Safety Protocols with Case Studies

**97**

**Chapter 6**

**Abstract**

*Agnes Iringová*

Slovak legislation.

**1. Introduction**

A Case Study on the Fire Safety in

This chapter deals with the issue of fire safety in historic buildings that undergo functional change, restoration, replacement of construction, facade or installation renovation. It analyzes the current technical state in relation to microclimate and fire safety in historic buildings in Slovakia. It pays attention to the legislative framework for building conservation in the Slovak Republic considering its impact on the reconstruction and restoration of historic buildings. It assesses approaches and methods for fire safety solutions in historic buildings depending on the extent of their modification—intervention in the layout, function and construction. It presents solution procedures and knowledge in terms of application of fire safety requirements in historic buildings using model examples in accordance with the

**Keywords:** fire safety, restoration, historic buildings, legislation, model examples

The successful restoration or renovation of a historic building depends on the integration of new operational requirements into the existing premises without the necessity of changing its original structure, layout and appearance. It is important for the building conservation to preserve the building's originality after its renovation and provide better microclimate and safety standard. The extent of the construction changes is connected with the extent of changes to fire safety solution. Restoration of a historic building can be defined as a set of layout and construction modifications implemented into the building structures in such a way that the building's original height and ground plan can be preserved. The construction interventions modify the building's technical parameters such as layout, load-bearing capacity, thermal and acoustic protection and fire safety. The building proceeding in the Slovak Republic related to the above-mentioned changes follows Act No.

Restoration of a historic building can be as follows: (a) an exact restoration,

Nowadays, most original historic buildings are not suitable for the occupation; they do not meet either hygiene or static, thermal and fire protection requirements. As for the restoration of a historic building, it is important to pay attention to the

based on the detailed documentation of the building's original condition; (b) analogous restoration, based on the verifiable similarity or sameness with a better preserved building; and (c) hypothetical restoration, based on a substantiated, scientifically formulated hypothesis (assumption), giving the base for

50/1976 Coll. on town planning and building code.

rebuilding a destroyed or disappeared building or its part.

Historic Buildings in Slovakia

#### **Chapter 6**

## A Case Study on the Fire Safety in Historic Buildings in Slovakia

*Agnes Iringová*

#### **Abstract**

This chapter deals with the issue of fire safety in historic buildings that undergo functional change, restoration, replacement of construction, facade or installation renovation. It analyzes the current technical state in relation to microclimate and fire safety in historic buildings in Slovakia. It pays attention to the legislative framework for building conservation in the Slovak Republic considering its impact on the reconstruction and restoration of historic buildings. It assesses approaches and methods for fire safety solutions in historic buildings depending on the extent of their modification—intervention in the layout, function and construction. It presents solution procedures and knowledge in terms of application of fire safety requirements in historic buildings using model examples in accordance with the Slovak legislation.

**Keywords:** fire safety, restoration, historic buildings, legislation, model examples

#### **1. Introduction**

The successful restoration or renovation of a historic building depends on the integration of new operational requirements into the existing premises without the necessity of changing its original structure, layout and appearance. It is important for the building conservation to preserve the building's originality after its renovation and provide better microclimate and safety standard. The extent of the construction changes is connected with the extent of changes to fire safety solution. Restoration of a historic building can be defined as a set of layout and construction modifications implemented into the building structures in such a way that the building's original height and ground plan can be preserved. The construction interventions modify the building's technical parameters such as layout, load-bearing capacity, thermal and acoustic protection and fire safety. The building proceeding in the Slovak Republic related to the above-mentioned changes follows Act No. 50/1976 Coll. on town planning and building code.

Restoration of a historic building can be as follows: (a) an exact restoration, based on the detailed documentation of the building's original condition; (b) analogous restoration, based on the verifiable similarity or sameness with a better preserved building; and (c) hypothetical restoration, based on a substantiated, scientifically formulated hypothesis (assumption), giving the base for rebuilding a destroyed or disappeared building or its part.

Nowadays, most original historic buildings are not suitable for the occupation; they do not meet either hygiene or static, thermal and fire protection requirements. As for the restoration of a historic building, it is important to pay attention to the

choice and optimization of building materials and the optimization of the building's functional use in terms of fire safety.

In these cases, the fire safety measures should be the result of a compromise among the fire protection, building conservation, building law and quality requirements for the building's new function. Fire safety in historic buildings is applied using passive and active fire protection of spaces and structures.

#### **2. Analysis of the current fire safety in historic buildings in Slovakia**

Based on the data from fire and rescue corps from 2013 to 2017, there are 2450 buildings of historic significance in Slovakia. Nowadays, the fire safety in historic buildings of great national and cultural importance (e.g. castles, cathedrals, mansions, etc.) where many rare museum exhibits are located is provided by electric fire signalization (EFS) equipment, fire extinguishers, internal and external fire cocks and firefighting measures applied in the building's operation. These measures are related to the fire training of employees who stay in the building during the operation. Each employee is trained how to eliminate fire in its initial phase, evacuate persons and exhibits and call the firefighters.

As stated in the Act of the Slovak Ministry of Interior No. 199/2009 on fire protection as amended, the building's operator is obliged to work up, keep and maintain the fire documentation according to the current condition and ensure it is respected. Each owner or administrator of a listed building should determine a qualified person who will be responsible for respecting all operational and organizational measures related to fire safety in a building and will keep and update the fire documentation. Trained persons provide and take regular prophylactic fire inspections of firefighting equipment.

Fire brigades regularly carry out training exercises in significant listed buildings to check their firefighting skills, means and methods and the accessibility of fire equipment in buildings. Despite the above measures, the real fire protection in most historic buildings in Slovakia is weak, and fire alarm systems are not located in all buildings. As Fire and Rescue Service Report 2018 states, there were 40 fires in such heritage buildings in the last 10 years. The most common cause was negligence, technical failure or deliberateness combined with the fire risk at the time of the building's operation.

Analysis of fire safety in listed buildings is primarily focused on firefighting equipment in terms of its location, availability and functionality as well as on staff readiness to use it effectively [1]. The most common deficiencies found during the fire inspections or in analyses of fire causes in such buildings are as follows:


**99**

**Figure 1.**

*present time.*

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

• Insufficient maintenance of public spaces in terms of fire spread, location and storage of flammable materials in the immediate vicinity of the building

• Improper handling with the heat or ignition source, that is heaters, welding kits and handling with an open fire, where smoking is prohibited, etc.

