General
A1 Many of the provisions in this Document are given in terms of performance in relation to standard methods of tests identified below. In such cases the material, product or structure should:
(a) be shown by test to be capable of meeting that performance, or
(b) have been assessed, analysed and appraised as meeting that performance (for this purpose, competent persons, laboratories accredited for conducting the relevant test, and other approving bodies might be expected to have the necessary expertise). For materials/products where European standards or approvals are not yet available and for a transition period after they become available, National Standards may continue to be used. Where European product standards or approvals are available, any body notified to the European Commission as competent to assess such materials or products against the relevant European standards or technical approval can be considered to have the appropriate expertise.(Refer to :New Approach Notified and Designated Organisations(NANDO)); or
(c) where tables of notional performance are included in this Document, conform with an appropriate specification given in these tables, or
(d) in the case of fire-resisting elements, conform with an appropriate specification given in Part II of the Building Research Establishments' Report (BR 128) 'Guidelines for the construction of fire-resisting structural elements' .
For buildings designed in accordance with the Eurocodes, the performance specified must be achieved when tested in accordance with the European test methods .
For existing buildings the performance may be achieved by reference to the test methods set out in BS 476.
A2 Building Regulations deal with fire safety in buildings as a whole and they are aimed at limiting fire hazard. The aim of standard fire tests is to measure or assess the response of a material, product, structure or system to one or more aspects of fire behaviour. Standard fire tests cannot normally measure fire hazard. They form only one of a number of factors that need to be taken into account. Other factors include those set out in this Technical Guidance Document.
Fire Resistance
A3 Factors having a bearing on fire resistance, that are considered in this document, are:
(a) fire severity,
(b) building height, or depth,
(c) building occupancy, and
(d) intervention by fire fighters.
A4 The standards of fire resistance given are based on assumptions about the severity of fires and the consequences should an element fail. Fire severity is estimated in very broad terms from the use of the building (its purpose group), on the assumption that the building contents (which constitute the fire load) are the same for buildings in the same use. In the simplest terms, the concentration of combustible material indicates the maximum temperature to which construction elements may be heated.
From estimates of the amount of combustible material per unit of floor area in various types of building (the fire load density), which were made for the Post-War Building Study No. 20 on the Fire Grading of Buildings, minimum standards have been devised for fire resistance. In this Technical Guidance Document, these basic standards have been modified according to particular features of the building affecting the risk to life, which are:
(a) height of the top floor above ground, which affects the ease of escape and of fire fighting operations, and the consequences should large scale collapse occur;
(b) occupancy, which reflects the ease with which the building can be evacuated quickly;
(c) basements, where the lack of an external wall through which to vent heat and smoke may increase heat build-up as well as complicating firefighting, thereby prolonging the fire; and
(d) single storey construction, where escape is direct and structural failure is unlikely to precede evacuation.
Because the use of buildings is subject to change, a precise estimate of fire severity based on the fire load due to a particular use may be misleading. A fire engineering approach of this kind must show a suitable factor of safety, to cater for these possible variations in fire load.
Fire Resistance Performance
A5 Performance in terms of the fire resistance to be met by elements of structure, doors and other forms of construction is determined by reference to either;
(a) Commission Decision 2003/629/EC of 27 August 2003 amending Commission Decision 2000/367/EC of 3 May 2000 implementing the Council Directive 89/106/EEC as regards the classification of the resistance to fire performance of construction products, construction works and parts thereof and any subsequent amendments, fire resisting elements tested to the Relevant European suite of test methods: I.S. EN 1364, I.S. EN1365, I.S. EN1366, I.S. EN 1636; or
(b) (National tests) BS 476: Parts 20-24: 1987 (or to BS 476 Part 8:1972 in respect of items tested or assessed prior to 1st January 1988).
All products are classified in accordance with:
I.S. EN 13501-2: 2016, Fire classification of construction products and building elements, Part 2 - Classification using data from fire resistance tests (excluding products for use in ventilation systems).
