Guide to Conversion of Traditional Buildings

2.11 Communication

Standard 2.11

Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building, the occupants are alerted to the outbreak of fire.

2.11.1 Type of standard

Mandatory Standard

In the case of conversions, as specified in regulation 4, the building as converted shall meet the requirement of this standard (regulation 12, schedule 6).

2.11.2 Commentary

Communication is a standard that applies to all buildings in order that the occupants are alerted to the outbreak of fire. The existing fire alarm system may or may not be appropriate for a proposed conversion. Traditional buildings in which other fire precautions, such as means of escape, depart from the Technical Handbook guidance should have in place fire alarm systems to compensate for such departures. BS5839 part 1: Category, L1- L5 systems or BS5839 Part 6 Grade A category LD1 systems should therefore be installed in the building. An assessment of the determined use should be carried out at the design stage, considering the building evacuation factors to specify the appropriate alarm category for the circumstances concerned. The significance of various evacuation factors will depend on use and occupancy. These factors are:

• whether occupants are awake and alert or asleep,
• whether they are familiar or not with the building,
• the complexity of the building,
• the number of occupants,
• the type of activity; and
• evacuation method.

In any building, one or more of the occupants may have impaired sensory, cognitive and/or mobility impairments which could create difficulties in perceiving or responding to a fire or in evacuating the building. There are devices, such as flashing beacons, vibrating pillows and vibrating pagers available to help persons with a hearing impairment respond to fire alarms.

Generally, the sympathetic installation of these systems in historic buildings can be achieved without significantly affecting their historic character and features.

Radio installations reduce significantly the need to run cables within the construction and, when this is done during a conversion, the additional disruption will be minimal, and BS 5839 Part 1 and Part 6 provide guidance for the design of such a system.

A radio survey should be undertaken at an early stage to make sure that the necessity for signal booster equipment is limited. Radio-linked components forming part of these fire alarm systems all contain individual batteries. While this reduces cabling, the ongoing replacement of batteries over the life of the system will need to be properly costed and managed. This aspect should be given consideration as part of the selection process.

The local authority and fire authority should be satisfied that the potential for accidental false alarms has been managed.

2.11.3 Issues to be considered

Issue - Risks to historic / traditional buildings

1. Siting of devices Location of field devices and routing of cables resulting in aesthetic damage to historic character and destruction of finishes.

2.11.4 Recommendations to meet the standard

It is recommended that specialist advice for design and construction should be sought from those with appropriate heritage and fire expertise.

Where there are deviations from the guidance it may be appropriate to install an enhanced automatic fire detection and alarm system, for example a Category L1 to BS 5839- 1 2017, to ensure the earliest possible warning in the event of an outbreak of fire.

The technical requirements for fire detection and alarm systems in different building types are well covered in publications referred to in the Technical Handbooks. BS 5839: 2017 Part 1 and BS 5839: 2019 Part 6 give details on the requirements for detection in non-domestic and domestic uses of buildings respectively.

The type of buildings for which automatic fire detection and alarm systems are required under the Building Regulations is contained within the guidance to the functional standard 2.11. It may also be necessary to enhance such systems for other reasons. This may be because the owner or occupier:

• requires compliance with fire safety legislation, such as meeting the tolerable standards under the Housing (Scotland) Act 1987.
• requires asset protection or a system for insurance purposes, or
• requires a system as part of a fire engineering solution to compensate for a failure to follow other fire safety guidance under the standards.

This third reason arises frequently in historic building conversions. The installation of an automatic fire detection and alarm system is generally the most practical way of overcoming difficulties in complying with normal requirements for escape routes, fire separation and the like. It should be noted that if the system is installed for this reason, it is usually necessary for the system to be specified to a high standard.

Typically, it will be necessary to design the installation to an BS5839 Part 1 (Non-domestic) L1 or L2 or BS5939 Part 6 Grade A LD1 (domestic) level of coverage and to make the installation fully addressable (i.e. so that individual detection devices can be uniquely identified at the fire alarm panels). This will give the building’s occupants and fire-fighters precise information about the areas of the building affected by fire.

The two main options for a fire detection system are:

a) fully wired installations and

b) radio detection.

Interlinked radio detection is regarded as a reliable alternative to wired detectors, and guidance is given in BS 5839 (Part 1 2017 or Part 6 2019). The advantage of radio detection is that it is not necessary to run fire-protected cables to all the devices. These systems can therefore be installed with least disruption to the building fabric. This is particularly useful if little or no other work is planned for certain areas of the building. They can also be installed at a very early stage in a conversion project and provide detection in the building during the contract – arguably the period of highest risk for a building.

A further option for some buildings with particularly fine, ornate ceiling finishes may be an aspirating smoke detection system. Sometimes it would be regarded as difficult to accept the installation of a normal detector head in such ceilings. Aspirating systems involve running lengths of pipe to small sampling points, which are generally only around 8mm in diameter.

The spacing of these sampling points must follow the same rules as for smoke detectors. However, it is usually possible to do this while also positioning the holes in a feature of the plasterwork that renders them practically invisible. These aspirating systems are usually integrated into a system with discreet detection devices so that they, in effect, behave as detectors in the larger installation. They do, however, have disadvantages:

• they are generally significantly more expensive than point detectors,
• they are more limited in the addressable information that they can provide to the central alarm panel and
• they have a mechanical vacuum fan that runs continuously and has a shorter life than a point detector

Even where the installation covers several zones, they often need to cover more than one room per zone to be cost effective (unless the rooms are exceptionally large), and so the grouping of rooms would require to be agreed with the verifying authority.

Multi sensor detectors, such as heat and optical smoke, or CO and smoke can help avoid false alarms, although the CO detector element should be checked to confirm its service life.