It is not always possible to prevent fire in a building despite the implementation of fire-protective and operational measures, especially in unforeseeable natural disasters. In general, if fire safety measures are kept at all levels of protection, it is supposed that the building does not collide with fire. If fire safety measures are missing, neglected or non-functional at the time of fire, it often causes big artistic

Here is the example of fire in the castle of Krásna Hôrka from 2012. The fire progress is shown in **Figure 1b**. Fire was caused by children who carelessly handled free flame near the castle hill. They threw a burning object into dry grass that ignited. As there was strong wind, fire spread rapidly onto the combustible castle roofs covered by wooden shingles (see **Figure 1a**). The castle consists of three buildings. The original upper castle dates from the fourteenth century; the middle and lower castles were built later by the original owners. The castle housed a permanent display of period works of art giving basic information on the castle and its original owners. There were original exhibits with a high museum value. The original roof structure consisted of timber trusses covered with wooden shingles and took the

castle has steel-bearing ceiling structure with a wooden flap. The castle has stone

Fire safety in the castle before fire included passive fire protection, roof space had no accidental fire load, and timber truss members were treated with fire coating

*The castle of Krásna Hôrka before fire, during fire, after fire and at the present time. (a) Original castle timber roofs before fire in 2012; (b) fire in the castle in 2012; (c) the castle after fire in 2012; (d) the castle at the* 

. The lower and middle castle has vaulted ceilings; the upper

• Technical defects in electrical installations or other equipment

*DOI: http://dx.doi.org/10.5772/intechopen.91241*

• Incendiarism, vandalism

and architectural losses.

area of about 5000 m<sup>2</sup>

and brick external walls.


*Fire Safety and Management Awareness*

functional use in terms of fire safety.

persons and exhibits and call the firefighters.

inspections of firefighting equipment.

sibility at the time of fire

• Missing or non-functional electrical fire alarm

and reinforcement or badly designed crossroads

• Missing, capacity-insufficient or unmaintained fire hydrants

building's operation.

choice and optimization of building materials and the optimization of the building's

In these cases, the fire safety measures should be the result of a compromise among the fire protection, building conservation, building law and quality requirements for the building's new function. Fire safety in historic buildings is applied

**2. Analysis of the current fire safety in historic buildings in Slovakia**

Based on the data from fire and rescue corps from 2013 to 2017, there are 2450 buildings of historic significance in Slovakia. Nowadays, the fire safety in historic buildings of great national and cultural importance (e.g. castles, cathedrals, mansions, etc.) where many rare museum exhibits are located is provided by electric fire signalization (EFS) equipment, fire extinguishers, internal and external fire cocks and firefighting measures applied in the building's operation. These measures are related to the fire training of employees who stay in the building during the operation. Each employee is trained how to eliminate fire in its initial phase, evacuate

As stated in the Act of the Slovak Ministry of Interior No. 199/2009 on fire protection as amended, the building's operator is obliged to work up, keep and maintain the fire documentation according to the current condition and ensure it is respected. Each owner or administrator of a listed building should determine a qualified person who will be responsible for respecting all operational and organizational measures related to fire safety in a building and will keep and update the fire documentation. Trained persons provide and take regular prophylactic fire

Fire brigades regularly carry out training exercises in significant listed buildings to check their firefighting skills, means and methods and the accessibility of fire equipment in buildings. Despite the above measures, the real fire protection in most historic buildings in Slovakia is weak, and fire alarm systems are not located in all buildings. As Fire and Rescue Service Report 2018 states, there were 40 fires in such heritage buildings in the last 10 years. The most common cause was negligence, technical failure or deliberateness combined with the fire risk at the time of the

Analysis of fire safety in listed buildings is primarily focused on firefighting equipment in terms of its location, availability and functionality as well as on staff readiness to use it effectively [1]. The most common deficiencies found during the fire inspections or in analyses of fire causes in such buildings are as follows:

• Non-functional hand fire extinguishers or their bad location in terms of acces-

• Access roads badly rideable for the fire brigade due to insufficient road width

• Employees inadequately trained for firefighting and missing fire documentation determining evacuation plans for employees, visitors or exhibits

using passive and active fire protection of spaces and structures.

**98**

It is not always possible to prevent fire in a building despite the implementation of fire-protective and operational measures, especially in unforeseeable natural disasters. In general, if fire safety measures are kept at all levels of protection, it is supposed that the building does not collide with fire. If fire safety measures are missing, neglected or non-functional at the time of fire, it often causes big artistic and architectural losses.

Here is the example of fire in the castle of Krásna Hôrka from 2012. The fire progress is shown in **Figure 1b**. Fire was caused by children who carelessly handled free flame near the castle hill. They threw a burning object into dry grass that ignited. As there was strong wind, fire spread rapidly onto the combustible castle roofs covered by wooden shingles (see **Figure 1a**). The castle consists of three buildings. The original upper castle dates from the fourteenth century; the middle and lower castles were built later by the original owners. The castle housed a permanent display of period works of art giving basic information on the castle and its original owners. There were original exhibits with a high museum value. The original roof structure consisted of timber trusses covered with wooden shingles and took the area of about 5000 m<sup>2</sup> . The lower and middle castle has vaulted ceilings; the upper castle has steel-bearing ceiling structure with a wooden flap. The castle has stone and brick external walls.

Fire safety in the castle before fire included passive fire protection, roof space had no accidental fire load, and timber truss members were treated with fire coating

#### **Figure 1.**

*The castle of Krásna Hôrka before fire, during fire, after fire and at the present time. (a) Original castle timber roofs before fire in 2012; (b) fire in the castle in 2012; (c) the castle after fire in 2012; (d) the castle at the present time.*

in 2000, and active fire protection—electric fire signalization—is installed in the roof space [2].

The Gothic tower contained a water reservoir of about 66 m3 ; the upper castle contained fire-water hose systems and wall hydrants. Powder fire extinguishers were installed in all spaces. Although the castle was protected at the time of fire by both passive and active fire protection, its protection was not sufficient considering the outside source of fire, climatic conditions and burning rate of dried roof timber.

The fire lasted for about 3 days in terms of the quantity of timber structures and unfavorable natural conditions—strong wind. The roofs burned down (see **Figure 1c**). The firefighting was slowed down due to the road that was badly accessible for the fire brigade—there is only one access road leading to the castle. The water source was far from the burning area, and it was not possible to use the water reservoir in the castle.

