Fire Strategies
Consultants and Contractors play a key role in considering all elements of the design of a building which may affect the fire risk assessment. This includes the selection of combustible materials for the construction process and in particular, flammable insulation, or indeed those products only classified as fire resistant or fire retardant.
In the United Kingdom, the RRSFO (Regulatory Reform Fire Safety Order), clearly states that individuals may face prosecution if they have not carried out a suitable or sufficient fire assessment.
The image you see is from a modern tower, where the origin of the fire was at roof level, however as seen, the flame spread down the tower due to the materials used in the construction.
Defining the standards:
Approved Document B: Provides important guidance on the use of both non-combustible and limited combustibility materials. B2 recognises that if a fire penetrates a roof near a compartment wall, there is a risk it will spread over the roof to the adjoining space
Euro-classes: The European Reaction to Fire Classification System has been developed to compare construction products for ignitability, flame spread, heat release, smoke production and their propensity for producing flaming droplets or other potentially harmful debris. Testing is standardised through the use of BS-EN 13501-1. Insulating materials are classified into 7 levels - A1,A2,B,C,D,E and F. This is further defined by smoke intensity levels of S1,S2 and S3 as well as burning droplet classes of D0,D1 and D2
National Building Codes are usually based upon the development of a fire. Requirements are defined for materials and construction based upon the building type, size, fire load and occupancy.
Class A1 = Non-combustible
Class A2 = Considered non-combustible as no flash-over takes place
Class A2 to D are considered in conjunction with smoke development S1-S3 and emission of burning droplets code D0-D2
Class F is an indicator that the product does not meet the criteria of any class or that the material has not be tested/declared by the manufacturer.
REI Classification: The fire resistance classification system, defines the effectiveness of materials in fire resistance considering:
I = Insulation, The time it takes for the cold side of the material to reach a certain temperature (typically 140 Celcius)
E = Integrity, The time the material will maintain its integrity to the passage of fire
R = Load Bearing Capacity, The time during which the material will maintain its load bearing capacity
M = Mechanical Action, The resistance against impact loads
Reaction to fire classification according to EN 13501-1
Class A1 = No contribution to fire, No flash over, No additional classes
Class A2 = No significant contribution to fire, No flash over, Production of smoke and flaming droplets
Class B = Very limited contribution to fire growth, No flash over, Production of smoke and flaming droplets
Class C = Limited contribution to fire growth, Flashover after 10 minutes, Production of smoke and flaming droplets
Class D = Contribution to fire growth, flashover between 2-10 minutes, Production of smoke and flaming droplets
Class E = Significant contribution to fire growth, flashover before 2 minutes, Production of smoke and flaming droplets, smoke release expected to be substantial
BS 9999:2008 Code of Practice for fire safety in the design management and use of buildings
This relatively new standard has been developed based upon performance based engineering and recognises longer travel distances, smaller exits and stair widths when added or enhanced forms of safety measures are used
B1: Means of Escape
B2: Internal Fire Spread (Linings)
B3: Internal Fire Spread (Structure)
B4: External Fire Spread
B5: Access and Facilities for the fire service
Useful web information as gathered from:
Michael Slattery & Associates Fire Safety Engineers
MIMA UK building regulation
PAROC fire classification
In the United Kingdom, the RRSFO (Regulatory Reform Fire Safety Order), clearly states that individuals may face prosecution if they have not carried out a suitable or sufficient fire assessment.
The image you see is from a modern tower, where the origin of the fire was at roof level, however as seen, the flame spread down the tower due to the materials used in the construction.
Defining the standards:
Approved Document B: Provides important guidance on the use of both non-combustible and limited combustibility materials. B2 recognises that if a fire penetrates a roof near a compartment wall, there is a risk it will spread over the roof to the adjoining space
Euro-classes: The European Reaction to Fire Classification System has been developed to compare construction products for ignitability, flame spread, heat release, smoke production and their propensity for producing flaming droplets or other potentially harmful debris. Testing is standardised through the use of BS-EN 13501-1. Insulating materials are classified into 7 levels - A1,A2,B,C,D,E and F. This is further defined by smoke intensity levels of S1,S2 and S3 as well as burning droplet classes of D0,D1 and D2
National Building Codes are usually based upon the development of a fire. Requirements are defined for materials and construction based upon the building type, size, fire load and occupancy.
