External wall systems in existing multi-storey residential buildings - fire risk: advice note - version 2

Version 2.0 of this Scottish Advice Note provides advice for those responsible for fire safety in residential buildings including building owners/managers/residents groups responsible for determining the fire risk posed by external wall systems on existing multi-storey residential buildings.

This document is part of a collection

Part 1: General Advice

Part 1 (General Advice) explains why it is important to determine the fire risk posed by external wall systems, the different ways this can be done and who can carry this out. It also advises on where to get information on the external wall system and any interim measures that may be necessary, pending the remediation of unsafe systems.

Part 2 (Technical Advice) explains how to determine the fire risk posed by external wall systems and so will be of particular interest to fire risk assessors and appraisal specialists. It also highlights the particular dangers associated with Highly Combustible MCM (Category 3) cladding.

1.1 Fire Safety Risk Assessment and Appraisals of External Wall Systems

A fire safety risk assessment must give consideration to risks to life from fire, including the potential for fire spread on external wall systems. Fire could break out through a window or door opening and spread on external combustible cladding and/or any other external wall system feature, posing a risk to those inside the building or in the immediate vicinity. Combustible external wall systems may also be at risk from an external fire which is close to the building.

A key principle of fire safety risk assessment is to take reasonable measures to ensure the safety of people from harm caused by fire. This principle applies whether or not the external wall system complies with current or previous requirements under Building Regulations (see Annex 3 for more information on the Scottish Building Standards system).

The fire risk assessor should consider all available evidence to inform their decision on the risk. This may include a number of specialist reports including an external wall system appraisal (referred to throughout this Note as "appraisals"). Where doubts remain regarding the safety of an external wall system, a more detailed intrusive investigation and fire performance test may be recommended. This is a specialised field and beyond the capabilities of most fire risk assessors. An appraisal should ultimately inform the fire safety risk assessment, but the need for an appraisal which may be part of a Single Building Assessment will depend upon the particular circumstances of each building.

The following approach is suggested. See Annex 5 for a Practical Guide for the Investigation of External Wall Systems in residential buildings and Annex 6 for External Wall System Appraisal Flowchart:

1. There may be no need for an intrusive investigation where an appropriately competent fire risk assessor is able to determine the fire risk from simple on-site observation and a desk top review of available documentation. This may be possible where, for example:

  • The external wall system (including system components) achieve European Classification A1 (non-combustible) or A2 (will not significantly contribute to fire load and fire growth);
  • The external wall system has other detailed and reliable supporting documentation to enable a decision to be made i.e. 'golden thread' information, such as BS 8644 digital fire safety information, Building Information Modelling data (BIM), building warrant information, photographic evidence, Operation & Maintenance manual information, relevant fire test evidence of the product as installed, including product identification etc;
  • The external wall system is known to give rise to significant fire spread so must be removed e.g. Aluminium Composite Material (ACM) Category 3 with an unmodified polyethylene core.

2. An intrusive investigation is likely to be required where a competent fire risk assessor, familiar with the building type in question, is unable to reach a decision or feels unable to offer appropriate advice on remediation. In such cases, those responsible for the building's fire safety may need to seek advice of a suitably competent specialist (see Competence below). An appraisal is likely to be required if:

  • The type / combustibility of the external wall system (including insulation exposed in the cavity behind the cladding) is unknown;
  • There is a lack of, or gaps in, supporting records and documentation;
  • There is evidence to suggest that product substitution has occurred;
  • There is evidence of systemic problems with a particular product/ manufacturer/ installer;
  • Doubts exist as to whether or not the constructed system adequately reflects the system as originally designed and tested;
  • Test evidence suggests that a combustible external wall system has failed (or is likely to fail) the performance criteria in BR 135 'Fire performance of external thermal insulation for walls of multi-storey buildings' when subjected to a British Standard large scale fire test (known as the BS 8414 fire test. ( See Annex 4);
  • Doubts exist as to whether the system as tested is relevant to the building in question e.g. a failure to apply test results appropriately (See Annex 4);
  • Alternative approaches to BS 8414 have been used to support the original design e.g. fire engineering from first principles;
  • Doubts exist regarding the independence of the testing facility e.g. not United Kingdom Accreditation Service (UKAS) accredited.