The fire affected mainly the Gothic castle that was restored in 1982. The part of the ceiling fell down; some exhibits such as swords and other historical weapons were destroyed. The interior exhibits in the lower and middle castle and the Francis Museum survived without harm. Overall, 90% of all historic exhibits were saved. The castle building suffered fire damage especially on its construction, and the total damage was estimated at approx. 8.05 million €.

Nowadays, the castle's restoration is coming to an end. All roofs, including loadbearing and truss structures, were built as replicas of the original structures, taking into account the forms they had at the time of the last major castle's style alternation after fire in 1817 (1818). The original wooden shingle roof is replaced by burnt ceramic roofing, and the bastions have metal roofing (see **Figure 1d**). In this case, fire was caused by negligence and climatic conditions.

#### **3. Past and contemporary legislative regulations for fire safety solutions in historic buildings in Slovakia**

#### **3.1 Legislative regulations in the past**

No legislative standards were applied to the construction of buildings in terms of fire protection in the Middle Ages. The fire protection criteria in buildings with timber load-bearing structures were set out in the regulation issued probably by William I. Conqueror (1028–1087). All fireplaces in buildings were required to be put out at night and in the absence of persons. Furthermore, this regulation was supplemented by the requirement to cover the fireplace to prevent air access to the hot ash [3]. It is known from history that after the fire outbreak in the settlement, the consequences were global and fatal for inhabitants due to the combustible roofs and limited possibilities of firefighting at the time. For this reason, the past legislation focused on the fire protection in buildings due to the high risk of easy and rapid fire spreading from building to building.

The oldest legislation valid in our territory for the royal free cities, as well as the towns and villages of higher importance with an authorized municipal office that deserved to be added to the royal free cities, was "Fire Regulations for the Kingdom of Hungary" issued in Presburg in 1788. This regulation was divided into four chapters:

1.How to prevent the occurrence of fire—related to the rules for construction of chimneys and internal fireplaces

**101**

changes.

buildings.

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

3.How to extinguish fire as quickly as possible—each settlement was obliged to have a public water reservoir, pond, lime trees planted on four sides of neigh-

Growth in the manufacturing sector in the late nineteenth century brings the use of technique for firefighting. Fire protection starts to be provided by professional fire brigades. Non-combustible building materials—reinforced concrete, burnt ceramic blocks, etc.—are used for the construction of buildings that have natural protection against fire spreading within the building as well as from one building to another. The timber load-bearing elements of ceilings were protected by plasters and embankments made of non-combustible materials. Wooden shingles, straw and reed on the roofs were replaced by ceramic roofing. The timber trusses were separated from chimneys and treated with fire-resistant coatings to reduce their flammability. There was no fire risk in the roof spaces with trusses; they were

**3.2 Contemporary legislative regulations for fire safety solutions in historic** 

The obligatory regulation for fire protection currently valid in Slovakia is Act No. 314/2001 as amended and implementary regulation issued by the Slovak Ministry of the Interior No. 121/2002 Coll. on fire prevention, as amended. The implementary regulation No. 94/2004 as amended specifies requirements for the project solution. The restoration of historic buildings takes into account mainly all society's requirements for the preservation of their original appearance and material solutions considering adequate fire safety. Legislation valid for the restoration of historic buildings in Slovakia is Act No. 49/2002 on the heritage protection as amended, issued by the Slovak National Council and followed by the implementary regulations. Details on the performance of monument research are specified in the implementary regulation No. 253/2010 Coll. issued by the Slovak Ministry of Culture. It determines, based on monumental survey, the conditions for methods and extent that can be used in the remediation of existing historic buildings. Survey conclusions are one of the bases for the design and extent of construction work as well as the choice of materials used in the renovation. The requirements and conditions for the restoration of historic buildings in terms of fire safety are limited due to the specific conditions. The restoration and renovation of buildings in Slovakia follows the criteria specified in Slovak Standard STN 730834 on construction

In terms of fire safety, the building's alternation is the only alternation resulting in a higher fire risk, number of persons, replacement of load-bearing structures and installations within the affected spaces. The extent of fire safety measures is determined by the extent of changes in the building's construction or operation [4].

The **first category** includes alternations without the functional change resulting in the higher fire risk. There are only minor repairs to the original structures done without changing their reaction to fire and modernization of installation systems in

The **second category** includes alternations to the functional use of the building's part or the entire building that will change the fire risk, fire resistance requirements for the fire-separating structures, number of people and related evacuation plan. Such alternations to the buildings are related to the fire compartmentation, fire

The alternations of buildings can be divided into three categories:

4.How to prevent harmful consequences that may occur after fire

*DOI: http://dx.doi.org/10.5772/intechopen.91241*

boring farm houses, etc.

separated from vertical shafts.

**buildings in Slovakia**

2.How to detect fire early if it occurs—signals generated by bells

*Fire Safety and Management Awareness*

roof space [2].

reservoir in the castle.

damage was estimated at approx. 8.05 million €.

fire was caused by negligence and climatic conditions.

**in historic buildings in Slovakia**

**3.1 Legislative regulations in the past**

fire spreading from building to building.

chimneys and internal fireplaces

in 2000, and active fire protection—electric fire signalization—is installed in the

contained fire-water hose systems and wall hydrants. Powder fire extinguishers were installed in all spaces. Although the castle was protected at the time of fire by both passive and active fire protection, its protection was not sufficient considering the outside source of fire, climatic conditions and burning rate of dried roof timber. The fire lasted for about 3 days in terms of the quantity of timber structures and unfavorable natural conditions—strong wind. The roofs burned down (see **Figure 1c**). The firefighting was slowed down due to the road that was badly accessible for the fire brigade—there is only one access road leading to the castle. The water source was far from the burning area, and it was not possible to use the water

The fire affected mainly the Gothic castle that was restored in 1982. The part of the ceiling fell down; some exhibits such as swords and other historical weapons were destroyed. The interior exhibits in the lower and middle castle and the Francis Museum survived without harm. Overall, 90% of all historic exhibits were saved. The castle building suffered fire damage especially on its construction, and the total

