Practical fire safety - existing high rise domestic buildings: guidance - updated March 2021

Chapter 2: Fire Safety in High Rise Buildings

15. This Chapter explains fire safety measures in high rise domestic property. It covers fire resistant construction, escape routes, fire detection and warning, evacuation strategies and facilities for use by SFRS.

Key points

• Each flat is a fire-resisting 'box' designed on the 'stay put' principle.
• Fire resisting construction is also provided to stair enclosures, service risers, lobbies and ancillary areas.
• A principle of fire safety is that escape from a fire should not rely on external rescue by the fire service.
• Fire detection and alarm systems give early warning of fire.
• High rise blocks do not normally require a communal fire alarm system.
• Facilities are provided to assist firefighters.

Fire Separation^[2] to Restrict Spread of Fire and Smoke

16. Each flat is built as a fire-resisting enclosure. It is bounded by non-combustible separating walls and floors that will resist the passage of fire for a period of time. There are also non-combustible separating walls and floors between flats and the common areas and those that enclose stairs and lift wells.

17. While there will be fire separation between each flat, when SFRS tackle a fire in a flat, its hose prevents doors from fully closing. This can result in smoke spreading into common areas.

Evacuation and Stay Put Policy

18. In the majority of fires in high rise buildings, most residents do not need to leave their flats. Fire separation provides fire resistance to contain a fire in the flat of fire origin. Accordingly, people in flats who are not affected by fire or smoke are normally safe to stay where they are. In some circumstances, residents might be at greater risk if they do leave their flat. This is the basis of the 'Stay Put' policy in response to fires in high rise properties. It has been in guidance since the 1960s and is the basis for high rise domestic building design. It is an appropriate strategy in the majority of high rise domestic buildings.

19. 'Stay Put' is the following approach:

• When a fire occurs within a flat, the occupants alert others in the flat, make their way out of the building and summon SFRS.
• If a fire starts in the common areas, anyone in these areas makes their way out of the building and summons SFRS.
• All other people in the building not directly affected by the fire would be expected to 'stay put' and remain in their flat unless directed to leave by SFRS or the Police.
• Any person not directly affected by fire or smoke can leave the building if they wish, although doing so could place them at greater risk.

20. Occupants evacuating a flat where there is fire can alert their neighbours so that they can evacuate if they feel threatened.

21. SFRS will give initial advice over the phone to residents who dial 999. Upon arrival, firefighters will take control of the incident and may advise further, as necessary. There may be fires where, for operational reasons, SFRS decides that a partial or total evacuation of a high rise is necessary. These uncommon situations include where a fire spreads beyond the flat of origin as a result of failings in the construction. More modern high rise domestic buildings may have an evacuation alert system for SFRS use, to allow them to instigate the evacuation of a floor, multiple floors or an entire building. (This was introduced on 1 October 2019 in the Scottish Domestic Technical Handbook).

22. The alternative to a 'stay put' policy is one involving simultaneous evacuation where all, or a number of residents, evacuate the building together. To operate in practice, this requires a system to alert all of these residents to the need to evacuate.

23. The range of physical and mental capabilities of the residents should be taken into account when considering evacuation. It may be that simultaneous evacuation is impracticable for certain residents, for example those with mobility issues or certain disabilities.

24. Simultaneous evacuation is sometimes advocated where there are doubts over construction, particularly fire separation. Resolving concerns and addressing deficiencies is usually more appropriate than changing the evacuation strategy. However, on rare occasions it may be necessary to temporarily adopt a simultaneous evacuation strategy until major deficiencies can be remedied (such as the use of inappropriate external cladding systems or widespread failure of fire separation). Where this is the case, specialist advice should be sought and SFRS consulted.

Means of escape

25. A principle of effective fire safety is that escape from a fire should not rely on external rescue by SFRS. Flats in high rise domestic buildings are designed on the basis that escape or rescue via windows should not be necessary. Above the third floor, rescue by SFRS ladder may not be possible. High reach appliances have limits to the height they can reach and there can be other restrictions which prevent access to the building.

26. Many high rise blocks have a single stair escape route. Even in buildings with two or more stairways, it is often necessary to travel along a single common corridor to reach a stairway.

27. Escape routes from a flat to safety outside the building rely on horizontal escape - from the flat entrance door using a corridor, lobby or an external balcony or deck (using the common areas); and then vertical escape via a stairway to a final exit. Lifts should not be used unless they have been designed and constructed specifically for use as evacuation lifts, and appropriate management procedures are in place.

28. Once out of the flat, escape for residents depends on the common areas being suitable for use in an emergency. There needs to be adequate levels of fire protection provided to the communal escape routes so that smoke and heat from a fire in a flat or ancillary room will not prevent the corridors, lobbies, external balconies or stairways being used.

