A1. What is the ASFP?

Formed in 1975, the ASFP is the trade association that represents the interests of the UK's manufacturers and installers of fire protections systems for steel, concrete, ductwork, penetration seals and fire stopping. These systems are sometime referred to as passive fire protection products. For a list of ASFP members go to http://asfp.associationhouse.org.uk/default.php?cmd=260

The ASFP works with Government and standard setting bodies both directly and via other sector group associations to increase the quality of the installed fire protection of the UK's buildings and industrial plants including onshore as well as offshore facilities.

A3. Who does the ASFP work with?

The Passive Fire Protection Federation (go to www.pfpf.org) which is the sector group for the entire passive fire protection industry, and includes apart form the ASFP the trade associations that are involved with fire doors, fire shutters, fire resistant glazing and partitions. Regulators, enforcers, insurers, test houses, certification bodies and other professional institutes are also members of the PFPF.

The European Association for Passive Fire Protection  www.eapfp.com  which provides the ASFP with a route into the European standard making scene.

The National Specialist Contractors Council (go to www.nscc.org.uk) which represents the interests at Government level of specialist contractors.

The Construction Industry Training Board (go to www.citb.co.uk). The ASFP participates with the CITB in the design of training courses, National Vocational Qualifications and Apprenticeships

The fire resistance of a component, such as a steel column, is its ability to resist the affects of fire for a period of time and this is usually measured by submitting the component to a firetest as defined in a nationally or internationally recognised standard. 

Most construction materials have some natural resistance to fire and as such comprise built-in fire protection. This natural fire resistance may be enhanced by the use of added materials or systems that are known by the collective term of passive fire protection. For example the fire resistance of steel may be enhanced by the use of intumescent coatings, and concrete by sprayed cementitious coatings. While holes in partitions around penetrating services may be sealed by proprietary mortars or batts.

At the website of the Passive Fire Protection Federation (go to www.pfpf.org) you will find links to the trade associations that are involved with fire doors, fire shutters, fire resistant glazing and partitions.

Under load steel will start to buckle and move when temperatures reach 550 C and in a steel framed building this will compromise its stability and compartmentation.

B5. Where can I find listings of independently validated products for the fire protection of structural steel?

The 'Yellow Book' (also known as 'Fire Protection for Structural Steel in Buildings') contains such listings and is available as a free download from this website, go to

B6. Why do service penetrations/openings through fire rated walls need sealing/stopping?

Because hot gases, fire and smoke will pass through thus spreading the fire and consequently the threat to life.

B7. What Guidance is available for the routine maintenance of fire protection systems?

The ASFP strongly advises building owners/users to ensure the routine maintenance of fire safety measures in buildings, arising from specific duties as defined in the Regulatory Reform (Fire Safety) Order 2005 – summarised in PowerPoint slides available elsewhere on this web site

There is no generic guidance available as maintenance will depend on the product sector, the working environment and service conditions; consult the fire protection manufacturer for advice for the maintenance of specific products.

In the case of structural steelwork, if refurbishment or upgrading of the fire protection is required, the ASFP publication TGD 10 may be helpful.

C1. Where can I find listings of independently certified products that are suitable for sealing/stopping penetrations/openings?

The 'Red Book' (also known as 'Fire Stopping and Penetration Seals for the Construction Industry') contains such listings and is available as a free download from this website, go to

C2. I have a fire protection problem for which there appears to be no tested passive fire protection system, what can I do?

The Passive Fire Protection Federation has a document entitled 'Guide to undertaking assessments in lieu of fire tests' and this gives guidance for the situation you describe, for a free download go to http://asfp.associationhouse.org.uk/default.php?cmd=210&doc_category=32

Yes the ASFP has a document, which was partly funded by the Department of Trade and Industry, entitled 'Ensuring Best Practice for Passive Fire Protection in Buildings' and this can be downloaded by going to the publication page.

D1. Who sets the level of passive fire protection in a building?

Generally the Building Regulations for new build. The Fire Authority has to be consulted if refurbishment projects are to be undertaken.

D2. What is Approved Document B (ADB) to The Building Regulations for England and Wales?

