Satisfactory fire and carbon monoxide detection: tolerable standard guidance

Guidance relating to the Tolerable Standard on satisfactory fire detection and satisfactory carbon monoxide detection.

Chapter 16 Satisfactory Fire Detection

16.1. A house meets the Tolerable Standard if it complies with the relevant requirements in relation to satisfactory smoke and heat alarms.


16.2. The Tolerable Standard is amended by the Housing (Scotland) Act 1987 (Tolerable Standard) (Extension of Criteria) Order 2019 and now includes this new element covering smoke and heat alarms. For the first time, assessors will consider the presence, type and condition of smoke and heat alarms in a house when deciding if the house meets the Tolerable Standard. These criteria, which already formed part of the Repairing Standard (as it applies to certain tenanted properties), now apply to all houses [see note 1].

16.3. This chapter of the guidance aims to provide the information and advice needed to carry out an assessment of the smoke and heat alarms in a house for the purposes of the Tolerable Standard. The methodology is based on the normal walk-through survey used for other elements of the Tolerable Standard, with the potential for support from a qualified specialist.


16.4. The Tolerable Standard was first defined in the Housing (Scotland) Act 1969 which was then repealed and replaced by the Housing (Scotland) Act 1987. The Housing (Scotland) Act 1987 (Tolerable Standard) (Extension of Criteria) Order 2019 added fire detection equipment to the Tolerable Standard. This is in recognition of the danger that fire poses to the occupants of a house, and is intended to reduce the risk of loss of life, injury and damage to property in the event of fire. The Tolerable Standard also forms part of the Repairing Standard under section 13 of the Housing (Scotland) Act 2006. Under section 14 of the 2006 Act, the landlord in a tenancy must ensure that the house meets the Repairing Standard at the start of the tenancy and at all times during the tenancy.


16.5. The revised Tolerable Standard includes criteria requiring that a house has 'satisfactory equipment installed for detecting, and for giving warning of, fire or suspected fire'. The Scottish Government considers that this aspect of the Tolerable Standard should be complied with via the installation of satisfactory smoke and heat alarms. This guidance defines what is 'satisfactory' by setting out the requirement for [see note 2]:

  • one smoke alarm installed in the room most frequently used for general daytime living purposes (normally the living room/lounge) [see note 3];
  • one smoke alarm in every circulation space on each storey, such as hallways and landings [see note 4];
  • one heat alarm installed in every kitchen;
  • all smoke and heat alarms to be ceiling mounted; and
  • all smoke and heat alarms to be interlinked [see note 5].

16.6 Mains-operated alarms (with battery backup) are permitted, and tamper proof long-life lithium battery alarms (i.e. not PP3 type or user-replaceable) are also permitted [see note 6]. Alarms should be regularly maintained and tested in accordance with manufacturer's instructions.

16.7. Smoke alarm: A fire detector that detects smoke as a primary indication of fire. It produces an audible and/or visible signal locally in a room or a home. Smoke alarms are usually housed in a small, round shaped plastic case, and ceiling mounted.Smoke alarms should conform to BS EN 14604. For more detailed information on smoke alarms, see BS 5839 Part 6.

16.8. Heat alarm: A fire detector that detects the presence of fire by monitoring the changes in temperature associated with combustion. It produces an audible and/or visible signal locally in a room or a home. Heat alarms should conform to BS 5446-2. For more detailed information on heat alarms, see BS 5839 Part 6. In a fire, heat alarms operate later than smoke alarms, so their use should be restricted to rooms in which smoke alarms would cause false alarms (e.g. kitchens). [see note 7].

16.9. Multi-sensor alarm: A fire detector that detects the presence of fire by monitoring more than one phenomenon of fire (e.g. smoke and heat). Multi-sensor alarms should conform to BS EN 54-29 or BS EN 14604.

16.10. Ceiling mounted: All smoke and heat alarms should be ceiling mounted, unless otherwise indicated as suitable for wall mounting in spaces of limited area (e.g. hallways) by the manufacturer [see note 8].

16.11. Interlinked: Interconnected alarms which communicate with each other and form an integrated system of protection in the home, so that when one alarm detects a fire, all alarms operate simultaneously. Alarms can be interlinked via wires (hardwired) or wirelessly (by radio communication). Where adding to an existing hardwired system, care should be taken to ensure that all alarms are interlinked, with all alarms sounding when any one device is activated. [see note 9]

Making the assessment

16.12. In some buildings, it may not be practical to fit heat and smoke alarms to this exact standard. There may be instances where the number of alarms specified would not be required to meet the standard, such as a kitchen/diner or open plan layout. Assessors should take account of the layout and design of the building, and any advice given by a competent person. Further information can be found in the Building Standards Domestic Technical Handbook.

