Fire Threat to Stones of Historic and Cultural Heritage Buildings

Many historic buildings are made with stone structures. In addition to the various benefits that this type of material, which is diversified by composition, aggregation and geometry according to historical periods and geographical areas, it must be remembered that exposure to fire constitutes in most cases an important vulnerability. Even recently, several cases of fire have highlighted the importance of designing from fire, in buildings belonging to the cultural heritage, building elements to which adequate attention is not always paid.

Plan and section of the Guarini Chapel in Turin, where the Holy Shroud is kept. The Chapel has been severely damaged by the fire on April 11, 1997.
Plan and section of the Guarini Chapel in Turin, where the Holy Shroud is kept. The Chapel has been severely damaged by the fire on April 11, 1997. Two thirds of its marble structural stones were damaged by the heat. he complex structure of the dome of the Chapel of the Holy Shroud, severely damaged by the fire of 1997, that was rebuilt using stones taken from a quarry opened for the occasion. The opening of the new quarry was due to the need to replace the numerous stone elements destroyed by the effects of the fire or no longer able to perform their load-bearing function. (image from Wikipedia

The case of the fire that seriously damaged the chapel that housed the Holy Shroud in Turin, on April 11, 1997, can be considered iconic in this regard. For its restoration it was necessary to open the quarry near the place from which at the time the stone material with which the supporting structures had been made had been extracted (see reference, page 25) . Among other things, the individual blocks had been designed and installed with techniques of which the memory had been lost and which forced the restorers to a specific study.

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Fire Safety Engineering and Cultural Heritage Buildings

Fire prevention is a discipline that relies in most cases on the use of building elements or standardized solutions. The verification of safety with respect to the risk of fire, therefore, normally starts from the control of parameters such as the width of the escape routes, the characteristics of fire resistance of the structures and the characteristics of the ignition behavior of the covering and furniture materials.  If a project lacks one or more of these aspects, it is modified by adding or changing elements. But what to do when the building has already been built and, above all, it cannot be modified because its construction elements, its visual impact and its history do not allow it to be modified without society accepting these changes?

The image shows the powerful wall behind the remains of the Augustus Forum in Rome was designed to protect the area of the monuments of ancient Rome from the frequent fires that spread in the city and which, in 64 AD. they destroyed large parts of the city. The history of buildings and cities has been marked by fires for centuries and thousands of years. Current safety standards are significantly higher than previous ones, but their application is frequently incompatible with the protection of historic buildings.
The powerful (meters thick) wall behind the remains of the Augustus Forum in Rome was designed to protect the area of the monuments of ancient Rome from the frequent fires that spread in the city from the timber houses of the Suburra district. A fire that started in another district, in 64 AD. destroyed large parts of the city. The history of buildings and cities has been marked by fires for centuries and thousands of years. Current safety standards are significantly higher than previous ones, but their application is frequently incompatible with the protection of historic buildings. (Image: https://it.wikipedia.org/wiki/Foro_di_Augusto)
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Performance based approach and fire protection of historic buildings

wooden beams inside ceiling of baroque church in Rome
wooden beams inside ceiling of baroque church in Rome

The strategy of protection of historical building against fire risk is different from almost any other type of building. In the most of case, the objective of fire protection, in fact, is preserving occupants of buildings or the their structure.  Sometimes the concern is both. In the case of fire protection of historical buildings, preservation must find solutions that are consistent with the particular needs of the building: such goal needs freedom e cannot be achieved with prescriptive approaches, which have been developed with the typical building in mind.

The most common gap of prescriptive systems, when applied to heritage buildings, in that they do not work well in unique buildings, when the possible solutions are constrained. Frequently encountered constraints include aesthetic objections to:

  • the degree of compartmentation required in the regulations;
  • the inability to meet egress requirements such as the required number of exits or maximum travel distances;
  • The frequent impossibility in installing active fire fighting systems

When these situations occur, designers usually use the equivalency provisions included in most prescriptive regulations. But such provisions normally have been studied for specific occupancy types and must be continually recalibrated as the prescriptive requirements evolve.

In this situation, performance-based regulations allow to meet conservation needs with safety standards provisions.

Explicit goals and objectives for life safety and historic preservation can be applied to performance solutions. Hazards and safety deficiencies should be identified in order to determine compliance options that satisfy safety objectives, respecting historical/aesthetical features. Solutions can be selected from traditional, prescriptive solutions or performance analysis approaches. Using such method, it’s fundamental that all parties involved in the construction understand the significant features that are to be preserved.

