The LWF Blog
Fire Engineering Design and Risk Assessment – Firefighting Shafts – Part 48January 16, 2020 5:36 pm
In LWF’s Fire Engineering blog series for Architects and others in the building design business, we have been discussing firefighting and the associated provisions that should be made for the Fire Service to attend and perform firefighting tasks as required. In part 47, we began to look at those general considerations which are incorporated in NFPA 5000. In part 48, we continue from that point by discussing smokeproof enclosures – most commonly referred to as firefighting shafts in the reference and guidance documents used in the UK – Approved Document B and BS 9999.
Access to a smokeproof enclosure should be gained through a vestibule or an exterior balcony only, unless the smokeproof enclosures consist of a pressurised enclosure. Each vestibule should have an area of not less than 16 ft2 of opening in an exterior wall facing an exterior court, yard or public space not less than 20 ft in width. Each vestibule should have a minimum dimension of not less than the required width of the corridor leading to it and a dimension of not less than 72 inches in the direction of travel.
In cases where a vestibule is used, it should be within the 2-hour rated enclosure and should be considered a part of the smokeproof enclosure.
Each smokeproof enclosure must discharge into a public way, a yard or court having direct access to a public way or into an exit passageway which only provides access to a public way (there should be no other openings in the passageway). The passageway must also be constructed as a separate fire resistant compartment from the rest of the building and have a 2-hour resistance rating.
It should be noted that the guidance given in NFPA 5000 is produced in the U.S. and therefore can only be used and accepted by the authorities outside of the U.S. if the guidance provided in that country is less onerous.
Although some of the recommendations and requirements given in Approved Document B, BS 9999 and NFPA 5000 are exacting, for most purposes they are considered necessary. However, there are a few exceptions where they might be considered too onerous for practicality which will be touched upon where they relate in future blogs.
In part 49 of this series, LWF will begin to look at the provision of firefighting shafts and the recommendations relating to them in the guidance documents. 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.