Listed buildings – it's what's inside that counts

One question that crops up frequently in heritage and property law is deceptively simple: when a building is listed, does that protection apply to the whole building — or can it just apply to the exterior?

In reality, listed building protection is much broader than many owners realise. While eye-catching exteriors often grab the attention, the legal protection will extend to the whole building, including its interior. Original staircases, fireplaces, panelling and even seemingly modest historic features can all fall within the scope of listed building control.

That distinction matters. Understanding what is – and is not – protected can save owners from costly mistakes and help ensure that proposed works are approached in the right way from the outset.

It's not just about kerb appeal

The starting point is the Planning (Listed Buildings and Conservation Areas) Act 1990 ('the Act').

Under section 1 of the Act, the Secretary of State has a duty to compile lists of buildings of special architectural or historic interest, with a view to guiding local planning authorities in the exercise of their functions.

A 'listed building' is defined as any building included in those lists, and — crucially — the definition extends to any object or structure fixed to the building, and any object or structure within the curtilage of the building which has formed part of the land since before 1 July 1948.

The key protection is found in section 7 of the Act. Listed building consent is required for works involving the demolition, alteration or extension of a listed building where those works would affect its character as a building of special architectural or historic interest.

Notice what the legislation does not say. It does not distinguish between external and internal works.

The question is simply whether the proposed works would affect the building's special character. Removing an historic staircase, original panelling or period fireplaces can be just as significant as replacing windows or altering the roof.

In fact, when owners are notified that a building has been listed, the statutory notice makes clear that listed building consent may be required for works affecting the character of the building 'either to the exterior or the interior'. The legislation therefore treats both equally.

This is consistent with Historic England's guidance, which emphasises that listed building control applies to works affecting a building's special architectural or historic interest, whether those works are carried out internally or externally. 

Listed for the Façade – protected inside too?

There is a provision in the Act that mentions exteriors specifically, but it does not do what people sometimes assume.

When deciding whether to include a building in the list, the Secretary of State may take into account not only the building itself but also any respect in which its exterior contributes to the architectural or historic interest of any group of buildings of which it forms part.

In other words, a building can be listed partly because of the contribution its façade makes to a wider streetscape. But that consideration is relevant to the decision to list — it does not mean that the protection, once granted, is confined to the exterior. Once the building is on the list, the full statutory regime applies.

The Exception: when features are specifically excluded

There is a mechanism for limiting what falls within the listing, but it is a relatively narrow one.

A list entry can expressly state that a particular feature, object or part of the building is not of special architectural or historic interest and is therefore excluded from protection.

The important point is that any exclusion must be stated expressly and clearly.

The absence of any reference to a feature does not mean it has been excluded. Silence is not the same as exemption. It is dangerous to assume that the listing description includes everything that the listed buildings officer would be interested in.

The meaning behind 'interiors: not inspected'

Many older list entries, particularly those produced during large-scale listing exercises in the 1970s, contain the short phrase: 'Interiors: not inspected.'

Those three words cause a surprising amount of confusion.

Owners often assume that if the interior was not inspected, it cannot be protected. Unfortunately, it is not quite that simple. The phrase merely records a historical fact: the inspector who assessed the building for listing did not inspect the interior at the time. It does not limit the legal extent of the listing and it does not exclude the interior from protection.

Unless the list entry specifically says otherwise, the interior remains part of the listed building.

Why owners shouldn't ignore those three words

Although 'Interiors: not inspected' does not reduce the legal protection, it can still be highly relevant.

If the interior was never inspected, Historic England (or its predecessor body) cannot have assessed the significance of the building's internal features when it was originally listed.

Historic England's guidance has long recognised that list descriptions are not intended to be exhaustive. They identify features of particular interest and assist with identification of the building, but they are not a complete catalogue of everything that may contribute to its significance. The courts have adopted a similar approach. In Maxwell v Wiltshire Council, the court endorsed the principle that list descriptions may draw attention to features of particular interest or value, but they are not definitive — other features of importance, including interiors, may come to light after the building's inclusion in the list. 

So, when a list entry states that the interior was not inspected, the message should not be interpreted as 'there is nothing important inside'. Instead, it often means the opposite: nobody has yet had the opportunity to assess what might be there.

What this means before you start any works

For owners, buyers and advisers, there are a few key takeaways:

• Listed building consent may be required for works affecting the character of the building, whether those works are internal or external.

• Just because an interior feature is not mentioned in the list entry does not mean it is unprotected.

• If the list entry states that interiors were not inspected, it is often sensible to seek pre-application advice from the local planning authority (and, where appropriate, Historic England) before undertaking internal works.

• Carrying out unauthorised works to a listed building is a criminal offence, whether those works are carried out inside or outside the building, and can result in substantial fines and, in serious cases, imprisonment