Passive Fire Protection Handbook - thefpa.co.uk€¦ · Passive Fire Protection Handbook Author...

Passive Fire Protection Handbook

Author

Sample content from FPA www.thefpa.co.uk

CO

NT

EN

TS

3

FOREWORD 6

INTRODUCTION 7 1.1 Legislation and enforcement 8 1.1.1 Signs 8 1.2 Building Regulations 9 1.3 Standards 13 1.4 Third party certification 15

PRINCIPLES OF PASSIVE FIRE PROTECTION 17 2.1 Fire risk assessment 19 2.2 Fire engineering 20 2.3 Compartmentation 20 2.3.1 Principles of compartmentation 20 2.3.2 Types of compartmentation 21 2.3.3 Design, uses and sizes of compartments 21 2.4 Fire testing 22 2.5 Spread of fire 25 2.5.1 Internal fire spread 26 2.5.2 Fire spread between buildings 26 2.6 Routine inspections 27 2.7 Building envelope protection 28 2.7.1 Security against arson 28 2.8 FPA Design guide: Essential principles 28

ELEMENTS OF PFP – BUILDING STRUCTURE 30 3.1 Materials used as structural elements in traditional construction 30 3.1.1 Stone 30 3.1.2 Steel 31 3.1.3 Reinforced concrete 34 3.1.4 Cast-iron 36 3.1.5 Timber 37 3.1.6 Brick and block 39 3.2 Modern methods of construction (MMC) 40 3.2.1 What are MMC? 40 3.2.2 Growth and benefits of MMC 42 3.2.3 FPA Design guide and MMC 42

Contents

1

2

3


4

CO

NT

EN

TS

3.3 External walls and cladding 43 3.3.1 Masonry 43 3.3.2 Externally rendered thermal insulation systems 45 3.3.3 Built-up cladding systems 45 3.3.4 Prefabricated composite panels 46 3.3.5 Glass façades 46 3.4 Protection of structural steel 47 3.4.1 Intumescent coatings 48 3.4.2 Non-reactive coatings 48 3.4.3 Fire-resistant boards 48 3.4.4 Concrete/masonry/stone enclosures 49 3.5 Tall buildings 49 3.6 Roofs 50

ELEMENTS OF PFP – INTERNAL NON-STRUCTURAL FEATURES 51 4.1 Internal walls, floors and ceilings 51 4.2 Partitions 56 4.2.1 Plasterboard and drywall systems 59 4.2.2 Demountable wall systems 60 4.2.3 Composite panel systems for internal walls 61 4.2.4 Special applications (cold stores etc) 62 4.3 Stairwells and lift shafts 62 4.3.1 Firefighting lifts and lobbies 63 4.4 Cavity barriers 64 4.5 Atriums 64 4.6 Fire curtains 66

ELEMENTS OF PFP – BUILDING SERVICES 67 5.1 Penetrations, openings and voids 68 5.1.1 Voids and cavities in heritage buildings 69 5.1.2 Protecting necessary apertures in internal fire walls 70 5.2 Ducts, shafts and dampers 71 5.3 Cables 75

ELEMENTS OF PFP – DOORS 76 6.1 Fire doors and doorsets 77 6.1.1 Timber 81 6.1.2 Steel 84 6.1.3 Aluminium 86 6.1.4 Hybrid 87 6.1.5 Composite 87 6.2 Seals 87 6.2.1 Rebates and gaps 87 6.2.2 Intumescent seals 87 6.2.3 Smoke seals 89 6.3 Glazing in doors 90

5

6

4


CO

NT

EN

TS

5

6.4 Hardware 91 6.4.1 Hinges, latches and other door fittings 91 6.4.2 Door closing, opening and hold-open devices 95 6.4.3 Maintenance 101 6.5 Fire detection and alarm systems 102

ELEMENTS OF PFP – GLAZING 103 7.1 Description 104 7.1.1 Risk evaluation 104 7.1.2 Fire-resistant glass 104 7.1.3 Types of fire-resistant glass – integrity 104 7.1.4 Types of fire-resistant glass – insulation 105 7.1.5 Fire-resistant glazed systems 106 7.1.6 Applications 107 7.2 Selection and design 108 7.2.1 Glass and fire 108 7.2.2 Hot glass and water 108 7.2.3 Safety and security glass 109 7.2.4 Glass and heat transmission 109 7.2.5 Additional considerations 109 7.3 Installation 110 7.4 Maintenance 111

ELEMENTS OF PFP – VENTILATION 112 8.1 Smoke control 115 8.2 Ducts 118

FURTHER INFORMATION AND TRAINING COURSES 120

INDEX 122

7

8


1IN

TR

OD

UC

TIO

N

7

The stability of a building in a fire depends upon the performance of all the component parts of its structure. Buildings are designed to keep products of combustion away from building occupants, allowing them time to escape safely.

Regulations that govern the design of buildings also take into consideration the safety of firefighters who attend an incident. Thus, if a building is adequately protected, it should withstand a fire for a reasonable time, without collapse.

Passive fire protection is the term applied to the components of a building that ensure it offers adequate fire performance. This may apply to the fire performance of the elements themselves or to the improvement in fire performance gained by the addition of specialised materials, products or systems.

When used within the fire safety design of a building, these materials and products generally offer either structural stability or act as fire-separating elements (or compartmentation). In both cases, the products must provide protection for a specified period of time. Passive protection provides the time necessary for the other parts of the fire strategy to operate. Within this strategy, the way in which the alarm is raised, how the occupants react and the manner in which the fire response systems (including firefighters) operate must be taken into account. Without this, the rest of the strategy cannot work.

Introduction1

HG

Esch Photography


1

INT

RO

DU

CT

ION

| Legislation and enforcement

8

Insurers also have an interest in the way in which buildings perform in a fire situation, not least because of their desire to avoid property or business loss. If, following a fire in the building, occupiers can resume operations with minimal business interruption, everyone’s interests are served. For this to happen, the spread of any fire must be restricted, if possible, to the compartment of origin. In all cases, the spread of smoke and flames can only be restricted or delayed by sound fire-separating elements, and this requires good design, good construction and regular inspection of the structure by those qualified to do so.

1.1 Legislation and enforcementThe Regulatory Reform (Fire Safety) Order 2005, which came into force in October 2006, requires there to be a person with specific responsibility for all aspects of fire safety in all workplaces in England and Wales. In Scotland, the Fire (Scotland) Act 2005 plus the Fire Safety (Scotland) Regulations 2006 which took effect in October 2006, and in Northern Ireland Part 3 of the Fire and Rescue Services (Northern Ireland) Order 2006 and the Fire Safety Regulations (Northern Ireland) 2010 which came into effect in November 2010, require a similar approach. In each case there is a duty is on the person responsible for the premises to ensure that a fire risk assessment is undertaken and to maintain general fire precautions. The requirements in all parts of the United Kingdom apply to virtually all non-domestic premises, and, if five or more people are employed, the assessment must be recorded.

