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Are you allowed to use Automist in tall buildings over 11m?

Yes, Approved Document B includes the requirement for sprinklers in buildings over 11m. The guidance document prescribes one method of achieving the functional requirements of the building regulations but does not mean you can not use others:

‘because the approved documents cannot cater for all circumstances, variations and innovations.… Where the guidance in the approved document has not been followed… the person carrying out building works should demonstrate that the requirements of the regulations have been complied with by some other acceptable means or method.’ 

This replaces the 18m threshold, which was applicable before the 26th of November 2020.

BS8458 prescribes a 45m limit for residential category watermist systems without additional measures:

‘The category of system should be determined by the type of building as shown in Table 1, up to a maximum height of 45 m. If the type of building is not listed in Table 1, or for buildings over 45 m, then the AHJs should be consulted to agree which type of occupancy should apply, whether additional measures are needed (see 4.6) or whether an alternative system (e.g. DD 8489-1 3) or BS EN 12845) is more appropriate.’

Click here to learn more about the residential category for Automist. It is worth noting that BS 9991 refers to the use of BS 8458 systems in buildings up to 30m in Table 2, and BS 7974 can also be used to justify the use of Automist for specific applications over and above the recommendations of the guidance documents as part of a fire engineered solution.

Read more - Is there any fire engineering research that supports the use of Automist?

Disclaimer: This information is not intended to be a comprehensive guide to all of the aspects of the building regulations but rather a useful source of background information. Whilst every care has been taken to ensure that the contents of this document are correct at the time of publication, it should never be used as any form of substitution for the guidance documents. Plumis shall be under no liability whatsoever in respect to the contents of this document. It should be noted that there may be specific additional requirements dependent upon local authority building regulations and/or fire authority.