This guidance covers planning, site selection and aspects of building design that should be considered when planning any mental health units.

It supersedes Health Building Note 35 – ‘Accommodation for people with mental illness’, Part 1: ‘The acute unit’ (1996).

Published 20 March 2013.

Health Building Note (HBN) 03-01 gives guidance on the design and planning of acute mental health facilities. HBN 03-01 does not cover low and medium secure facilities. This supplement to HBN 03-01 highlights the key additional requirements for low and medium secure environments. It excludes acute nonsecure in-patient facilities as these remain as described by the parent HBN 03-01.

Much of the environmental and space requirements outlined in the main HBN 03-01, where relevant, will apply to low or medium secure units and are not repeated in this supplement.

The HBN 03-02 supplement for low and medium secure children and young people’s (CYP) facilities has been published at the same time as this document. It is essential that this supplement be read in conjunction with the HBN 03 series of publications.

Separate schedule of accommodation, activity and component schedules are provided.

Published 13 November 2023.