Determining the fire performance characteristics of external wall systems will not, in itself, be sufficient to determine the fire risk posed by such systems and a wide range of risk factors need to be considered. The conclusions of an appraisal should inform the fire safety risk assessment to ensure that all hazards, risks and fire safety measures are considered holistically, and not in isolation. Therefore, the appraisal specialist should also be a suitably competent fire risk assessor. Alternatively, the appraisal outcomes should be reviewed by a suitably competent fire risk assessor who can interpret the results and use them to inform their fire safety risk assessment. More information on competence can be found in the next section.

Where an external wall system is thought to pose a significant risk to life, contact the Scottish Fire and Rescue Service (SFRS) as soon as possible. Temporary measures may need to be put in place until such times as the situation is fully remediated.

A fire safety risk assessor or appraisal specialist may also advise that additional fire safety measures are required on a permanent basis. If so, all relevant documentation should be updated accordingly e.g. the fire safety risk assessment, fire strategy, emergency evacuation plans, Operation and Maintenance (O&M) manuals etc. Building warrant approval may be required in some cases. Advice on work requiring a building warrant can be obtained from your local authority building standards service.


The consideration of external wall systems on existing buildings should only be undertaken by suitably competent professionals. All professionals must recognise the limits of their own competency and act ethically at all times.

The Competency Steering Group report Setting the Bar provides more information on competency and acknowledges that fire risk assessors require an enhanced level of competence to assess high risk residential buildings. This should include a consideration of external wall systems and an understanding of BS 8414 large scale fire tests (see Part 2 of this Advice Note) and all other tests where applicable.

For those looking to contract the services of a fire risk assessor, the Scottish Government and SFRS recommend selecting an individual or company that is registered with a Professional Registration Body or is third party certificated by a United Kingdom Accreditation Service (UKAS) accredited Certification Body. More information can be found on the SFRS website and in existing fire safety guidance. Those with responsibility for fire safety should check their fire risk assessor is competent to work on their particular building as not all fire risk assessors will have the required skill set to undertake this work. It is also worth checking that appropriate Professional Indemnity Insurance and limits of liability are in place.

If an appraisal is required, it will likely be beyond the capabilities of most fire risk assessors. An appraisal specialist could be, but is not limited to, a chartered/incorporated engineer (registered with the UK Engineering Council), facade engineer or chartered building surveyor. Whoever undertakes the appraisal should be able to provide evidence of their competence to advise on the construction and fire performance of the external wall system in question.

A list of chartered and incorporated engineers is maintained by the Institution of Fire Engineers.

Documentation / evidence

Those with responsibility for fire safety may be able to obtain relevant information from but not limited to as-built drawings or the Operation and Maintenance (O&M) manual for the building. Advice and information should also be available from product manufacturers and/or contractors/developers about the fire performance and installation of external wall systems. Building Information Modelling (BIM) data or BS 8644 digital information on building fire safety may be available for newer developments.

Information may also be available from local authorities. Local Authorities maintain a building standards register in two parts: Part 1 of the register contains property data and is available online to anyone. Part 2 contains copies of warrants, completion certificates, principle drawings, specifications and are available for inspection during normal office hours (usually by appointment). The procedure regulations also require registers kept under previous legislation to be retained, although they will contain less detailed information.

Those with responsibilities for relevant premises under Part 3 of the Fire (Scotland) Act 2005 and associated Regulations may also hold records.

1.2 Temporary Measures

Temporary measures are introduced to improve fire safety where it has been confirmed that an external wall system poses an unacceptable risk to the safety of building occupants. Where required, the measures should be implemented without delay. Once in place, the removal or remediation of unsafe systems should be carried out as soon as possible.

SFRS and residents in affected buildings should be notified if an unsafe external wall system is identified. SFRS local fire safety enforcement officers will work with whoever has responsibility for fire safety to ensure that proposed interim measures and timescales are appropriate and may re-visit the building once measures are in place.

The fire safety risk assessment that identifies the unacceptable risks should include an improvement plan (also known as an action plan) which sets out short term to long term actions that are necessary and timescales for completion.