Nowadays, the castle's restoration is coming to an end. All roofs, including loadbearing and truss structures, were built as replicas of the original structures, taking into account the forms they had at the time of the last major castle's style alternation after fire in 1817 (1818). The original wooden shingle roof is replaced by burnt ceramic roofing, and the bastions have metal roofing (see **Figure 1d**). In this case,

**3. Past and contemporary legislative regulations for fire safety solutions** 

No legislative standards were applied to the construction of buildings in terms of fire protection in the Middle Ages. The fire protection criteria in buildings with timber load-bearing structures were set out in the regulation issued probably by William I. Conqueror (1028–1087). All fireplaces in buildings were required to be put out at night and in the absence of persons. Furthermore, this regulation was supplemented by the requirement to cover the fireplace to prevent air access to the hot ash [3]. It is known from history that after the fire outbreak in the settlement, the consequences were global and fatal for inhabitants due to the combustible roofs and limited possibilities of firefighting at the time. For this reason, the past legislation focused on the fire protection in buildings due to the high risk of easy and rapid

The oldest legislation valid in our territory for the royal free cities, as well as the towns and villages of higher importance with an authorized municipal office that deserved to be added to the royal free cities, was "Fire Regulations for the Kingdom of Hungary" issued in Presburg in 1788. This regulation was divided into four

1.How to prevent the occurrence of fire—related to the rules for construction of

2.How to detect fire early if it occurs—signals generated by bells

; the upper castle

The Gothic tower contained a water reservoir of about 66 m3

**100**

chapters:


Growth in the manufacturing sector in the late nineteenth century brings the use of technique for firefighting. Fire protection starts to be provided by professional fire brigades. Non-combustible building materials—reinforced concrete, burnt ceramic blocks, etc.—are used for the construction of buildings that have natural protection against fire spreading within the building as well as from one building to another. The timber load-bearing elements of ceilings were protected by plasters and embankments made of non-combustible materials. Wooden shingles, straw and reed on the roofs were replaced by ceramic roofing. The timber trusses were separated from chimneys and treated with fire-resistant coatings to reduce their flammability. There was no fire risk in the roof spaces with trusses; they were separated from vertical shafts.

#### **3.2 Contemporary legislative regulations for fire safety solutions in historic buildings in Slovakia**

The obligatory regulation for fire protection currently valid in Slovakia is Act No. 314/2001 as amended and implementary regulation issued by the Slovak Ministry of the Interior No. 121/2002 Coll. on fire prevention, as amended. The implementary regulation No. 94/2004 as amended specifies requirements for the project solution. The restoration of historic buildings takes into account mainly all society's requirements for the preservation of their original appearance and material solutions considering adequate fire safety. Legislation valid for the restoration of historic buildings in Slovakia is Act No. 49/2002 on the heritage protection as amended, issued by the Slovak National Council and followed by the implementary regulations. Details on the performance of monument research are specified in the implementary regulation No. 253/2010 Coll. issued by the Slovak Ministry of Culture. It determines, based on monumental survey, the conditions for methods and extent that can be used in the remediation of existing historic buildings. Survey conclusions are one of the bases for the design and extent of construction work as well as the choice of materials used in the renovation. The requirements and conditions for the restoration of historic buildings in terms of fire safety are limited due to the specific conditions. The restoration and renovation of buildings in Slovakia follows the criteria specified in Slovak Standard STN 730834 on construction changes.

In terms of fire safety, the building's alternation is the only alternation resulting in a higher fire risk, number of persons, replacement of load-bearing structures and installations within the affected spaces. The extent of fire safety measures is determined by the extent of changes in the building's construction or operation [4]. The alternations of buildings can be divided into three categories:

The **first category** includes alternations without the functional change resulting in the higher fire risk. There are only minor repairs to the original structures done without changing their reaction to fire and modernization of installation systems in buildings.

The **second category** includes alternations to the functional use of the building's part or the entire building that will change the fire risk, fire resistance requirements for the fire-separating structures, number of people and related evacuation plan. Such alternations to the buildings are related to the fire compartmentation, fire

protection, changes in ventilation system, fire separation of evacuation routes and requirements for the installation of firefighting equipment.

The **third category** includes restorations of buildings, changing the use, useful area and fire height. This is related to the buildings where more than 50% of the total floor area in the fire section changed is found in the building's extension or superstructure [1]. In such cases, the fire safety measures are required to be done completely as in the new buildings, and their assessment is also in accordance with the legislation applicable to the new buildings.

The building's functional change often brings the exchange of a building's owner or manager whose criteria for the heat-moisture regime in the indoor environment are higher. As a result of this change, there is a requirement to increase building's thermal protection if the building conservationists give the permit. Thermal protection in historic buildings is done at least to eliminate microclimate deficiencies, optimally considering the building's energy efficiency and sustainability in terms of its environmental impact [5].

If listed buildings are restored, the fire safety solution must contain an expert opinion analyzing the specific building's conditions and determining requirements for its fire safety depending on the boundary conditions such as functional use, design, layout in the vertical direction, occupancy, number and quality of emergency routes, availability of access roads and firefighting water. The fire safety solution should take into account at least the following requirements: the operations with the high fire load and fire factor higher than 1.1, except theaters, exhibition halls, museums and areas for visitors, cannot be situated in the listed buildings whose original function of spaces is modified.

The fire alarm systems are required to be installed in the unique historic spaces, e.g. spaces containing murals, unique historic collections, unique structures or elements made of flammable materials.

The fire safety reassessment is required to be done if alternations to historic buildings result in their restoration or renewal.

#### **4. Theoretical analysis of physical, design and layout determinants affecting the restoration of historic buildings in terms of fire safety**

Historic buildings were usually constructed using a combination of combustible and non-combustible materials. The most used building material was wood—in roof structures, ceilings and stairs. It was used in the past as a single building material to construct buildings of folk architecture in Slovakia. Historic buildings usually contain composite construction systems. The cellars and basements had stone or masonry walls, and ceilings had ceramic vaults. The above-ground floors had peripheral walls that were built using a combination of non-combustible masonry made of burnt and non-burnt bricks or stone and combustible wood-beamed ceilings. The ceilings were either visible or covered with plaster usually applied to the reed mats. Roof load-bearing structures contained roof trusses with wooden purlins statically independent on the last floor ceiling. Depending on the building's ground plan dimensions, the purlin or collar systems were mostly used for small spans in folk architecture; a combination of standing saddles and hanging trusses or strut frames was used for larger spans, e.g. mansions, castles or churches.

