Fire safety: Approved Document B

This guidance note outlines the revisions to Approved Document B which come into effect on 6 April 2007 and is based upon information available at the time of issue and may be subject to change. The Approved Documents should be consulted for full details in any particular case.

General

Approved Document B has been split into two volumes. Volume 1 deals with dwellinghouses, Volume 2 deals with buildings other than dwellinghouses.

Volume 1: dwellinghouses

Introduction:

• Residential sprinklers: The use of sprinkler systems in accordance with BS 9251:2005 is recognised.
• Certification schemes: Suitable schemes may be accepted by Building Control Bodies as evidence of compliance.
• Adult placements: Reference is made to the code of practice for fire safety in adult placements.

B1 Means of warning and escape

• Fire alarms: The guidance on smoke alarms has been amended such that alarms should be installed in accordance with BS5839- 6:2004. Simple guidance has been retained, in the form of a commentary on this standard, so that most users of the Approved Document will not necessarily need to obtain a copy of the standard. All smoke alarms should have a standby power supply. Where a dwellinghouse is extended smoke alarms should be provided in the circulation spaces.
• Means of escape: The guidance on means of escape has been restructured to enable easier use.
  • Additional guidance has been provided in relation to work on existing houses.
  • Locks and child resistant safety stays may be provided on escape windows.
  • The alternative approach for loft conversions to two storey houses has been removed ie escape windows and roof lights.
  • New guidance has been provided on the provision of galleries and inner inner rooms
  • An option of providing sprinkler protection instead of alternative escape routes has been included for dwellinghouses with a floor more than 7.5m above ground level.
  • Guidance on the application of B1 to replacement windows has been included.
  • Guidance on the use of air circulation systems in houses with protected stairways is given.

B3 Internal fire spread (structure)

• Integral garages: The provision of a sloping floor has been included as an alternative to the 100mm step between dwellinghouses and integral garages.
• Compartmentation: Guidance on the junction between compartment walls and roofs has been clarified and expanded.
• Cavity barriers: Window and door frames are only suitable for use as cavity barriers if they are constructed of steel or timber of an appropriate thickness.

B4 External fire spread

• Roof Coverings: The guidance on roof coverings incorporates the new European system of classification as set out in BS EN 13501 - 5:2005.

B5 Access and facilities for the fire service

• Vehicle Access: There should be access for a pump appliance to within 45m of all points within a dwellinghouse.

Appendix B

• Self Closing Devices: Other than doors between a dwellinghouse and an integral garage fire doors need not be provided with self closing devices.

Volume 2: Building other than dwellinghouses

General

• Regulation 38 has been introduced to ensure that sufficient information is recorded to assist the eventual owner/occupier/employer to meet their statutory duties under the Regulatory Reform (Fire Safety) Order 2005.

Introduction

• Management of premises: New guidance is given on the need to ensure that management regimes are realistic.
• Certification schemes: Suitable schemes may be accepted by Building Control Bodies as evidence of compliance.
• Residential sprinklers: The use of sprinkler systems in accordance with BS 9251; 2005 is recognised.
• Alternative approaches:
  • HTM 05 "Firecode" should be used for the design of hospitals and similar health care premises.
  • BB100 should be used for the design of schools.

B1 Means of warning and escape

• Fire alarms in flats: The guidance on smoke alarms in flats has been amended such that alarms should be installed in accordance with BS 5839- 6:2004. Simple guidance has been retained, in the form of commentary on this standard, so that most users of the Approved Document should not need to obtain a copy of this British Standard.
  • All smoke alarms should have a standby power supply.
• Fire alarms: The guidance for buildings other than dwellings has been updated to take account of the 2002 edition of BS 5839-1.
• Means of escape:
  • Locks and child resistant safety stays may be provided on escape windows.
  • New guidance has been provided on the provision of galleries and inner inner rooms.
  • Additional options of providing sprinkler protection and/or a protected stairway instead of alternative escape routes has been included for flats with more than one storey.
  • Guidance on the use of air circulation systems in flats with protected entrance halls or stairways is given.
  • The provisions for smoke control in the common areas of flats have been changed.
  • Guidance on means of escape in buildings with open special planning has been included.
  • A method has been provided for calculating acceptable final exit widths for merging escape routes at ground floor level.
  • Guidance on the provision of cavity barriers associated with subdivided corridors has been moved to Section 3 and clarified.
  • Guidance applicable to small premises, previously in BS 5588-11, has been incorporated into the text.
  • New guidance on the design of residential care homes has been given including the use of sprinklers and/or free swing door closing devices. Greater flexibility is also given where sprinkler systems are provided.
  • Guidance on means of escape for disabled people has been incorporated in the general guidance on means of escape.
  • In tall buildings with phased evacuation consideration needs to be given to the interaction of firefighters with people attempting to evacuate the building.
  • More detailed guidance has been provided on the protection of ventilation systems.

B3 Internal fire spread (structure)

• Compartment Walls: The predicted deflection of a floor, in the event of a fire, should be accommodated in the design of compartment walls.
• Sprinkler protection in flats: Sprinkler systems should be provided in blocks of flats exceeding 30m in height.
• Warehouses: A maximum compartment size has been introduced for unsprinklered single storey warehouse buildings.
• Concealed spaces: This section has been completely restructured. Table 13 (AD B 2000) has now been incorporated into the text to reduce confusion.
• Openings: Window and door frames should only be regarded as cavity barriers if they are constructed of steel or timber of an appropriate thickness
• Under floor voids: Extensive cavities in floor voids should be subdivided with cavity barriers.
• Fire dampers: Guidance on the specification and installation of fire dampers has been provided.
• Car parks: Non combustible materials should be used in the construction of a car park for it to be regarded as "open sided" for the purposes of establishing the necessary period of fire resistance. Other car parks should achieve the standard period of fire resistance.

B4 External fire spread

• Notional boundaries: Space separation should be considered where more than one building is on the same site but operated by different 'organisations'.
• Roof coverings: The guidance on roof coverings incorporates the new European system of classification set out in BS EN 13501-5:2005.

B5 Access and facilities for the fire service

• Private hydrants: A building with a compartment of 280m2 or more, constructed more than 100m from a highway should be provided with suitable hydrants.
• Vehicle access: There should be access for a pump appliance to within 45m of all points within a dwelling or a suitable fire main should be provided.
• Firefighting shafts: Assembly buildings with a floor exceeding 900m2, with a floor over 7.5m above ground level, should be provided with firefighting shafts.
• Hose distances: In unsprinklered buildings every part of every storey over 18m in height should be within 45m of a fire main outlet.
• Self-closing devices: Fire doors within flats need not be provided with self-closing devices.

Appendix C

• Occupant capacity: The floor space factors table has been updated and moved to this Appendix.
• Door width: The method of measurement for door widths has been changed to align with Approved Document M.
• Smoke ventilators: Guidance is given on the measurement of free area for smoke ventilators

Appendix G

• Fire safety information: This new Appendix provides guidance on the requirement for fire safety information to be recorded and passed on to the 'responsible person'.

Useful links

• Part B fire safety on the planning portal
• Fire safety: Approved Document B on GOV.UK