ADB is a Fire Safety document that provides practical guidance on meeting the requirements of the Building Regulations. There may also be alternative ways of achieving compliance with the requirements of the Building Regulations. For a copy of Approved Document B click here

D3. But I live in Scotland, what documents are available from the Scottish Executive?

Technical Standards for fire performance of buildings are available from the Scottish Building Standards Agency at www.sbsa.gov.uk

Details on Scottish fire safety legislation is available from www.infoscotland.com/firelaw

D4. But what about Northern Ireland?

Go to http://www.northernireland-legislation.hmso.gov.uk/sr/sr2000/20000389.htm for Part E Fire Safety of the Building Regulations (Northern Ireland) 2000 to see how compliance may be achieved.

D5. I understand that in the UK Building Regulations with regard to fire are aimed mainly at saving life. If I want to go further and install extra passive fire protection to enhance the preservation of the building in a fire situation where can I find information?

The Fire Protection Association and the Association of British Insures publish a document called ' The LPC Design Guide for the Fire Protection of Buildings' and this will give you guidance with regard to increasing the level of passive fire protection in your building. For a free download go to http://www.thefpa.co.uk/News/FPA+Design+Guide.htm 

E1. Third Party Certification Schemes

Why should I use a third party certificated contractor to install passive fire protection systems?

Approved Document B (Fire Safety) to the England and Wales Building Regulations states "Since the fire performance of a product, component or structure is dependent upon satisfactory site installation and maintenance, independent schemes of certification and registration of installers and maintenance firms of such will provide confidence in the appropriate standard of workmanship being provided.

E2. Where can I find information concerning third party certificated schemes for installers of passive fire protection systems?

The following companies are known to provide such schemes:-

BM TRADA Certification, go to http://www.trada.co.uk/services/410360.html

BRE Global, go to http://www.redbooklive.com

IFC Certification , go to http://www.ifccertification.com

Warrington Certification Limited, go to http://www.warringtonfire.net

F1. Structural Steel Fire Protection

How do passive fire protection products protect structural steel?

For a general overview please go to http://asfp.associationhouse.org.uk/default.php?cmd=8

G1. I have specific questions with regard to the use of intumescent coatings for structural steel fire protection can you help?

Can intumescent paints be used for the fire protection of beams at the heads of compartment walls or fire resisting walls?

A generic answer  can be provided. Yes, intumescent coatings can usually provide the necessary structural fire protection to the steel beam/section.

N.B.Where any fire separating wall forms a junction with the steel structure, there may also be a need to satisfy the fire integrity and insulation criteria of the entire fire wall division, so additional protection may be required to the steel section to meet these additional criteria, and/or to address any firestopping requirement between the junction of the protected steelwork and the wall itself.

Where the steel beam is at right angles to the fire resisting wall, additional firestopping is likely to be required to close the path to passage of fire in any space created in the web of the steel beam, and above or below the beam.
For any further guidance on fire integrity and insulation criteria consult Building Control.

G2. Can intumescent paints be used to protect beams and columns where external cladding systems are intended to be abutted to the steel surfaces?

In general, a minimum gap of 50  x dry film thickness of the reactive coating is recommended to allow adequate expansion in a fire, This guidance applies to the gap between the cladding and the flat surfaces of the protected steel section,  as well as the flange tips unless specific fire tests prove otherwise.

Gap sizes may be reduced where manufacturers have specific fire test evidence.

Continuous linear fixings [timber or metal] should be considered as part of the main beam, and duly protected from fire., unless other supporting fire test evidence can be provided.

G3. Brackets and angles are often added to perimeter steel beams to allow cladding systems to be fixed to the structural framework. What is the recommended treatment of these angles and brackets so that the fire resistance of the beam is not inadvertently reduced?

