The LWF Blog
Fire Engineering Design and Risk Assessment – Firefighting Shafts – Part 45June 10, 2019 12:28 pm
In LWF’s Fire Engineering blog series for Architects and others in the building design business, we have been looking at the subject of firefighting and what should be done to assist firefighting efforts. In part 44 of this series, LWF discussed the regulations in England and Wales relating to internal access for the Fire Service. In part 45, we will talk about the necessity for and design of firefighting shafts in buildings.
Firefighting shafts provide a protected area encompassing all floor levels of a building which gives protection from fire and smoke of two hours minimum for firefighters tackling a fire. The shaft will contain connectors for the rising main and will be ventilated with fresh air. The necessity of providing firefighting shafts in a building will be decided upon the basis of the guidance given in the relevant documents.
Approved Document B recommends a minimum number of firefighting shafts related to the largest qualifying floor area.
BS 9999, Section 6 states the following:
At least two firefighting shafts should be provided in buildings with a storey of 900 m2 or more in area and should be located to meet the maximum hose distances set out in (a) and (b) below.
(a) If the building is fitted throughout with an automatic sprinkler system in accordance with BS EN 12845, then sufficient firefighting shafts should be provided such that every part of every qualifying storey is no more than 60 m from a fire main outlet in a firefighting shaft, measured on a route suitable for laying hose.
(b) If the building is not fitted with sprinklers, then every part of every qualifying storey should be no more than 45 m from a fire main outlet contained in a protected stairway and 60 m from a fire main in a firefighting shaft, measured on a route suitable for laying hose.
Note 1. Qualifying storey means a floor with a height of more than 18 m, or basements more than 10 m in depth.
Note 2. In order to meet the 45 m hose criterion in (b), it might be necessary to provide additional fire mains in escape stairs. This does not imply that these stairs need to be designed as firefighting shafts.
Note 3. It is not necessary for lobbies to be provided to escape stairs solely to accommodate dry riser outlets. The riser outlets may be sited on landings or half-landings to the stair, provided that sufficient space is available for their use by firefighters without obstructing the opening of doors.
NFPA 5000, the U.S. publication, (https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=5000) which may be used in the UK when its requirements exceed those already laid out in national and local guidance, does not differentiate between escape staircases and firefighting shafts, which are known as smokeproof enclosures. In this guidance, each escape staircase would be considered suitable to undertake firefighting activities from.
In part 46 of this series, LWF will look at the general design considerations in Approved Document B and BS 9999 for firefighting shafts. In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.
Lawrence Webster Forrest has been working with their clients for over 25 years to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact Peter Gyere on 0800 410 1130.
While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.