Approved Document B (ADB) (see section 1.2) makes reference to the Regulatory Reform (Fire Safety) Order. The cross-referencing of ADB and the Fire Safety Order in this way gives architects, specifiers, builders, owners and occupiers another platform from which to consider the importance of fire safety when designing, constructing and occupying a building. Scotland and Northern Ireland have technical standards that are based on the same principles as ADB in respect of the structure, and the main consideration, as elsewhere in the UK, is for life safety. In Scotland, for example, the technical handbooks provide guidance on achieving the standards set in the Building

(Scotland) Regulations 2004 and are available in two volumes, Domestic buildings and Non-domestic buildings. In this chapter, where reference is made to ADB, the reader may infer application in Scotland and Northern Ireland as well as England and Wales.

1.1.1 SignsIt is the duty of the responsible person to make sure that all reasonable measures are taken to ensure that their premises are safe in order to protect their employees, and anyone who may be on site or within the vicinity of the site. Consideration of the choice

The important thing to note is that ADB now requires developers to pass on to the owner/occupier information about the fire safety strategy for the building and the products used, the details of which are set out in Appendix G of the approved document. A key aim of passing this information to the person who operates and maintains the building is that it will help with the preparation of fire risk assessments. This is particularly important because passive fire protection must be maintained throughout a building’s lifetime.


1IN

TR

OD

UC

TIO

N | B

uilding Regulations

9

and location of safety signs should be addressed as part of this requirement and must form part of the fire risk assessment. The Fire Safety Order, for example, includes a specific requirement for emergency routes and exits to be indicated by signs.

The Safety Signs Directive was adopted in 1992 by all EU Member States, and has been implemented in the UK through the Health and Safety (Safety Signs and Signals) Regulations 1996, which apply to all places of work. These require the provision and maintenance of appropriate signs for the following purposes:• to warn workers of any risk to their health and safety. Employers must conduct a

risk assessment as part of their duties under the Management of Health and Safety at Work Regulations 1999 and reduce any risk identified in such an assessment. If a hazard remains, a sign should be provided to indicate the type of hazard; and

• to augment the requirement for fire safety signs made under any other Act or Regulation – that is, if fire safety signs are required under other legislation, such as the Fire Safety Order, the Health and Safety (Safety Signs and Signals) Regulations must also be complied with.

The Health and Safety (Safety Signs and Signals) Regulations contain specific requirements for the shape, colour and pattern of signs. The objective is to provide signs that are readily understandable even if they do not contain words – eg by using pictograms. An important part of the Regulations is the requirement for employers to provide employees with ‘comprehensible and relevant information’ and to ‘ensure that each [employee] receives suitable and sufficient training’ in the meaning of safety signs and the measures to be taken in connection with safety signs. Consequently, signs put up to indicate an escape route must be accompanied by some training so that employees are familiar with the route to use under emergency conditions.

1.2 Building Regulations The current Building Act was passed in 1984. The Building Act 1984 is primary legislation; if you contravene the Building Act, you have broken the law. Having said that, what is significant about the Building Act to fire safety practitioners is that it gives the Secretary of State (Communities and Local Government) the power to issue regulations. These regulations are called the ‘Building Regulations’. The Building Regulations are brief descriptions of the standards which must be met by new building projects. They have the force of law, and, like primary legislation, failure to comply with them is an offence.

As an example, the following is a Requirement from Part B of Schedule 1 to the Building Regulations 2000:

Requirement Limits on application

Means of warning and escape

B1. The building shall be designed and constructed so that there are appropriate provisions for the early warning of fire, and appropriate means of escape in case of fire from the building to a place of safety outside the building capable of being safely and effectively used at all material times.

Requirement B1 does not apply to any prison provided under section 33 of the Prisons Act 1952 (power to provide prisons etc).


1

INT

RO

DU

CT

ION

| Building R

egulations

10

There is very little detail here about how to construct a building. It would be difficult to prosecute someone for breaching this Building Regulation, because it is full of relative terms such as ‘appropriate’, ‘early’, ‘a place of safety’ and so on. What one person considers a place of safety and what another considers a place of safety may be two completely different things. If this was all there was, the courts would be full of builders, engineers, and building control officers arguing over interpretations.

To add clarity to the Building Regulations, the Secretary of State publishes ‘approved documents’. A range of approved documents has been issued by the Secretary of State for the purpose of providing practical guidance with respect to the requirements of the Building Regulations 2000, including:A structure;B fire safety: two volumes dealing with dwellinghouses and buildings other than

dwellinghouses;C site preparation and resistance to contaminants and moisture;D toxic substances;E resistance to the passage of sound;F ventilation;G sanitation, hot water safety and water efficiency;H drainage and waste disposal;J combustion appliances and fuel storage systems;K protection from falling, collision and impact;L conservation of fuel and power;M access to and use of buildings;N glazing – safety in relation to impact, opening and cleaning; andP electrical safety – dwellings, Approved Document to support Regulation 7 on

material and workmanship.

There are two important points to note:

1 approved documents are not the Building Regulations. Architects, fire officers, and even some building control officers, will happily talk about what the Building Regulations say, when in fact they mean the approved documents. It is important not to fall into that trap, as it may lead to serious confusion; and

2 approved documents do not have the force of law. When you are constructing a building, you must comply with the Building Regulations, but you are not required to take any notice of the approved documents.

Approved Document B is the guidance supporting the fire safety aspects of the Building Regulations in England and Wales, and it comprises two volumes, the first covering dwellinghouses and the second covering other buildings. ADB is concerned primarily with life safety and recommends that building elements have up to 2-hours’ resistance to fire to allow for safe evacuation. But while protecting the lives of occupants has to be the first concern, it is also important to ask: what happens next? Everyone may have evacuated safely but that pile of smoldering ash and rubble that was once your workplace could now be useless.


1IN

TR

OD

UC

TIO

N | B

uilding Regulations

11

As such, fire protection should be about saving assets – the buildings themselves and their contents – not just lives. And yet many UK businesses fail within 12 months of a catastrophe such as a major fire. This places a massive burden on our communities and economy and should not be overlooked.

The significance of the approved documents is that they define those ‘relative’ terms in the Building Regulations. Taking the example above, Approved Document B defines a place of safety as ‘the open air clear of the effects of the fire. However, in modern buildings which are large and complex, reasonable safety may be reached within the building, provided suitable planning and protection measures are incorporated.’

Note: Of course, if the Building Regulations are met in some other way (other than following Approved Document B), a prosecution will not necessarily follow. The Millennium Dome, for example, was so big and open, that escape to a ‘place of safety’ was impossible within the bounds of the approved documents, and ‘suitable protection measures’ were impractical. Fire engineering, however, showed that the dome was so big, that for all practical purposes, the inside of the dome was a ‘place of safety’, and the Building Regulation requirement was met, even though the Approved Document definition wasn’t. (See section 2.2 for more on fire engineering.)

