Internal works to a listed building: when consent is needed, and how to prove it isn't

Internal works to a listed building need listed building consent whenever they would affect its character as a building of special architectural or historic interest. Listing covers the inside as well as the outside. If you believe the works fall below that line, you can ask the council to confirm it in writing.

That written confirmation is a Certificate of Lawfulness of Proposed Works. For a borderline internal change, it settles the question before work starts.

What is the legal test for internal works?

Section 7 of the Planning (Listed Buildings and Conservation Areas) Act 1990 restricts works "for the demolition of a listed building or for its alteration or extension in any manner which would affect its character as a building of special architectural or historic interest", unless they are authorised.

The test draws no line between interior and exterior. It asks one question: would this work affect the building's special interest?

Carrying out such works without consent is an offence under section 9. Our post on what happens if you alter a listed building without consent sets out the consequences.

Is the interior protected if the list entry doesn't mention it?

Yes. The Act protects the listed building, not just the features its list entry describes. Under section 1(5), any object or structure fixed to the building is treated as part of it. So is any curtilage structure that has formed part of the land since before 1 July 1948.

A list entry can leave things out, but it has to say so. Section 1(5A) allows an entry to state that an attached object or curtilage structure is not part of the building, or that a part or feature is not of special interest. An entry that is silent about a staircase, a fireplace or a run of panelling has excluded none of them.

Which internal works commonly need consent?

Council guidance gives a practical list. North Hertfordshire District Council's advice for listed buildings says:

"Adding new partitions or openings and blocking up existing openings or by removing and replacing historic fittings such as historic fitted cupboards, fireplace surrounds, a staircase or window shutters will require Listed Building Consent."

The same guidance notes that "small-scale like-for-like repairs and regular maintenance do not normally need consent."

A pre-design checklist for internal works

Before treating an internal change as minor, check:

• Does it add or remove a partition, or form or block an opening?
• Does it remove or replace a historic fitting: a fitted cupboard, a fireplace surround, a staircase, shutters?
• Does it alter how the rooms relate to one another?
• Does it touch anything fixed to the building, or a curtilage structure in place before 1 July 1948?
• Does the list entry expressly exclude the part you are changing?
• Is it truly like-for-like repair, with matching materials and no change of form?

If the answer to any of the first four is yes, assume consent is needed until the evidence shows otherwise.

How do you prove internal works don't need consent?

Apply for a Certificate of Lawfulness of Proposed Works. The procedure sits in sections 26H and 26I of the 1990 Act, added by the Enterprise and Regulatory Reform Act 2013.

Under section 26H, works are lawful "if they would not affect the character of the listed building as a building of special architectural or historic interest." If the council is satisfied of that, it must issue a certificate; otherwise it must refuse. Certified works are conclusively presumed lawful, provided they are carried out within 10 years of the date of issue and the certificate is not revoked.

According to the Planning Portal's guidance on these applications, you need to provide:

• a detailed description of the works, including existing and proposed materials and finishes, and the parts of the building affected;
• your reasons for believing the works do not affect the building's special interest;
• a plan identifying the listed building;
• a statement of your interest in the building;
• the building's grade.

Four points from the same guidance matter in practice:

• The burden is yours. The applicant must provide the evidence. The council may refuse if it has reasonable grounds to doubt the claim.
• It cannot be used after the event. A certificate cannot be sought for works already carried out.
• It is not a Lawful Development Certificate. It sits within the listed building consent regime. It does not remove any need for planning permission.
• Accuracy is enforced. Under section 26J, giving false or misleading information, or withholding material information with intent to deceive, is an offence. A certificate obtained that way can be revoked.

Consent, certificate or pre-application advice: which route fits?

• Listed building consent: authorisation for works that would affect the building's special interest. Use it when the works will change significant fabric, fittings or plan form.
• Certificate of Lawfulness of Proposed Works: a formal finding that the works do not need consent, presumed lawful for 10 years. Use it when you believe the works fall below the line and want that in writing before you start.
• Pre-application advice: the council's view before you choose a route. Use it when you are genuinely unsure which side of the line the works fall.

The Planning Portal notes that discussing a proposal with the council first is often helpful, and that most councils publish how to request this. Pre-application advice is a view, not a determination.

What evidence makes either application stronger?

Both routes turn on the same question: what makes this building special, and does the work touch it? The answer comes from dating and assessing the fabric you plan to change.

For a consent application, policy HE5 in Chapter 20 of the National Planning Policy Framework (NPPF) expects proposals affecting heritage assets to be accompanied by an assessment of their significance, with the level of detail proportionate. A certificate application needs the same reasoning, made in the opposite direction.

That reasoning is what a Statement of Heritage Significance sets out. Our guide to the Statement of Heritage Significance explains what it covers.

Where does HeritageAI fit?

The Preliminary Planning and Heritage Appraisal (PPHA) is a quick first read for a building. HeritageAI generates it automatically from the details you provide and sends it by email. Where you give a list entry number, the listing is checked against the National Heritage List for England.

It sets out what is listed, what is protected, and which consents are likely to apply. It is not professional advice, and it is not individually reviewed by a person before it is sent. The judgement about a specific internal change stays with your practice.

You can see what one looks like in the Old Posingford sample PPHA.

What this means for your practice

• Read the building, not just the entry. A silent list entry excludes nothing.
• Run the checklist before you draw. Partitions, openings, fittings and plan form are the usual triggers.
• Choose a route deliberately. Apply for consent, or apply for a certificate if you are confident the works fall below the line.
• Keep the certificate on the project file. Its protection lasts 10 years from issue.
• Never rely on a certificate after the fact. It cannot cover works already done.

When should you bring in a heritage professional?

If you cannot date the fabric you are about to change, you do not yet know whether the works need consent. That is the point to commission a significance assessment or bring in a heritage consultant, before the drawings fix the scheme.

For how an architect makes these calls room by room on a real building, read the companion piece on judging a listed interior, at SOANE.

Book a 30-minute call with Giles to run a first read on one of your own projects.