by Anthony Lymath
Designing for fire safety in construction can be a complex subject. Successive revisions to the Building Regulations over the past 30 years have tightened up rules and learned lessons from notable fires in public places, such as Summerland (1973), Bradford Football Club (1985), and Eastbourne Pier in 2014.
Although small-scale buildings such as individual dwellings are relatively simple, interpreting the rules for larger developments such as stadia, shopping centres and hospitals can require the services of a specialist consultant. Here we round up some key documentation and other issues that may need to be considered when planning the fire strategy of your next project. While not an exhaustive account, it gives guidance on issues to consider and sources of further information.
1. Approved Document B – Fire Safety
The Approved Documents give guidance on how to comply with the Building Regulations. Fire safety is covered by Approved Document B, which in 2006 was split into two separate sections:
- Volume 1 – Dwellinghouses
- Volume 2 – Buildings other than dwellinghouses
The two volumes are broadly similar in coverage and appearance, differing only to draw the distinction between the different building types. Volume 1 includes individual dwellings, and sheltered housing (where each individual unit is self-contained). Volume 2 covers everything else, but is assisted by supplementary guidance for special or complex building types such as healthcare buildings (see HTM 05-02, below). Volume 2 also covers houses in multiple occupation, flats and student accommodation. They both have five parts, covering:
- B1 Means of warning and escape – split into horizontal and vertical escape, i.e. moving across a floor of a building to a stairwell, and then vertical escape down that stair to a place of safety. Escape stairs need to lead directly to the outside without passing through another compartment.Every room needs to lead directly to a protected escape route, without passing through another room (in which case it is identified as an ‘inner room’).The exception to this is kitchens, laundry or utility rooms, dressing rooms or bathrooms, and cupboards (but not store rooms). Vertical circulation, where a building is likely to be used by persons in a wheelchair, must be provided with space on each landing of the protected escape stairwell, so that they can await assistance in safety. Elderly residential care homes have special provisions for phased evacuation known as ‘progressive horizontal escape’, whereby staff can move residents from one compartment to the next, without having to evacuate all residents simultaneously.
- B2 Internal fire spread (linings) – fire is propagated across flammable materials, and the risk (and rate) of the spread of flames across that material is restricted by this section of the Approved Document. Certain areas are required to achieve a higher performance than others, for example escape routes. Flames are spread largely via walls and ceilings, rather than floors, although furniture and fixtures can also play a part. See BS 476 and BS EN 13501 below.
- B3 Internal fire spread (structure) – this introduces the concept of ‘compartmentation’ of the building into smaller areas office-resisting construction, in order to restrict the spread of a fire. Typically, each floor will be regarded as a compartment, and that floor may be further subdivided. The vertical circulation shaft (containing lifts and stairs) is in effect another compartment, albeit spanning the building vertically. Its purpose is defined as a ‘protected route’. Another aspect of this section of the Approved Document is the prevention of cold smoke transfer. Small spaces such as the cavities in external walls also need to be enclosed at compartment boundaries (both horizontal and vertical) by fire-resisting material, to prevent the spread of fire from one storey to another.
- B4 External fire spread – not only should a building provide a reasonable degree of fire resistance internally, but it should also prevent an internal fire from spreading to another building.Boundary and external walls need to achieve a degree of fire resistance (insulation and integrity), depending on how close they are to neighbouring structures or property. This can be a particular issue for glass, and also where an external escape route passes immediately adjacent to a window, for example.
- B5 Access and facilities for the fire service – covers a range of measures that are designed to assist the fire service in attending to an emergency. A certain proportion of the perimeter of the building needs to be accessible to a fire appliance, and no part of the building should be out of reach of a fire hose.If this is likely to be impossible to achieve (such as in high-rise buildings), then ‘dry risers’ need to be installed vertically within the building, to allow the fire service to connect their tenders. Very tall buildings may also need dedicated firefighting stairways.
2. Regulatory Reform (Fire Safety) Order 2005
A statutory instrument in England and Wales that obligates those responsible for property (except individual domestic dwellings) to conduct a fire risk assessment and take reasonable steps to mitigate any risks identified. It replaced the fire certification required under the Fire Precautions Act 1971. In addition to the statutory instrument, the government published a set of sixteen guides to assist business owners, including guidance on conducting a fire safety risk assessment for a variety of different types of premises, ranging from transportation to entertainment, industrial to healthcare. The key feature of the Order is that it places responsibility for fire safety of premises on those individuals who are responsible for those premises in some way. Previously, the local fire safety officer would define their requirements for fire safety and firefighting equipment. In practical terms, a business owner will employ a suitably-qualified person to carry out their duties on their behalf; in the case of building design, this will normally involve the architect.