The roof space was usually naturally ventilated and had no functional use. The attic was accessible via wooden or stone single or spiral stairs due to the repairs and maintenance. The wooden ceilings and trusses as well as the dimensions of their members were based primarily on the spans they covered and empirical and technical possibilities of the builders at the time of construction. Due to the

**103**

fire resistance.

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

technical possibilities of the joints affecting the load-bearing capacity of the purlin system, the wooden members were dimensioned with a significant static reserve. The wooden members were usually joined by mortising or lapping, and their fire

The fire safety degree is determined on the basis of fire load density with dependence on the ventilation parameter, fire risk, building's fire height and combustibility of used building elements according to Table 8 STN 730802/10. The degree of fire safety in building structures (DFSB) value is the basis for determining fire safety requirements of load-bearing and fire-separating structures given in Table 12 STN 730802/10. These requirements are compared to the current fire resistance of

The fire resistance of the original structures can be taken from the table in STN

Fire resistance is the ability of building structures to withstand the effect of fire. It is defined by the time during which the structures can be exposed to fire without damaging their function. The fire structures can be divided into loadbearing and non-load-bearing, in terms of their function, and fire-separating or interior load-bearing, in terms of their location in a fire compartment. If the fire-separating structure is load-bearing and located at the frontier between fire compartments, it must meet the criteria of load-bearing capacity (R), integrity (E) and thermal insulation (I) at the time of fire. If the load-bearing structure within the fire compartment is a post, it must meet the R criterion at the required time. The stability of fire structures along the building's height must not depend on the stability of structures with lower fire resistance on lower floors. The fire resistance of fire-separating structures is determined by a test or calculation. The design and assessment of fire resistance of building structures follow a set of standards— Eurocodes EN 1991-1-2, EN 1992-1-2, EN 1993-1-2, EN 1994-1-2, EN 1995-1-2, EN

The fire resistance of building structures is calculated using the design procedure in terms of the requirement for the result accuracy and specific boundary conditions of a fire compartment. First, thermal analysis of a fire compartment is done, then the heat transfer into the structure and temperature development within the structure is determined, and finally the fire-separating structure is analyzed. Detailed analyses of the temperature in a fire compartment are determined by dynamic simulations and end-element methods. Simpler procedures are used to determine the temperature in a fire compartment by parametric temperature curves or nominal temperature curves. The resulting fire resistance determined according

to the nominal standard curves is the standard fire resistance (**Figure 2**).

The heat transfer within the structure for detailed solutions is determined by the end-element method; for less detailed solutions, it is determined by incremental or direct methods. Direct methods used for heat transfer are conservative and valid only to a limited extent and can be used to assess only particular elements of a fire-separating structure. The calculation is based on room temperature [7–9]. Fire resistance verification of a fire-separating structure can be done by the three following views: *Time*—clearly expresses the reliability reserves of the structural element:

where tfi,d is the design time of fire resistance and tfi,requ is the required time of

tfi,d≥ tfi,requ (1)

730821 or calculated according to Eurocodes depending on their static stress.

**4.1 Fire resistance of load-bearing and fire-separating structures**

*DOI: http://dx.doi.org/10.5772/intechopen.91241*

resistance was achieved by partial walling [6].

the existing structures.

1996-1-2 and EN 1999-1-2.

*A Case Study on the Fire Safety in Historic Buildings in Slovakia DOI: http://dx.doi.org/10.5772/intechopen.91241*

*Fire Safety and Management Awareness*

its environmental impact [5].

protection, changes in ventilation system, fire separation of evacuation routes and

The **third category** includes restorations of buildings, changing the use, useful area and fire height. This is related to the buildings where more than 50% of the total floor area in the fire section changed is found in the building's extension or superstructure [1]. In such cases, the fire safety measures are required to be done completely as in the new buildings, and their assessment is also in accordance with

The building's functional change often brings the exchange of a building's owner or manager whose criteria for the heat-moisture regime in the indoor environment are higher. As a result of this change, there is a requirement to increase building's thermal protection if the building conservationists give the permit. Thermal protection in historic buildings is done at least to eliminate microclimate deficiencies, optimally considering the building's energy efficiency and sustainability in terms of

If listed buildings are restored, the fire safety solution must contain an expert opinion analyzing the specific building's conditions and determining requirements for its fire safety depending on the boundary conditions such as functional use, design, layout in the vertical direction, occupancy, number and quality of emergency routes, availability of access roads and firefighting water. The fire safety solution should take into account at least the following requirements: the operations with the high fire load and fire factor higher than 1.1, except theaters, exhibition halls, museums and areas for visitors, cannot be situated in the listed buildings

The fire alarm systems are required to be installed in the unique historic spaces,

Historic buildings were usually constructed using a combination of combustible and non-combustible materials. The most used building material was wood—in roof structures, ceilings and stairs. It was used in the past as a single building material to construct buildings of folk architecture in Slovakia. Historic buildings usually contain composite construction systems. The cellars and basements had stone or masonry walls, and ceilings had ceramic vaults. The above-ground floors had peripheral walls that were built using a combination of non-combustible masonry made of burnt and non-burnt bricks or stone and combustible wood-beamed ceilings. The ceilings were either visible or covered with plaster usually applied to the reed mats. Roof load-bearing structures contained roof trusses with wooden purlins statically independent on the last floor ceiling. Depending on the building's ground plan dimensions, the purlin or collar systems were mostly used for small spans in folk architecture; a combination of standing saddles and hanging trusses or strut

The roof space was usually naturally ventilated and had no functional use. The attic was accessible via wooden or stone single or spiral stairs due to the repairs and maintenance. The wooden ceilings and trusses as well as the dimensions of their members were based primarily on the spans they covered and empirical and technical possibilities of the builders at the time of construction. Due to the

e.g. spaces containing murals, unique historic collections, unique structures or

**4. Theoretical analysis of physical, design and layout determinants affecting the restoration of historic buildings in terms of fire safety**

frames was used for larger spans, e.g. mansions, castles or churches.

The fire safety reassessment is required to be done if alternations to historic

requirements for the installation of firefighting equipment.

the legislation applicable to the new buildings.

whose original function of spaces is modified.

buildings result in their restoration or renewal.

elements made of flammable materials.

**102**

technical possibilities of the joints affecting the load-bearing capacity of the purlin system, the wooden members were dimensioned with a significant static reserve. The wooden members were usually joined by mortising or lapping, and their fire resistance was achieved by partial walling [6].

