Chapter 6: Restricting The Spread Of Fire And Smoke
155. To reduce the risk to persons from fire, it is necessary to consider how to control or restrict the spread of fire and smoke. The majority of people who die in fires are overcome by smoke. To evaluate the risk requires a basic appreciation of the way fires grow and how smoke can spread through a building. A fire in a building can generate smoke that is thick and black, obscures vision, causes difficulty in breathing, and can block escape routes. Smoke is a serious threat to life which should not be underestimated.
156. Fire is spread by convection, conduction and radiation. Convection causes the major proportion of injuries and deaths. When fire starts in a building, the smoke rising from the fire becomes trapped by the ceiling and then spreads in all directions to form an ever-deepening layer over the entire room space. The smoke will pass through any holes or gaps in the walls, ceiling and floor into other parts of the building. The heat from the fire gets trapped in the building and the temperature rises. Some materials, such as metal beams can absorb heat readily and transmit it to other rooms by conduction, where it can set fire to combustible items that are in contact with the heated material. Radiation transfers heat in the air in the same way that an electric bar heater heats a room. Combustible material close to a fire will absorb the heat until the item starts to smoulder and then burn.
157. A fire compartment is part of a building constructed to provide a physical fire-resisting barrier to prevent the spread of fire and smoke to or from another part of the building. A compartment can be further sub-divided into sub-compartments to aid progressive evacuation.
158. Where residents are dependent on staff assistance in the event of a fire and the evacuation strategy is progressive evacuation, the building should be divided into different fire-resisting compartments or sub-compartments by fire-resisting doors, walls and floors. This restricts the number of residents who would be at immediate risk in the event of a fire occurring and allows their evacuation, as a first stage, to an adjoining compartment or sub-compartment. Figure 3 shows the principle of sub-compartmentation.
159. The following benchmarks are relevant to compartmentation in premises where progressive evacuation is adopted:
- Floors are compartment floors so that every upper storey and every basement storey is a separate compartment.
- A storey area exceeding 1500m22, sub-divided into separate compartments, each no greater than 1500m.
- Compartments divided into at least two sub-compartments by a sub-compartment wall and door(s) so that each sub-compartment is no greater than 750m2.
- Fire-resistance of compartment walls, floors and doors at least 60 minutes, or in premises with only medium and/or low dependency residents where no residents are sleeping above the ground floor, at least 30 minutes.
- Fire-resistance of sub-compartment walls and doors at least 30 minutes.
160. Lateral fire spread could occur where a compartment wall or sub-compartment wall abuts an external wall. A precaution against this is for the external wall to have fire-resistance for a 1m wide projection. This measure is likely to be unnecessary where an automatic suppression system is provided.
161. Any door in a compartment wall or sub-compartment wall should be a self-closing fire door with at least the same fire-resistance duration as the wall and have smoke seals.
162. The normal standard for bedroom corridors in a care home is for the corridors to be protected routes whereby the doors and walls forming the bedroom corridor, other than doors serving only toilets where the potential for fire is low, have at least a nominal 30 minutes fire resistance. The doors should be self-closing and have smoke seals (see paragraphs 168 -172). This offers protection to the bedroom corridor escape route from fire and smoke if a fire starts in a bedroom or other room, maintaining the tenability of the escape route to give maximum evacuation time. Figure 4 shows a floor layout with a protected bedroom corridor.
163. For the purposes of smoke control, corridors which are not protected corridors, that have at least two directions of escape, and are more than 12m in length between the exits, may be divided in the middle third of the corridor with a wall or screen with at least 30 minutes fire-resistance (for integrity only) and the door in the wall or screen at least an FD 30S self-closing fire door.
164. In situations other than in bedroom corridors, some rooms may need to be enclosed by floors, walls, doors and ceilings, to provide at least 30 minutes fire-resistance, in order to contain a fire in its early stages. Some examples are shown in Table 4.
Table 4 – Examples where fire-resistance may be required
- Storage rooms and cupboards
- Smoking rooms
- Staff changing and locker rooms
- Kitchens and laundry rooms
- Disposal rooms
- Day rooms
- Rooms containing a lift drive mechanism (unless already within an enclosure)
165. A lift well can be a route for vertical fire spread. A lift well which is enclosed by walls with at least 60 minutes fire-resistance will be a barrier to fire spread. A lift well which is totally within a protected area such as an enclosed stair, is already within a fire-resisting enclosure. Where a lift well is not the full height of the building, the fire-resistance of the floor and/or ceiling needs to be considered.