I.S. EN 13501-3: 2005+A1:2009 Fire classification of construction products and building elements, Part 3 - Classification using data from fire resistance tests on components of normal building service installations (other than smoke control systems).
I.S. EN 13501-4: 2007+A1:2009 Fire classification of construction products and building elements, Part 4 - Classification using data from fire resistance tests on smoke control systems.
Table A1 gives the specific requirements for each element in terms of the three following performance criteria (provisions for fire doors are set out in Appendix B, Table B1):
(a) resistance to collapse (loadbearing capacity), which applies to loadbearing elements, denoted R in the European classification of the resistance to fire performance;
(b) resistance to fire, smoke and hot gases penetration (integrity), which applies to fire separating elements, denoted E in the European classification of the resistance to fire performance; and
(c) resistance to the transfer of excessive heat (insulation), which applies to fire separating elements, denoted I in the European classification of resistance to fire performance.
Table A1 also sets out the minimum periods of fire resistance for elements of structure.
Table A2 sets out criteria appropriate to the suspended ceilings that can be accepted as contributing to the fire resistance of a floor.
Table A3 sets out limitations on the use of uninsulated fire-resisting glazed elements.
Information on tested elements is frequently given in literature available from manufacturers and trade associations. Any reference used to substantiate the fire resistance rating of a construction should be carefully checked to ensure that it is suitable, adequate and applicable to the construction to be used. Small differences in detail (such as fixing method, joints, dimensions, etc.) may significantly affect the rating.
Fire resisting elements of construction should be strictly in accordance with the specification and method of construction which, by the criteria indicated at A1, can be shown to be capable of meeting the required performance. Fire resisting elements of construction should not incorporate any components, such as building services, which could compromise their fire resistance performance.
Any openings for services which pass through fire resisting construction should be adequately protected and fire stopped to ensure that the fire resistance of the element
is not impaired (see 3.7). Care and attention to detail should also be taken at the junctions between fire resisting elements of construction to ensure that the integrity of the fire resistance is maintained.
Roofs
A6 Performance in terms of the resistance of roofs to external fire exposure is determined by reference to either:
(a) Commission Decisions 2005/823/EC amending Decision 2001/671/EC of 22 November 2005 establishing a classification system for the external fire performance of roofs and roof coverings and any subsequent amendments ;or
(b) I.S. ENV 1187: 2002; or
(c) (National tests) BS 476: part 3: 2004
All constructions are classified within the European system as BROOF(t4), CROOF(t4), DROOF(t4), EROOF(t4) or FROOF(t4) (with BROOF(t4) being the highest performance and FROOF(t4) being the lowest) in accordance with I.S. EN 13501-5: 2005+A1:2009, Fire classification of construction products and building elements, Part 5 – Classification using test data from external fire exposure to roof tests.
Roof covering products (and/or materials) can be considered to fulfil all of the requirements for the performance characteristic “external fire performance” without the need for testing if they are listed in Commission Decision 2000/553/EC of 6 September 2000 implementing Council Directive 89/106/EEC as regards the external fire performance of roof coverings.
Commentary - All constructions are classified within the National system by 2 letters in the range A to D, with an AA designation being the best. The first letter indicates the time to penetration and the second letter a measure of the spread of flame. Table A4 gives notional designations of some generic roof coverings.
Reaction to fire
A7 Performance in terms of reaction to fire to be met by construction products is determined by Commission Delegated Regulation (EU) 2016/364 of the 1 July 2015 and any subsequent amendments. All products, excluding floorings, are classified as A1, A2, B, C, D, E or F (with class A1 being the highest performance and F being the lowest) in accordance with I.S. EN 135011: 2007+A1:2009 Fire classification of construction products and building elements, Part 1-Classification using data from reaction to fire tests.
The relevant European test methods are specified as follows;
I.S. EN ISO 1182: 2010 Reaction to fire tests for building products - Non-combustibility test.