16.13. Local authorities may use their statutory powers to require owners to carry out work on substandard housing. However, as is the case for other elements of the Tolerable Standard (e.g. serious structural problems through to other failures such as insufficient loft insulation), it is expected that any intervention is proportionate, rational and reasonable. Local authorities are to consider the cost of any intervention alongside the cost of assisting owners to bring their property up to the minimum standard for satisfactory fire detection. As a general rule it is preferable that owners should carry out necessary works on a voluntary basis rather than as a result of enforcement action, with further information set out in Chapter 2 – local authority powers.

16.14. Recent cases in the sheriff court support the view that local authorities have to consider carefully which enforcement powers are appropriate to address a failure in meeting the Tolerable Standard and careful investigation must be carried out as to the cause of the failure as well as engagement with the owners.

16.15. The next part of this chapter gives advice for assessors on making judgements on this element of the Tolerable Standard.

16.16. The flow chart below will help guide an assessor through the process of determining whether the house has smoke and heat alarms which meet the Tolerable Standard. This should be followed in the absence of any technical advice provided against fitting to the standard.

Flow Chart describing the process to be followed by an assessor when determining whether the house has smoke and heat alarms which meet the Tolerable Standard. If there is a smoke alarm in the room most frequently used through the day, there is one in each circulation space on each storey, there is a heat alarm in every kitchen, all the alarms are ceiling mounted, interlinked and either mains-wired or tamper-proof long life battery powered, then the house meets the Tolerable Standard. Otherwise it is below Tolerable Standard.


The following notes have been added to clarify some technical points in Chapter 16 of this guidance:

1. The Tolerable Standard (as detailed in section 86 of the 1987 Act) applies to all houses. For guidance on fire safety standards in non-domestic residential property see"

2. The Tolerable Standard is a minimum standard, and does not preclude more effective or extensive systems provided that they meet the basic requirement of (a) a secure power source for the lifetime of the unit, and (b) effective means to provide an immediate alert in the event of any part of the system being actuated.

In particular, the Standard can be met by the use of Grade A or Grade C alarms which should be installed in compliance with BS 5839-6. Grade A alarms are smoke, heat and multi-sensor detectors; Grade C alarms are smoke, heat and multi-sensor detectors along with devices such as fire alarm sounders, visual and/or vibrating alarm devices.

Additional standards may apply if work is carried out under a building warrant or where an electrician is installing mains-wired alarms.

See also note 9 below.

3. Open plan combined rooms, such as kitchen/living rooms will only require one alarm, provided that it can be located no more than 7.5 metres from any point in the room. The type of alarm used should be appropriate for the room, see note 7.

4. A "circulation space" is a room that you have to go through to get to another part of the house. This does not require alarms in small spaces such as a vestibule, front porch or half-landing with no or minimal space for furniture, storage or appliances.

In order to provide effective warning, there should be an alarm on a landing or hall located no more than 3 metres from the door of the main bedroom. See Building Standards Technical Handbook: Domestic, section 2.11.7,

5. All the alarms required to provide a compliant system must be interlinked. If there are additional alarms that are not required by the Tolerable Standard, for example, in bedrooms, the system does not fail the Tolerable Standard if these additional alarms are not interlinked to the system.

6. The requirement is for the main power supply to the unit. Mains-wired units may have a back-up supply in case of a power cut, and wireless interlinking may use a separate power supply for the radio signal. Alarms will not be below Tolerable Standard if these additional supplies use replaceable batteries.

7. The Tolerable Standard does not require a heat alarm and a smoke alarm. Whichever type is most appropriate should be used. Because heat alarms are less sensitive than smoke alarms, they should be used only where there is a risk of false alarms from cookers, open fires, or other appliances. BS 5839-6:2019, Clause 12.2(f) states that only heat alarms should be used in kitchens. However, if an existing alarm system includes a smoke alarm in a kitchen, it is not necessary to replace this until the alarm reaches the end of its manufacturer's recommended lifespan.

8. Wall mounted alarms should only be installed where this is in accordance with the manufacturer's recommended installation. Alarms on walls should be located within 30 cm of the ceiling at its highest end. Wall mounting may be appropriate where ceilings are sloped or uneven, or in order to avoid disturbing asbestos.

9.Under the Equality Act 2010, deaf people can expect the same level of protection from fire as specified in this guidance through provision of specialist deaf alerts. For homeowners these may be provided by Health and Social Care Partnerships. Specialist deaf alerts must be compatible with the new interlinked systems to avoid multiple alert systems within properties and to ensure a single system arrangement consistent with the level of protection required for those who are not deaf.

Landlords have a duty to make reasonable adjustments to properties for disabled people. Therefore, they require to provide deaf alerts compatible with the new interlinked systems.

Where telecare is in use, effective warning interlinked smoke and heat alarms should be installed which are compatible with any telecare alarms, and connected to the telecare system, ensuring a single system approach.



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