Second staircases: which way now?
Matt Brook Architects’ innovative core design includes two fully separated staircases to achieve compliance with future regulations and deliver resident and firefighter safety as part of a highly efficient arrangement that drives value and viability.
During July 2023, the UK Government confirmed that all new residential buildings in England above 18m in height will require the provision of two staircases. This requirement will be active following the end of a 30 month transition period from the date of publication of the forthcoming amendment to Part B of the Building Regulations.
The National Fire Chiefs Council highlights that in the event of a fire, a correctly designed second staircase removes the risk of a single point of failure, buying critical time for firefighting activities, and providing residents with multiple escape routes. However, realising this safety benefit through the incorporation of a second staircase does reduce the quantum of sellable area within a building floorplate, affecting the value and potential viability of a development.
Matt Brook Architects’ unique two-stair core design embraces the forthcoming regulation changes, maximising the safety and accessibility benefits of a two-stair design whilst increasing the net/ sellable floorspace by circa. 5% over that of a typical two-stair floorplate arrangement. Variants of the core design have also been developed to respond to buildings across a range of heights; from the requirement through to and including those of 70+ storeys.
The core is based upon the provision of two interlocking, but independent, staircases arranged around a separating fire-rated wall, enabling two stairs to occupy a highly-limited footprint. The core within which the staircases are located is split into two halves by double doors located within the lift lobby. Typically, these doors are held open, but in the event of a fire they close, providing separation between each half.
This division of the core separates each staircase from another at the point of ingress/ egress on the floorplate but also means that each half also has its own fire and evacuation lifts as well as its own dedicated smoke ventilation system.
The core arrangement also provides all residents with the means to self-evacuate, negating the need for stairwell refuge points as well as enhanced firefighting provision and safety for firefighters by enabling two vertical wet risers to be provided in each staircase.
In addition to consultation with the Greater Manchester Fire Service during its development, the core has been reviewed by the Health and Safety Executive (HSE) as part of the pre-application process for the Regent Park project. In their pre-application advice note, the HSE noted the arrangement as being suitable, recognising that the design does not involve a scissor stair arrangement.
Further reading on the innovative core design can be found within the RIBA Journal’s print edition for November/ December 2023 as well as online.
RIBA Journal’s article in full can be read here.
