The Fire Safety Characteristics of PBSA

Purpose-built student accommodation (PBSA) is one of the fastest-growing residential building types in the UK. It presents a distinctive combination of fire safety characteristics: high occupancy densities, predominantly young occupants unfamiliar with the building, significant variation in occupancy patterns (full during term time, partially occupied in vacation periods), and a diverse mix of unit types from en-suite studios to cluster flats sharing kitchen and living areas.

The Applicable Standards

Fire strategies for PBSA are primarily developed against BS 9991 (for residential buildings) and Approved Document B. The residential nature of PBSA means that the same general principles apply as for blocks of flats — compartmentation between units, protected means of escape, and adequate fire detection and warning throughout. However, PBSA has specific characteristics that require tailored fire strategy design.

Evacuation Strategy for PBSA

One of the most significant fire strategy decisions for PBSA is the evacuation strategy. Unlike traditional blocks of flats — where stay-put is the standard approach — PBSA is often designed for simultaneous evacuation. This reflects the characteristics of the occupant group: young people who are likely to respond positively to evacuation alarms, unfamiliarity with the building and its fire compartmentation, and the potential for social gatherings that create unpredictable occupancy patterns.

Simultaneous evacuation of large PBSA buildings requires careful attention to escape route capacity and the management of large numbers of people evacuating simultaneously. The fire strategy must specify escape route widths, exit discharge arrangements and the management procedures for evacuation.

Cluster Flat Arrangements

Many PBSA developments use cluster flat arrangements — individual study-bedrooms each forming a separate compartment, arranged around a shared kitchen and living area. The compartmentation between study-bedrooms and the shared areas is critical: the fire strategy must specify fire-rated construction between bedrooms and corridors, and self-closing fire doors to each bedroom.

Higher-Risk PBSA Buildings

For PBSA buildings over 18 metres, the higher-risk building requirements of the Building Safety Act 2022 apply — Gateway 1 fire statement at planning, Gateway 2 BSR approval before construction, and ongoing building safety case requirements once occupied. PBSA over 18 metres is one of the most common types of higher-risk building development in UK cities.