Building standards technical handbook 2020: domestic

Life safety is the paramount objective of fire safety. Domestic buildings should be designed and constructed in such a way that the risk of fire is reduced and, if a fire does occur, there are measures in place to restrict the growth of fire and smoke to enable the occupants to escape safely and fire-fighters to deal with fire safely and effectively.

There are almost 5000 reported fires in dwellings (e.g. houses, flats and maisonettes) every year in Scotland. Fires can have a devastating effect on the lives of people and results in around 40 deaths and 900 injuries each year. The most common cause of accidental fires in dwellings involved cooking appliances (62%), electrical supply or electrical lighting (14%), combustibles ignited due to being too close to candles or other heat source (9%), the remaining 15% is accounted for by the careless disposal of cigarettes and matches and other domestic appliances. Evidence also shows that the consumption of alcohol and/or smoking are contributory factors which increases the risk of an accidental fire occurring. Occupants who are alone at the time of the fire and are in the room of fire origin, are more likely to suffer injury (e.g. burns and smoke inhalation) or even death in some cases.

It is impossible to eliminate the risks from fire altogether and the prevention of deliberate or accidental fires caused by the actions of occupants within a dwelling are outside the scope of building standards. For advice on best practice relating to fire safety in the home, visit the Scottish Fire and Rescue Service website http://www.firescotland.gov.uk/ or contact the community fire safety team at your local fire station. Although beyond the scope of this guidance, the adoption of good fire safety practices should be encouraged to reduce the risk of fire occurring in the first place. Fire prevention will not only save lives but will protect property and reduce environmental pollution.

The standards and guidance in this section are designed to work together to provide a balanced approach to fire safety. The building elements, materials, components or other parts of the building identified in the guidance should follow the appropriate performance levels that are recommended throughout the guidance. However where an element, material, component, or other part of a building is covered by more than one standard, the more demanding guidance should be followed in most cases.

The purpose of the guidance in Section 2 is to achieve the following objectives in the case of an outbreak of fire within the building:

Protection of life - it is important to recognise that the standards will not guarantee the life safety of all building occupants. Occupants in dwellings do not normally perceive themselves to be at risk from fire and are not usually aware of the speed that fire can spread. The risk to occupants is greater if they are asleep during the outbreak of fire as they are likely to be roused more slowly. Occupants should be warned as soon as possible following the outbreak of fire and the guidance to Standard 2.11 provides recommendations for the installation of alarm and detection systems in domestic buildings.

Fire and rescue service - in some cases, occupants will not react quickly enough before being overcome by the effects of the fire and smoke and as a result, may require to be rescued by the fire and rescue service. For facilities to assist the fire and rescue service, see Standards 2.12 to 2.14.

Sustainability - the building regulations are primarily concerned with the protection of people from the dangers inherent in buildings, rather than protecting the owners of buildings from any economic loss which might occur. However following the guidance in the handbook will continue to embed active and passive fire protection systems within buildings which should reduce the likelihood of the total destruction of the building following the outbreak of fire.

Guidance in this section may not be appropriate for the following buildings as they are rarely designed and constructed in Scotland:

For the purposes of (a) above, the area of an individual storey includes the area of a gallery or sleeping deck but excludes the area of an integral domestic garage.

In the case of a mixed use building containing non-domestic and domestic accommodation, reference should be made to the Technical Handbook for non-domestic buildings as well as the guidance contained in this Handbook.

In the case of sub-clauses (a) to (h) above, the alternative approach described in clause 2.0.7 should be used.

The rules of measurement in Section 0 of the Technical Handbook may not be appropriate for the guidance in Section 2 Fire. For example, to establish the height of the topmost storey for fire and rescue service facilities, the height should be measured from the fire and rescue service access level and not necessarily the lowest ground level. Therefore, methods of measurement unique to fire are described within the guidance under each of the relevant standards.

Plant Storeys - for the purpose of measurement, the height above ground to the top most storey excludes, roof-top plant areas and any top storeys consisting exclusively of plant rooms.

