Building Control
Charnwood Borough Council
Southfield Road
Loughborough
LE11 2TN
BUILDING CONTROL GUIDANCE SHEET
SMOKE ALARMS IN STANDARD DWELLINGS
Last updated 16/12/2010
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PURPOSE:
This Guidance Note is for the benefit of local architects, builders and the general public.
Its purpose is to provide information, promote good practice and encourage consistency
of interpretation for all. It is purely advisory in nature and does not cover every aspect
of the topic concerned, but tries to cover the main, commonly encountered points. If
more details are required then the relevant Approved Documents, British Standards or
manufacturers’ instructions should be consulted. The Guidance Note is not intended to
outline the only way of carrying out the type of work referred to. If in doubt, please
contact your local Building Control Authority.
This document should not be submitted as part of any Building Control application.
The Council offers a complete Building Control service, from pre application advice on
technical aspects and how to make an application, through to plan checking and an
inspection regime to ensure a safe and compliant building. We also offer an Energy
Performance Assessment service which uses SAP methodology to produce Energy
Performance Certificates in respect of both new and existing dwellings. Please contact
Building Control for any further information:
Building Control Contact Details:
General enquiries:
Tel:
01509 634757
01509 634924
01509 634749 (24 hour answer machine)
Fax:
01509 260536
Email: building.control@charnwood.gov.uk
Web: www.charnwood.gov.uk/pages/buildingcontrol1
Further information can be obtained from The Building Regulations 2010 or from the
Council’s Building Control Service on request. The views expressed in this document are
those of Charnwood Borough Council and do not necessarily represent a guaranteed
methodology for compliance with the requirements of the Building Regulations 2010.
Charnwood Borough Council accepts no liability for any claim that may arise in relation to
reliance on the information contained in this document.
1.0 Introduction
1.1 BS5839 part 6 2004 quotes “In the United Kingdom, around 80 % of all fire
deaths and injuries occur in dwellings, a total of 450 to 500 deaths and around
14000 injuries per annum.”
1.2 The installation of a fire detection and alarm system can substantially
reduce the risk of death or injury and for this reason the Building Regulation
2010 through the Approved Document B require the installation of system
design to the British Standard for all new dwellings (including those created by
a change of use) and additionally extended dwellings where new habitable
rooms are created without a door to fresh air.
1.3 See the Approved Document B for a full definition, but we would always
recommend smoke detectors be added as part of a project.
1.4 This guide is aimed at standard dwelling types with floor area of less than
200m2 and one or two storey.
NOTE: It is important to note than many properties require an enhanced
system to offset a higher risk or as an alternative design to those within
Approved Document B.
2.0 BS5839 part 6 2004
2.1 This is the British Standard relevant to domestic properties such as
houses, bungalows and flats. Your Electrician should be aware of this
standard and work in accordance with its requirements.
2.2 Grades of Systems for life protection
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LD1: A system installed throughout the dwelling incorporating detectors
in all circulation spaces that form part of the escape routes from the
dwelling, and in all rooms and areas in which fire might start, other than
toilets, bathrooms and shower rooms
LD2: A system incorporating detectors in all circulation spaces that
form part of the escape routes from the dwelling, and in all rooms or
areas that present a high fire risk to occupants
LD3: A system incorporating detectors in all circulation spaces that
form part of the escape routes from the dwelling
2.3 Further graded regarding power supplies as follows:
 Grade A, B and C: These systems are more advance and beyond this
guidance note but obviously offer a far more advanced system and
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more often used in very large dwellings, or House of Multiple
Occupation or those considered higher risk.
 Grade D: A system of one or more mains-powered smoke alarms, each
with an integral standby supply. The system may, in addition,
incorporate one or more mains-powered heat alarms, each with an
integral standby supply. One or more batteries or capacitors are
provided to ensure protection is available under loss of mains
conditions.
 Grade E: A system of one or more mains-powered smoke alarms with
no standby supply. The system may, in addition, incorporate one or
more heat alarms, with or without standby supplies. The system is
potentially more reliable than a Grade F system, because it requires
less attention by the user. The cost of the system is higher as a mains
supply and interlinking cables are required and the detectors
themselves cost slightly more. Loss of mains results in loss of
protection, these are not permitted under Building regulations.
 Grade F: A system of one or more battery-powered smoke alarms.
Building Regulations do not allow these as they are not mains wired.
NOTE: Cables used for the mains supply to smoke alarms, any heat alarms
and any interconnecting wiring may comprise any cable suitable for domestic
mains wiring
2.4 For a standard dwelling (less than 200m2 per floor) a grade D LD3 system
is required.