Continuous linear fixings should be considered as part of the main beam, and duly protected from fire.
The mass, spacing and orientation of fixings can all play a part in the total potential heat transfer into the steel structure. The effect from the heating of brackets fixed at intervals to different masses of steel structure is very difficult to quantify. It is not possible to give generalised guidance on the effect of spaced fixings to steelwork protected by reactive coating products.  The intumescent coating manufacturer should be contacted for specific advice. Fire protection may well be advised.
The manufacturer of the intumescent coating should be contacted for advice on the extent of any fire protection onto the cladding beyond its junction with the fixing bracket.

G4. What clearance is required between the steel sections coated with intumescent paints and any services penetrating through apertures in the web of  protected steel sections?

No generic answer can be provided.
Consult individual intumescent paint manufacturers for advice.

G5. In the case of deep web beams, the deepest web that is fire tested is 610mm and the steel section  is not loaded when tested. Does this mean that the tested intumescent paint can be used to protect any steel with a deeper web depth, with or without additional retention of the coating by mesh systems? Do any limitations apply?

Guidance is given in Draft prEN 13381-8 Reactive Coatings as follows:-
Provided that one of the beams tested has a web depth of at least 600mm there will be no limitation on the maximum web depth that can be protected, otherwise the assessment will be limited to the maximum web depth tested plus 50%. The intumescent coating manufacturer should be asked to comment on any limitations or reinforcement.

G6. Most new steel frames need to be fire protected before the external envelope is added to the building stucture, whilst adequate space exists. The protected steelwork may therefore become exposed to the weather elements for a time. Is this a problem for intumescent coatings?

Intumescent coatings are available for all types of service environments when used in conjunction with the correct topcoat system.
However, there is no generic guidance available. Consult individual manufacturers for advice

There are many ways of demonstrating durability of intumescent products. The obvious and most important is track record of real projects over many years. In addition some products have been tested to BS 8202 Part 2.
Underwriters Laboratory have a range of environmental testing requirements for both internal and external uses.
Most recently the European Technical Approval Guidance for intumescents (ETAG 18 Part 2) also has specific durability testing depending on service conditions.

G7. Does the passage of time effect the ability of intumescent coatings to develop char when subsequently exposed to fire?

As in Q6 there are many standard aging test requirements in the national and European requirements previously mentioned.
There is no generic guidance available. Consult individual manufacturers for advice.

G8. What is the effect when steel sections protected by intumescent paint systems are overpainted by a ‘house proud’ client or  building management team? 

Some manufacturers have a range of fire test data where multiple topcoats have been applied prior to fire testing. It may be possible to overpaint certain intumescent coating systems.
Consult individual manufacturers for advice.

G9. Can intumescent coatings be used to protect cellular beams

Yes, in the case of cellular beams with circular holes – Refer to the fire test protocol as detailed in Section 6.2 of the ASFP publication ‘Fire protection for structural steel in buildings’ – 4th Edition 2007. This publication can be downoaded from the publication page free of charge.

In the case of  cellular beams with other shaped apertures, refer to the manufacturer who must provide specific third party verification of the performance

‘Information is also provided in Technical Guidance Document 09: Code of Practice for the fire protection of steel beams with web openings. This document can be downloaded free of charge from the ‘publications’ section of this website

G10. Is fire protection required for steel  bolt  heads connecting steel sections?

Yes bolt heads should have the same resistance to fire exposure as the steel section, unless the fire protection manufacturer can demonstrate otherwise through third party verification of the performance.

G11. Can I spray another coat of  intumescent paint over a system which already has a top coat?

Generally this is not advisable unless the coating manufacturer has relevant fire test data.  The applicator MUST first consult the manufacturer of the coating system. It is likely  that the manufacturer will advise full removal of the top coat before re-application.

G12.Can fire test data obtained from curcular hollow steel (CHS) sections be used for the fire protection of solid steel bars or rods?

Fire protected solid steel bars may behave differently from fire protected hollow steel sections in fire. The use of a specific protection system and its thickness should be based on a proven capabiity suitable to the application.

It is necessary to generate a multi-temperature  thermal analysis based on the fire testing of solid bars over a range of diameters.

Consult the fire protection manufacturer for advice on the use of specific products.

NOTE – ASFP Technical Committee agreed on 080513 to develop a specific ASFP fire test protocol for assessing the fire protection for solid steel bars and rods.