I.S. EN ISO 1716: 2010 Reaction to fire tests for building products - Determination of the gross calorific value.
I.S. EN 13823: 2010 Reaction to fire tests for building products - Building products excluding floorings exposed to the thermal attack by a single burning item.
I.S. EN ISO 11925 - 2: 2010 Reaction to fire tests for building Products, Part 2 - Ignitability when subjected to direct impingement of a flame.
I.S. EN 13238:2010 +A7 2014 Reaction to fire tests for building products - conditioning procedures and general rules for selection of substrates.
Note: The classes of reaction to fire performance of A1, A2, B, C, D and E are
accompanied by additional classifications related to the production of smoke (s1, s2, s3, with s1being the highest performance) and/or flaming droplets/particles (d0, d1, d2, with d0 being the highest performance).
Internal Linings
A8 Flame spread over wall or ceiling surfaces is controlled by providing for the lining materials or products to meet given performance levels in tests appropriate to the materials or products involved.
A9 Under the European classifications, lining systems are classified in accordance with I.S. EN 13501-1: 2007+A1:2009, Fire classification of construction products and building elements, Part 1 - Classification using data from reaction to fire tests. Materials or products are classified as A1, A2, B, C, D, E or F with A1 being the highest. When a classification includes “s3, d2”, it means that there is no limit set for smoke production and/or flaming droplets/particles.
Under the National classifications, lining systems which can be effectively tested for 'surface spread of flame' are rated for performance by reference to the method specified in BS 476: Part 7: 1971 or 1987 under which materials or products are classified 1, 2, 3 or 4 - with Class1 being the highest (Class 4 ratings are not acceptable under the provisions in this document).
A10 The European reaction to fire classification system is based on the principle that construction products should be tested in the I.S. EN 13823 test in a manner that is representative of their “end use” application. This means that realistic jointing and fixing arrangements should be included within the specimens that are tested. It is important to recognise this fact since as a consequence, a construction product may have several different European reaction to fire classes depending upon its “end use” application. Clearly, for many construction products there are a large number of combinations and variations possible. Where European Technical Specifications for products have been published or are being developed, guidance on appropriate reaction to fire test arrangements should be available. However, for those products for which no specific guidance exists, general guidance is available in I.S CEN/TS 15447(2006), Technical Specification “Mounting and fixing in reaction to fire tests under the CPD”.
A11 To restrict to a minimum the use of materials which ignite easily, have a high rate of heat release and/or which reduce the time to flashover, maximum acceptable 'fire propagation' indices are specified. These are determined by reference to the method specified in BS 476: Part 6: 1981 or 1989. Index of performance (I) relates to the overall test performance, where sub-index (11) is derived from the first three minutes of test.
A12 The highest product performance classification is Class 0. This is achieved if a material or the surface together with its substrate of a composite product is either:
(a) composed throughout of materials of limited combustibility (see A18); or
(b) a Class 1 material which has a fire propagation index (I) of not more than 12 and sub-index (11) of not more than 6.
Note: Class 0 is not a classification identified in any Standard test.
A13 No thermoplastic material in isolation can be assumed to protect a surface underlying it. The surface rating of both products must meet the required classification. If however, the thermoplastic material is fully bonded to a non-thermoplastic substrate, then only the surface rating of the composite will need to comply.
A14 Composite products defined as materials of limited combustibility (see A18) in Table A6 should in addition comply with the test requirement appropriate to any surface rating specified in Sections 2, 3 and 4.
A15 The notional performance ratings of certain widely-used generic materials or products are listed in Table A5 in terms of their performance in the traditional lining tests (BS 476: Parts 6 and 7) or in accordance with I.S. EN 13501-1: 2007+A1;2009, Fire classification of construction products and building elements, Part 1- Classification using data from reaction to fire tests.
Note: Information on tests on proprietary materials is frequently given in literature available from manufacturers and trade associations.
