Fire Safety

Fire is the single greatest threat to occupants, contents and fabric of any building. Whilst life safety should always remain paramount, where ﬁre occurs in a historic building the loss of authentic fabric and valuable contents is inevitable. As an out-of-control room ﬁre can reach temperatures of 1000° Celsius in just over 3 minutes, the risks are considerable. During the last 12 years press reports have revealed that at least one Category A or B Listed Building in Scotland is lost, or signiﬁcantly damaged, each month as a result of ﬁre, and it is believed that many others suﬀer lesser damage. So, an awareness and implementation of ﬁre management measures is essential if the current levels of loss to the eﬀects of ﬁre are to be reduced.

What creates a fire risk?
A combination of heat, oxygen and fuel has to be available for ﬁre to take hold and develop. For ﬁre to be able to spread, it requires unhindered progress through apartments adjacent to where it started. In this regard, historic buildings are particularly vulnerable. This is due to their traditional methods of construction, the numerous voids which can exist between apartments, and the lack of eﬀective separation between various rooms and large enclosed spaces. Frequently, this combination of factors has lead to the total loss of the building, and all its contents. Given that smoke inhalation is the principle cause of ﬁre-related deaths, in the early stages of a ﬁre it is important that the building’s occupants are alerted to its outbreak as soon as possible. Early detection of ﬁre is therefore essential, especially in areas of high risk such as kitchens or where naked ﬂames might be present. Detection systems are vital in alerting occupants to escape, so they may summon support from the local Fire and Rescue Services. But, due to the time it will take for the Services appliances to arrive and set up ﬁre ﬁghting actions, degrees of loss will have already occurred.

The development of fire
Each ﬁre incident develops in its own complex manner, but all ﬁres fall into four distinct stages: Embryonic ﬁre following a malfunction or incident Fire growth following ignition Developed ﬁre following a “ﬂashover” Fire decay with the destruction of all consumable fuel The primary production of combustion is heat, and this can transfer to other materials (fuel) by convection, radiation and conduction. The ease by which this can occur will inﬂuence the rate at which the ﬁre spreads. The amount of smoke that is produced will be dependent upon what is burning and the amount of air (oxygen) that is available in the room where the ﬁre is. Smoke contains irritants and toxic gases, which are particularly life-threatening. Freely burning materials will quickly produce high temperatures. The presence of ﬂame reveals that a quantity of high temperature particles has been created. Unless the ﬂames are quickly controlled and extinguished, the ﬁre will speedily develop and lead to a greater degree of destruction and loss. As it grows, the increasing temperatures will lead to a situation called “ﬂashover” where all remaining combustible fuel sources ignite - with some considerable intensity. During these four stages the atmosphere develops from being polluted to becoming unpleasant, intolerable and, subsequently, lethal for remaining occupants. The combustible building contents and structure become smoke tainted, blackened, charred and, eventually, destroyed. The incombustible structure becomes warmed, heated and, eventually, distressed through melting or expansion and fracturing, leading to partial or complete destruction. During each stage the ﬁnancial implications and associated remedial costs escalates dramatically. In a historic building, the level of cultural, architectural and artistic loss at each of the four stages also increases incrementally where the authentic value and quality of what remains following the ﬁre is greatly reduced, or eliminated. The reality, and consequences, of these factors are generally not appreciated, and much complacency exists in the minds of building owners and occupants on the basis “that it will never happen to me”. A more realistic consideration might lie in reﬂecting on the diﬃcult question – “What do you want left after the ﬁre?” In numerous cases in the past, the reality of a ﬁre has been “a burnt out shell.”

Compartmentation
Historic buildings were built when an understanding of the eﬀects of ﬁre did not exist in the way it does today. Continuous roof spaces over the entire building or wings, hidden voids behind plasterwork in masonry partition walls, and holes left in walls during later works, all contribute to a high risk of a rapid spread of ﬁre should an incident occur. They can also contribute to ﬁre growth by allowing a continuous supply of fresh air (oxygen) into the seat of a developing ﬁre. The concept of compartmentation involves ﬁnding an appropriate way of eﬀectively blocking up any voids, and/or creating ﬁre breaks in spaces of large volume (such as in roof spaces, or improving the ﬁre resistance of doors), so that distinct “compartments” or sections of the building are created within which any outbreak of ﬁre might be contained, fought and controlled. It is work that requires careful consideration, design and implementation if the welfare, quality and value of the building is not to suﬀer through the installation work.