ADB is divided into five ‘requirements’ and each of these requirements is then subdivided into sections:• B1 – Means of escape:

• Section 1 – Fire alarm and fire detection systems;• Section 2 – Means of escape from flats;• Section 3 – Design for horizontal escape in buildings other than flats;• Section 4 – Design for vertical escape;• Section 5 – General provisions;

• B2 – Internal fire spread (linings):• Section 6 – Wall and ceiling linings;

• B3 – Internal fire spread (structure):• Section 7 – Loadbearing elements of structure;• Section 8 – Compartmentation;• Section 9 – Concealed spaces (cavities);• Section 10 – Protection of openings and fire stopping;• Section 11 – Special provisions for car parks and shopping complexes;

• B4 – External fire spread:• Section 12 – Construction of external walls;• Section 13 – Space separation;• Section 14 – Roof coverings; and

• B5 – Access and facilities for the fire service:• Section 15 – Fire mains;• Section 16 – Vehicle access;• Section 17 – Access to buildings for firefighting personnel; and• Section 18 – Venting of heat and smoke from basements.

Regulation 38Where a building is erected or extended, or has undergone a material change of use, and the Regulatory Reform (Fire Safety) Order applies to that building or extension, Regulation 38 (previously Regulation 16B) of the Building Regulations requires that


1

INT

RO

DU

CT

ION

| Building R

egulations

12

a package of fire safety information must be assembled and given to the person responsible for the premises. This is in the form of ‘as built’ information that records the fire safety design of the building or extension.

The information provided should include accurate details of all fire safety design measures to assist the responsible person to operate and maintain the building in reasonable safety. Where a fire safety strategy or a preliminary fire risk assessment has been prepared, these should also be included. The exact amount of information and level of detail necessary will vary depending on the nature and complexity of the building’s design. Further guidance on what information should be provided is given in Appendix G of ADB Volume 2.

Alternative approachesAn enhanced version of ADB, incorporating insurers’ requirements for property protection, is available from RISCAuthority or Royal Institute of British Architects (RIBA). This offers additional technical guidance about how to protect commercial buildings from fire beyond the Building Regulations’ critical life safety measures. It also includes RISCAuthority’s Insurer requirements for the implementation of fire safety engineering solutions, which considers the property protection dimension of engineered fire safety designs.

In some large and complex buildings the provisions contained in ADB may prove inadequate or difficult to apply. In such buildings, the only viable way to achieve a satisfactory standard of fire safety may be to adopt a fire safety engineering approach which takes into account the total fire safety package.

BS 7974: 2001: Application of fire safety engineering principles to the design of buildings. Code of practice offers an approach to fire engineering that supersedes the earlier DD 240: Fire safety engineering in buildings, which is mentioned in ADB.ADB also recognises alternative codes of practice that are more appropriate (or, at least, more focused) on particular building types. For example, if you build a shopping complex, the local authority building control department should not apply the standards of ADB, rather they should instead consider the design against the standards of BS 9999: 2008: Code of practice for fire safety in the design, management and use of buildings: Annex E (normative): Recommendations for shopping complexes.

Standards such as the BS 9999 series sit in between ADB and fire engineering. They provide detailed guidance on suitable standards for larger or more complex buildings of certain types than can adequately be covered by ADB, but the standards still provide detailed guidance.

Some difficulty may also be encountered when trying to apply the provisions of ADB to existing buildings, particularly when they are of special historic or architectural importance. In buildings of this type ADB suggests that it may be appropriate to carry out an assessment of the potential fire hazard or risk to life, and then incorporate in the design a sufficient number of fire safety features to alleviate the danger. It suggests that the risk assessment should take account of:• the likelihood of a fire occurring;• the anticipated severity of the fire;• how well the structure of the building is able to resist the spread of smoke and

flames; and


1IN

TR

OD

UC

TIO

N | S

tandards

13

• the consequential danger to persons in or near the building.

And the fire safety measures which can be incorporated in the design should include:• an assessment of the means to prevent fire;• the installation of automatic fire detection and warning systems;• the provision of adequate means of escape;• the provision of smoke control;• design features aimed at controlling the rate of growth of a fire if one does occur;• improvement of the ability of a structure to resist the effects of fire;• the extent of fire containment offered by the building;• the fire separation from other buildings or parts of the same building;• the standard of firefighting equipment in the building;• the ease with which the fire service may gain access to fight a potential fire;• the existence of legislative controls to require staff training in fire safety and fire

routines or licensing and registration controls; and• the existence of continuing control so that fire safety systems can be seen to

be maintained.This boils down to using a probabilistic (risk assessed) fire engineering approach, rather than the ADB.

1.3 Standards Insurers have for a very long time required additional performance beyond the Building Regulations. They must have confidence in a reliable fire barrier to prevent undue loss and damage to the building and its contents.

For example, controlled schemes for testing and certifying sprinklers and barriers were begun under the Fire Offices’ Committee (FOC), which became the Loss Prevention Council (LPC) in 1985. Subsequently, the staff involved with this work were transferred from the LPC to the BRE Foundation in 1999. The Loss Prevention Certification Board (LPCB) is now part of BRE Certification and runs many passive and active fire safety schemes – Loss Prevention Standards (LPS).

Many British and international standards and certain other test standards exist which relate to the suitability of building materials and methods in relation to their performance in the event of fire. The following summarises some of the principal standards.

BS 9999BS 9999: Code of Practice for fire safety in the design, management and use ofbuildings replaced most parts of BS 5588: Fire precautions in the design,construction and use of buildings in April 2009. This standard offers an approachin between that in Approved Document B and BS 7974: Application of fire safetyengineering principles to the design of buildings, for use in complex buildings. BothBS 9999 and BS 7974 use risk assessment for all measures in the building.

BS 476Likewise, the parts of BS 476: Fire tests on building materials and structures provide test methods for determining the fire resistance of construction elements and an insurer will be reassured to learn that a particular component or material has been tested successfully to a relevant part of Part of BS 476. (See section 2.4 Fire testing.)


1

INT

RO

DU

CT

ION

| Standards

14

BS EN 1363/1364/1365/1366There are a number of European test standards:• BS EN 1363: Fire resistance tests;• BS EN 1364: Fire resistance tests for non-loadbearing elements;• BS EN 1365: Fire resistance tests for loadbearing elements; and• BS EN 1366: Fire resistance tests for service installations.(See section 2.4 Fire testing.)

Timber frameworkBS 5268: Structural use of timber has its highly relevant Part 4, Fire resistance oftimber structures, in which 4.1 is entitled Recommendations for calculating fire resistance of timber members and 4.2 deals similarly with timber stud walls and joisted floor constructions. Fire performance should be demonstrated through appropriate structural design calculations to 4.1 or through evidence of the load-bearing performance during test to BS 476-21: Fire tests on building materials and structures: Methods for determination of the fire resistance of non-load bearing elements of construction or via BS EN 1365-3: 2000: Fire resistance tests for loadbearing elements. Beams or -4: 1999: Columns.

Structural steelworkThe principal standard is BS 5950: Structural use of steelwork in building. Part 1: 2000 is Code of practice for design. Rolled and welded sections. Part 5: 1998 is Code of practice for design of cold formed thin gauge sections.

