The LWF Blog
Fire Engineering Design and Risk Assessment – Sprinkler Design Codes – Part 12September 13, 2017 11:24 am
In this Fire Engineering Design and Risk Assessment blog series by LWF for Architects and others in the building design business, we have been discussing sprinklers and the design codes affecting installation and use. In Part 11, it was noted that there may be areas of a building in which sprinklers are not advisable but that in these cases, suitable alternative protection must be provided.
With that in mind, most design codes lay out the need for protection throughout a building, as well as any connected buildings and any neighbouring sites which are in close proximity. Where connecting or closely positioned buildings are not suitably protected, it will be necessary to further protect the original structure from the additional risk of the unprotected building.
While this additional protection is usually provided in a structural manner, it is not uncommon to see drencher systems used externally to make sure that fire cannot pass between the two buildings.
While codes give prescriptive solutions to such problems, a fire engineered approach will differ in that it approaches the situation through assessment of circumstances such as fire load, the level of fire-resistant construction and the risk of fire spreading. Through this method, it is possible to pinpoint the risk areas and use sprinklers for protection.
Where buildings are to have areas which are sprinklered and those which are not, it is important that suitable compartmentation is implemented between those areas, or indeed that areas without fire load are used to provide virtual compartmentation. One such example would be railway platforms.
When considering the protection of a building, it may be that there are areas which would not be safe if sprinklers were to be in use, such as working areas where metal would be melted or in some kitchen environments. In these cases, it is essential that the risk of the non-sprinklered area is mitigated and a suitable solution chosen to ‘fill the gap’. It may be that a gaseous or water mist system is required, or, depending upon circumstances, separation by fire-resisting construction may be sufficient.
Of course, while each unsprinklered area must be considered fully, there may be areas of the building where sprinklers are not required due to a lack of fire load. Most commonly, these might be toilets, lifts and stairways. In each case, fire-resistant construction should be employed to avoid the fire spreading through these unprotected areas.
In the area between the protected (sprinklered) area and the non-protected area, there may be a need to install cut off sprinklers. These units are positioned above windows, doorways or other potential apertures on the unprotected side to improve fire-resistance and separation.
In part 13 of this series, we will look at the hazard classifications of risks which enable them to be suitably matched with sprinkler systems. 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 020 8668 8663.