3. Fire safety in Adult Placements Code of PracticeThis Code of Practice was published in 2005 and gives guidance on fire safety in Adult Placement properties. These are defined as domestic dwellings of up to three storeys, where an Adult Placement Carer provides accommodation in their own home to a maximum of three vulnerable persons. In effect it identifies these private dwellings as being places of business, imposing similar duties and requirements such as designated fire escape routes, firefighting equipment and evacuation plans. Although the document was published before the Regulatory Reform (Fire Safety) Order, and now appears on the National Archives website, it is still listed on Planning Portal as a relevant document.
4. Building Regulations and Fire Safety Procedural Guidance
A document published by the government and available on the Planning Portal website, that acts as a guide to the steps needed to gain approval for fire safety aspects of construction work. It also explains how the Building Regulations interact with other statutory fire safety requirements, such as the Regulatory Reform (Fire Safety) Order. In addition to the Building Control Body, designers need to satisfy the Fire Safety Enforcing Authority in respect of the Order; this is typically the local Fire and Rescue Authority. The key difference to the previous procedure under the 1971 Act is that the Fire Safety Enforcing Authority now approves the fire safety design of others, rather than carrying out that design themselves.
5. BS 476-7
The British Standard that has dealt with the testing and measurement of combustibility of building materials. It measures the surface spread of flame of a material, grading the results from 1 at best to 4 at worst performance. While still current, it is likely to be withdrawn in future in favour of BS EN 13501-1 (see below).
6. BS EN 13501-1A Harmonized European Standard that is approximately the equivalent of BS 476-7, but applicable across the European Union. It is a more in-depth test, measuring the material’s performance in respect of combustion characteristics, flame spread, heat release, and toxicity of smoke. Each aspect of performance that is measured receives its own classification. At present it may be used as an alternative to BS 476 until such time as the older British Standard is withdrawn.
7. Fire engineering
As an alternative to following the guidance in Approved Document B, compliance can also be demonstrated by adopting a fire engineered solution. This can be particularly useful for very large or multi-use complexes such as shopping centres or airports. In these cases, compartmentation would lead to an excessively enclosed and restrictive layout, which may not be conducive to the light, open nature required to enable e.g. shoppers to navigate between different retailers. Employing a specialist consultant can lead to a more flexible and versatile scheme, where the ‘fire load’ is calculated and offset by measures such as drop-down smoke curtains, sprinkler systems and fire shutters that can isolate and contain a fire when detected.
Installing a sprinkler system can relax the performance requirements of certain aspects of the fire safety design. For example, fire resistance periods of structure can be reduced if a building is sprinklered. Sprinkler systems for residential buildings must comply with the requirements of BS 9251, whereas non-residential sprinkler systems are covered by BS 5306-2 (note that whereas this has been superseded by BS EN 12845, it is still cited in the Building Regulations at the time of writing). In addition to these, however, sprinklers may be demanded by other (non-statutory) sources such as buildings insurance companies. This is becoming more common as US finance companies are investing in the UK construction industry post-recession, and it should be ascertained what specific requirements they may demand – for example, they may or may not be required to comply with the British Standards referred to above.
9. Fire Sector Federation
The Fire Sector Federation is an industry body whose members include representatives from organisations involved in fire and rescue. The Federation takes part in consultation on changes to the Approved Documents in relation to fire safety design. It was formed in 2012 out of a merger between two preceding organizations, in response to the Fire Futures review of July 2010 by the Fire and Rescue Minister. This review changed the perspective from government-led control of fire and rescue services delivery, to industry-led policy shaping.
10. HTM 05-02
Part of the Health Technical Memoranda series, which provides guidance on fire safety design for healthcare buildings. Its purpose is to provide specific guidance that relates directly to healthcare premises, in order to demonstrate compliance with Part B of the Building Regulations. Produced by the Department of Health, it acts as a guidance document to assist in applying the requirements of Part B to healthcare premises, and its scope covers all types of healthcare buildings that are under the control and regulation of the Care Quality Commission.