Steelwork frames will typically need to be protected against the effects of fire and the degree of protection will be ascertained from fire tests on individual beams and columns to BS 476-21: 1987: Fire tests on building materials and structures: Methods for determination of the fire resistance of non-load bearing elements of construction or via BS EN 1365-3: 2000: Fire resistance tests for loadbearing elements. Beams or -4: 1999: Columns.

Internal liningsIn order that the spread of flame over wall or ceiling surfaces is controlled, the lining materials and products chosen for those surfaces should meet given performance levels set by tests specified in technical standards. The established national standardfor testing for the surface spread of flame is BS 476-7: 1997: Method of test to determine the classification of the surface spread of flame of products, which developed from earlier versions in 1971 and 1987. The 1997 standard classifies materials or products in Classes 1, 2, 3 and 4, of which Class 1 is the best and Class 4 the worst.

ADB states: ‘The highest national product performance classification for lining materials is Class 0. This is achieved if a material or the surface of a composite material is either: a. composed throughout of materials of limited combustibility; or b. a Class 1 material which has a fire propagation index (I) of not more than 12 and sub-index (i1) of not more than 6.’ The Approved Document notes that Class 0 is not a classification identified in any British Standard test. The European alternative has lining systems classified in line with BS EN 13501-1: 2007 + A1: 2009: Fire classification of construction products and building elements. Classification using test data from reaction to fire tests. Materials or products are classified as A1 (best), A2, B, C, D, E, or F (worst).


1IN

TR

OD

UC

TIO

N | Third party certification

15

The UK’s national classifications do not have direct equivalents in the European classifications. Options relating to the choice of materials with British or European tests’ evidence is contained in guidance published by the Passive Fire Protection Federation (Guide to demonstrating the performance of passive fire protection products, 2004).

Insulating materials/componentsThe insulation properties of building materials or components – in the case of a wall panel, for example, its ability to resist a rise of temperature on the face not exposed to fire – may be demonstrated by testing to the requisite criteria via appropriate standards, which may be relevant parts of BS 476, BS EN 1364 or BS EN 1365. If module walls or floors are insulated by the inclusion of an insulating material, insurers should be certain to seek assurances about the performance of the insulating material in a fire.

External wallsThe ability of non-loadbearing walls to deliver appropriate performance in terms ofintegrity and insulation in the event of fire may be tested via BS 476-22 or BS EN 1364-1. Load-bearing walls need to satisfy the requirements of BS 476-21 or BS EN 1365-1.Roof coveringsMaterials used for roof coverings have their fire resistance performances designated via the test methods of BS 476-3 or determined in accordance with BS EN 13501-5: 2005 + A1: 2009: Fire classification of construction products and building elements. Classification using data from external fire exposure to roofs tests. Table A5 of Appendix A of Approved Document B to the Building Regulations cites notional designations (national/European) of fire performance of types of roof coverings.

Electrical circuits and fittingsElectrical circuits and fittings always have potential as an ignition hazard. Relevant controls include the requirements of the Electrical Equipment (Safety) Regulations 1994, which place on the manufacturers of such equipment duties in respect of matters such as marking, safety and fitness for purpose. There are also the Plugs and Sockets etc (Safety) Regulations 1994. The IEE Wiring Regulations (BS 7671: 2008: Requirements for electrical installations. IEE Wiring Regulations. Seventeenth edition) are the safety standard for electrical installations for buildings.

1.4 Third party certification The latest revision of ADB extends the value of third party certification. Building control bodies can now accept certification of materials by accredited third parties and the installation by similarly accredited contractors as proof of compliance with the regulations. Certification by an independent, qualified assessor reassures the specifier that the product they are buying is as good as the one originally tested for fire performance.

Products to be tested are selected at random by the third party from the production line, the stock or even the market. Typically, a number of fire tests are conducted to establish a comprehensive and robust field of application covering the product’s use in a wide range of applications.


1

INT

RO

DU

CT

ION

| Third party certification

16

As with manufacturers, third party certification of installers is ongoing process. In any company, workers come and go, so competence assessment of all relevant workers is key and, if the company as a whole is constantly monitored, it ensures continuity and justifies its accreditation.

Third party certification usually has a three or five-year life, after which it must be renewed. Certification, once granted, can also be withdrawn. In the UK, the national accreditation body is the United Kingdom Accreditation Service (UKAS). Its remit is ‘to assess, against internationally agreed standards, organisations that provide certification, testing, inspection and calibration services’.

There are other, overseas certification and testing bodies which are also recognised by the UK Government, and by UKAS, as providing an equivalent service. They should be accredited by a national accreditation body (like UKAS) and should be party to international agreement through one of the following: the European Cooperation for Accord, the International Accreditation Forum, or the International Laboratory Accreditation Co-operation.

The Passive Fire Protection Federation (PFPF) has defined five criteria for judging the value of any scheme being offered for passive fire prevention work:

1 it must be independent – the certifier must be independent of buyer, seller and manufacturer;

2 it must have experience of product testing and evaluation, leading to an understanding of product characteristics and the potential mode of failure of fire protection systems;

3 the certification body must have accreditation from an organisation such as UKAS;

4 publication of technical requirements and how they are evaluated should be publicly available; and

5 any certification scheme should be subject to endorsement by the relevant industry’s representative body – in the case of passive fire safety systems, by the PFPF.


2P

RIN

CIP

LE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N

17

Passive fire protection provides primary protection for a building, its contents and occupants by providing, in the event of fire, fundamental compartmentation, structural stability, fire separation and safe means of escape. Passive systems

include: steelwork protection, drywall systems and boards, protected ductwork, dampers, fire stopping and penetration seals, fire doors and shutters, sealants for doors, special hardware for doors, fire-resisting glazing and glazing seals.

The overall objective of passive fire protection is to contain a fire, limit the effects of flame, heat and smoke, and prevent fire spread, either within the same building or to an adjacent building.

Passive fire protection measures achieve this objective by a combination of effects:• raising the fire resistance of the structure;• reducing fire spread through secondary ignition;• providing resistant physical barriers against flame;• providing insulating barriers against heat;• limiting the movement of smoke and other products of combustion; and • minimising the danger of fire-induced collapse or structural distortion.

Principles of passive fire protection

2H

GEsch P

hotography


2

PR

INC

IPLE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N

18

Passive fire protection design combines fire protection materials, systems and assemblies within an integrated design. Such a design should be used to protect life and to safeguard the building structure and other assets. Protecting the structure will also maintain building serviceability after fire by limiting its impact, helping to minimise rebuild costs, and facilitating quicker business recovery and continuity after a fire.

Building design incorporating passive fire protection should consider the performance of the building as a whole in case of fire. This means that passive fire protection of the structure will be combined and integrated with other fire protection measures of different types, which will be based on different technologies with different functions to achieve different objectives. It is not acceptable to consider superficial trade-offs between such measures. Fire protection design should therefore be a balance of both active and passive systems, working together to achieve their intended (and separate) performance levels. Trade-offs are routinely used as a tool to achieving cost-effective design solutions, but caution is advised, particularly if they are utilised only to save money.

