Meeting Building Regulations with Automist (AWFSS)

Meeting Building Regulations with Automist (AWFSS)

Automist is commonly used as a direct replacement for traditional sprinklers (BS 9251). There is a legal requirement to install fire sprinklers (or an equivalent Automatic Water Fire Suppression System (AWFSS)) into all new houses, flats, apartments and other types of accommodation that stand above 11 metres tall throughout the UK, and all new homes regardless of height in Wales. Care homes, registered group homes and sheltered housing also require suppression. There is no doubt that fire suppression systems save lives, reduce property damage and reduce the cost of restoration and rehousing after a fire.

Other typical applications for Automist

Automist conforms with BS 8458. It can be used to contain the fire within the room of origin and also to provide a 'compensatory measure' when other building features do not meet one of the functional building requirements, as explained in 4.2 of BS 9991.

‘Automatic water fire suppression system (AWFSS) The installation of an AWFSS can offer designers considerable flexibility. An AWFSS controls a fire to a small size, reducing the production of smoke and toxic gases and preventing the fire from spreading beyond the room or dwelling of origin. This means that there can be flexibility achieved in the design of the building.’

It is commonly used for permitted variations:

  • 6.5.2. Loft conversions 
    Open plan arrangements on the ground floor are permissible should AWFSS be installed throughout, in conjunction with a fire-resisting partition and door at first-floor level.
  • Multi-basement buildings 
    For dwellings with multiple floors below ground level, a protected stairway and an AWFSS, 9m metres should not be exceeded from the foot of the protected stair to any habitable room.
  • 6.3(c) Dwelling houses with one or more storeys greater than 4.5m in height (three storeys) 
    Open plan arrangements on the ground floor can be achieved on the condition that AWFSS are installed throughout the property in addition to a fire-rated partition and door at the first-floor level.
  • 6.4.(b) Dwelling houses with one or more storey greater than 7.5m in height (four storeys) 
    A second, separate protected stairwell is not required if AWFSS are fitted throughout.
  • 9.1(d) Internal Planning of Flats and Maisonettes 
    Flats or maisonettes with an open plan arrangement and more than one floor should have a protected stairway and AWFSS fitted. This allows escape to the shared external entrance.
  • 9.3(b) Provision of inner rooms in flats not more than 4.5 m in height.
    Inner rooms are not suggested unless the use of an AWFSS is utilised throughout the entire building, along with a grade D LD1 fire detection and fire alarm system in accordance with BS 5839-6:2013. 
  • 9.4.2(a) Extended travel distances within an open-plan flat.
    Flats more than 4.5m above ground level that are entered on the same level can increase total travel distances to the entrances from 9m to 20m with the use of an AWFSS throughout the entire building, along with an LD1 fire detection and fire alarm system in accordance with BS 5839-6:2013.
  • 9.5.2(d) Maisonettes with floors greater than 4.5m 
    No requirement to provide a separate means of escape if the maisonette has a protected stairwell and a fully fitted AWFSS.
  • 9.7 Open Plan Layouts 
    Open planned flats are permissible with a fully fitted AWFSS.
  • 11.1 Flats where occupants are not capable of independent evacuation
    It is possible to use provisions of an AWFSS where the use of the building is required for people not capable of independent evacuation (excluding common corridors and stairways.) It is further possible to protect common areas (excluding common corridors and stairways,) using provisions of an AWFSS where the use of the building is required for people not capable of independent evacuation.
  • 19.1.2 Vehicular Access 
    Access can be increased significantly if an AWFSS is installed and where the arrival time for the fire service is not more than ten minutes: - 90m for houses less than 4.5m in height. - 75m for houses/flats not more than one floor above 4.5m.
  • 23.1 Extra care housing
    Extra care housing must be fitted throughout with an AWFSS.
  • 23.2 Travel distances 
    If an AWFSS is fitted throughout a block of flats, then travel distances can be doubled on common escape from 7.5m to 15m and 30m to 60m
  • 29.4.2 Boundary Distance 
    Boundary distances can be reduced by 50% with a fitted AWFSS.

Are you allowed to use Automist in 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 cannot use others. BS 8458 prescribes a 45m building height 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.’

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.

  Keen to learn more? Explore some real-life examples where Automist was approved to meet building regulations

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 article 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 article. It should be noted that there may be specific additional requirements dependent upon local authority building regulations and/or fire authority.