The fire safety degree is determined on the basis of fire load density with dependence on the ventilation parameter, fire risk, building's fire height and combustibility of used building elements according to Table 8 STN 730802/10. The degree of fire safety in building structures (DFSB) value is the basis for determining fire safety requirements of load-bearing and fire-separating structures given in Table 12 STN 730802/10. These requirements are compared to the current fire resistance of the existing structures.

The fire resistance of the original structures can be taken from the table in STN 730821 or calculated according to Eurocodes depending on their static stress.

#### **4.1 Fire resistance of load-bearing and fire-separating structures**

Fire resistance is the ability of building structures to withstand the effect of fire. It is defined by the time during which the structures can be exposed to fire without damaging their function. The fire structures can be divided into loadbearing and non-load-bearing, in terms of their function, and fire-separating or interior load-bearing, in terms of their location in a fire compartment. If the fire-separating structure is load-bearing and located at the frontier between fire compartments, it must meet the criteria of load-bearing capacity (R), integrity (E) and thermal insulation (I) at the time of fire. If the load-bearing structure within the fire compartment is a post, it must meet the R criterion at the required time. The stability of fire structures along the building's height must not depend on the stability of structures with lower fire resistance on lower floors. The fire resistance of fire-separating structures is determined by a test or calculation. The design and assessment of fire resistance of building structures follow a set of standards— Eurocodes EN 1991-1-2, EN 1992-1-2, EN 1993-1-2, EN 1994-1-2, EN 1995-1-2, EN 1996-1-2 and EN 1999-1-2.

The fire resistance of building structures is calculated using the design procedure in terms of the requirement for the result accuracy and specific boundary conditions of a fire compartment. First, thermal analysis of a fire compartment is done, then the heat transfer into the structure and temperature development within the structure is determined, and finally the fire-separating structure is analyzed. Detailed analyses of the temperature in a fire compartment are determined by dynamic simulations and end-element methods. Simpler procedures are used to determine the temperature in a fire compartment by parametric temperature curves or nominal temperature curves. The resulting fire resistance determined according to the nominal standard curves is the standard fire resistance (**Figure 2**).

The heat transfer within the structure for detailed solutions is determined by the end-element method; for less detailed solutions, it is determined by incremental or direct methods. Direct methods used for heat transfer are conservative and valid only to a limited extent and can be used to assess only particular elements of a fire-separating structure. The calculation is based on room temperature [7–9]. Fire resistance verification of a fire-separating structure can be done by the three following views:

*Time*—clearly expresses the reliability reserves of the structural element:

$$\mathbf{t}\_{\text{fi,dz}} \mathbf{t}\_{\text{fi,requ}} \tag{1}$$

where tfi,d is the design time of fire resistance and tfi,requ is the required time of fire resistance.

**Figure 2.**

*Surface temperature on fire-separating structures without surface fire protection and with fire-protective lining during standard fire [10].*

*Load-bearing capacity*—the easiest in terms of calculation because the method is similar to the assessment at the room temperature:

$$\mathbf{R}\_{\text{fi,d,t}} \succeq \mathbf{E}\_{\text{fi,d,t}} \tag{2}$$

Rfi,d,t is the design value of load-bearing capacity of a member in fire during the time t and Efi,d,t is the design value of fire load effects during the time t.

*Temperature*:

$$
\Theta\_{\mathbf{d}} \succeq \Theta\_{\mathbf{cr,d}} \tag{3}
$$

**105**

731701

**Table 1.**

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

fire safety degree was not changed compared to the original one. The attic spaces used as living rooms serve today only to show the original truss construction. Considering the fire height of 0 m and the combined building's construction, the required fire safety degree is I, that is the same as in the original functional use. The fire resistance requirement for the original load-bearing and fire-separating structures was not changed after the functional change of the restored spaces. The fire resistance requirement for the load-bearing ceiling members and perimeter wall is given according to STN 73082 and is dependent on the average fire load, that is the sum of the accidental and permanent fire load, coefficients of ventilation, flammability factor and use and type of firefighting equipment. In terms of the calculated fire

REI 30 (building envelope and roof), and the fire resistance requirement for loadbearing structures of a non-compact ceiling in an assessed fire compartment is R 30.

The external wall is made of stone and brick and has a variable thickness of 530–630 mm. The required fire resistance for this model solution is REI 30 min. In accordance with the values given in Table 1A STN 730821, the real fire resis-

As the dimensions of the assessed wooden ceiling members and column in a model solution are different from the members given in the standard, their real fire resistance is calculated according to EN 1996-1-2: 2004 Eurocode 6: Design of masonry structures, Section 1.2 general rules—fire resistance design of masonry

In specific cases, the fire resistance of fire-separating structures can be determined by a calculation according to EN 1996-1-2: 2004 Eurocode 6: Design of masonry structures, Section 1.2 general rules—fire resistance design of masonry

There is a wooden beamed ceiling above the ground plan in the model example.

The ceiling beams are supported by a wooden beam. The wooden beam is fastened on the load-bearing peripheral walls and supported by a wooden column

The real fire resistance for load-bearing and fire-separating structures was calculated according to the methodology given in STN EN 1991-1-2: 2004; the

**Type of a structural member Thickness [mm] Fire** 

Wooden beams loaded in bending, unprotected from three sides 140/200 40

**resistance REI**

>180 240

200/200 20

**4.3 Fire resistance of the external wall in a model solution**

tance of the perimeter wall is well above the required value (**Table 1**).

**4.4 Fire resistance of the wooden ceiling in a model solution**

The ceiling material and structure are visible (see **Figure 3**).

Masonry walls made of solid bricks perforated up to 15% of the volume, built on mortar of 4-CSN 2430 class, loaded and non-loaded

Unprotected wooden columns loaded in buckling at λ = 75, see CSN

*Fire resistance of the fire-separating structures according to STN 730821 [12].*

, the fire resistance requirement for the fire-separated structures is

*DOI: http://dx.doi.org/10.5772/intechopen.91241*

load pv = 66 kg/m2

structures.

structures.

(see **Figure 4**).

with double-sided plaster

where θd is the design value of material temperature and θcr,d is the design value of critical material temperature.

