Sprinklers in UK fire codes

All the major Government published documents describing methods of designing buildings to safeguard life in buildings in the event of fire: Approved Document B; Scottish Technical Handbook 2022 and Technical Booklet E in Northern Ireland allow the use of life safety sprinklers in buildings. In some instances, the use of life safety sprinklers is mandatory. BS 9999 also makes provision for their use. Note that, since 2014, a separate version of Approved Document B has existed for Wales.

Where sprinklers operate on the exploding bulb principle, the sprinkler head activates when the fluid expands under the effects of rising temperatures and breaks the glass. Only the sprinklers in the vicinity of the fire are activated. Around 60% of fires are supressed by the activation of no more than four sprinkler heads. Further information on the operating principles for automatic sprinklers and their efficiency at controlling and extinguishing fires can be found at the British Automatic Fire Sprinkler Association website.

• 
• 

Sprinklers in UK fire codes and standards

The emphasis placed on the use of sprinklers in buildings in fire codes and standards varies between Approved Document B; Scottish Technical Handbook 2022 , Technical Booklet E and BS 9999.

For dwellings and residential buildings, guidance on the installation of life safety sprinklers is given in BS 9251. For non-residential buildings or dwellings and residential buildings outside the scope of BS 9251, the requirements of BS EN 12845 should be followed.

Concessions for sprinkler use

Concessions in terms of fire precautions when life safety sprinkler systems are installed in new buildings can take a variety of forms. Most commonly sprinkler installation can be used to justify reductions in periods of fire resistance for the building, modifications to escape travel distances and number of fire escapes. This section describes concessions that are available in the four most common documents which prescribe design fire precautions in buildings in the UK. These regulatory concessions do not include solutions that might be developed as part of a fire engineered solution for a building.

Concessions in Approved Document B

Approved Document B allows a 30 minute reduction in fire resistance requirements for most buildings under 30 metres in height when life safety sprinkler systems are installed

The following is a list of the concessions that may be invoked where an appropriate life safety sprinkler system is installed:

• In residential homes, fire doors need not be self-closing and changes may be made to the occupancies of safe areas (Section 2.46)
• Restrictions on the area allowed for raised storage are removed (Section 7.7)
• Allowable maximum dimensions of a compartment in a building are increased (Table 8.1)
• A building in a boundary condition does not need to be designed for base fixity (Section 13.15)
• Where a buildings is in a boundary condition, the boundary distance ...can be halved, to a minimum distance of 1m. Alternatively, the amount of unprotected area can be doubled (Section 13.21).
• For buildings requiring fire fighting shafts, the number can be reduced in certain circumstances (Section 17.8)
• Mechanical extraction may be used instead of natural ventilation in basements (Section 18.11)

The specific provisions for fire resistance for most fire resisting elements, including the structural frame, can be reduced by 30 minutes in many buildings under 30 metres in height (Tables B3, B4).

Concessions in Technical Handbook 2022

Life safety sprinklers are not mandatory in most buildings in Scotland, with the following exceptions: enclosed shopping centres; residential care buildings; sheltered housing complexes; school buildings; a building containing flats or maisonettes; social housing and shared multi-occupancy residential buildings.

Allowable compartment or storey floor areas can be doubled in most buildings if an automatic fire suppression system conforming to the LPC Rules for Automatic Sprinkler Installations are followed. As fire resistance periods increase with larger floor areas, the introduction of automatic fire suppression systems and the doubling of limiting floor areas may mean that a lower period of fire resistance is required.

SCI P313 makes the following statement on design for base fixity for single storey buildings in fire boundary conditions: In Scotland, relaxations on boundary conditions are permitted if the building is fitted with a sprinkler system....The Technical Handbook does not state explicitly that fitting sprinklers removes the need to design the column foundations to resist overturning....it is up to the local authorities to grant relaxations to the regulations on an individual basis.

Concessions in Technical Booklet E

Concessions are broadly similar to those in Approved Document B:

• The specific provisions for fire resistance for most fire resisting elements, including the structural frame, can be reduced by 30 minutes in many buildings under 30 metres in height (Tables 4.1, 4.2)
• Restrictions on the area allowed for raised storage are removed (Section 4.14)
• Allowable maximum floor areas of a compartment in a building are increased (Table 4.4)
• Where a buildings is in a boundary condition, the thermal radiation intensities ....and the distances .....may be halved subject to there being a minimum distance of 1 m. Alternatively, the amount of unprotected area may be doubled if the calculated boundary distance is maintained (Section 5.13)
• For buildings requiring fire fighting shafts, the number can be reduced in certain circumstances (Section 6.4)
• Mechanical extraction may be used instead of natural ventilation in basements (Section 6.16)

Concessions in BS 9999

BS 9999 generally allows more attractive concessions for automatic sprinkler installation and automatic fire detection than are generally available in Approved Document B or Technical Booklet E. The provision of an automatic fire suppression system permits a reduction in fire growth rate, allowing longer travel distances, smaller doors, larger compartments and reduced fire resistance periods.

Further reading

• Sprinklers for safety: the use and benefits of incorporating sprinklers in buildings and structures. The British Automatic Fire Sprinkler Association.
• Assessing the role for fire sprinklers. The Business Sprinkler Alliance and Bureau Veritas.

Resources

• Steel construction - Fire Protection supplement, 2013
• SCI P313 Single storey steel framed buildings in fire boundary conditions. 2002

See also

• Fire protecting structural steelwork
• Single storey buildings in fire boundary conditions
• Structural fire engineering
• Structural fire resistance requirements

External links

• British Automatic Fire Sprinkler Association

CPD

• Design for fire
• Fire engineering seminars 2013