Reducing the risk
Risk of ﬁre can be greatly reduced by a proper awareness of how ﬁres start and how they can spread. Eﬀective ﬁre safety management of properties will greatly reduce the impact and consequences of ﬁres. A better understanding of all the issues involved can also assist in overcoming any complacency. By focusing on the three factors heat, oxygen and fuel much can be done at a basic level to reduce the levels of risks through greater vigilance.

Heat
Heat can be produced by a wide variety of sources. These include – Paint stripping (especially with the use of blow lamps) Plumbing work Smoking material Naked ﬂames, including the use of candles Cooking Faulty appliances Electrical faults and lack of maintenance Open ﬁres, cracked hearths and faulty ﬂues Glass items focusing the sun’s rays Fire-raising Awareness of the risks and proper controls of these activities can do much to stop ﬁre from starting, and taking hold.

Oxygen
Oxygen is essential to both human life and ﬁre. Whilst modern ﬁre ﬁghting techniques have created systems that can reduce the oxygen content inside buildings so that ﬁres are prevented from developing, such techniques are only applicable to very speciﬁc situations. Building owners can reduce the air supply available to encourage a ﬁre by ensuring that there is adequate separation (compartmentation) between the various apartments in their building. At its most basic level, this might simply mean that all separating doors between diﬀerent rooms in the building are closed (particularly at night) to help prevent any outbreak of ﬁre from spreading. Along with other more invasive works, this might also involve installing intumescent strips round the separating door edges. These strips expand with heat and seal the gaps around the door in event of a ﬁre.

Fuel
Anything which can burn should be considered as adding to the fuel load inside a building. Some materials, such as ﬂammable liquids, will obviously ignite sooner than a library shelf of books, and building contents will generally ignite quicker that the building’s structure. Within a historic interior the contents - furniture, carpets, curtains, paintings, wall ﬁnishes and loosely stored materials (particularly in boiler rooms and roof attics) - can all be deemed as providing a source of fuel. From the building’s structural point of view original timber ﬂoors, supporting joists, waxed panelling, doors, shutters, lath and plaster work, and the roof construction can all add to the overall fuel loading. Particular care therefore needs to be paid to where any combustible materials are liable to exist in the near vicinity to a likely source of ignition.

Suppression and detection
Fire detection is an essential tool to help ensure life safety and oﬀer early warning of a ﬁre incident occurring. Battery operated smoke alarms are cheap, relatively ﬂexible and easily installed, but require regular checking to keep them operative. Alarms linked to the mains electrical supply will require more consideration in where they should be placed and wired, particularly in ﬁnely detailed and decorated important historic interiors. In such cases, air-aspirating detection systems oﬀer more ﬂexibility in the placing of the air sampling points, and are less visually invasive. These systems work by frequently drawing, and monitoring, the quality of samples of air from the room. Airborne contaminants, such as smoke, are readily detected and a consequential alarm sounded. Suppression systems will not only activate as an alarm if a ﬁre occurs, they also operate to ﬁght and control its growth through water sprinkling, water misting or oxygen reduction techniques. Designing and installing such systems into sensitive historic interiors require careful consideration to integrate them with the internal ﬁnishes and details. They should be considered as a part of a more comprehensive system of ﬁre protection. Here, the joint expertise of building professionals versed in conservation working techniques, and ﬁre engineers, need to be brought together to assess, balance, and achieve the most appropriate solution for each particular set of circumstances - often on a room by room basis. The introduction of a suite of ﬁre engineering solutions into a historic building is best considered when other major works are planned. That way they can be more successfully integrated during the course of the other disruptions. The introduction of such schemes will require Listed Building Consent, and early advice should be sought when thinking about proceeding in this manner.

Fire and rescue services
Given the known scale of loss to the built heritage from the eﬀects of ﬁre, in 2003 Historic Scotland and the Royal Commission of the Ancient and Historical Monuments in Scotland started co-operating with the eight Scottish Fire and Rescue Services to create a Scottish Historic Buildings National Fire Database. This has subsequently emerged as part of the Services’ current approach to Integrated Risk Management. The database will provide ﬁre ﬁghting crews with relevant information about the importance and value of each Category A listed building in Scotland. This will assist them in managing their attendance at any future incidents at these properties. A second stage to this process will involve producing generic guidance, established from the ﬁrst phase of the database, so that this might be applied to assist in the management of future ﬁre incidents at other historic buildings in the country.