Simplified assessment of structural elements in terms of their fire resistance is given in tables in STN 730821: 1973, which is currently valid for the assessment of building structures during construction changes. The fire resistance values of building structures are given in particular tables considering building materials and static load of the structures—walls, columns and ceilings [11].

#### **4.2 Fire resistance assessment of existing fire-separating structures in a model solution**

The following model example shows a fire safety solution used in the restoration of a folk house situated in the village of Vel'ké Leváre. The folk house is dated to the Hutterian culture period. It was restored with the intention of preserving its original layout including the original constructions and elements. The building has a combined structural system—the brick external walls, wooden beam ceiling and collar beam truss. It was necessary to optimize the boundary conditions of the given solution so that the consequences of a functional change regarding the current constructions could be minimal. The museum display showing the original culture was situated in the restored space after the original supporting elements, roof covering and original wall and floor surfaces had been replaced or repaired. The external wall is combined stone with bricks. There are wooden ceilings with visible beams supported by a wooden beam. This beam is embedded into the perimeter walls, and its center is supported by a column. The wooden truss has a two-level collar beam.

The building's functional use was changed in terms of fire safety—it became a museum, that is its original residential function was changed into an exhibition one. The fire load increased but only on the first floor. The required value of the

#### *A Case Study on the Fire Safety in Historic Buildings in Slovakia DOI: http://dx.doi.org/10.5772/intechopen.91241*

*Fire Safety and Management Awareness*

similar to the assessment at the room temperature:

*Temperature*:

*during standard fire [10].*

**Figure 2.**

**solution**

two-level collar beam.

of critical material temperature.

*Load-bearing capacity*—the easiest in terms of calculation because the method is

*Surface temperature on fire-separating structures without surface fire protection and with fire-protective lining* 

Rfi,d,t is the design value of load-bearing capacity of a member in fire during the

where θd is the design value of material temperature and θcr,d is the design value

Simplified assessment of structural elements in terms of their fire resistance is given in tables in STN 730821: 1973, which is currently valid for the assessment of building structures during construction changes. The fire resistance values of building structures are given in particular tables considering building materials and

**4.2 Fire resistance assessment of existing fire-separating structures in a model** 

The following model example shows a fire safety solution used in the restoration of a folk house situated in the village of Vel'ké Leváre. The folk house is dated to the Hutterian culture period. It was restored with the intention of preserving its original layout including the original constructions and elements. The building has a combined structural system—the brick external walls, wooden beam ceiling and collar beam truss. It was necessary to optimize the boundary conditions of the given solution so that the consequences of a functional change regarding the current constructions could be minimal. The museum display showing the original culture was situated in the restored space after the original supporting elements, roof covering and original wall and floor surfaces had been replaced or repaired. The external wall is combined stone with bricks. There are wooden ceilings with visible beams supported by a wooden beam. This beam is embedded into the perimeter walls, and its center is supported by a column. The wooden truss has a

The building's functional use was changed in terms of fire safety—it became a museum, that is its original residential function was changed into an exhibition one. The fire load increased but only on the first floor. The required value of the

time t and Efi,d,t is the design value of fire load effects during the time t.

static load of the structures—walls, columns and ceilings [11].

Rfi,d,t ≥ Efi,d,t (2)

θd ≥ θcr,d (3)

**104**

fire safety degree was not changed compared to the original one. The attic spaces used as living rooms serve today only to show the original truss construction. Considering the fire height of 0 m and the combined building's construction, the required fire safety degree is I, that is the same as in the original functional use.

The fire resistance requirement for the original load-bearing and fire-separating structures was not changed after the functional change of the restored spaces. The fire resistance requirement for the load-bearing ceiling members and perimeter wall is given according to STN 73082 and is dependent on the average fire load, that is the sum of the accidental and permanent fire load, coefficients of ventilation, flammability factor and use and type of firefighting equipment. In terms of the calculated fire load pv = 66 kg/m2 , the fire resistance requirement for the fire-separated structures is REI 30 (building envelope and roof), and the fire resistance requirement for loadbearing structures of a non-compact ceiling in an assessed fire compartment is R 30.

#### **4.3 Fire resistance of the external wall in a model solution**

The external wall is made of stone and brick and has a variable thickness of 530–630 mm. The required fire resistance for this model solution is REI 30 min.

In accordance with the values given in Table 1A STN 730821, the real fire resistance of the perimeter wall is well above the required value (**Table 1**).

As the dimensions of the assessed wooden ceiling members and column in a model solution are different from the members given in the standard, their real fire resistance is calculated according to EN 1996-1-2: 2004 Eurocode 6: Design of masonry structures, Section 1.2 general rules—fire resistance design of masonry structures.

In specific cases, the fire resistance of fire-separating structures can be determined by a calculation according to EN 1996-1-2: 2004 Eurocode 6: Design of masonry structures, Section 1.2 general rules—fire resistance design of masonry structures.

#### **4.4 Fire resistance of the wooden ceiling in a model solution**

There is a wooden beamed ceiling above the ground plan in the model example. The ceiling material and structure are visible (see **Figure 3**).

The ceiling beams are supported by a wooden beam. The wooden beam is fastened on the load-bearing peripheral walls and supported by a wooden column (see **Figure 4**).

The real fire resistance for load-bearing and fire-separating structures was calculated according to the methodology given in STN EN 1991-1-2: 2004; the


#### **Table 1.**

*Fire resistance of the fire-separating structures according to STN 730821 [12].*

fire resistance of wooden members was calculated according to STN EN 1995-1-2 (Eurocode 5) depending on their mechanical stress [13, 14].

The real fire resistance for load-bearing and fire-separating structures is primarily dependent on their mechanical load during fire and fire load density caused by building's operation. Determination of fire resistance for structures in a fire compartment depends on the typical fire load density per unit of floor area (qf, d), burning rate coefficient, fire risk coefficients and fire protection coefficients. Estimated fire duration in the assessed fire compartment is determined after considering the influence of structures, ventilation and active firefighting equipment.

The fire resistance of wooden members affected by fire (wooden beam ceiling, column and girder) was specified using the effective cross-section method [15]. The methodology is based on the assumption that the first phase of burning wooden elements causes the surface burning and forms a carbonized layer. Such element becomes partially thermo-insulated by further thermal stress, which prolongs its fire resistance. The charring thickness is determined by the fire duration to which the element is exposed and by the charring rate. This interface or the location of the carbonized line in most coniferous and deciduous trees corresponds to the isothermal position of 300°C. After obtaining an effective cross-section, the element is assessed according to [16]. The method of reduced properties works with the residual cross-section (obtained after reading the carbonized layer) taking into account the changed strength and stiffness material properties based on the modified coefficient. In light of this assessment, all wooden load-bearing members in the assessed fire section of the museum met the required fire resistance without additional structural modifications.

