Application of UK Fire Safety Engineering Design Guidance - Case Study Example

liсаtiоn of UK Fire Safety Еnginееring Design Guidаnсе to Араrtmеnt Building Design for Mеаns of Еsсаре Case Study: Five (5) Storey Block Apartment Building The floor plan for the apartment building being considered is as shown; Figure 1: Ground Floor Plan The main entrance to the structure opens to the main corridor to access the flats on the ground floor and a flight of stairs to access the upper floors. The main corridor gives access to the lift as well. Figure 2: Typical Floor Plan (1-4) Fire Risk Assessment The apartment block contains a ground floor and four (4) upper floors, with three self- contained flat units on each floor, totaling to 15 flat units across the building. Each of the flats on the upper floors can be accessed indirectly off a single stairway and a single lift servicing a common corridor. Type 3 fire risk assessment1 is recommended for the structure. This is in line with the requirements of the Regulatory Reform (Fire Safety) Order of 2005 [The10] and is most appropriate for rented flats with no reason to suspect serious risk to the residents in the occurrence of a fire. It is also a non- destructive assessment, meaning that no damage gets done to the structure during an investigation. It is, however, relatively expensive to conduct. The structure is of substantial construction, comprising of concrete floors, 150mm thick, with external masonry walls, 200mm thick. Partitioning walls are 150mm thick. This structure provides a good standard of fire resistance between adjacent flats, between flats and common parts and between different floors. The lack of any communal fire alarm system depicts the adoption of the ‘stay put’ policy, which is supported by the construction materials. All doors are made of hardwood, except those covering closets, which are thin panels of softwood. The lift doors are made of rigidized metal (steel) as well as the whole lift assembly. There are large, openable windows in all rooms with outside facing walls, to allow adequate venting of smoke. The staircase also has large openable windows on the outside facing wall. However, the main corridor and lobbies for each flat do not have any windows, which could present a hazard of smoke build- up should the fire reach these locations. The largest travel distance from the farthest point to the flat entrance was found to be. It is crucial to mention that this exceeds the maximum travel distance allowed in Approved Document B[The10] – Diagram 32 Figure 3: Flat with restricted travel distance from furthest point to entrance The flat closest to the lift has the smallest internal entrance halls. The other flats have relatively long internal entrance halls, which could pose a hazard as occupants will be required to travel longer distances, in a fire outbreak, to reach areas of safety. The bedroom of the single flat is also located closer to the flat entrance door than the kitchen. For the other flats, occupants in the bedrooms may be exposed to fire as they try to exit the flat. The floor space for the larger flats was found to be and for the smaller flat, totaling to, excluding the common corridor. Using a floor space factor of [The10] – Table C13, the maximum total occupancy for each floor comes to approximately32 persons per floor. The total number of people who will use the ground floor stairs in the case of evacuation will be 160 persons. The widths of the individual flat lobbies, the common corridor and the staircase are large enough to evacuate all the occupants in the case of an outbreak and also provide the firefighting service access to the blaze. [The10] – Table 64 Means of Escape The occupants of the structure have ONLY ONE OPTION as a means of escape they can use in a fire outbreak. This is very inappropriate and would likely lead to endangerment if the available means of escape becomes incapacitated by the fire. The lift is not recommended as a means of escape option as the fire could lead to malfunction of the lift system, exposing the occupants who choose to use it to more danger than they would be if they used the staircase. The only exception to this could be if the fire outbreak occurs at a location that would render the use of the staircase impossible. This will require efficient phased evacuation to prevent overloading of the lift. Occupants of the floor where the fire started should be evacuated first, followed by those on the floor directly above, as these floors will be most affected by the outbreak. The means of escape from the rooms in the flats will be of the general direction shown; Figure 4: Means of Escape The stairs should be properly designed to handle the influx of people during an escape. Openable windows and vents should be installed to allow for proper ventilation to prevent a buildup of smoke, which could hinder the escape process. The means of escape should be distinctively and conspicuously marked by emergency exit signs of adequate size, complying with the Health and Safety Regulations [2]. Fire Alarm and Fire Detection Systems The landlord did not provide for any smoke or heat sensors in any of the units. There are also no fire alarms to inform the occupants of a fire outbreak. The only available method of conveying information about a fire is by ‘shouting’. This is, however, not very effective as some areas within the structure are out of earshot range, and some occupants may be endangered. Internal Fire Spread Materials which are easily flammable or have a high rate of heat release should not be used as linings in locations likely to be sources of fire as they will facilitate its spread. Concrete and masonry are relatively resistant to fire spread, but linings such as paint or fabric are very susceptible to fire. Fire poses a significant hazard to the stability of the structure as it undermines the integrity of the construction elements. It is crucial to maintain