Building Regulations – Part B Fire Safety

Approved Document B Volume 1The Building Regulations Part B deal with fire safety and are divided into 2 sections. Volume 1 deals with dwelling houses and Volume 2 addresses fire safety in buildings other than dwelling houses.

For the purposes of definition, a dwelling house is a residential building shared by 6 people or less. The term dwelling house does not include flats or buildings containing a flat.

Part B Volume 1 – Dwelling Houses

B1 – Means of Warning and Escape

Makes provision for the early warning of a fire and an appropriate means of escape to a place of safety.

B2 – Internal Fire Spread (Linings)

Prevention of the spread of fire through the internal linings of the building, such as walls, ceilings and partitions.

B3 – Internal Fire Spread (Structure)

This section deals with the actual structure of the building to ensure that its stability is maintained for a reasonable period in the event of a fire.
Party walls should be adequately constructed so as to prevent the spread of fire from one building to another.
Where appropriate, measures must be taken to avoid internal spread of fire by sub-dividing large, open areas of a building with fire-resistant materials.
The spread of unseen smoke and fire within concealed spaces also needs to be impeded.

B4 – External Fire Spread

Measures must be taken in order to prevent the spread of fire over the external walls to other parts of the building as well as neighbouring properties.
The roof of the building should also be constructed in such a way as to prevent the spread of fire.

B5 – Access and Facilities for Fire & Rescue Services

The building design should make reasonable provision of facilities for fire and rescue services to gain access and t protect the inhabitants in the event of a fire.

Document B Volume 2 Buildings other than Dwelling Houses

Approved Document B Volume 2Volume 2 deals with other types of buildings including offices, public buildings, multi-story and industrial buildings as well as flats.

Because of the nature of these type of buildings, having multi-occupancy and a greater risk of fire, the regulatory requirements are much more thorough than for domestic premises. While damage to buildings can never be eliminated the regulations provide adequate measures ao as to minimize the potential loss of of life should the worse case happen.

B1 – Means of Warning and Escape

As with Volume 1, this section deals with early warning or fire and a safe means of escape. Volume 2 makes specific provision for multi-occupancy buildings and flats, the requirements being rather more demanding than for dwelling houses.

B2 – B2 – Internal Fire Spread (Linings)

Again this section deals with the internal linings of the building in relation to preventing the spread of fire.

B3 – Internal Fire Spread (Structure)

The prevention of the ability of fire to spread is particularly important for larger, multi-occupancy and multi-use buildings; hence the regulations go into some depth regarding measures to achieve this.

B4 – External Fire Spread

Prevention of the spread of fire across the external elements of the building as in Volume 1, but with particular regard to framed and multi-storey buildings as well as large roof areas.

B5 – Access and Facilities for Fire & Rescue Services

Depending upon the type and use of building, Section B5 deals with the provision of access and services for the Fire Services, such as suitable internal fire mains and equipment, as well as providing sufficient means of escape for the building’s occupants. There are special measure required, also, for the venting of heat and smoke from fires in basements.

3 thoughts on “Building Regulations – Part B Fire Safety”

  1. Is it permissible to allow for a means of escape through a window from a lower ground floor bedroom. the height of the cill is 900mm from the floor level, both inside and outside. Escape would be to a garden.

    • From the information given, yes. But you need to ensure the window is the correct size, at least 45 high x 45 cm wide.

      From the regulations document B1. Section 2

      Provisions for escape from the ground storey.
      2.3 (b). a means of escape must be provided with a window or door which complies with 2.8

      (abbreviated for clarity)

      …the window should have an openable area of at least 0.33 m2 and at least 450 mm wide x 450 mm high…

      …the bottom of the open area should be no more than 1100 cm above the floor…

      …the window should enable a person escaping to reach a place free from the danger of fire (ideally, outside and away from the building).

  2. Would part B volum2, B3 internal fire spread apply to the lack of roof compartmentation in a timber frame three storey building used as a hospital?

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