29. Design of communal means of escape in high rise blocks of flats is based on the following:

• There is fire separation between flats, between flats and the common areas, and between common areas and ancillary accommodation, to provide a barrier to fire and smoke spread.
• The materials used in the construction of the building or the protection afforded to them are such that fire is inhibited from spreading through the fabric of the building.
• The materials and construction of the building envelope resist external fire spread.
• Common areas are constructed and used in a way that any fire originating in these areas should not spread beyond the immediate vicinity.
• Corridors leading to stairways are enclosed in fire-resisting construction.
• Where there is escape in only one direction along a corridor, the distance travelled in such 'dead ends' is limited.
• Access decks and communal balconies are limited in length if escape is only possible in one direction.
• Fire-resisting construction should protect people passing flats to reach a stairway.
• Escape stairways are enclosed in fire-resisting construction.
• In a single escape stairway, the stair should have a protected lobby approach (with automatic smoke ventilation in the lobby).
• Doors opening onto communal escape corridors and stairways should be fire-resisting and self-closing (or locked shut in the case of service riser and ancillary room doors).
• Arrangements are provided for smoke control in stairways, protected corridors, and protected lobbies (often with control provision for SFRS use).
• Emergency lighting or protected circuit escape route lighting is provided.
• The building's elements of structure have sufficient fire resistance to resist fire-spread and prevent structural collapse. The means of escape also provides fire protection and space for firefighters to set up a forward control point and a bridgehead to commence firefighting.

Fire detection and alarm systems

Smoke and Heat Alarms in Flats

30. Early warning of fire in a flat is essential to ensure that residents can evacuate safely from the flat. Smoke alarms in individual flats give early warning of fire and, along with heat alarms, are basic components of fire safety. They are important in reducing the number of casualties in dwelling fires.

Communal Smoke Detection

31. The common areas may have separate smoke detection to automatically open vents to clear smoke. Such systems do not incorporate an audible warning, as the detection is part of the smoke control system, not the fire warning system.

Communal fire detection and alarm systems

32. Rarely will a communal fire detection and alarm system be appropriate for a high rise domestic building. This could be where it is impossible to upgrade other measures to enable a 'stay put' policy to be adopted and where the residents can respond to an alarm, evacuate without assistance, and where the building has capacity for simultaneous evacuation. For most high rise domestic buildings, this would not be possible.

33. There are limited circumstances when a fire detection system could be provided in the communal areas but without a simultaneous evacuation procedure. This is where the objective of the system is to compensate for a particular shortcoming in an aspect of escape route design or fire separation. In such a case, system actuation would not sound a general evacuation but notify automatically an alarm receiving centre and is passed to SFRS. These systems are only applicable in specific circumstances, and require careful consideration.

Life safety automatic fire suppression

34. Life safety automatic fire suppression systems have been required in newly built high rise domestic buildings since May 2005 under Scottish Building Regulations. Suppression systems (sprinklers and water mist mainly) may have been retrofitted into blocks built before that date. They are fitted in every flat and often in all ancillary rooms and spaces throughout the building to help suppress a fire.

35. Properly designed and maintained automatic suppression systems are effective at controlling fires and may even extinguish them in the areas protected by the system.

Other fire safety measures in the building

36. There is emergency escape lighting in high rise buildings to provide adequate illumination for escape routes in an emergency, if the mains powered lighting fails (See Chapter 5 for further information on lighting).

37. There is rarely a need for fire exit signs in a single stairway building. Fire exit signs might be needed for unfamiliar escape routes (See Chapter 5 for further on signage).

38. Fire extinguishers and other fire-fighting equipment should only be used by people trained in its use. It is not normally appropriate or practicable for residents to be expected to use these or receive training, nor provide them in common areas.

39. In addition, if a fire occurs in a flat, the provision of fire extinguishing appliances in the common areas might encourage the occupants of the flat to enter the common area to obtain an appliance and then return to their flat to fight a fire. Such action is normally inappropriate.

40. Fire-fighting equipment may be required in plant rooms and other rooms, for use by staff or contractors.

41. Residents can buy their own fire extinguishers and fire blankets for their flats if they wish.

Facilities for SFRS

42. There are facilities in high rise buildings for SFRS to effect rescues and fight a fire. These normally include protected stairways and lobbies, specially designed lifts for use by firefighters and rising fire mains for SFRS to obtain water. Additional requirements for: evacuation alert systems; firefighting stairs; and floor/dwelling identification signage were introduced on 1 October 2019. These apply to Building Warrants submitted on or after that date.