For domestic buildings, the fire risk assessor may advise whether a 'stay put' strategy is still appropriate or if the risk is so high that on a temporary basis, a simultaneous evacuation strategy should be adopted. In such cases, those with responsibility for fire safety should liaise with SFRS who can offer advice and will, where necessary, update its operational procedures. If a simultaneous evacuation strategy is recommended, it will need to be properly managed. It is likely to necessitate a communal fire alarm system to alert all residents of the need to evacuate. In large domestic buildings, there may be a need for persons to operate a waking watch on a 24/7 basis. Further guidance, based on Guidance to support a temporary change to a simultaneous evacuation strategy in purpose-built blocks of flats can be provided by contacting SFRS.

In cases of extreme risk, consideration may be given to moving residents out of the block until satisfactory remedial work is completed. Where some residents remain, access to the building will require careful management before and during remedial works.

Engagement with occupants/residents will ensure that they fully understand the emergency fire procedures in the building, and fire procedure notices may need to be updated. This is particularly important where a 'stay put' strategy is temporarily changed to simultaneous evacuation, pending replacement of the cladding.

1.3 General considerations

The following should always be considered as part of any fire safety risk assessment and where temporary measures are required:

  • Any potential routes for fire spread to the cladding system should be checked . This may include, for example, the risk of ignition to the external wall system via the interior of the building, plant, low level roofs, adjoining buildings etc. Fire risk assessors and appraisal experts should advise of any remedial actions required;
  • No combustible materials such as refuse should be allowed in the vicinity of the cladding system and steps should be taken to prevent accumulation of such materials, for example the use of temporary barriers and instruction to residents;
  • Balconies should be free from any ignition risks: the use of electrical appliances or heaters within affected balconies should be avoided. Residents should be advised not to smoke or have barbecues on balconies;
  • Parking spaces, where a vehicle fire could impinge on cladding, may need to be taken out of use/closed;
  • Flat entrance doors, and doors that open onto escape corridors and stairways, should be checked to ensure they are fire-resisting and effectively self-closing.
  • Bin rooms, plant rooms and electrical cupboards should be kept locked shut. Plant rooms and electrical cupboards should not be used to store combustible items. Large unwanted items left in bin rooms should be uplifted as soon as possible or removed to secure, dedicated storage areas;
  • A policy should be in place to prohibit items being kept in common areas and escape routes. This policy should be enforced by regular walk rounds by caretakers or members of resident committees;
  • Walls and floors that separate flats, plant and store rooms, etc. from escape routes should be checked to ensure there are no obvious routes for fire or smoke spread (e.g. holes where services pass through, such as pipes and cables);
  • Where provided, smoke control systems and associated fire detection systems, should be tested and maintained in good working order.
  • Facilities provided for fire-fighters, including fire-fighting lifts and dry or wet rising mains should be checked and any concerns reported as soon as possible to SFRS who will, if they have not already done so, carry out an inspection to assess functionality.
  • Sufficient roadway access and hardstanding for firefighting vehicles should be maintained;
  • Residents must be advised to check that smoke and heat alarms in their flats are present and working and to report any fire safety concerns to those with responsibility for fire safety. Changes in the law relating to fire and smoke alarms came into force in February 2022. Residents should understand the purpose and importance of any short-term interim measures being taken.
  • Those responsible for domestic premises should co-operate with any commercial premises within the building to ensure they do not pose any significant risk;
  • Residents in domestic premises should be encouraged to request a Home Fire Safety Visit (HFSV) by SFRS;
  • Where appropriate and practicable, an up to date list should be held of any occupants who may require assistance in the event of a full evacuation. This list should be kept up to date and proactively made available to SFRS;
  • Maintaining existing fire safety measures should be a priority and repairs carried out as a matter of urgency;
  • The external perimeter of the building should be checked for any potential fire risks which are in close proximity that may be vulnerable to accidental/deliberate ignition;
  • Appropriate security measures such as electronic access control should be put in place and maintained to mitigate the risk of wilful fire raising. Such measures should not impede escape or fire service access. Effective lighting should be provided internally and externally and, where appropriate, monitored CCTV may be considered particularly on entrances and external facades. This may reduce loitering or disorder and identify at an early stage, any potential for external fire spread;
  • Records should be checked to ensure that fixed electrical installations have been adequately maintained;
  • Any building lightning protection systems should be subject to regular maintenance.

More information on the above (including relevant British Standards that cover maintenance and testing of systems and equipment) can be found in existing Scottish Government fire safety guidance.


Email: BuildingStandards@gov.scot

Back to top