Last reviewed 13 July 2017

Mike Sopp looks at British Standard (BS) 5839 and the importance of selecting an appropriate fire detection and alarm system.


Afire detection and alarm (FD&A) system gives a fast response to a fire situation and can greatly reduce the risk to life and limit damage to property. To achieve these objectives, it is essential that the system is selected and specified so as to reflect the fire risks associated with the property using best industry practice.

This will typically be in the guise of BS 5839 Fire Detection and Fire Alarm Systems for Buildings, which contains detailed information on various system categories.

However, as the Fire Industry Association (FIA) notes, “there still remains confusion, particularly among users, specifiers and fire risk assessors, regarding the application of these categories and the responsibility for specifying the appropriate category for any building”.

Systems and risks

For new builds and refurbishments, designers under the Construction (Design and Management) Regulations 2015, must eliminate, reduce or control risks through good design practice.

Most importantly, they should be meeting the statutory requirements under the relevant Building Regulations, which include a requirement for buildings to be designed and constructed “so that there are appropriate provisions for the early warning of fire”.

For existing (occupied) buildings, the responsible person under the Regulatory Reform (Fire Safety) Order 2005 (or its equivalent) is required to ensure that appropriate fire detection and alarms are installed commensurate with the fire risks. Therefore the responsible person must ensure systems remain relevant in the event of any significant change to property use.

The fire risk assessment process will play a significant role in meeting these requirements, particularly for the responsible person to meet their duties under the Reform Order where the assessment should be informing the responsible person of the general fire precautions required (including detection and alarm needs).

However, Approved Document B notes that although the requirement to undertake a fire risk assessment is for premises while in operation, “it would be useful for the designers of a building to carry out a preliminary fire risk assessment as part of the design process”.

Clearly from the above, any system must be specified so that it is commensurate with the risk of fire as determined through the assessment using best practice to identify system requirements.

In this case best practice would be BS 5839-1:2013 Code of Practice for Design, Installation, Commissioning and Maintenance of Systems in Non-domestic Premises, which contains details of various categories of system for a number of building types.

Specification determination

BS 5839-1 states that it “does not recommend whether or not a fire detection and fire alarm system should be installed in any given premises”, rather it details the type of systems that can be considered.

The need for a system in any specific building will normally be determined by the authority responsible for enforcing fire safety legislation and/or by a fire risk assessment carried out by the designer, owner, landlord, occupier or employer, as appropriate.

Guidance from the FIA notes that a reference to BS 5839-1 in any documentation, such as a specification tender document, fire risk assessment recommendations, building control application or insurance survey should make reference to the category of system, otherwise, as BS 5839 notes, it will have “little meaning”.

It continues by stating that the decision for determining the appropriate system category for any application “rests with the fire safety specialist rather than the fire alarm system specialist” even though it is recognised that alarm systems specialists may have the expertise to do this.

The fire safety specialists referred to are detailed in the FIA guidance document Selection and Specification of Fire Alarm Category in Accordance with BS 5839-1, and reflect the legal position, as they identify the following as specialists.

  • Building designers.

  • Building control and enforcing authorities.

  • Fire safety consultants and fire risk assessors.

Within the BS 5839-1 categories, a number of systems enable some level of flexibility as to coverage (namely L2, L3, L5 and P2) in terms of rooms or areas to be protected and types of detectors to be installed. Therefore, when specifying these categories, the specification should include this more detailed information.

There may also be occasions when variations are made from the recommendations made in BS 5839-1. In such circumstances, these should be highlighted in the specification for the system and made known to all relevant parties.

Once a system is agreed and/or approved, it is for the system purchaser (or their agent) to pass on the necessary specification information onto the alarm systems specialists so that they can then design the system.

The FIA guidance notes this but also states that commonly this does not occur as a result of a lack of understanding on the part of users and specifiers of the necessary process. It therefore recommends that designers make the above clear of the category of system that is proposed prior to an order for the system being placed.

It also suggests that contractors “protect their liability by recommending to purchasers that before placing an order for the system, they should seek further advice from a competent person or the relevant enforcing authority to ensure that the system proposed satisfies the requirements of legislation and the insurer of the property”.

Collaboration and competency

BS 5839-1 states that “it is important that system design suitably supports the required fire evacuation procedures, rather than those procedures being designed around a predetermined system design”.

From the above, it can be concluded that there is a need for a certain level of collaboration between the various parties involved when specifying FD&A systems.

Indeed, BS 5839-1 continues by stating that “the system requirements, including those imposed by the evacuation procedures, the configuration of the building, and the use to which the building is put, need to be ascertained as accurately as possible by consultation between the user or purchaser and other interested parties” such as enforcing authorities and system designers.

In addition, the purchaser/user of the system should be ensuring that the system designer is made aware of the objectives of the system (for example whether it aims to meet not only life safety but property safety requirements) along with any specific requirements detailed by enforcers or insurers.

Throughout the process of specifying an appropriate system, there is a clear need for a certain level of competency. For example, to undertake a suitable and sufficient risk assessment, the Fire Risk Assessment Competency Council recommends that assessors should “be able to determine the appropriate category of FD&A system to match the risks for a premises” and be aware of the relevant guidance.

Similarly, the FIA guidance document notes that “it is of value for contractors and designers to have a good awareness of the category of system that will commonly be appropriate”.

Another key element is the provision of appropriate documentation for FD&A systems. This will include a “system design certificate” which should clearly state “the Category of system that has been designed and should, except in the case of a Category M, L1 or P1 system, provide a brief description of the areas of the building that are protected by automatic fire detection”.

On completion of the system, a “Certificate of Acceptance” should be issued to the purchaser/user by the appropriate contractor for completion. This certificate acts as evidence that the purchaser/user is satisfied that the system is meeting the requirements specified and that adequate documentation has been handed over.

Further information

British Standards are available from the BSI Shop.

  • BS 5839-1:2013 Fire Detection and Fire Alarm Systems for Buildings. Code of Practice for System Design, Installation, Commissioning and Maintenance of Systems in Non-domestic Premises.

Fire Industry Association publications are available at

  • Selection and Specification of Fire Alarm Category in Accordance with BS 5839-1.