When is a Heritage Impact Assessment needed?
Since the Planning (Listed Buildings and Conservation Areas) Act 1990, owners must conduct a Heritage Impact Assessment before making any changes to listed buildings.Planning Policy Statement 5 states that:
Heritage Impact Assessments will always be required for the following:
Why is a Heritage Impact Assessment needed?
Understanding the significance of an historic building, complex or area (the ‘asset’) and the possible impact of the proposed scheme on this significance is the key to good conservation practice. Good information, available from the outset, can speed up the processing of applications, reduce costs and lead to better overall design.
If the significance of a site has been clearly understood from the outset (based on how the site has changed through time and what survives today), then both the applicant and the District Planning Authority can better understand the impact of the proposal and seek to minimise the impact of the proposal on that significance. Therefore it is important to understand the significance of a heritage asset when considering proposals to alter, demolish or extend the asset or develop within its setting. An early understanding of the significance will inform the direction of an application and help provide a clear and convincing justification of the proposal (as required by paragraph 132 of the NPPF).
The level of detail in the assessment will depend on the heritage asset and the extent of the proposal. The Heritage Impact Assessment should be written by a competent person.