If a developing and ventilated fire without sprinklers present does not have fire brigade intervention in time, a critical stage develops when all combustible materials in the fire room will spontaneously ignite. This is called ‘flashover’, which is a near explosive event; fire resistance testing is designed to represent these conditions. For an element to claim that it is fire resisting, it has to be able to satisfy the criteria given in the appropriate fire resistance test. Currently, this is BS 476-22 or BS EN 1364-1.

The time/temperature curve for testing fire resistance is intended to represent the rapid increase in temperature that occurs at and immediately after flashover. It is used to provide basic product classification. It is contentious whether the fire resistance standard test on this basis truly represents the various fire conditions that may occur in practice, and therefore it is advisable not to assume a direct one-for-one correlation between time in a fire test and resilience time in a real fire.

As aluminium is a significant material in the manufacture of hardware for use in the construction industry, one can see how little it can be relied upon to provide fire resistance, albeit that it is a non-combustible material. More surprisingly however, is that even before the aluminium has melted, steel, another important material in many constructions, has lost half of its strength.

Glass is another important material in construction. Modern architecture includes large areas of glazing in the façade and throughout modern buildings to develop light, openness and attractive aesthetics, providing separation without losing connections between the internal spaces and the outside. Although glass softens gradually with increasing temperature over the range 700°C to 1500°C, the working point (where the viscosity of glass is somewhat of the consistency of sticky toffee) is only reached after 2 hours in a standard fire test.

More significantly, standard ‘window’ glass cracks on exposure to quite mild thermal stress. Fire-resistant glass, therefore, needs specially developed technologies to counter this glass characteristic, which can be such a weak point in fire. For example, the integral wire mesh in familiar Georgian wired glass does that by simply reinforcing the glass and holding it together. Other successful fire-resistant glass types are based on special technologies, some of which use laminated interlayers. The term ‘laminated’


2P

RIN

CIP

LE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | Fire risk assessm

ent

19

however does not necessarily offer a promise of fire resistance. Organic, that is plastic and resin, interlayers in other types of laminated glass are liable to burn and smoke in an exposed fire condition.

To make things even more difficult in a real fire event, the production of combustion products (smoke and gases) coupled with the expansion of the air means that a positive pressure is generated in the room where the fire is contained. These hot, pressurised gases will be trying to flow to the lower pressure zones that exist in the protection area, and will therefore be exploiting any small gap that they can find. Gases with a temperature of between 700 and 900°C flowing through a small gap very rapidly increases the temperature of the unexposed face potentially above the critical temperatures for adjacent materials. As well as having critical phases when the materials’ properties change dramatically, as outlined above, another complication is that all metal components exhibit fairly high coefficients of expansion. The higher the coefficient of expansion, the greater the change in size the material goes through when it is subjected to temperature changes.

2.1 Fire risk assessmentA responsible person has to ensure that a fire risk assessment is undertaken. This must include fire safety management (risk reduction, staff training, fire drills, maintenance and recording of incidents), active fire precautions (such as alarm and detection units, firefighting equipment and sprinklers) and passive fire prevention systems (the fire resistance and containment capability of the building’s structure).

The first two of these requirements can be met relatively easily – regular fire drills and maintenance of the firefighting systems are not difficult to organise. It is straightforward to check that escape routes are kept clear and exit doors can be easily opened.

It is the third part – checking the passive fire protection measures – that requires more specialised knowledge on the part of the fire risk assessor. A thorough risk assessment means the fabric of the building must be examined.

The responsible person has to know that the building can be divided into compartments that can delay the spread of smoke and flames through the building. In cases where the original plans of the building show good compartmentation, it must be established that none of the fire-separating elements have been compromised in any way.

In buildings with multiple occupancy, the responsibility can extend beyond the premises occupied by a single business. Ducting and wiring can run through a building and it has to be assessed. Escape routes must be maintained and the materials used, including the decorative finishes, all have to meet certain standards. The fire risk assessor must have access to such information, and the expertise to decide if it complies with the standard required. The responsible persons for the various occupants of a building must cooperate with each other to check communal areas or ducting which travels through various levels before reaching the outside. Some situations could even need structural engineering skills to make a complete risk assessment.

In the face of all these complexities, the responsible person in many businesses often decides to employ a fire safety consultant. The legislation demands that the risk assessment is carried out by a competent person, so employing an ‘expert’ should satisfy


2

PR

INC

IPLE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | Fire engineering

20

the legal requirement. But it is essential to check that the consultant does have specific fire safety qualifications, as well as general health and safety credentials. Many do not. Failure to take ‘reasonable measures’ to check could mean the employer is still liable.

The Fire Protection Association has a number of publications designed to assist those responsible for a fire risk assessment. These include the books Essentials of fire safety management and Fire risk assessment for small businesses, and the DVD Fire risk assessment at work – see www.thefpa.co.uk

2.2 Fire engineeringThe guidance provided by ADB allows the use of expert judgment in determining fire safety provisions, but on the basis that differences from the guidance in ADB are specifically and separately justified. We have grown accustomed to fire safety engineers being involved in the design of buildings. They are increasingly a part of the design team and the fact that UK Building Regulations are goal-based, rather than prescriptive, gives the designers more flexibility than is the case in some other countries.

A fire engineer is typically called in for one of two reasons:• to design the fire safety systems when a proposed structure is of novel design or

use, or for a complex structure that does not easily fit existing guidelines in Approved Document B (ADB) – for example, when a very tall building is being constructed; or

• to ensure that the fire safety strategy achieves the required level of public safety optimally in all respects.

The specialist fire engineer will balance many factors in the design and will trade-off redundant measures against more effective techniques that achieve the same or a better result. A basic problem for the fire specialist is that testing theories is expensive and elemental work may not represent reality, so assumptions have to be made. Many specialists in other countries see UK Building Regulations as a good example of imaginative, performance-based regulation. Others suggest that fire engineering is based on assumptions and opinions that can only be properly tested when there is a real fire, at which point it may be too late.

BS 5950-8: 2003: Structural use of steelwork in building. Code of practice for fire-resistant design, BS 7974: 2001: Application of fire safety engineering principles to the design of buildings. Code of practice, various Eurocodes, the Steel Construction Institute report P288: Fire Safe Design: A new approach to multi-storey steel-framed buildings and BS 9999: 2005: Code of practice for fire safety in the design, construction and use of buildings are all well-researched documents that, together with a raft of analytical models, enable the practitioner to prove a design.

2.3 Compartmentation2.3.1 Principles of compartmentationThere are techniques that will minimise the effect a fire has on the fabric of a building and these should form an integral part of the design of all new buildings. Specifiers and architects must look at dividing a building into compartments that can be closed to stop the spread of fire – this is known as compartmentation.


2P

RIN

CIP

LE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | C

ompartm

entation

21

Confining a fire to its point of origin is the key objective of any fire safety measure. Active fire safety systems, such as automatic sprinklers or portable fire extinguishers, can be useful, but they cannot prevent the spread of smoke and flames on their own.