the structure’s integrity for a sufficient period to allow for the process of escape to be completed. The masonry walls and concrete floors should provide fire protection to the occupants [The10] – Table A25. The doors to the individual flat entrances and exit from the main corridor should not have a heat leakage rate exceeding when tested at under BS 476. The doors should also have fire protection equal to the wall they are installed in, that is, 60 minutes. The doors not located on the escape route should have relative fire protection to prevent excessive fire spread within the flat unit. Compartmentation The masonry walls around the central corridor and the lift are wider than the partitioning walls. These provide added protection to these areas in the case of a fire and are taken to meet the minimum fire protection requirements. The fire risk assessment showed that these walls have a protection for about 60 minutes. To provide further protection for the structure, compartmentation is recommended to separate locations where a fire is likely to start and areas where loss of life and property is likely to occur, in this case, kitchens and bedrooms respectively. The staircase should also be compartmentalized as it forms an integral part of the means of escape, and its premature compromise could result in a wanton loss. However, the partitioning walls between different flat units are thin and may not be adequate to prevent ingress and spread of fire between the flat units. Recommendations Solutions proposed for the structure in order to provide additional fire protection are among the following. These solutions may be short, medium or long term solutions and the choice of which is implemented is governed mainly by level of risk of fire and the cost of implementation. Compartmentation The partitioning walls between different flat units should be lined by a fire resistant material to increase their fire protection time, limiting further spread of fire. Fire doors Fire doors should be installed where compartmentation has been done so as not to provide the fire with an avenue for spread, compromising the structure. The fire doors should provide the same level of fire protection as the wall it is installed on. Figure 5: Compartmentation and Fire Doors Extra caution needs to be given to the doors that are on the escape route. These doors should not have a high rate of heat release as this could harm the occupants as they try to exit the building. The doors leading to the staircase should be free swing self- closing fire doors. This is so as to prevent ingress and accumulation of smoke, which could hamper the escape process. Alternative routes Fire escapes or other alternative exits should be provided for all flats. These alternative routes should be directly accessible from the bedroom areas of the flats, and should provide safe route away from the fire. The doors to the fire escape should activate the alarm when opened in case the occupants are not able to raise the alarm in the conventional way. The occupants of the larger flat units who are in the living room in the outbreak of fire should be provided with an alternative means of escape should the fire compromise their escape through the main corridor to the staircase. Figure 6: Means of escape showing alternative routes Emergency lighting The escape route should have adequate artificial lighting with enough luminescence to be visible even when there has been a buildup of smoke. The circuitry for emergency lighting should be independent from the standard lighting, in case it gets compromised by the fire. Exit signs can also be fitted with flashing lights to give better guidance to the occupants. Sensors and Alarms Smoke and heat sensors should be provided in circulation areas, between the most likely sources of fire and the sleeping places [The10]. The sensors should not be placed in bathrooms and kitchens, where heat and steam may give false alarms. The alarms should be mains- operated and conform to BS EN 4604: 2005. Standby power should be provided in case the fire disables the main source of electricity, and should be triggered by opening of emergency doors. Sound alarms should be placed at the entrance of all flats, as an indication of where the occupants of the flat should escape to. A sound and visual alarm should be placed at the exit to the staircase in case smoke may have found its way to the common corridor. Sprinklers The use of sprinklers reduce the risk of loss of life and the fire damage to property. Sprinklers need only be installed in the individual flat units, where loss of life and property is most likely, and are not necessary for common areas such as corridors or the stairs. Sprinklers may be installed in the kitchen and living rooms in the flat units. Sprinklers should be fed by water conveyed by two independent distribution systems. The water could be extracted from a single reservoir, such as a tank, or from multiple sources by either gravity or suction means. The sprinkler system should not interfere with electric conduits as this may result in sparking, and a fire outbreak. Areas of refuge These are relatively safe waiting areas for short periods. These allow for people who cannot use the available means of escape due to different circumstances to be sheltered as better alternatives are arranged. Areas of refuge can be provided for at the landings of the stairs, which are fire protected. Firefighting equipment Fire extinguishers and fire blankets should be provided at locations likely to be sources of fire to increase the chances of controlling the fire, extinguishing it before it spreads to other areas. This is very effective for incidental fires, such as sparks from electric mains or burnt cooking. However, this is inconsequential for large fires, such as explosion of gas mains where the fire immediately gets out of control. References The10: , (Anon., 2010), The10: , (Anon., 2010), Read More