H1.When intumescent coatings are applied over other types of passive fire protection, such as boards or non-reactive sprays, or a different intumescent coating, are the individual contributions to fire resistance additive?
Definitely not. We do not advise mixing fire protection systems of any type unless there is specific test evidence available from the manufacturers concerned. Combinations of individual fire resistance periods are not additive in any circumstances, unless supported by relevant test information.

H2. I have specific questions with regard to the use of sprayed cementitious coatings or boards for structural steel fire protection can you help?

How do we protect deep web beams ?

Fire protection board systems may be applied in a boxed or profiled configuration.
[1] For profiled board applications,
Flexible boards such as those made from mineral wool may require cover          strips    at all joints.
The use of rigid boards in this situation is generally not practical.

[2] For boxed board applications,
      The use of solid or “T-shaped “ noggings will usually be required on all beams    with web depths of 533mm or greater. Contact the manufacturer for specific          requirements.
      Flexible boards may require more internal support and cover strips at joints than            rigid boards. Contact the manufacturer for specific requirements.
      Rigid boards are more self supporting but may require protection to the web joint          or secondary support. Consult the manufacturer for specific requirements.

Fire protection cementitious spray applications will require the use of retention mesh where the web depth between the flanges exceeds 650mm. Consult the manufacturer for fixing details.
Note: mesh retention is also required where flange width exceeds 325mm.

H3. How do we protect beams with multiple web openings?

The section factor of the steel beam is established using the equation 1400/t where t is the thickness (mm) of the lower part of the steel web-post. The thickness of the fire protection system to be applied is then calculated based on the limiting temperature of the beam and a further 20% is added to the thickness.
Unless specific product data exists, protect all edges, dependent on the fire protection period required.
Further guidance is provided in Section 6.1 ASFP publication “Fire protection for structural steel in buildings. 4th Edition”

Information is also provided in Technical Guidance Document 09: Code of Practice for the fire protection of steel beams with web openings. This document can be downloaded free of charge from the ‘publications’ section of this website

H4. How do we deal with columns and beams within and passing through compartment walls?

Where a beam is passing through a compartment wall it should be fire protected to the appropriate level up to the wall and a fire seal should be utilised to prevent passage of fire through the compartment where the beam meets the wall. This fire seal should provide the necessary level of fire resistance, including fire integrity and insulation, and should be capable of dealing with any expected differential movement.

Where a beam or column forms part of a fire compartment wall there are two separate issues,  
[a]  fire protection of the steel
[b] fire separation criteria for the wall.

The criteria for [b]may be the dominant feature, such that additional protection thickness/measures will then be required for the steel work in the region of the wall, in order to deal with the fire integrity and insulation requirement from Approved Document B – Appendix A.
Specifically, under normal circumstances, a maximum 140ºC rise in the average temperature of the surfaces on the non- fire side of the compartment wall will be permitted. This is to be contrasted with keeping steel temperatures below 550ºC or so to maintain the structural load-bearing capability of the steel.

In the case of non load-bearing walls consideration should be given to the deflection of the beam during fire and the effect that this may have on the integrity of the compartment wall.

Guidance on the fire protection of partially exposed steel members can be found in Section 1.63.ASFP publication “Fire protection for structural steel in buildings. 4th Edition”

H5. How do we address the issue of brackets and angles fixed to columns and beams?

Where brackets, angles and other secondary fixings are to be attached to a steel beam, or column, the passage of heat into the structural steel via these fixings must be kept to a minimum. In order to achieve this fire protection of the fixing may be required. Consult the fire protection system manufacturer for specific details.

Where fixings are installed prior to the fire protection:

1. Boards can be cut to fit around them.
2. In the case of cementitious sprays, the fixings should be masked and then the spray may be applied in the normal way and the masking removed afterwards to reveal the fixings.

If fixings are installed after the fire protection system then areas of fire protection, of a minimum size, can be cut away to allow the fixings to be attached. A patch repair may be required in some circumstances to reinstate the required level of fire resistance.
Contact the fire protection system manufacturer for specific requirements and procedures.