Compartments with fire-separating elements, on the other hand, can confine a fire to its area of origin in excess of the 30 minutes usually required by ADB. Rooms, corridors and offices can be closed off and safe areas for evacuation can be protected against fire until the blaze is extinguished by the attending fire and rescue service.

Moreover, in tall buildings, compartmentation can be vertical, as well as horizontal – for example, lift shafts, stairwells, and ventilation and heating ducts can all be compartmentalised. In designated firefighting shafts and firefighting lifts, protection should last for up to 2 hours.

If there is no compartmentation, or if the original structure has been compromised by alteration or poor maintenance, it is possible for fire to spread quickly and break out in seemingly unrelated areas.

2.3.2 Types of compartmentation A compartment will include doors, windows and other elements, such as wiring and ducting, which penetrate the walls and floors, so fire stopping and penetration seals must be part of the design. When rewiring, replacing doors and windows or moving partitions, the compartment could easily be compromised. Floors, roofs and ceilings are important parts of the building compartmentation, which should not therefore escape attention for important aspects such as penetrations and junctions with other building elements.

It is generally understood that one of the most important aspects of the fire risk assessment is to have available an outline plan of the main fire protection compartments and the designated fire safety escape routes.

2.3.3 Design, uses and sizes of compartments ADB covers new builds – future building work, such as the erection, extension or material alteration of a building – but older buildings can also benefit from compartmentation. In fact, simple measures like closing doors apply the principle of compartmentation to a structure which may have been designed long before modern regulations were introduced.

In addition, adjoining properties – terraces, linked, semi-detached – ought to have their separating walls carefully maintained and extended through the roof to ensure resistance to the spread of fire. The example of a fire in Bridlington, Yorkshire, in early 2007 is a case in point. Here, a fire at one end of a row of houses rapidly spread across the roofs. All of the houses were evacuated and extensive damage was caused. Clearly, better division between the properties would have resulted in less damage and disruption.

Fire doors and fire-rated ductwork are further examples of how compartmentation can prevent fire spread. Fire doors are required in places such as escape routes from loft conversions, and when garages have integrated access to dwelling places. However, ADB has now removed the need for self-closing devices on fire doors because homeowners were found to remove them, or to wedge doors open. This brings into


2

PR

INC

IPLE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | Fire testing

22

question the very nature of fire door functionality. A fire door is only a fire door when closed. This also applies to any door, whether fire rated or not. All well fitting doors, when closed, will slow the spread of smoke and fire.

One of the most dangerous methods for fire spread is ductwork, particularly from a kitchen, where naked flames are often present and grease can coat the inside of the duct. A kitchen extraction duct should therefore be fire-rated throughout its length to the same rating as the kitchen as it is an extension of the kitchen. Air-conditioning and smoke extract ducts should also be considered.

2.4 Fire testingIn the European Union, the drive is from individual member states’ own fire tests towards a common system of fire testing. Thus, the older British Standards are gradually being replaced with EN standards. Current fire tests standards for buildings are:• BS 476: Fire tests on building materials and structures:

• Part 3: 2004: Classification and method of test for external fire exposure to roofs;• Part 4: 1970: Non-combustibility test for materials;• Part 6: 1989 + A1: 2009: Method of test for fire propagation for products;• Part 7: 1997: Method of test to determine the classification of the surface spread

of flame of products;• Part 10: 2009: Guide to the principles, selection, role and application of fire

testing and their outputs;• Part 11: 1982: Method for assessing the heat emission from building materials;• Part 12: 1991: Method of test for ignitability of products by direct flame

impingement;• Part 13: 1987: Method of measuring the ignitability of products subjected to

thermal irradiance;• Part 15: 1993: Method for measuring the rate of heat release of products;• Part 20: 1987: Method for determination of the fire resistance of elements of

construction (general principles);• Part 21: 1987: Methods for determination of the fire resistance of loadbearing

elements of construction;• Part 22: 1987: Methods for determination of the fire resistance of non-

loadbearing elements of construction;• Part 23: 1987; Methods for determination of the contribution of components to

the fire resistance of a structure;• Part 24: 1987: Method for determination of the fire resistance of ventilation

ducts;• Part 31.1: 1983: Methods for measuring smoke penetration through doorsets

and shutter assemblies. Method of measurement under ambient temperature conditions;

• Part 32: 1989: Guide to full scale fire tests within buildings;• Part 33: 1993: Full-scale room test for surface products;

• BS EN 1363: Fire resistance tests:• Part 1: 1999: General requirements;• Part 2: 1999: Alternative and additional procedures;

• BS EN 1364: Fire resistance tests for non-loadbearing elements:• Part 1: 1999: Walls;• Part 2: 1999: Ceilings;


2P

RIN

CIP

LE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | Fire testing

23

• Part 3: 2006: Curtain walling. Full configuration (complete assembly);• Part 4: 2007: Curtain walling. Part configuration;

• BS EN 1365: Fire resistance tests for loadbearing elements:• Part 1: 1999: Walls;• Part 2: 2000: Floors and roofs;• Part 3: 2000: Beams;• Part 4: 1999: Columns;• Part 5: 2004: Balconies and walkways;• Part 6: 2004: Stairs;

• BS EN 1366: Fire resistance tests for service installations: • Part 1: 1999: Fire resistance tests for service installations. Ducts;• Part 2: 1999: Fire dampers;• Part 3: 2009: Penetration seals;• Part 4: 2006 + A1: 2010: Linear joint seals:• Part 5: 2010: Service ducts and shafts;• Part 7: 2004: Conveyor systems and their closures;• Part 8: 2004: Smoke extraction ducts;• Part 9: 2004: Single compartment smoke extraction ducts;

• BS EN 1634: Fire resistance and smoke control tests for door, shutter and openable window assemblies and elements of building hardware:• Part 1: 2008: Fire resistance tests for doors, shutters and openable windows;• Part 2: 2008: Fire resistance characterisation test for elements of building

hardware;• Part 3: 2004: Smoke control test for door and shutter assemblies.

There are currently three well-known standardised fire resistance tests:• the ‘standard’ or cellulosic test;• the hydrocarbon test; and • the RWS tunnel test (named after the Rijkswaterstaat, Ministry of Transport in

the Netherlands). Jet fire tests, to represent the combustion of hydrocarbon escaping from a pressurised vessel or pipe, also are in use in large and medium-scale versions (OTI 95 6345 and Draft BS under FSH/22 for the small-scale test). The force of the impingement of the jet flame on the test element can rapidly erode the passive fire protection material.

The fire resistance test is designed to represent flashover conditions. For an element to claim that it is fire-resisting, it has to be able to satisfy the criteria given in the appropriate fire resistance test.

Currently, in England and Wales, this is BS 476-22: 1987: Fire tests on building materials and structures. Methods for determination of the fire resistance of non-loadbearing elements of construction/BS EN 1364-1: 1999: Fire resistance tests for non-loadbearing elements. Walls. Consequently, the time/temperature curve of the fire resistance test represents the rapid rise of heating and the on-going growth of a post-flashover fire event.

