Heritage statement vs heritage impact assessment

The short answer

In policy terms there is no difference. National Planning Policy Framework paragraph 200 requires applicants to describe significance and assess impact, proportionate to the asset's importance. Both 'heritage statement' and 'heritage impact assessment' satisfy that requirement. The label is a matter of local authority preference and, in practice, the depth of analysis required.

Where the terminology comes from

'Heritage statement' is the term used by most London boroughs on validation checklists. It descends from the heritage desk-based assessment tradition, where a single document accompanied an application and addressed both significance and impact.

'Heritage impact assessment' (HIA) is borrowed from international heritage practice, particularly the ICOMOS guidance on assessing impact on World Heritage properties (2011). In England, the term has been adopted by some local authorities and by Historic England as shorthand for a more detailed analysis, typically on higher-grade assets, large schemes or sites engaging multiple designations.

When each is appropriate

A heritage statement is the default for most applications affecting a listed building, conservation area or non-designated heritage asset in England. It is what the validation checklist usually asks for.

A heritage impact assessment is appropriate where:

• The asset is Grade I or Grade II*, where Historic England consultation will be triggered
• The application affects a World Heritage Site or its buffer zone
• The scheme is large enough that significance and impact need to be analysed across multiple receptors
• The local authority's pre-application advice has specifically asked for an HIA
• The application will be referred to the Mayor of London under the London Plan

How the structure differs in practice

Both documents share the same backbone: identification of the asset, statement of significance, description of the proposal, impact analysis, public benefits balance, policy framework, sources. The differences sit in depth and granularity.

A focused heritage statement on a Grade II rear extension might run to twenty pages, with a room-by-room significance summary and a paragraph of impact analysis per change. A heritage impact assessment on a Grade II* church conversion might run to eighty pages, with phased archival research, comparative analysis against similar buildings, and a setting analysis using Historic England's five-step methodology.

Both should reach a reasoned conclusion on the harm category (none, less than substantial at the lower or upper end, substantial), and both should engage explicitly with the public benefits relied on.

How asset grade affects the choice

• Grade II: Heritage statement, calibrated to the scale of works.
• Grade II*: Heritage statement or HIA, depending on the scale of works and the local authority's pre-application advice.
• Grade I: HIA, written to a standard that withstands Historic England scrutiny.
• Conservation area, unlisted: Heritage statement focused on character and appearance.
• Scheduled monument: HIA, with explicit engagement on archaeological significance.

What officers actually expect

Conservation officers in inner London boroughs (Westminster, RBKC, Camden, Islington, Tower Hamlets, Hackney) expect a heritage statement on every listed building application, however the document is labelled, written by someone with heritage credentials and engaged with the listing entry. The label matters less than the substance: evidenced significance, proportionate impact analysis, explicit policy engagement, a reasoned conclusion on harm.

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