Flat or maisonette - for the purposes of the guidance in Section 2 Fire, except in relation to the guidance to Standard 2.15, a flat or maisonette entered only from the open air at ground level and with no storey at a height of more than 4.5m should be regarded as a house and follow the guidance accordingly.

Protected routes of escape - throughout the document there are references to protected routes of escape these include: open access balconies, galleries wholly or partly enclosed below, protected lobbies, protected zones, protected enclosures, external escape stairs, basements and alternative exits. This list is not exhaustive and is not intended to cover all parts of a building providing protected routes of escape. For example, separating walls and separating floors also protect routes of escape but are covered by the guidance to Standard 2.2.

External areas - a roof, an external balcony or an enclosed courtyard open to the external air, where the area is more than 8m2 and to which there is access for a purpose other than maintenance, should be regarded as a room. It is not intended that these external areas be treated as apartments which create inner rooms to dwellings.

A circulation space in a dwelling is an area mainly used as a means of access and egress between a room and an exit (e.g. hallways and stairwells).

A sleeping deck within a room should be regarded as being part of that room. However for the purposes of the guidance to Standard 2.9, sleeping decks which do not fall within the definition of a gallery should be regarded as a separate room or storey as the case maybe.

Alternative means of complying with building standards - the guidance contained within this Technical Handbook indicates one or sometimes more than one means of complying with the mandatory building standards 2.1 to 2.15. In the majority of projects it is envisaged that meeting the guidance will be the usual means of showing that compliance with the building standards has been achieved.

However, it should be appreciated that, due to the generic nature of the guidance it cannot cover all building designs or, for example, innovative or new methods of construction. In such cases the designer or engineer will be required to show, by alternative means, that compliance with the building standards will be achieved in the completed building. For example, where the elements of structure are engineered timber (including cross laminated timber), the structure should maintain stability during the fire growth and fully developed post flashover phases of the fire without reliance on intervention from the fire and rescue services. Encapsulation of combustible elements of structure may require to be provided to protect the structure against ignition and charring for the duration of the fire. Where encapsulation (i.e. both physically and in terms of the period of fire resistance duration) is not provided or does not protect the combustible material against ignition and charring for the duration of the fire, the structural fire engineer should consider the additional contribution of the exposed combustible material to the fire load density including an assessment of the structural stability of the building due to both potential delamination and failure of the fixings at elevated temperatures.

Fire safety engineering - it is reasonable to demonstrate compliance with the functional standards by alternative means and in such cases, the fire engineer, the building standards verifier and the fire and rescue service should be consulted early in the design process.

Fire safety engineering may be the only practical way to achieve a satisfactory level of fire safety in some large and complex buildings or where innovative or new methods of construction are used. In such cases a holistic approach is desirable from first principles rather than following, in part or wholly, the guidance contained in the Technical Handbooks. In such cases the building standards verifier and the fire and rescue service should be consulted as part of the Qualitative Design Review (QDR) process.

For many projects it is likely that designers will follow the guidance in the Technical Handbooks and fire engineering techniques will not be necessary. In its simplest form the QDR team may define the acceptance criteria in terms of compliance with the Handbooks.

However, it is common for fire engineers and regulators to be engaged relatively late in the design process to resolve fire safety issues raised during the verification or, in extreme cases, the construction process. This is unhelpful as fire engineers are often commissioned to resolve specific issues where the design does not follow the guidance rather than assessing the building holistically. This can lead to a comparative exercise against unrealistic worse case scenarios of a “code compliant” design to justify deviations. This is not the intent of the guidance and it is important that the safety goals are well defined and achieved with a sufficient margin of safety. The objective of a comparative study should be to demonstrate that the building design, as a whole, presents no greater risk to the occupants than a similar type of building designed in accordance with the Technical Handbook guidance. Further, it is common for the inappropriate use of Computational Fluid Dynamics where the deviations from the Handbooks would not merit such an exercise to be carried out. It is recognised that there may be instances where small deviations from the guidance do not warrant a “whole building” fire engineered design and inevitably involves a degree of negotiation without the need for detailed analysis.