When subjected to fire test exposure, the construction must show itself capable of satisfying certain criteria. The amount of heat flowing into the adjacent compartment as a result of holes and gaps is evaluated by the integrity criteria:• to prevent the movement of flames, fumes and smoke;• the collapse of part, or all of the element;


2

PR

INC

IPLE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | Fire testing

24

• the ignition of the material forming part of the unexposed face; and• the ignition of a small pad of oven dry cotton wool/fibre placed in the gas stream

egressing from any such gap, or when the temperature of the unexposed face is so great that it may cause the pad to ignite then the gap is measured by gauges to ensure that it does not exceed 150mm x 6mm or 25mm in any direction.

The amount of heat being conducted across the construction is evaluated by the insulating criteria through the of monitoring the temperature rise on the unexposed face. The critical temperature conditions are:• the average unexposed face temperature, as measured by five thermocouples fixed

in pre-determined positions, shall not indicate a rise in temperature of greater than 140°C; and

• the maximum unexposed face temperature, as measured by one of the above thermocouples or other thermocouples is attached for this purpose or by means of a mobile thermocouple, shall not indicate a rise in temperature of greater than 180°C.

There are exemptions to these criteria in respect of small areas or where the surface does not have a zone that can accommodate the 12mm diameter thin gauge copper disc that forms the measuring junction of these thermocouples.

The classification for surface spread of flame and combustibility of the material depends on the distance that burning travels in a given time. Class 3 is the poorest performance, Class 1 is the best. To gain Class 0 status, a Class1 material is subjected to a BS 476-6 test which ascertains if its combustibility is limited and similar to plasterboard. Approved Document B states that the surface linings of walls and ceilings should meet the following classifications:

Classification of linings

Location Class

Small rooms of area not more than:a. 4m2 in residential accommodation;b. 30m2 in non-residential accommodation. 3

Domestic garages of area not more than 40m2

Other rooms (including garages)1

Circulation spaces within dwellings

Other circulation spaces, including the common areas of flats and maisonettes

0

Examples:Class 0: Brickwork, blockwork, concrete, plasterboard, ceramic tiles, plaster finishes (including rendering on wood or metal lathes), woodwool slab, thin vinyl and paper coverings on inorganic surface (other than heavy flock wallpapers) and certain thermosetting plastics.Class 1: Timber, hardboard, blockboard, particleboard (chipboard), heavy flock wallpapers, thermosetting plastics, that have been flame retardant treated.Class 3: Timber, hardboard, blockboard, particleboard (chipboard), heavy flock wallpapers, thermosetting plastics and thermoplastics (expanded polystyrene wall and ceiling linings).


2P

RIN

CIP

LE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | S

pread of fire

25

ADB recognises the use of European tests as well as British Standard tests. The equivalent European tests for surface spread of flame are quite different from the BS tests:• single burning item (SBI) test: BS EN 13823: 2010: Reaction to fire tests for

building products. Building products excluding floorings exposed to the thermal attack by a single burning item – The reaction to fire test method adopted in the

European suite of fire tests incorporates a totally different method that exposes the products to direct flame impingement. The single burning item test is designed to simulate the flaming exposure that would be experienced by a material lining the walls of a room when a ‘waste paper bucket’ has ignited adjacent to the wall within the corner of a room. The test method primarily measures the heat energy contribution to the fire from the specimen and calculates a fire growth rate. Secondary measurements conducted by the test apparatus to calculate the volume of smoke produced by the fire, categorised by smoke growth rate values. The test apparatus also measures oxygen consumption, carbon dioxide production and carbon monoxide production. These gas concentrations help identify the heat release and the burning characteristics of the tested specimens.

• single flame ignitability test: BS EN ISO 11925-2: Reaction to fire tests. Ignitability of building products subjected to direct impingement of flame. Single-flame source test. Before undergoing the single burning Item test, all products must pass the single flame ignitability test. The test involves a small, cigarette lighter size, flame being impinged upon either the edge or the surface of the specimens for a short duration.

2.5 Spread of fireRegardless of how well an individual component of a building is designed and manufactured and even, to some extent, how well it is installed, the reduction of fire spread can only be effective if the building itself behaves in a predictable manner. The interaction between the elements of construction, in the event of a fire, should not cause elements to move and produce large gaps or to collapse prematurely.

In design terms, this means the specification of a regime of compartmentation which, in the event of a fire, will not be thwarted by any unsatisfactory performance of elements of a building or any unhelpful features of its design and assembly. This applies to both traditional construction and modern methods of construction (MMC).

Fire spreads by the physical movement of flames and surface ignition by contact with flames, igniting volatiles. When a fire does break out, essentially it spreads by the following mechanisms:• convection;• conduction; and• radiation.

Following the initial ignition, the air around the burning object is heated, the temperature of which is then further increased by the volatile gases and products of combustion (normally smoke) from the item on fire. The hot air rises by convection, losing heat to adjacent items and the room surfaces until these reach a similar temperature. If they are combustible the increase in temperature will normally take them above their own critical ignition


2

PR

INC

IPLE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | S

pread of fire

26

temperature at which point they start to add their own heat and gases to the convective flow. This is the main mechanism of fire spread during the developing phase of the fire.

As the temperature of the burning item, the surrounding structure, and the gases produced increase, they become luminous and emit heat by means of radiation. This radiation will vary in its intensity in proportion to the temperature and the emissivity of the surface of the burning objects or the particles in the gas. Whilst convection takes hot gases upwards and away from the fire, radiation is multi-directional and will heat up objects to the side of and below the fire or gas plume.

Any solid that is heated will conduct heat at a rate proportional to its thermal conductivity. This has the effect of heating up areas beyond the zone directly heated by flame, hot gases or radiation. Within a fire cell, it is probably one of the least efficient causes of fire spread although with certain materials the heat being conducted can release gases that are themselves volatile, making them more easily ignited by the convective heat. Any barrier, fire door, firewall or fire-separating floor is designed to contain the fire to one face. Here conductivity is more likely to be a significant cause of fire spread than it is in the fire cell. The barrier may remain unbreached, but because of the heat building up on one face, this may be conducted through the construction to the protected face, raising it to a point where spontaneous ignition may occur in any materials that are in contact with the surface.

This is a particular hazard with either thin metal barriers or with metal surfaces, such as pipes or cables that run from one face to the other. Fire protection has the objective of retarding the rate at which combustible materials get involved, ensuring that the structure does not reach the critical temperatures that could cause the structure to fail, and to use barriers that are able to resist the fire in order to protect escape routes or contain the fire to the enclosure of origin.

2.5.1 Internal fire spreadIt is common for smaller or self-contained buildings to rely on passive measures where the construction is designed to reduce the rate of spread. This is achieved by controlling the surface spread of flame of the linings, by providing protected escape routes, or even by reducing the internal fire spread by erecting fire-resisting barriers. In order to ensure a consistent approach to the specification of both the surface spread of flame requirements and fire resistance, it is important that the materials and constructions satisfy certain requirements determined by test.