H6. How do we deal with deflection at interfaces of steelwork with non load-bearing walls?

The limits of deflection are described in the guidance provided in Approved Document B – section 8.2.7, in support of the UK  Building Regulations 
This guidance will limit the steel deflection and allow the partition supplier to provide an interface detail.

H7. What primer systems are compatible with spray applied fire protection?

Gypsum based products are generally less chemically aggressive than those based on cement.

Where cement based products are applied to primed steel, an epoxy type primer will generally be compatible whereas an alkyd based primer will not be compatible.

Cementitious sprays are often applied to bare steel.

It is essential that installers and the designer consult with the cementitious spray manufacturer to confirm the compatibility of any steel priming system.

H8. How do we protect steel beams supporting timber joists or concrete slabs?

Where timber joists are located into the web of a beam the steel beam will usually need protection from fire in order to comply with the requirements of Approved Document B Appendix A. The timber joists which penetrate through the fire protecting layer must be fire stopped with a tested method or appropriately fire tested penetration seal. Consult manufacturer for specific guidance.

In addition, the timber floor will need to be fire resisting to the appropriate level and fire protection to the timber floor and timber joists may be required. The methods used to fix any fire protection system to the timber shall be as tested in a relevant fire test.

The fire protection of concrete slabs will depend on [a] the construction, density, the thickness, the thickness of concrete over reinforcement steel, the fire resistance requirements for the concrete floor slab, and [b] the thermal requirements arising from the location of the slab in the building.
Consult the manufacturer for specific guidance.

H9. Does steelwork (columns, beams, etc) in boundary wall condition require full protection?

The fire resistance requirements of the wall may change according to the requirements of Building Regulations Approved Document B 2006, and particularly where the building wall is less than 1 metre from the boundary of the property.   

The requirements for the fire resistance criteria of the boundary wall must be ascertained in order to assess any additional requirements for the structural steel associated with the boundary wall.

Consult the manufacturer for specific guidance

To access these go to ASFP Publications

I1. What is the difference between Class 1 and Class O Spread of Flame classifications?

See TGN 5 Guide to Class 0 and Class 1

To access these go to ASFP Publications

J1. How do I use passive fire protection products for roof components and secondary steelwork of portal framed buildings?

See TGN 4 Fire protection of roof components and secondary steelwork of portal framed buildings

To access these go to ASFP Publications

K1. Can I upgrade the fire protection of a concrete floor using passive fire protection products?

Yes see TGN 1 Spray Coatings for fire protection of concrete floors

To access these go to ASFP Publications

L1. What is the Regulatory Reform (Fire Safety) Order?

Changes to Fire Safety Law - UK fire safety legislation has been contained in a total of 118 separate pieces of legislation.  These include Fire Precautions Act 1971, the Fire Precautions (Workplace) Regulations 1997 as amended and a host of local Acts and Bye-Laws. 

The Order - intends to simplify the requirements as one Order, and takes forward many of the requirements for risk assessments from the Workplace Regulations.  The Order was laid before Parliament on 10th May 2004 and resultant evidence to the Parliamentary Committee is now being considered, as well as interactions with other legislation.  It's expected that 'The Order' will come into force around November 2005, or as soon as possible after that date. 

Responsible persons - The Order places a firm responsibility on the 'Responsible Person' for the fire safety measures that must be taken to ensure the safety of all the people they are responsible for, directly or indirectly.  It will apply to the majority of premises and workplaces in the UK excepting dwellings; offshore installations; building sites; military sites; underground parts of mines; or any structure that floats, flies or runs on wheels. 

The 'responsible person' is required to carry out a Fire Risk Assessment, produce a Policy, develop Procedures especially for evacuation, provide Staff Training and carry out Fire Drills.  The responsible person MUST provide and maintain clear Means of Escape, Signs, Notices, Emergency Lighting, Fire Detection and Alarm and Extinguishers.  The risk assessment must be reviewed regularly and amended whenever necessary.  It must be formally recorded if the responsible person employs 5 or more people, if the premises are licensed of if the Inspector requires it. 