Not all cases of variance from the guidance will require the appointment of a fire engineer. Reference could be made to ‘A simplified approach to alternative fire safety strategies’ Scottish Government (2010), which provides additional advice.

Existing buildings - it may be appropriate to vary the guidance contained in this Handbook when assessing the guidance against the constraints in existing buildings especially those buildings which are listed in terms of their architectural or historic interest. In such cases, it would be appropriate to take into account a range of fire safety features, some of which are dealt with in this Handbook and some of which are not addressed in any detail. For more detailed information, guidance is contained in the ‘Guide for Practitioners 6 – Conversion of traditional buildings’ (Historic Scotland).

Fire engineering designs can be complex and many require extensive use of engineering judgement. The following documents are cited to ensure that the guidance given encompasses best practice worldwide:

The use of either document assumes that those carrying out or assessing a fire engineering approach have sufficient technical training, knowledge and experience to understand fully the risks involved.

The objectives of any fire safety strategy should be established first and designers and verifiers should be aware of the importance of the design assumptions. For example, the strategy should include an assessment of the system reliability. This will help to ensure that the fire safety objectives have been met.

Responsible person - it is important that owners/responsible person understand that the fire safety measures installed in a building need to be maintained and tested over the life time of the building so that they will operate effectively. BS 7974 and IFEG assume that all aspects of the fire engineering strategy are capable of being maintained and deployed over the lifetime of the building. If for example, alterations are found to be necessary due to changes to the building layout, the original strategy may need to be re-evaluated to ensure the fire safety provisions have not been compromised. For this reason, the fire strategy should preferably support any fire safety risk assessment required under Part 3 of the Fire (Scotland) Act 2005, as amended.

Fire safety engineering involves the use of scientific based calculations and/or statistical information to demonstrate an adequate level of safety for a specific building, structure or installation. In this regard the fire safety strategy is based on performance rather than prescription. Therefore fire safety engineering is about the need to identify the fire hazard, assess the fire risks, understand the consequences and to offer fire safety strategies and designs to show how the objectives have been met. The ‘tools’ that support fire engineering can include calculation methods which are used to demonstrate that under a worst reasonable case, tenable conditions are maintained during the evacuation period. For example, a smoke exhaust fan in a smoke reservoir within an atrium space fails to operate but the smoke layer height continues to be maintained by the activation of a stand-by fan.

It is recognised that fire engineering is still a rapidly developing field and as such does not have the standardised codes for approaching and solving problems compared to other engineering disciplines. The documents identified above aim to provide a structured framework for assessing the interaction between, buildings, people and fire, and to facilitate innovation in design without compromising safety. They provide information on how to undertake a detailed analysis of specific aspects of fire safety engineering in buildings.

In practice, both frameworks provide a flexible but formalised engineering approach to fire safety which can be applied to new or existing buildings to show that the functional standards have been met.

BS 7974: 2019 Application of fire safety engineering principles to the design of buildings is supported by 7 published documents:

International Fire Engineering Guidelines IFEG have been developed for use in the fire engineering design and approval of buildings. The objectives of the guidelines are to provide:

The IFEG sub-systems bear a very close resemblance to the sub-systems used in BS 7974: 2019 and are set out below:

Clause 1.3.2 of IFEG states that "Typically, each building project is unique and similarly, each fire engineering evaluation is unique". It is not sensible, therefore, to set down detailed guidance on how the fire safety analysis should be undertaken. Instead, it is the responsibility of the fire engineer to plan the analysis for the particular project, based on the decisions taken during the preparation of the fire engineering brief as discussed in Chapter 1.2.

It is important to be aware that there is other legislation, apart from building regulations, imposing requirements for means of escape in case of fire and other fire safety measures that will come into force when the building is occupied. It is therefore recommended that consultation with those responsible for such legislation takes place before the application for building warrant is finalised. Any necessary fire precaution requiring additional building work can then be included in the application.