Other issues of paramount importance in dealing with fire safety of cultural heritage is the need for special care during:

  • work projects when the structure is particularly vulnerable. When there are temporary collections of combustibles and construction equipment as well as operations that can represent sources of ignition not normally present. Ceilings and walls may be open for repair, exposing combustible structural elements and void spaces that might allow a fire to spread throughout the structure. Existing fire protection equipment may be disabled or removed as a part of the work.
  • special events that may bring large occupant loads, consumption of alcohol that may impair these occupants, and catering or special food preparation activities that can involve additional quantities of combustibles and ignition sources. All activities at special events need to be evaluated and precautions taken to avoid threats.

Historic Underground Premises and Visitors Safety

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During the international conference on safety issues of rescue operations in underground structures, held in Rome (Italy) on march 3rd, 2011, the argument of visitors’s safety of  secret wartime tunnels in Dover  has been discussed.

The presentation, made by Mr Steve Emery (English Heritage) has focused the attention on how fire safety engineering can be used to improve safety in historical buildings. In particular, the premise are underground. The first tunnels under Dover Castle were constructed in the Middle Ages to provide a protected line of communication for the soldiers. During the Napoleonic Wars, this system of tunnels was expanded to fortify the Castle. Seven tunnels were dug as barracks for the soldiers and officers. These were capable of accommodating up to 2,000 troops.

In May 1940 the tunnels became the nerve centre for ‘Operation Dynamo’ – the evacuation of the British Expeditionary Force (BEF) and French troops from Dunkirk’s beaches. In the Cold War the tunnels were further expanded to form a Regional Centre of Government in the event of nuclear war.

The presentation, taken from the Conference proceedings, shows how fire simulations have guided in developing a correct safety management for visitors:

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Water mist for Protection of Heritage – Cost C17 Final report

In the final Report of the Cost C17 Action different aspects of fire protection of Cultural Heritage buildings have been addressed, as the water mist for fire protection, which at the time was a relatively new technology with specific advantages to the built heritage.

The standard design and manufacturing processes do not currently address heritage applications, but performance-based codes are favourable for introducing new water mist systems. This report establishes the current level of experience, and presents basic information about water mist for the heritage community. The challenges, implications and perspectives of the technology are outlined in order to ensure the best protection of European heritage. A guide on how to accept or approve mist systems in heritage properties is given. Continue reading “Water mist for Protection of Heritage – Cost C17 Final report”

Impacts of Fire on Stone-Built Heritage

Spalling Fire is one of the major threat to stone-built cultural heritage and this    paper is a review of the existing research into fire damage on building  stone. From early research based on anecdotal evidence of macroscopic  observations, scientists have moved on to develop various techniques  for approaching the investigation of fire damage to stone (high-    temperature heating in ovens, lasers, real flame tests), different aspects    of the damage that fire does have been learned from each, developing    understanding of how microscopic changes affect the whole.

This paper, published on the Journal of Architectural Conservation seeks to highlight the need for a greater awareness of the threat that fire poses (and the need to take precautionary measures in the form of fire-suppression systems), of the immediate effects, and of the long-term management issues of natural stone structures which have experienced fire.

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Scottish Historic Buildings National Fire Database. Annual Report 2008-2009

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The Minute of Agreement between Historic  Scotland and the Scottish Fire and  Rescue  Services  for the development of The Scottish Historic  Buildings National  Fire Database (SHBNFD)  continues to provide the structure to enable  Scotland to  remain a world leader in the  protection of the built heritage from the  devastating  effects of fire.

Mike Coull of Grampian Fire and Rescue Service  continues to serve in the role  of Heritage Co-  ordinator for the Scottish Fire Services. This post is  considered  crucial in not only delivering the key objectives set out in the Minute of  Agreement, but also to enable further research developing strategies with the Fire S ervice that will contribute to the protection of the built heritage.

The current Minute of Agreement was signed in October 2007 and sets out a wider set of outcomes to reflect the fact that the SHBNFD is much more than a database, it is a project setting out objectives driving forward the protection of the built heritage. To meet those objectives it was vital to ensure effective partnership working, through this it has been possible to establish protocols with each of the eight Scottish fire and rescue services for the exchange of information on Category B-listed buildings.

This Annual Summary Report aims to demonstrate that significant progress has been made in many of the outcomes identified within the Minute of Agreement over the past twelve months. In addition to the agreed outcomes, two significant tasks have been undertaken; a major International conference on ‘Fire Protection of the Built Heritage’ was held at Elphinstone Hall, Aberdeen on 5th May 2009 and a research project involving a series of fire tests on historic doors. Further details of these two initiatives are included within this report.

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