Any reference used to substantiate the surface spread of flame rating of a material or product should be carefully checked to ensure that it is suitable, adequate and applicable to the construction to be used. Small differences in detail, such as thickness, substrate, fixings, adhesive etc., may significantly affect the rating.
A16 A thermoplastic material means any polymeric material which has a softening point below 200°C if tested to I.S. EN ISO 306: 2013. Specimens for this test may be fabricated from the original polymer where the thickness of material of the end product is less than 2.5 mm.
For the purposes of Sections 2 and 4 thermoplastic materials should be used according to the performance set out in A8 and A9 above or be classified as TP (a) or TP (b) as follows:
TP (a) rigid:
Rigid solid pvc sheet;
solid (as distinct from double - or multiple-skin) polycarbonate sheet at least 3 mm thick;
multi-skinned rigid sheet made from unplasticised pvc or polycarbonate which has Class 1 rating when tested to BS 476: Part 7:1971 or 1987;
any other rigid thermoplastic product, a specimen of which, when tested to BS 2782-0: 2011 method 508A, performs so that the test flame extinguishes before the first mark, and the duration of flaming or afterglow does not exceed 5 seconds following removal of the burner.
TP (b):
Rigid solid polycarbonate sheet products less than 3 mm thick, or multiple skin polycarbonate sheet products which do not qualify as TP(a) by test; or
Other products which, when a specimen of the material between 1.5 and 3 mm thick is tested in accordance with BS 2782-0: 2011 Annex A method 508A, has a rate of burning which does not exceed 50 mm/minute (if it is not possible to cut or machine a 3 mm thick specimen from the product then a 3 mm test specimen can be moulded from the same material as that used for the manufacture of the product); and
the product, when ignited, does not produce burning droplets which could contribute to the spread of fire within a building.
A17 Concessions are made for thermoplastic materials used for windows, rooflights and within suspended ceilings if they cannot be tested as specified in pars. A9 , A10 and A11. They are described in Sections 2 and 4.
Materials of Limited Combustibility
A18 Materials of limited combustibility are defined in Table A6,
(a) (European classes) in terms of performance when classified as class A2-s3, d2 in accordance with I.S. EN 13501-1: 2007+A1:2009 , Fire classification of construction products and building elements, Part 1 - Classification using data from reaction to fire tests when tested to I.S. EN ISO 1182: 2002, Reaction to fire tests for building products - Non combustibility test or I.S. EN ISO 1716: 2002 Reaction to fire tests for building products - Determination of the gross calorific value and I.S. EN 13823: 2010 Reaction to fire tests for building products - Building products excluding floorings exposed to the thermal attack by a single burning item or
(b) (National classes) by reference to the method specified in BS 476: Part 11: 1982
(c) (National classes) Table A6 also includes composite products (such as plasterboard) which are considered acceptable, and where they are exposed as linings they should also meet any appropriate flame spread rating.
Non-combustible Materials
A19 Non-combustible materials are defined in Table A7 either as listed products, or in terms of performance;
(a) (European classes) when classified as class A1 in accordance with I.S. EN 13501-1: 2007+A1:2009, Fire classification of construction products and building elements, Part 1 - Classification using data from reaction to fire tests when tested to I.S. EN ISO 1182: 2002, Reaction to fire tests for
(b) building products - Non combustibility test and I.S. EN ISO 1716: 2002 Reaction to fire tests for building products - Determination of the gross calorific value; or
(c) (National classes) when tested to BS 476: Part 4: 1970 or Part 11: 1982.
Only non-combustible materials may be used where there is a provision for noncombustibility and also for the specific application in the elements listed in Table A7. Non-combustible materials may be used whenever there is a requirement for materials of limited combustibility.
Fire Test Methods
A20 A guide to the various test methods in BS 476 and BS 2782 is given in PD 6520: 1988 (BSI).
A guide to the development and presentation of fire tests and their use in hazard assessment is given in BS 6336: 1998.