The 'responsible person' must appoint  one or more 'competent persons' to assist him, with sufficient training, experience and knowledge, and have 3rd party accreditation if acting as a sub-contractor. 

Employees rights must be respected.  They must be consulted under the Order and be provided with information. 

New Guidance - The Office of the Deputy Prime Minister will provide 11 Guidance documents appropriate to a variety of occupational uses of buildings - including Shops and Offices, Educational premises, Place of Assembly, Factories and Warehouses, premises providing Sleeping Accommodation, Residential Care, Theatres and Cinemas, Outdoor Events and in the Transport Network. 

Enforcement - Enforcement will be the province of Fire Authorities, HSE, MOD or the Local Authority (sports grounds) - by force id necessary.  Failure to comply with Articles 8 to 21 and 38 may result in a fine or up to 2 years in prison.  Enforcers will have new rights of entry, to identify responsible persons, the limits of the premises, to inspect or copy records, and to take samples. 

Fire Certificates will be abolished - Previously issued fire certificates will be abolished and cease legal status. 

Further details - More information is available on the ODPM website

M1. Cast and wrought iron

Can fire test data obtained from mild steel be used to determine fire protection thicknesses for cast and wrought iron?

ASFP are of the opinion that data obtained from mild steel fire tests can be used to provide protection thicknesses for cast iron and wrought iron using the same limiting temperatures, subject to the conditions referenced in the following reports [a] and/or [b]

[a] BCIRA Report ‘Cast iron in building structures – revived interest in a proven case’ by E.R.Evans dated November 1984.
Further information can be obtained from:-
Castings Technology International, Advanced Manufacturing Park, Brunel Way, Rotherham S60 5WG. T: +44 (0)114 254 1144, E: info@castingstechnology.com

[b] ‘ Historic buildings and fire performance of cast iron structural elements’  by J R Barnfield & A M Porter

NOTE that the Structural Engineer must establish the Section Factors and be satisfied with the integrity of the iron work before specifing fire protection.

What action is needed where fire resisting ducts pass through oversized openings in fire resisting elements of construction?

ANSWER. Any oversized gap shall be reduced in size such that the additional fire penetration seal around the duct can function as fire tested within a maximum residual opening.

Responsibility for the satisfactory performance of each element of building construction (e.g. walls, floors, cavity barriers, etc.) lies with the installer of each particular element. The ‘change over’ of responsibility occurs at the interface between the fire resisting ductwork and the elements. It is imperative that the interface detail does not compromise the fire performance of either the element of building construction or the fire rated duct. The building designer, mechanical services designer and the installer all have a responsibility to pay ‘due care’ to this detail.

Further details are provided in ASFP ‘Blue Book’ publication ‘Fire resisting ductwork – 2nd Edition, Section 7 available at www.asfp.org.uk/publications.

The gap between the duct and the reveal of the opening in the wall or floor should be the same as the gap fire tested ± 10%.

• For gap sizes greater than this range, unless the duct manufacturer can provide additional supporting assessment data to the contrary, the aperture should be reduced in size using similar materials to those forming the enlarged opening, to provide a ‘window’ that conforms to the tested configuration, in order to accommodate the tested penetration seal detail.
  • For gap sizes smaller than this range and for alternative solutions to reducing the gap size of larger openings, any proposal must be independently assessed by competent independent persons or organisations.

ANSWER – In general the answer is no, especially in the case of ductwork used for smoke extraction.

Any such mounting is likely to compromise another essential function of the ductwork system, where it passes through a fire resisting element of constructions, unless other proven measures have been incorporated to mitigate such an effect.

ANSWER - This may be possible to accommodate at the time of installation, providing that a risk assessment determines that stresses on the hanger cannot go beyond that of the tested product. For example, this could include the potential effect of extra load arising from collapse from the secondary service.

Consultation should always be made with the system manufacturer/supplier. See ASFP ‘Blue Book’ publication ‘Fire resisting ductwork – 2nd Edition sections 6.1.2 note 2 and 6.2.1.3.