The assessment of ceiling supporting members in terms of static load at a room temperature is given in **Table 2**. **Table 3** gives the assessment of supporting ceiling members in terms of static and fire load during a standard fire [17].

For material characteristics the following are considered: kfi, coefficient of solid timber, kfi = 1.25; kmod,fi, modification factor for fire, kmod,fi = 1.0; and γM,fi, partial factor for timber in fire, γM,fi = 1.0. For the calculation of charring depth, the following are considered: βn, notional design charring rate under standard fire exposure, βn = 0.8 mm/min (for solid timber); k0, coefficient for non-protected

**Figure 3.** *Layout and visible ceiling in a model solution (left) and ground plan with assessed wooden truss (right).*

**107**

d0 = 7 mm.

*EN 1995-1-2).*

*1*

*2*

**Table 2.**

**Figure 4.**

*decking (right).*

**5. Solution methods**

**5.1 Analysis of fire risk**

meet the required fire resistance value [16].

*The average column diameter at its narrowest spot.*

*A Case Study on the Fire Safety in Historic Buildings in Slovakia*

surfaces, k0 = 1.0; and d0, layer thickness with assumed zero strength and stiffness,

**[kNm]**

 Ceiling beam 200 250 6.35 0.63 0.53 0.6 Roof girder 300 270 14.64 −0.16 15.8 0.6 Column d = 2302 0.11 1.30 55.50 0.6 *where: ηfi—reducing factor for combined load. As simplification it is possible to use the value 0.6 (according to STN* 

**Mz,Ed [kNm]**

**NEd1 [kN]** *ηfi* **[-]**

If the restoration of listed buildings is designed, its preparatory phase analyzes the current fire risk in the building. The fire risk analysis examines the current fire

*Analysis of the current building solution in terms of fire safety*—includes assessment of current or planned layouts, flammability of structures and materials, number of

risk and the extent of fire-technical and organizational measures [5].

The fire risk assessment can be divided into four phases:

The structures assessed in terms of table values given in STN 730821 (see **Tables 3** and **5**) as well as values determined by a calculation in dependence on the current boundary conditions—static load and material characteristics of wood—

*Supporting using a wooden beam and column (left) and ceiling wooden beam with a wooden* 

**No Member b [mm] h [mm] My,Ed**

*Positive sign (+) means tensile force; negative sign (−) means compression force.*

*Parameters of static load of wooden ceiling supporting members at the room temperature.*

*DOI: http://dx.doi.org/10.5772/intechopen.91241*

*A Case Study on the Fire Safety in Historic Buildings in Slovakia DOI: http://dx.doi.org/10.5772/intechopen.91241*

#### **Figure 4.**

*Fire Safety and Management Awareness*

additional structural modifications.

fire resistance of wooden members was calculated according to STN EN 1995-1-2

The real fire resistance for load-bearing and fire-separating structures is primarily dependent on their mechanical load during fire and fire load density caused by building's operation. Determination of fire resistance for structures in a fire compartment depends on the typical fire load density per unit of floor area (qf, d), burning rate coefficient, fire risk coefficients and fire protection coefficients. Estimated fire duration in the assessed fire compartment is determined after considering the influ-

The fire resistance of wooden members affected by fire (wooden beam ceiling, column and girder) was specified using the effective cross-section method [15]. The methodology is based on the assumption that the first phase of burning wooden elements causes the surface burning and forms a carbonized layer. Such element becomes partially thermo-insulated by further thermal stress, which prolongs its fire resistance. The charring thickness is determined by the fire duration to which the element is exposed and by the charring rate. This interface or the location of the carbonized line in most coniferous and deciduous trees corresponds to the isothermal position of 300°C. After obtaining an effective cross-section, the element is assessed according to [16]. The method of reduced properties works with the residual cross-section (obtained after reading the carbonized layer) taking into account the changed strength and stiffness material properties based on the modified coefficient. In light of this assessment, all wooden load-bearing members in the assessed fire section of the museum met the required fire resistance without

The assessment of ceiling supporting members in terms of static load at a room temperature is given in **Table 2**. **Table 3** gives the assessment of supporting ceiling

For material characteristics the following are considered: kfi, coefficient of solid timber, kfi = 1.25; kmod,fi, modification factor for fire, kmod,fi = 1.0; and γM,fi, partial factor for timber in fire, γM,fi = 1.0. For the calculation of charring depth, the following are considered: βn, notional design charring rate under standard fire exposure, βn = 0.8 mm/min (for solid timber); k0, coefficient for non-protected

*Layout and visible ceiling in a model solution (left) and ground plan with assessed wooden truss (right).*

members in terms of static and fire load during a standard fire [17].

(Eurocode 5) depending on their mechanical stress [13, 14].

ence of structures, ventilation and active firefighting equipment.

**106**

**Figure 3.**

*Supporting using a wooden beam and column (left) and ceiling wooden beam with a wooden decking (right).*


*where: ηfi—reducing factor for combined load. As simplification it is possible to use the value 0.6 (according to STN EN 1995-1-2).*

*1 Positive sign (+) means tensile force; negative sign (−) means compression force.*

*2 The average column diameter at its narrowest spot.*

#### **Table 2.**

*Parameters of static load of wooden ceiling supporting members at the room temperature.*

surfaces, k0 = 1.0; and d0, layer thickness with assumed zero strength and stiffness, d0 = 7 mm.

The structures assessed in terms of table values given in STN 730821 (see **Tables 3** and **5**) as well as values determined by a calculation in dependence on the current boundary conditions—static load and material characteristics of wood meet the required fire resistance value [16].

#### **5. Solution methods**

If the restoration of listed buildings is designed, its preparatory phase analyzes the current fire risk in the building. The fire risk analysis examines the current fire risk and the extent of fire-technical and organizational measures [5].

#### **5.1 Analysis of fire risk**

The fire risk assessment can be divided into four phases:

*Analysis of the current building solution in terms of fire safety*—includes assessment of current or planned layouts, flammability of structures and materials, number of