166. Where services pass through any fire-resisting structure, any gaps should be sealed or fire-stopped to maintain the fire-resistance of the structure and prevent the passage of fire or smoke. Pipes should be fitted with a proprietary sealing system capable of maintaining the fire-resistance. A similar consideration exists for penetration by ventilation ducts (see page 42).
167. Boiler rooms and plant rooms are a possible source of fire. To contain a fire, a room may be enclosed by walls with at least 60 minutes fire-resistance where it contains an appliance (solid fuel, oil or gas fired, or fuel oil tanks). Where the appliance or equipment uses liquid fuel, the room should be able to contain all the liquid in the appliance or equipment, plus 10%.
168. A ‘fire door’ is a fire-resisting door which is rated by performance to fire under test conditions. Fire doors are used to prevent fire spread as part of a fire compartment and for the protection of means of escape. A self-closing device is a normal feature of a fire door, though there are some exceptions such as doors to small cupboards which are kept locked shut.
169. A fire door rated to 30 minutes is described as FD 30  or E 30 . A suffix is added to denote that the door has a smoke control function giving FD 30S and E 30Sa respectively. A 60 minutes fire door with smoke control is designated FD 60S or E 60Sa. The rating is an indication of test performance and not necessarily how a door will perform in a real fire.
170. The level of protection provided by a fire door is determined by the time taken for a fire to breach the integrity of the door assembly, together with its resistance to the passage of smoke, hot gases and flame. The gap between the door leaf and the frame is normally fitted with intumescent strips, in either the door or the frame (except at the bottom of the door). The strips expand in response to heat from a fire, to seal the gap between the door leaf and the frame. Smoke seals prevent the spread of smoke at ambient temperatures.
171. In determining the performance of a door in fire, it is necessary to consider the whole door assembly including the frame, glazing, side-panels, transoms and ironmongery. To ensure the rated fire performance of a new door assembly, the manufacturer’s installation instructions should be followed.
172. Some existing doors may have the potential to be upgraded to nominal 30 minutes standard, but replacement of existing doors and frames is often preferable.
173. A fire door will only fulfil its function to provide a barrier to fire and smoke if it is closed at the time a fire occurs. It is inappropriate to rely on a procedure whereby staff will attend and close doors as an alternative to fitting self-closers. A controlled self-closing device, complying with BS EN 1154, should therefore be fitted to each fire door, including rooms off bedroom corridors (other than to cupboard doors that are normally kept locked shut).
174. The closing pressure of the self-closing device needs to be sufficient to overcome any latch mechanism. The force or speed of the self-closing action of a door could be a source of injury to some residents. Additionally a self-closing door may be difficult for some residents to open. These factors should be considered when selecting or assessing the suitability of self-closer type.
Hold-open and Door Release Devices
175. Doors with self-closing devices may pose an obstacle to the day-to-day operation of a care home. Many residents may wish (or need) to keep their bedroom doors open for ventilation or communication with other residents or staff. Open doors can assist staff to monitor residents with a minimum of disturbance. There are devices which allow self-closing fire doors to be held in the open position until the fire warning system operates.
176. A self-closing fire door can be held open by an electromagnetic hold-open device (which complies, where appropriate, to BS EN 1155 or BS 5839: Part 3) or with electromagnetic hold-open door closers (to BS EN 1155). Electrically operated hold-open devices should deactivate and release the door on operation of the fire warning system or any loss of power to the hold-open device. In the case of doors to stairways, the doors should close automatically in the event of fault in the fire warning system, including total loss of power (mains and standby) to the system.
177. An alternative type of release is an acoustically-activated door release mechanism complying with BS EN 1155. Acoustic devices should not be used on fire doors to protected stairs in care homes. Acoustic devices actuate in response to the sound from the fire alarm sounders so will be inappropriate where there is a voice alarm or where the initial fire alarm warning alerts staff only.
178. A further type of self-closing device comprises a ‘swing free’ arm , allowing the door leaf to work normally and independently of the closing device in normal conditions. On the operation of the fire alarm or on power failure, the self-closer operates and closes the door. This type is particularly suitable for use on bedroom doors.
179. Some hold-open and ‘swing-free’ devices are able to be radio-linked to reduce the need for wiring. Some acoustic systems are battery powered.
180. BS 7273: Part 4 contains detailed guidance on conditions for use of door release devices.
181. A hold-open or swing-free device should not be used on a fire door protecting an escape stair if there is only one escape stair in the building, or if it is the only escape stair serving part of the building. They should also not be used for a door to a room in which the type of automatic fire detector is solely a heat detector.