ANSWER – Ordinarily, contact the installation contractor and confirm that there has been relevant fire testing and competent assessment on the system. If there is no satisfaction then contact the main contractor/employer/CDM Coordinator to raise any concerns. Ultimately contact the local enforcing authority.

Approved Document B Appendix G summarises the legal duties on contractors arising under Regulation 16B to ensure that users of building [responsible persons] can make a relevant risk assessment as required under the Regulatory Reform (Fire Safety) Order 2005.  Observers have a Duty of Care.

ANSWER – When the specification is for a prescribed period of fire resistance then all fire resistance criteria shall apply, in terms of the load-bearing capacity (stability), integrity and insulation criteria. Removal of the insulation criteria shall only apply in exceptional circumstances

It is a requirement that where these compartment walls/floors are penetrated by ducts or other building services, the fire performance criteria for the penetrated wall or floor are maintained, such that fire in one compartment may not spread to other areas.

In specific installations, Building Control authorities may waive the insulation requirement or allow a reduced period of insulation, Examples include some car parks, where enforcers have considered that there was not a possibility of combustible materials being in close proximity of the ductwork. 

ANSWER - The supports used must be as fire tested in the ductwork system. Because of the way duct supports are fixed or anchored in fire tests, alternative fixings are permitted provided that suitable test evidence is available to justify the use on the intended duct system.

Further information is available in ASFP ‘Blue Book’ publication ‘Fire resisting ductwork – 2nd Edition’ at section 6.2.1.3 and 7.2

ANSWER – The answer comes in two parts. DIAP and EXAP rules are an output from European harmonization of fire testing methods and classifications. At a national level, experienced persons or fire test organisations have previously provided assessments of expected performance based on expert judgement.

[a] The direct field of application (DIAP)

DIAP rules are provided in BS EN 1366 test standards. They are derived from information obtained from tests carried out in accordance with relevant EN 1366 tests at recognised laboratories in Europe.  The test results achieved by a particular design may be directly applied to a limited number of variations (e.g. a reduction in duct size) without recourse to expert advice, providing the design remains substantially as tested.

The scope of the current BS 476 test method does not consider the effect, detrimental or not, that variations in the test construction may have on the achieved performance of the duct.  The test result only applies to the tested design and size; the field of direct application is very limited. The ASFP ‘Blue Book’ publication ‘Fire Resisting ductwork – 2nd Edition’ contains information in Section 6.

[b] The extended field of application (EXAP) rules are derived from test evidence to relevant BS EN 1366 test standards and is provided in the relevant section of BS EN 15080. EXAPs shall be based on primary test evidence to BS EN 1366 and may be supplemented by appropriate test evidence generated from other sources, or other relevant historical data. 

The EXAP rules consider changes in the tested design beyond the scope of direct application and may also consider variations to the tested design.  For example, an increase in duct size which necessitates the inclusion of a joint in the duct walls.

At a national level, for the purpose of assessments for the extended field of application, laboratories accredited by UKAS for conducting the relevant tests might be expected to have the necessary expertise or competent authority/persons appropriate to the complexity of the evaluation undertaken.

ANSWER - Access panels are frequently fitted to fire resisting ductwork for purposes such as cleaning or access to dampers.  The panels are fitted in the walls of the duct but must not interrupt the duct structure, e.g cross joints, stiffeners and supports.  Ideally the access panel will have been tested as part of the fire resisting ductwork system.  The test must have demonstrated that the design of access panel is able to maintain the required fire performance requirements of the ductwork system without weakening the structure of the duct.  The maximum size of panel is that tested.

Proprietary access panel systems are available.  To be acceptable for use as part of a ductwork system they must have been shown by test to be capable of maintaining the required fire performance requirements of the ductwork system when mounted in a similar type of duct.  The access panel assembly includes the panel, the mounting frame, the fixings holding the panel in the frame, the fixings fastening the mounting frame to the duct and any seals.

ANSWER
[a] A test result for fire resisting horizontal ducts is applicable to horizontal ducts only.

[b] A test result obtained for fire resisting vertical ducts is applicable to vertical ducts without a horizontal branch.