Structural Fire Design
A21 The Eurocodes are a set of harmonised European structural design codes for building and civil engineering works and are produced by CEN (European Committee for Standardisation).
There are 10 Eurocodes made up of 58 Parts. Each Part is implemented nationally with a National Annex. These Annexes contain information on Nationally Determined Parameters to be used for the design of building and civil engineering works to be constructed addressing for example particular national safety parameters, geographical and climatic conditions, and procedures.
Irish National choices are contained in the Irish National Annex or National Foreword to each Part. Therefore, any reference to the Eurocodes must be taken to include reference to the relevant Irish National Annex.
Attention is drawn to the fire parts of the Structural Eurocodes I.S. EN 1991-1-2: 2002, I.S. EN 1992-1-2: 2004, I.S. EN 1993-1-2: 2005, I.S. EN 1994-1-2: 2005, I.S. EN 1995-1-2: 2004, I.S. EN 1996-1-2: 2005, I.S. EN 1999-1-2: 2007
which present a range of options for the designer ranging from prescriptive rules based on standard fire resistance periods and the use of tabulated data, to calculation procedures based on a natural fire exposure and whole building behaviour.
When assessing existing structural elements in existing dwelling houses guidance on the design for different structural materials is contained in Part 1 of the Building Research Establishment Report (BR 128) “Guidelines for the construction of fire-resisting structural elements".
Table HB9 - Specific provisions of test for fire resistance of elements of structure, etc. in dwelling houses - Extract from TGD B Vol. 2
Application of the Fire Resistance Standards in Table A1
Where one element of structure supports or carries or gives stability to another, the fire resistance of the supporting element should be no less than the minimum period of fire resistance for the other element (whether that other element is loadbearing or not).
There are circumstances where it may be reasonable to vary this principle, for example:
(i) where the supporting structure is in the open air; or
(ii) Where an element of structure forms part of more than one building or compartment, that element should be constructed to the standard of the greater of the relevant provisions.
Although some elements of structure in a single storey building may be excluded from needing fire resistance (see Section 3 Par.3.4.4) fire resistance will be needed if the element:
(i) is part of (or supports) an external wall and there is provision in Section 4 to limit the extent of openings and other unprotected areas in the wall: or
(ii) is part of (or supports) a compartment wall, a separating wall or a wall between a dwelling house and an attached or integral garage; or
(iii) supports a gallery.
For the purposes of this paragraph, the ground storey of a building which has one or more basement storeys and no upper storeys, may be considered as single storey.
The fire resistance of the basement storeys should be that appropriate to basements. Where one side of a basement is (due to the slope of the ground) open at ground level, giving an opportunity for smoke venting and access for fire fighting, it may be appropriate to adopt for elements of structure in that storey, the standard of fire resistance applicable to above ground structure.
Table HB10 - Limitations on fire-protecting suspended ceilings - Extract from TGD B Vol. 2
Table HB11 - Limitations on the use of uninsulated fire resisting glazed elements on escape routes - Extract from TGD B Vol. 2
Table HB12 - Notional designations on roof coverings, Part I: Pitched roofs covered with slates or tiles - Extract from TGD B Vol. 2
Table HB13 - Notional designations on roof coverings, Part II: Pitched roofs covered with pre-formed self-supporting sheets - Extract from TGD B Vol. 2
Table HB14 - Notional designations on roof coverings, Part III: Pitched or flat roofs covered with fully supporting material - Extract from TGD B Vol. 2
Table HB15 - Notional designations on roof coverings, Part IV(A): Flat roofs covered with bitumen felt - Extract from TGD B Vol. 2
Table HB16 - Notional designations on roof coverings, Part IV(B): Pitched roofs covered with bitumen felt - Extract from TGD B Vol. 2
Table HB17 - Typical performance ratings of some generic materials and products - Extract from TGD B Vol. 2
Table HB18 - Use of materials of limited combustibility - Extract from TGD B Vol. 2
Materials of limited combustibility:
European class
(a) Any material classified as Class A1 in accordance with I.S. EN 13501-1: 2002, Fire classification of construction products and building elements, Part 1 - Classification using data from reaction to fire tests.