2.5 Grade D LD3, This is a system incorporating detectors in all circulation
spaces that form part of the escape routes from the dwelling of one or more
mains-powered smoke alarms, each with an integral standby supply. The
system may, in addition, incorporate one or more mains-powered heat alarms,
each with an integral standby supply. One or more batteries or capacitors are
provided to ensure protection is available under loss of mains conditions.
NOTE: It is important to note if you need to pass through a room to exit
the building this becomes the circulation space not always just the
hallway.
2.6 Basic Guide for a Dwelling Requiring a Grade D, LD3 System (2
storey)
 At least one smoke alarm provided on each and every floor in the
circulation space (hallway in this example) if the hallways are long more
may be required
 In hallways at no point should a detector be more than 7.5m away
 No bedroom door should be more than 3m from a detector
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At least one smoke detector should be located between every bedroom
and every other room in the dwelling, other than a toilet, bathroom or
shower room. (where a bedroom is directly off a kitchen this would
need a smoke detector in the bedroom and a heat detector in the
kitchen)
In open plan accommodation these area should be treated as
circulation space and extra detectors added.
Only one door should separate a smoke detector and a room that
requires early warning as closed doors reduce sound levels
Generally is ceiling mounted, 300mm horizontally from a wall or light
fitting, unless manufacturers details state a different location is
acceptable?
Ceiling-mounted detectors should be located such that their sensitive
elements are between 25 mm and 150mm below the ceiling in the case
of heat detectors, or between 25 mm and 600 mm below the ceiling in
the case of smoke detectors.
Be fixed where they can be reached to maintain, therefore not over the
stairs
Not placed above heaters or air conditioning units/vents
Where the stairs are open to the rooms at ground floor including the
kitchen a heat detector is required in the kitchen
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3.0 False Alarms
3.1 BS5839 part 6 list the following as the most common causes of false
alarm
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
m)
fumes from cooking processes (including toasting of bread);
steam (from bathrooms, shower rooms and kitchens);
tobacco smoke;
dust (whether built up over a period of time or generated while
cleaning)
insects;
aerosol spray (e.g. deodorants and cleaning fluids);
smoke from sources other than a fire in the building (e.g. from an
external bonfire);
“hot work”, such as burning off paintwork with a blowlamp;
processes that produce smoke or flame (e.g. flambéing of food);
incense;
candles;
high humidity;
Water ingress.
3.2 Detector Choice to Reduce false Alarms
3.3 Types of Detectors Commonly Available (the detector should have a
silencing button)
BS5839 part 6 states the most common false alarm is cooking related
including toast
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Ionization detectors, best suited to living rooms or dining rooms or
rooms in which heavy tobacco smoke will be produced,
Optical detectors, best suited for circulation spaces and less likely to
give false alarm from cooking smells, but do not like heavy tobacco
smoke.
Heat detectors, react to a fixed high temperature, so generally used in
Kitchens, slower to react but do not react to cooking smells. Heat
detector are not suited to rooms in which people may sleep
Carbon Monoxide detectors or Multi-Sensor detectors, these are
more sophisticated devices and can reduce false alarms but are more
expensive and if using these please consult the manufacturers advice.
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Note: It is good practice to shut doors at night to reduce fire spread
additionally provide adequate escape routes such as windows and/or door, in
a fire situation you need to be alerted (smoke alarm) and then be able to get
out the building. Modern Buildings meeting the building regulations have this
standard but often older buildings do not!
Do you have an escape plan?
4.0 Installation and Maintenance
4.1 All electrical works are required to meet the requirements of Part P
(Electrical Safety) and must be designed, installed, inspected and tested by a
person competent to do so.
4.2 The power supply should be from the dwellings main electricity supply.
The mains supply should be either a single independent circuit off the
consumer unit or a single regularly used local lighting circuit. This is often the
safest choice as people rarely leave the light circuit off at night but there
should be a means of isolating the power to the alarms without isolating the
lights.
4.3 All should conform to the IEE Wiring regulations. There is no need to have
any special fireproof wiring. The alarm should preferably not be protected by
any residual current device (RCD)
4.4 Smoke alarms in Grade D, E and F systems should be cleaned
periodically in accordance with the manufacturer’s instructions. Where
experience shows that undue deposits of dust and dirt are likely to
accumulate, so affecting the performance of the system before detectors are
cleaned or changed, more frequent cleaning or changing should be carried
out.
4.5 The installation of smoke alarms needs to be carried out by a member of a
self certification body or a Building regulation application is generally required.
Competent person schemes are explained further at;
http://www.charnwood.gov.uk/pages/othercontrol
Application forms for Building Regulations are at:
http://www.charnwood.gov.uk/pages/downloaddocuments
NOTE: The manufacturers instructions containing the operating, testing
and maintenance of the unit should always be passed to, and retained
by the occupier of the dwelling.
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