Part 3 of the Fire (Scotland) Act 2005 (2005 Act), as amended introduced a fire safety regime which applies mainly to non-domestic buildings. The regime does not generally apply to domestic buildings but may apply where staff are employed or members of the general public have access e.g. a dental surgery within a dwelling. The regime also applies to domestic buildings that are licensed as Houses in Multiple Occupation and to some domestic buildings where certain care services are provided. Those domestic premises covered by Part 3 of the 2005 Act, as amended are defined in Section 78 of the Act.

Persons with obligations under the Act are required to carry out a fire safety risk assessment which may require additional fire safety precautions to reduce the risk to life in case of fire. For example, measures to reduce the risk and spread of fire, means of escape, fire-fighting equipment, fire detection and warning, instruction and training. Other measures are prescribed by regulation. The fire safety risk assessment should be kept under continuous review.

There is sector specific guidance for various building types on how to comply with Part 3 of the Act, on the Firelaw website.

In many premises, existing fire safety measures have been incorporated in accordance with building regulations, however it is possible for a higher standard to be applied as a consequence of a fire safety risk assessment.

Section 71 of the 2005 Act makes it clear that terms, conditions or restrictions in licences, including statutory certification or registration schemes, are to have no effect if they relate to fire safety requirements or prohibitions which are or could be imposed under Part 3 of the 2005 Act, as amended.

The Fire Safety (Scotland) Regulations 2006 made under the Fire (Scotland) Act 2005 and contain provisions which are part of the fire safety regime. These regulations must be considered along with Part 3 of the 2005 Act, as amended. The regulations contain further requirements in respect of fire safety risk assessment and obligations of duty holders.

The Construction (Design and Management) Regulations 2015 are intended to protect people working in construction and others who may be affected by their activities. The regulations require the systematic management of projects from concept to completion and throughout the life cycle of the structure, including eventual demolition. The CDM Regulations require designers and those who control or carry out construction work to identify hazards associated with their designs or work (including risk from fire) and plan to eliminate, reduce or control the risks.

Houses in Multiple Occupation (HMOs) - Section 2 Fire of the Domestic Technical Handbook should be used for multi-occupancy dwellings designed for not more than six individuals living together as a single household. This includes houses, maisonettes and flats (including flatted student accommodation and cluster flats that are essentially designed as self-contained flats), regardless of the evacuation strategy. Section 2 Fire of the Non-domestic Technical Handbook should be used for shared multi-occupancy residential buildings designed for more than six individuals including student accommodation designed on the traditional "halls of residence" principle, with bedrooms having shared sanitary and cooking facilities.

It should be noted that multi-occupancy dwellings and shared multi-occupancy residential buildings may also require to be licensed for use as a 'House in Multiple Occupation’ (HMO) under the Civic Government (Scotland) Act 1982 (Licensing of Houses in Multiple Occupation) Order 2000. In relation to fire safety aspects, HMOs which require a licence are also subject to Part 3 of the Fire (Scotland) Act 2005, as amended, and guidance is available on the Firelaw website.

The Care Inspectorate is responsible for regulating a diverse range of care services some of which are delivered in non-domestic buildings (e.g. care homes, nurseries, independent hospitals, hospices, residential schools, secure accommodation) and some in domestic buildings (e.g. childminding, supported accommodation, adult placement services). The services are inspected by the Inspectorate against national care standards issued by Scottish Ministers some of which include physical standards for the premises. The Inspectorate consults with the fire and rescue service on fire safety matters as part of the care service registration process. Where the applicant for a warrant intends to use or provide such a service, they should consult the Inspectorate and fire and rescue service for advice.