[c] However, for fire outside ducts, if a test is successfully made on a horizontal duct with a branch, for a stated period of fire resistance, then vertical ducts may include a horizontal branch for that same period of fire resistance.

[d] For a rectangular duct, the maximum aspect ratio between the longer and shorter sides is 4:1

ANSWER – The answers are different for those ducts tested to BS 476 Part 24 or tested to BS EN 1366 test methods.

In the case of BS 476 Part 24 test data, circular and flat oval straight seamed and spirally wound steel ducts may be assessed on the basis of the tests on rectangular ducts. Details of the construction of circular and flat oval, straight seamed and spirally wound steel ducts must be provided by the duct manufacturer. Further details are provided in ASFP ‘Blue Book’ publication ‘Fire resisting ductwork – 2nd Edition Section 6.2.1.10’

In the case of BS EN 1366 test data, no equivalence is permitted and all ductwork systems must be individually tested. The published European DIAP and EXAP rules apply.

As the vast majority of fire tests on ducts are conducted with rigid ducts it is not appropriate to extrapolate this data for flexible ducts. Therefore, unless the flexible duct system has been fire tested, the guidance cannot be assumed to apply.

O1. What data/documentation should I ask for to demonstrate that product X is suitable for use?

Manufacturer’s marketing information may not always include information for a particular field of application. The suitability of use is best justified by the manufacturer, by:-

The production of a valid fire test or assessment report against the requirements of BS 476: Part 20, or a European fire classification report to EN 13501-2 (when tested to EN 1366 Parts 3 or 4 as appropriate) as issued by a UKAS accredited fire test laboratory or in the case of an assessment by a competent person or body, which should adequately demonstrate the suitability of a fire stopping product for use within a specific application or a range of applications.

See ASFP ‘Red Book: Fire stopping - 3rd Edition’ section 11.3 for an expanded explanation.

O2. Should I provide fire stopping around combustible pipes which are less than 40 mm in diameter?

Yes, Approved Document B states: “If a fire-separating element is to be effective, every joint or imperfection of fit, or opening to allow services to pass through the element, should be adequately protected by sealing or fire-stopping so that the fire resistance of the element is not impaired”.

Also see 10.4.4 in ASFP ‘RED Book’ 3rd Edition

O3. Under what circumstances can fire stopping include pattressed solutions?

Any system intended to be used as a pattress cover to the void behind must be proven by fire test or assessment for the intended field of application and for the required fire resistance period. Ad hoc patching will not meet all the fire resistance criteria required.

O4. A plastic service penetrates a tightly cored drilled floor slab and immediately turns through 90 degree into the horizontal plane.  However, there is no or limited space for the application of wraps, collars or sleeves?  What should be done?

Under these circumstances it will be impractical to achieve an adequate fire stop with any of the common pipe closure solutions, but this does not remove the requirement to provide such a fire stop. It will therefore be necessary to either:-

[a] reposition/extend the pipe such that a pipe collar can be fitted to the soffit of the floor or

[b] use a smaller diameter pipe so that a collar/wrap/sleeve can be fitted within the floor, or

[c] re-drill the hole in the floor, so that a collar/wrap/sleeve can be fitted within the floor, or

[d] the pipe could be boxed in by fire resisting construction, or

[e] more innovative pipe closure devices, specifically designed and tested to cope with this situation, would be required.

O5. We are making refurbishment of an existing building. The existing services are both installed and ‘live’ and the required fire resistance of a wall is increased. How should I proceed and deal with inaccessible areas?

The law requires that a relevant fire risk assessment is made and maintained to identify all potential hazards and associated risks throughout the life and use of the building, and that all actions taken are recorded. The fire resistance and or other provisions should be enhanced in accordance with regulatory requirements to reduce risks to an acceptable level. The methods used can only be determined in relation to the particular problem.

O6. I want to seal the point where a duct or pipe passes through a fire resisting wall, and need 60 minutes fire resistance.  How much product do I need?

We refer you to ASFP Red Book and 3rd party certificated data sheets for the appropriate application. The required performance and guidance on quantity shall be confirmed with the manufacturer, and installer, of the selected product.