(b) Any material or product classified as Class A2-s3, d2 or better in accordance with I.S. EN 13501-1: 2002, Fire classification of construction products and building elements, Part 1 - Classification using data from reaction to fire tests
Notes: The National classifications do not automatically equate with the equivalent classifications in the European column, therefore products cannot typically assume a European class unless they have been tested accordingly. When a classification includes “s3, d2”, this means that there is no limit set for smoke production and/or flaming droplets/particles.
National class
(c) Any non-combustible material listed in Table A7.
(d) Any material of density 300 kg/m3 or more which when tested to BS 476: Part 11, does not flame and the rise in temperature on the furnace thermocouple is not more than 20 degrees celsius.
(e) Any material with a non-combustible core at least 8 mm thick having combustible facings (on one or both sides) not more than 0.5 mm thick (when a flame spread rating is specified, these materials must also meet the appropriate test requirements).
(f) Any material of density less than 300 kg/m3, which when tested to BS 476: Part 11 does not flame for more than 10 seconds and the rise in temperature on the centre (specimen) thermocouple is not more than 35 degrees celsius and on the furnace thermocouple is not more than 25 degrees celsius.
Table HB19 - Use of non-combustible materials - Extract from TGD B Vol. 2
Non-combustible materials:
European class
(a) Any material classified as Class A1 in accordance with I.S. EN 13501-1: 2002, Fire classification of construction products and building elements, Part 1 - Classification using data from reaction to fire tests.
(b) Products made from one or more of the materials considered as Class A1 without the need for testing, as defined in Commission Decision 2003/424/EC of 6 June 2003 amending Commission Decision 96/603/EC of 4 October 1996 establishing the list of products belonging to Class A1 (No contribution to fire) provided for in the Decision 94/61 1/EC implementing Article 20 of the Council Directive 89/106/EEC on construction products. None of the materials shall contain more than 1% by weight or volume (whichever is the lower) of homogeneously distributed organic material.
Note: The National classifications do not automatically equate with the equivalent classifications in the European column, therefore products cannot typically assume a European class unless they have been tested accordingly.
National class
(a) Any material which when tested to BS 476: Part 11: 1982 does not flame and there is no rise in temperature on either the centre (specimen) or furnace thermocouples.
(b) Totally inorganic materials such as concrete, fired clay, ceramics, metals, plaster and masonry containing not more than 1 per cent by weight or volume of organic material (use in buildings of combustible metals such as magnesium/aluminium alloys should be assessed in each individual case).
(c) Concrete bricks or blocks meeting) I.S. EN 771-3: 2011
(d) Products classified as non-combustible under BS 476: Part 4: 1970.
ANNEX
Materials to be considered as reaction to fire classes Al and A1 FL as provided for in Decision 2000/147/EC without the need for testing
General notes
Products should be made only of one or more of the following materials if they are to be considered as Class Al and Class A 1FL without testing. Products made by gluing one or more of the following materials together will be considered Class Al and Class A1FL without testing provided that the glue does not exceed 0.1% by weight or volume (whichever is the more onerous).
Panel products (e.g. of insulating material) with one or more organic layers, or products containing organic material which is not homogeneously distributed (with the exception of glue) are excluded from the list.
Products made by coating one of the following materials with an inorganic layer (e.g. coated metal products) may also be considered as Class Al and Class A1FL without testing.
None of the materials in the table is allowed to contain more than 1.0% by weight or volume (whichever is the more onerous) of homogeneously distributed organic material.
Table HB20 - Materials to be considered as reaction to fire classes Al and A1 FL - Extract from TGD B Vol. 2
Table HB21 - Materials to be considered as reaction to fire classes Al and A1 FL (cont'd) - Extract from TGD B Vol. 2