182. The automatic closing of a door fitted with a hold-open or release device should occur when the fire warning system operates. The closing of doors may take residents by surprise and the force of the closing mechanism could knock a resident over and may be a source of injury. Consequently precautions should be taken to avoid injury. Any scheduled test or action which will result in release of the doors, should occur when residents will not be passing through the doors.
183. There may be a need to consider the situation of mobile residents in bedrooms with door-release or swing-free devices. Some residents, who may be accustomed to passing through their doorway unaided, may be unable to overcome the force of the self-closer and therefore be unable to open the door and exit the room, in the event of the fire warning system actuating.
184. Fire separation is construction designed to restrict fire and smoke spread between different occupancies. Where a care home adjoins or is part of a larger building, such as where it is semi-detached or in a terrace, the potential for an outbreak of fire in the neighbouring building ultimately spreading to the care premises, such as through a roof void, should be considered.
185. A separating wall or separating floor provided between parts of a building where they are in different occupation should have at least 60 minutes fire-resistance and have no openings. Ideally, there should be no pipes, wires or other services between occupancies, but where these already exist, they should be fire-stopped or protected by intumescent materials to maintain the fire-resistance.
Fire Spread through Cavities
186. Many buildings have cavities and voids, sometimes hidden from view, which may allow smoke and fire to spread. Examples are:
- Vertical shafts and dumb waiters.
- False ceilings, especially if walls do not continue above the ceiling.
- Voids behind wall panelling.
- Unsealed holes in walls and ceilings for pipe work, cables or other services.
- A roof space or attic.
- A duct or any other space used to run services around the building.
187. Potential fire spread through cavities and voids should be assessed and, where practical, physically examined to see if there are voids that fire and smoke could spread through.
188. Cavity barriers may be necessary to restrict the spread of fire in cavities, particularly for those cavities that could allow fire spread between compartments and/or sub-compartments.
189. Modern timber frame buildings have cavities within the frame and these should have been installed with fire resisting cavity barriers between the external cladding and the timber wall panel at the time of construction.
190. The potential for ventilation systems to allow the spread of fire and smoke should be assessed. A powered ventilation system may assist the spread of smoke unless it is designed to shut down automatically if fire is detected.
191. Ventilation ducts may provide a pathway for the spread of fire and smoke between compartments or sub-compartments or into stairs. Where ventilation ducts penetrate the walls or floors of these enclosures, automatic dampers provided inside the ducts hold back fire and smoke. Dampers may need to be actuated by smoke detection. Specialist guidance on the use of dampers is contained in BS 9999.
Fire Spread on Internal Surfaces
192. Fire can rapidly spread on the surfaces of walls and ceilings, significantly affecting overall fire spread and rate of fire growth and smoke production. The potential for fire spread on surfaces in escape routes is particularly important as this could prevent occupants from escaping. The internal surfaces of care homes can be compared by reference to the ‘reaction to fire grading’ shown in Table 5.
|Dependency of the residents||Surface||Rooms
less than 4m2
4m22 to 30m
|Rooms more than 30m2
|Protected stairs & corridors*
* includes any toilet or washroom within the enclosure of a protected stair
193. The surface spread of fire grading system relates to performance against tests set out in certain British Standards. Examples of materials which may fall into these categories are:
Category 0 - brickwork, blockwork, concrete, ceramic tiles, plaster finishes (including rendering on wood or metal lathes), wood-wool cement slabs and mineral fibre tiles or sheets with cement or resin binding.
Category 1 - timber, hardboard, blockboard and particle board, which have been treated to achieve this category.
Category 2 - timber, hardboard, blockboard, particle board and certain dense timber or plywood.
194. Additional finishes may be detrimental to the fire performance of the surface. Multiple layers of wallpaper or certain paints applied to the face of a wall or ceiling surface can increase surface flame spread.
195. The use of plastics for surface finishes is a complex issue and outwith the scope of this guidance document. Information on the suitability of plastic materials can be found in the Scottish Building Standards Technical Handbook for Non-Domestic Premises.
Fire Spread on External Walls
196. If there is combustible external wall cladding or construction, it will be necessary to consider the potential for an outbreak of fire within the building, or from an external source, to spread on the external walls of the building and pose a risk, especially where there are high dependency residents and extended evacuation times. Further guidance is available: Scottish Advice Note: Determining the fire risk posed by external wall systems in existing multi-storey residential buildings - gov.scot (www.gov.scot)
Fire Spread from Neighbouring Buildings
197. An assessment should be made in respect of the potential for a fire to spread to the premises from any neighbouring buildings or structures and whether this could pose a risk to occupants.
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