in the scope, this follows the cleaning phase, with lime mortar works curing over several weeks before the scaffold comes down.

What affects the timeline most

The access method is usually the biggest practical variable for unlisted projects. A MEWP can be booked within a week and has no erection time; scaffold requires a contractor programme and erection time, adding at least three to five days to the project. For large or tall buildings, scaffold is often the only viable option; for most London terraces, a MEWP is sufficient and faster.

For listed buildings, the consent process is the dominant variable. Nothing can happen on the building until consent is granted, and the clock starts when the application is submitted — not when the enquiry is made. Planning ahead is essential. We can prepare the method statement and consent application documentation quickly after the initial site visit, but the consent decision is in the hands of the local planning authority.

Seasonal considerations

Stone cleaning can be carried out year-round in London, with one significant caveat: lime mortar work cannot be carried out below 4°C or in wet conditions. Projects that combine cleaning with repointing or stone repair are therefore best planned for spring to autumn, with cleaning only possible as a winter phase if the mortar work can wait.

Summer projects on south-facing facades need careful attention to drying conditions — rapid evaporation in direct sun can cause lime mortar repairs to crack before they carbonate properly. Hessian protection and damp curing are standard practice.

Common questions

How long does DOFF cleaning take?

A single-facade terrace house can typically be cleaned in one to two days. A full Victorian terrace frontage is usually two to four days. Larger commercial or institutional buildings depend on the access method — hanging scaffold takes longer to erect than a MEWP but allows faster cleaning of larger areas.

Does stone cleaning need to dry before it can be assessed?

Yes. After cleaning, the surface needs to be dry before the result can be properly assessed. Depending on the weather and the porosity of the substrate, this takes between 24 and 72 hours. The trial panel result is assessed in dry conditions — this is why the trial is done before full works are committed.

How far in advance should I book stone cleaning?

For straightforward domestic projects, two to four weeks lead time is usually sufficient. For listed buildings requiring consent, allow three to six months from initial enquiry to works commencement. Projects requiring scaffold erection have additional lead time for scaffold contractors.

Can stone cleaning be done in winter?

DOFF cleaning can be carried out in winter provided temperatures remain above 4°C and there is no frost forecast. Lime mortar work cannot be carried out below 4°C or in wet conditions. If the project involves both cleaning and lime work, it is usually staged across seasons.