The LWF Blog
Fire Engineering Design and Risk Assessment – Firefighting Shafts – Part 46June 17, 2019 1:07 pm
In LWF’s recent Fire Engineering blog series for Architects and others in the building design industry, we have been looking at Firefighting. In part 45, we looked at recommendations for the provision of firefighting shafts contained in Approved Document B and BS 9999. In part 46, we consider what those documents have to say on general design considerations for firefighting shafts.
Approved Document B and BS 9999 both contain information in relation to the provision and design of firefighting shafts in buildings and coincide with their recommendations overall. While an overview of the general standards can be helpful, the source documents should be read for design detail.
A firefighting shaft might consist of lobbies and a staircase within a protected enclosure and/or a firefighting lift. The shaft should serve every storey it passes through and be located in the building so that every part of every storey is no more than 60 m travel distance from the fire main outlet.
Only those services which are required for the firefighting shaft should be contained within the protected enclosure of the shaft and none may pass through. The shaft should not contain any cupboards or access to service shafts servicing the remainder of the building.
Firefighting lobbies and stairs contained within the shaft must have facilities for smoke control and have emergency lighting fitted and operational.
The lobbies in a firefighting shaft must have a clear floor area of not less than 5 m2. The floor area should not exceed 20 m2 for lobbies serving up to four lifts, and the basis for expanding on that for lobbies containing more than four lifts should be 5 m2 per lift. Principal dimensions should be not less than 1.5 m and should not exceed 8 m in lobbies serving up to four lifts, or 2 m per lift in those lobbies which serve more than four lifts. Lobbies are restricted in size to reduce the likelihood of inappropriate use, for ad-hoc storage for example.
In blocks of flats, or buildings containing flats, protected ventilated common corridors or lobbies are expected to protect the firefighting stairs without the need to provide additional dedicated ventilated lobbies. In circumstances where a firefighting shaft is pressurised, however, a lobby should be provided.
Entrance to a firefighting shaft at Fire Service access level (usually ground) should be available either from the open air or by way of a protected corridor not exceeding 18 m in length, reducing the distance firefighters have to travel. In circumstances where a corridor is required as part of the design, the corridor should be considered a part of the firefighting shaft and any access to the corridor from the accommodation should be by way of protected lobbies.
In part 47 of this series, LWF will continue to 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.