Review of Approved Document B: Fire Safety

80. The introduction of provisions within Approved Document B for a second staircase to be provided within residential buildings above 18m supported the evolution of safety within new buildings. Through the consultation responses and wider engagement with the sector, industry and residents, there was clear support for the guidance to introduce a provision for evacuation lifts.  

81. Evacuation lifts for residential buildings are a recent technological innovation that may allow the independent evacuation of people who are unable, or may find it challenging, to use the stairs. Historically the guidance did not call for evacuation lifts, instead relying on a stay-put strategy and intervention from the fire and rescue service to assist with building evacuation.  

82. To align with the principle of inclusive design guidance, building design should consider the needs of everyone who may access and exit the building. In keeping Approved Document B up to date with current construction and design practices, and recognising that a range of industry and planning guidance already calls for evacuation lifts to be provided, BSR aims to align the guidance with these.  

83. The introduction of evacuation lifts will have a positive impact on society, especially for protected groups characterised under the Equalities Act 2010 for age, disability, pregnancy and maternity.  

84. BSR is proposing to introduce a new provision for evacuation lifts. Approved Document B will call for a minimum of two stairs and two evacuation lifts in all new residential buildings above 18m. Where a firefighting lift is already provided, the lift can have a dual function. 

85. Setting the threshold at 18m aligns with the threshold for the high-risk building regime. The threshold also algins with recent changes to the guidance, which come into force in September 2026, on the provision of a second staircase in residential buildings that are 18m or more in height.  

86. The draft introduces specific guidance around the height threshold for the inclusion of evacuation lifts in residential blocks of flats as well as provisions to support their safe use, and principles of evacuation lift design.  

87. Engagement with industry has highlighted a knowledge gap in the design of smoke control systems for buildings with complex footprints. Features such as second staircases and evacuation lift lobbies present challenges to the codified solutions in Approved Document B and may require more bespoke design approaches.  

88. This is why as part of the technical review, we intend to commission new research into smoke control approaches for blocks of flats. The objective will be to assess the current provisions as well as current practice to develop a more detailed, and transparent codified guidance on smoke control provisions.

89. Overall, the preferred policy option to introduce an 18m height threshold is estimated to provide a total present cost of £31.5 million over 10 years, with an equivalent annual net direct cost to business (EANDCB) of around £3.7 million. 

90. The options being explored: 

1. Option 1 (Preferred): Introduce a threshold of 18m+ above which evacuation lifts should be provided in residential buildings 

2. Option 2: Introduce a threshold of 11m+ above which evacuation lifts should be provided in residential buildings 

3. Option 3: Introduce a threshold of 18m+ above which evacuation lifts should be provided in residential buildings. For buildings above 30m+, mechanical smoke extraction systems should be provided.  

91. Across the 3 options, the total present cost to business varies from around £41 million for an 11m threshold. The EANDCB estimated is estimated around £4.8 million for an 11m threshold. 

92. All estimates are in 2025 prices and 2027 present values. The policy implementation period is 2027 to 2036. The costs and benefits of the policy are appraised over the lifetime of the building elements that are impacted by the changes. 

93. Under each policy option, developers will install evacuation lifts and associated provisions in any new tall residential building designed in accordance with Approved Document B. The policy options differentiate by the height threshold at which an evacuation lift must be installed, from 11m, 18m, 18m with mechanical ventilation above 30m, buildings. The costs covered are broken into 2 groups, annual costs and transition costs. 

Annual costs 

a. Capital cost of upgrading lift/s to an evacuation lift 

b. Capital costs of associated provisions 

c. Maintenance costs of the evacuation lift/s 

Transition costs 

1. Redesign costs 

94. The uplift in cost per building of the provisions is in the range of 0.1% and 0.2% of total build cost. The cost of the provision of evacuation lift/s is unlikely to impact the viability of high-rise buildings. It is unlikely to reduce the amount of affordable housing that can be provided by developers.

95. Benefits have not been monetised due to limited evidence. Instead, these are captured through illustrative analysis. Other non-monetised benefits have been detailed qualitatively. The main benefits of this policy are expected to be:

1. reduction in injuries and fatalities from fires for residents and risk to fire and rescue services

2. improved evacuation strategies for physically disabled residents, for instance, in cases of isolated fires, evacuation lifts can be used to avoid smoke inhalation 

3. wellbeing improvement due to reduced fear of future fires for residents and family members