The surface spread of flame phenomena is solely a function of the wall or ceiling lining together with its immediate substrate and not the element in its entirety. As such the tests involved use relatively small sample sizes and unlike the fire resistance test, there is generally no need to incorporate the whole construction. There are two tests to control the surface burning characteristics:• the surface spread of flame test; and• the fire propagation test.

2.5.2 Fire spread between buildings In Approved Document B, section B4 covers external fire spread, and deals with the topic in three parts:


2P

RIN

CIP

LE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | R

outine inspections

27

• construction of external walls;• space separation; and • roof coverings.

Provisions are made to restrict the combustibility of external walls of buildings that are less than 1000mm from the relevant boundary, high buildings, and buildings that are places of assembly or for recreation purposes. This is in order to reduce the surface’s susceptibility to ignition from an external source, and to reduce the danger from fire spread up the external face of the building. There are also limits on the use near a boundary of roof coverings that will not give adequate protection against the spread of fire.

Radiant heat from intense fires frequently ignites combustible material some distance away, and burning brands often spread fires over even greater distances. Unprotected openings are windows and other parts of the external walls that have little resistance to the passage of fire.

Heat increases the risk of fire spreading. The external walls of buildings should be non-combustible and the space allowed between buildings should be related to the:• fire resistance of the external walls;• extent of unprotected openings;• type of occupancy;• size of the largest compartment; and• nature of the roof covering.

Even if the windows are not opening, fire-resistant glazed façades should be considered where the spacing between buildings provides a risk of fire spread from building to building, either by flame impingement (integrity) or radiation with flame impingement (insulation with integrity performance).

2.6 Routine inspectionsFire protection is not just a question of the systems that are in place. Housekeeping, reduction of general clutter and safe storage of combustible items are also important elements. That, for example, would include the dangers of storing materials in escape ways and of blocking off escape doors. As the law contains a requirement for relevant fire protection systems to be maintained, routine inspection and record keeping is vital. Inspections should cover the following areas:• escape routes;• security measures;• fire doors;• fire alarm and detection systems;• emergency lighting; • extinguishers;• sprinklers; and • business/production equipment.

Routine building maintenance and the installation or replacement of other building services often negate protection by leaving hidden breaches in compartment walls or fire barriers.


2

PR

INC

IPLE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | B

uilding envelope protection

28

2.7 Building envelope protection2.7.1 Security against arson Protection against arson involves contributions from three areas: • security systems;• automatic fire detection and firefighting installations; and• fire safety management procedures.

The approach that should be taken depends on the nature of the premises, the type of business and the number and distribution of staff. It will therefore vary from business to business. The strategy that should be adopted will be determined after the arson risk assessment (that is a key element of the fire risk assessment) has been carried out. The FPA’s book The prevention and control of arson has more information on this area.The construction of the building envelope should provide a degree of strength to resist intrusion appropriate for the location and type of business; a bank will require a high degree of strength while a rural grocery store may accept lesser levels. An outline of the physical resistance of typical construction materials is as follows:• large glazed areas, even double- or triple-glazed, are not compatible with security.

Laminated glass offers better security. Basic laminated glass is very common and is widely used to provide basic protection against arson from outside, though it is not significantly fire resistant;

• timber and plastic cladding can be removed with little or no noise and simple tools. Where they are used for external decoration, a lining that is resistant to cutting with hand tools should be installed;

• hanging tiles are little better than timber cladding from a security viewpoint, and the same precautions need to be taken;

• plastic sheets vary in their properties. For example, thermoplastic sheets are usually flimsy; thermosetting plastic sheets can be forced away or burnt, though a good deal of smoke will be produced; and polycarbonate sheet will resist vandals’ missiles but are transparent;

• glass reinforced polyester (GRP) can be extremely tough; attention must be paid to fixings to ensure panels are secure;

• profiled metal sheet cladding provides a good standard of resistance to physical attack, provided suitable fixings are used. It may need protection from damage caused by vehicles, and is often used above ground level for this reason; and

• brick and blockwork generally provides adequate protection, other than for high risk areas that are vulnerable to vehicular attack.

2.8 FPA Design guide: Essential principlesThe FPA Design guide: the fire protection of buildings is principally on the subject of passive fire protection and is intended to provide loss prevention guidance for those who:• design;• specify;• construct;• own;• advise about;• equip; or• insure industrial and commercial buildings.


2P

RIN

CIP

LE

S O

F P

AS

SIV

E F

IRE

PR

OT

EC

TIO

N | FPA

Design guide

29

The Design guide delivers an insurance industry equivalent of the basic fire safety objectives which are contained in Part B of Schedule 1 to the Building Regulations.Building Regulations’ requirements are essentially life-safety based while insurers’ requirements are generally more stringent, on the basis of protecting property from fire, and when applied are likely then to result in premises which are even safer to work in or visit.

Essential principlesThe Design guide sets out a series of principles, which are intended to yield buildings that are safer from the risk of fire and better able to cope with the effect of fire in the event that it breaks out. The Design guide’s approach is described in the FPA’s Essential principles publication and the principles can be summarised as:1. Use building materials which will not make a significant contribution to a fire at any

stage of its growth;2. Design a building’s structure to have resistance to collapse or excessive deflection in

the event of a fire;3. Construct a building in such a way as to minimise the extent of fire and smoke

damage in the event of fire;4. Incorporate all necessary safeguards against the threat of arson;5. Construct the building in such a way that fire cannot spread in from an adjoining

building or other external fire source;6. Install an appropriate automatic fire alarm system;7. Ensure that fire protection systems are regularly inspected and maintained;8. Initiate a comprehensive regime of fire safety management for the premises;9. Give regard, at the design stage, to the potential damage from firefighting water and

plan to minimise any undesired environmental effects that might relate thereto;10. Specify only third party certificated fire protection products;11. Commission competent, specialist installers to fit fire protection products/systems;12. Ensure that services and related components are designed/constructed/installed/

maintained to guard against their becoming accidental sources of ignition.

By defining essential principles to be followed when designing and constructing commercial and industrial premises, the objectives of the Design guide are:

1 to minimise the effects of a fire on a business;2 to limit the effects of business interruption;3 to allow a business to be trading within 24 hours of a fire; and4 to protect the buildings within a business.

ASFP Best practice guide The Association for Specialist Fire Protection also publishes a useful guide called Ensuring best practice for passive fire protection in buildings, covering specific and specialised passive fire protection systems. It is intended to offer architects, designers, constructors, building occupiers and others, effective and feasible recommendations and selection criteria for the use of passive fire protection systems in buildings. A digital version of the guide may be found at www.asfp.org.uk.


Passive Fire Protection Handbook - thefpa.co.uk€¦ · Passive Fire Protection Handbook Author...

Documents

Transcript of Passive Fire Protection Handbook - thefpa.co.uk€¦ · Passive Fire Protection Handbook Author...