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Comparison

Conservation Area Appraisal vs Heritage Impact Assessment

Reviewed by
Oliver Wakefield-Smith
Founder, Digital Signet
Last reviewed 22 June 2026 · Refreshed quarterly
Direct answer
CAA or HIA?

A Conservation Area Appraisal (CAA) is an LPA-authored document describing what makes a whole conservation area special. A Heritage Impact Assessment (HIA) is an applicant-authored document describing the impact of a specific proposal on a specific asset. They are not substitutes , an HIA for a site in a conservation area should cite the CAA as evidence, not replace it.

Who produces each

  • CAA: the LPA, often with a heritage consultant. Subject to public consultation. Periodically refreshed.
  • HIA: the applicant or their consultant. Submitted with the application. Not consulted on.

How to cite a CAA inside an HIA

Quote the CAA's character-area description for the part of the conservation area where the site sits. Cross-reference the CAA's identified key views. Where the CAA identifies the site itself as a positive contributor, that is your starting position for the significance assessment. Where the CAA identifies the site as 'neutral' or 'negative', you have more room to argue improvement as a public benefit.

When no CAA exists

Construct a proportionate character description using HEAN 7 as the methodological template and cite primary sources directly (historic OS maps, listing descriptions, archival photographs). State explicitly in the HIA that no published CAA exists.