Wall paintings and finishes discovered during works

A wall painting discovered behind plaster during approved works to a listed building stops the job in that area and, almost always, changes the consent you are working to. Listed building consent authorises specific works to a building as it was understood at the time. Once a concealed historic finish appears, the approved works may cause harm that nobody assessed, and carrying on regardless is unauthorised work under the Planning (Listed Buildings and Conservation Areas) Act 1990, which is a criminal offence rather than a procedural slip.

Why discoveries happen in these buildings

Concealed decoration is common in exactly the buildings most likely to be altered. Medieval and post-medieval domestic interiors were painted, then limewashed, then papered, then plastered. Sixteenth and seventeenth century timber framed houses frequently carry painted schemes on the frame and on the panels between. Georgian interiors hide earlier fabric behind later linings. Public houses, inns and former merchant houses are particularly rich.

So the probability is not low. On a building of the right date, opening up plaster should be treated as likely to reveal something, not as a remote possibility.

That is a design assumption as much as a risk register entry. A scheme that depends on stripping every wall to the frame is a scheme with a discovery problem built into it, and the alternative of lining over with a reversible build-up avoids both the discovery and the harm.

The first hour

What happens in the first hour usually determines whether the painting survives in a recoverable state.

1. Stop work in the affected area, and only in that area. There is no need to close the whole site.
2. Do not clean, brush, wash, spray or touch the surface. Well-meaning cleaning has destroyed more discovered paintings than neglect.
3. Do not apply water, solvents or consolidants of any kind.
4. Protect the surface from mechanical damage with a standoff screen rather than anything in contact with it.
5. Avoid sudden changes in temperature and humidity. Turning on a dehumidifier or a heater in the room can cause immediate flaking.
6. Photograph with a scale and a colour reference, in raking light as well as flat light, and record the location on a floor plan.
7. Tell the contract administrator and the client the same day.

Loose fragments that have already fallen should be collected, bagged, labelled with their position and kept dry. They are evidence and sometimes they can be reattached.

Telling the authority

Contact the conservation officer at the local planning authority immediately, in writing, with the photographs. This is not a confession, it is the start of a conversation you need to have.

Where the building is listed at Grade I or Grade II*, Historic England should be informed as well, and the authority will usually consult them in any event. For a place of worship in a denomination holding the ecclesiastical exemption, the internal advisory system is the route instead.

Two things to say in that first message. What has been exposed, as factually as you can describe it. And what you have done to protect it. An officer who can see that the site has behaved responsibly will approach the variation discussion very differently from one arriving to find a painting half scrubbed.

Do not offer a conclusion about date or importance. That is what the specialist is for, and an early guess in writing will follow the project around.

Specialist assessment and paint research

Bring in an accredited wall paintings conservator rather than a general building conservator or an archaeologist. It is a narrow specialism and the number of practitioners is small, so expect to wait a week or two.

The assessment will normally cover four things. Condition, including the stability of the plaster substrate and the paint layer. Extent, established by careful investigation of adjacent areas. Date and significance, from technique, pigments and iconography. And options, ranging from full exposure and conservation through partial exposure to recording and reburial behind a reversible covering.

Paint research may run alongside it. Cross-sections taken from small samples reveal the stratigraphy of finishes, which can date the scheme and identify earlier decorative arrangements across the whole room. On a building where the decorative history matters, that analysis often produces more useful information than the painting itself.

Reburial is a legitimate and frequently correct answer. A painting that has survived four centuries under plaster may survive best under a new reversible lining, properly recorded, rather than exposed in a room that will be heated to modern comfort levels.

Changing the approved scheme

Here is the procedural trap. Planning permission has a statutory route for non-material amendments. Listed building consent does not.

That means any material change to the approved works needs a fresh application for listed building consent. Some authorities will accept minor departures informally, by letter, where the change really is trivial, and that practice has no statutory basis. Get any such agreement in writing and keep it with the consent.

Where the change is to a condition rather than to the works themselves, section 19 of the 1990 Act allows an application to vary or discharge conditions attached to a listed building consent.

Budget eight weeks for a fresh consent and build that into the programme discussion with the contractor on the day of discovery rather than a fortnight later. The revised application should be supported by the specialist assessment and by an updated Heritage Statement covering the newly understood significance, because the building you are now altering is not the building described in the original application. The same reasoning applies to any other change that affects interior fabric, as set out in internal alterations that harm significance.

Conditions that anticipate discovery

The better outcome is to have planned for this at application stage. Three condition types are worth proposing yourself.

A written scheme of investigation agreed before work starts turns a crisis into a process. It also gives the quantity surveyor something to price.

Recording obligations frequently follow, and Historic Building Recording to an appropriate level is the usual mechanism. Where the recording covers fabric about to be concealed or removed, the reasoning in recording a building before demolition or conversion applies directly, and the archive and reporting stage follows the same pattern as post-excavation assessment, archive and publication.

Contract provisions that share the risk

Standard building contracts carry antiquities provisions requiring the contractor to stop work on discovering an object of interest or value, take steps to preserve it, and inform the contract administrator. Those provisions typically make the discovery a relevant event for extension of time and a relevant matter for loss and expense, which is to say the employer carries the risk.

That allocation is correct, and the way to manage it is to price for it. Include a provisional sum for investigation and specialist attendance on any building where discovery is foreseeable. Agree in advance how the contractor will be dealt with for standing time in the affected area. And write the notification procedure into the preliminaries so the site manager knows who to call.

As an illustrative example, a seventeenth century town house is being converted to offices with consent for removal of later partitions. Stripping a partition reveals a painted scheme on the original wall behind it. Work stops in that room, the conservator confirms a scheme of some interest in fragile condition, and the revised application proposes reburial behind an independent reversible lining with a full photographic and measured record. The partition removal elsewhere continues under the original consent. Eight weeks lost on one room, rather than the whole contract.

To see which heritage documents your project is likely to need, enter your postcode on PlanScope.

This is general guidance, not legal advice, so check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.