Some care services may be provided in a domestic setting where there is a requirement to comply with the Fire (Scotland) Act 2005 and associated legislation e.g. any premises in which a “care home service” is provided will always fall within the scope of the legislation. Some, but not all, premises in which a “housing support service” is provided may also be required to comply e.g. where a House in Multiple Occupation licence is required, etc. It is important that a proportionate approach is taken to ensure the fire safety of the occupants in the event of an outbreak of fire and as such, the dutyholder should take account of the level of dependency of the residents when carrying out a fire risk assessment. Additional fire safety measures including automatic fire suppression may be required in those premises where highly vulnerable occupants cannot self-evacuate the building, for example, where the occupant is bed-ridden or has limited mental capacity and may not respond to the fire alarm.

Where care services are to be provided in a domestic setting to which the Fire (Scotland) Act 2005 does not apply, the safety of the occupants in the event of an outbreak of fire must still be considered. Any fire safety risk assessment should take account of the level of dependency of the residents. For example, it may be appropriate to consider fire safety equipment such as portable fire suppression and automatic cut-off devices for cookers depending on the risk identified.

‘Practical Fire Safety Guidance for existing Specialised Housing and similar premises’ provides guidance for many domestic premises where the Fire (Scotland) Act 2005 does not apply. In those cases it is recommended that a fire safety risk assessment (of both the building and the person) is the best way to protect residents from the risk of fire.

Annex 2.A - Resistance to fire

Resistance to fire is expressed in terms of fire resistance duration and reference throughout this document to a short, medium or long fire resistance duration, are explained in annex 2.A. The performance levels include properties such as loadbearing capacity, integrity and insulation.

Annex 2B - Reaction to fire

Reaction to fire of construction products is expressed as European Classification A1, A2, B, C and D and explained in annex 2.B. The performance levels include properties such as the ease of ignition and the rate at which the product gives off heat when burning. When reference is made to European Classification A2, B, C and D throughout this Handbook, the performance criteria should be read as including sub-indices “s3, d2”. This means there is no limit set for smoke production (s3) and/or flaming droplets/particles (d2).

Annex 2C - Vulnerability of roof coverings

Roof coverings are expressed in terms of low, medium or high vulnerability and explained in annex 2.C. The performance levels relate to the capability of a roof to resist penetration from fire and flame spread when the external surface is exposed to radiation and flames.

Certification - Scottish Ministers can, under Section 7 of the Building (Scotland) Act 2003, approve schemes for the certification of design or construction for compliance with the mandatory functional standards. Such schemes are approved on the basis that the procedures adopted by the scheme will take account of the need to co-ordinate the work of various designers and specialist contractors. Individuals approved to provide certification services under the scheme are assessed to ensure that they have the qualifications, skills and experience required to certify compliance for the work covered by the scope of the scheme. Checking procedures adopted by Approved Certifiers will deliver design or installation reliability in accordance with legislation.

Third party accreditation - Since the performance of a system, product, component or structure is dependent upon satisfactory site installation, testing and maintenance, independent schemes of certification and accreditation of installers and maintenance firms of such will provide confidence in the appropriate standard of workmanship being provided.

Confidence that the required level of performance can be achieved will be demonstrated by the use of a system, material, product or structure which is provided under the arrangements of a product conformity certification scheme and an accreditation of installers scheme. Third party accredited product conformity certification schemes not only provide a means of identifying materials and designs of systems, products or structures which have demonstrated that they have the requisite performance in fire, but additionally provide confidence that the systems, materials, products or structures actually supplied are provided to the same specification or design as that tested/assessed.

Third party accreditation of installers of systems, materials, products or structures provides a means of ensuring that installations have been conducted by knowledgeable contractors to appropriate standards, thereby increasing the reliability of the anticipated performance in fire.

Local authority verifiers may accept the certification of products, components, materials or structures under such schemes as evidence of compliance with the relevant standard. Similarly, local authority verifiers may accept the certification of the installation or maintenance of products, components, materials or structures under such schemes as evidence of compliance with the relevant standard. Nonetheless, a local authority verifier may wish to establish, in advance of the work, that any such scheme is adequate for the purposes of the Building Regulations.

Many certification bodies which approve such schemes are accredited by UKAS.