Class A1 = Non-combustible
Class A2 = Considered non-combustible as no flash-over takes place
Class A2 to D are considered in conjunction with smoke development S1-S3 and emission of burning droplets code D0-D2
Class F is an indicator that the product does not meet the criteria of any class or that the material has not be tested/declared by the manufacturer.
REI Classification: The fire resistance classification system, defines the effectiveness of materials in fire resistance considering:
I = Insulation, The time it takes for the cold side of the material to reach a certain temperature (typically 140 Celcius)
E = Integrity, The time the material will maintain its integrity to the passage of fire
R = Load Bearing Capacity, The time during which the material will maintain its load bearing capacity
M = Mechanical Action, The resistance against impact loads
Reaction to fire classification according to EN 13501-1
Class A1 = No contribution to fire, No flash over, No additional classes
Class A2 = No significant contribution to fire, No flash over, Production of smoke and flaming droplets
Class B = Very limited contribution to fire growth, No flash over, Production of smoke and flaming droplets
Class C = Limited contribution to fire growth, Flashover after 10 minutes, Production of smoke and flaming droplets
Class D = Contribution to fire growth, flashover between 2-10 minutes, Production of smoke and flaming droplets
Class E = Significant contribution to fire growth, flashover before 2 minutes, Production of smoke and flaming droplets, smoke release expected to be substantial
BS 9999:2008 Code of Practice for fire safety in the design management and use of buildings
This relatively new standard has been developed based upon performance based engineering and recognises longer travel distances, smaller exits and stair widths when added or enhanced forms of safety measures are used
B1: Means of Escape
B2: Internal Fire Spread (Linings)
B3: Internal Fire Spread (Structure)
B4: External Fire Spread
B5: Access and Facilities for the fire service
Useful web information as gathered from:
Michael Slattery & Associates Fire Safety Engineers
MIMA UK building regulation
PAROC fire classification
Fire Stop System for Facades
A slab edge fire stop system must meet the demands of the Authority Having Jurisdiction (AHJ), which typically will be the Civil Defence Department governing the building verification in regard to its suitability.
The consequence of same is a strict regime of procedures which are defined and administered to ensure compliance, such as:
1. Fire stop system tested or competently designed through Engineering Judgements by a recognised authority
2. Fire stop installation completed by a competent and validated professional installation contractor
3. Fire stop system installation verified by an independent certified third party inspector, recognised and authorised by the AHJ.
A typical facade fire stop containment system begins with the slab edge to back of facade panels system, and would include (As defined within the Hilti CFS-SP WB system as an example):
1. A minimum 100mm deep fire batt mineral wool of minimum density 64kg/m3, compressed to a minimum of 25%
2. A minimum 3mm wet thickness of CFS-SP WB (or CP672) to completely cover the surface of the mineral wool, plus an additional overlap of minimum 13mm onto the concrete floor and galvanised back pan of the facade.
In addition to fire containment, the Hilti system provides a sound flanking reduction of 31dB
Further enhancements are normally made for the benefit of enhanced acoustics, which typically would include the mineral wool extending to the full depth of the slab edge, and the addition of a minimum 1.5mm thick galvanised pressing either above, below or both faces, to cover the mineral wool filled void. For the top of slab, this has the added advantage of providing a protective surface to the elastomeric seal which could otherwise become damaged during following trades work.
In the event the facade is split on plan by separating core walls, the same principle of fire stop containment would be installed vertically in a similar manner as detailed above.
As a comparative, an alternative verified system is the Lamatherm CW-FS
This uses pre-compressed laminated rockfibre with a non-combustible core, which is either pre-cut or cut on site to suit the opening (plus nominal addition for compression), which is installed with impaled clips which in turn are secured to the slab.
As with the Hilti System, fire containment can be easily achieved to 2 hours as is defined in most building codes.
Governing bodies and recognised authorities include:
Firestop Contractors International Association (FCIA)
Association for Specialist Fire Protection (ASFP)
FIRAS - Third party certification for installation contractors (UK)
The Loss Prevention Certification Board (LPCB)
Certifire - Third party certification for the verification of products and system performance
Underwriters Laboratory (UL) - Third party certification for the verification of products and system performance
FM 4991 - Standard for approval of Firestop Contractors (USA)