Items where Subject is "Appendix B: Performance of materials, products and structures"
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- Appendix B: Performance of materials, products and structures (34)
BS 476-11
BS 476-7
NOTE:
The national classifications do not automatically equate with the transposed classifications in the ‘BS EN 13501-1 classification’ column, therefore products cannot typically assume a European class unless they have been tested accordingly.
NOTE:
A classification of s3, d2 indicates that no limit is set for production of smoke and/or flaming droplets/particles. If a performance for production of smoke and/or flaming droplets/ particles is specified, then only the European classes can be used. For example, a national class may not be used as an alternative to a classification which includes s1, d0.
BS EN 13501-5
BS 476-3
NOTE:
The national classifications do not automatically equate with the transposed classifications
in the European column, therefore products cannot typically assume a European class unless they
have been tested accordingly.
see Table B4
See Table C1
See Appendix C
NOTES:
1. BS EN 13501-2 Classification using data from fire resistance tests, excluding ventilation services.BS EN 13501-3
Classification using data from fire resistance tests on products and elements used in building service installations: fire resisting ducts and fire dampers. BS EN 13501-4 Classification using data from fire resistance tests on components of smoke control systems.
In the European classification:
‘R’ is the resistance to fire in terms of loadbearing capacity.
‘E’ is the resistance to fire in terms of integrity.
‘I’ is the resistance to fire in terms of insulation.
The national classifications do not automatically equate with the alternative classifications in the European column, therefore products cannot typically assume a European class unless they have been tested accordingly.
2. BS 476-20 for general principles,BS 476-21 for loadbearing elements,BS 476-22 for non-loadbearing elements,BS 476-23 for fire-protecting suspended ceilings and BS 476-24 for ventilation ducts.
3. Applies to loadbearing elements only (see paragraph B19).
4. Guidance on increasing the fire resistance of existing timber floors is given in BRE Digest 208.
5. Only if a suspended ceiling meets the appropriate provisions should it be relied on to add to the fire resistance of the floor.
6. Such walls may contain areas that do not need to be fire resisting (unprotected areas). See Section 11.
7. Unless needed as part of a wall in item 5a or 5b.
8. Except for any limitations on uninsulated glazed elements given in Table B5.
NOTES:
For single storey buildings, the periods under the heading ‘Up to 5’ apply. If single storey buildings have basements, for the basement storeys the period appropriate to their depth applies.
* For the floor over a basement or, if there is more than one basement, the floor over the topmost basement, the higher of the period for the basement storey and the period for the ground or upper storey applies.
† For compartment walls that separate buildings, the period is increased to a minimum of 60 minutes.
+ For any floor that does not contribute to the support of the building within a flat of more than one storey, the period is reduced to 30 minutes.
§ For flat conversions, refer to paragraphs 6.5 to 6.7 regarding the acceptability of 30 minutes.
‡ For elements that do not form part of the structural frame, the period is reduced to 90 minutes.
# For elements that protect the means of escape, the period is increased to 30 minutes.
1. Refer to note 1, Table B3 for the specific provisions of test.
2. Blocks of flats with a floor more than 30m above ground level should be fitted with a sprinkler system in accordance with Appendix E.
NOTE:
Sprinklers only need to be provided within the individual flats, they are not required in the common areas such as stairs, corridors or landings when these areas are fire sterile.
3.‘With sprinkler system’ means that the building is fitted throughout with an automatic sprinkler system in accordance with Appendix E.
4. Very large (over 18m in height or with a 10m deep basement) or unusual dwellinghouses are outside the scope of the guidance provided with regard to dwellinghouses.
5. A minimum of 30 minutes in the case of three storey dwellinghouses, increased to 60 minutes minimum for compartment walls separating buildings.
6. Buildings within the ‘office’, ‘shop and commercial’, ‘assembly and recreation’, ‘industrial’ and ‘storage and other non-residential’ (except car parks for light vehicles) purpose groups (purpose groups 3 to 7(a)) require sprinklers where there is a top storey above 30m.
The sprinkler system should be provided in accordance with Appendix E.
7. The car park should comply with the relevant provisions in the guidance on requirement B3, Section 11 of
Approved Document B Volume 2.
8. For the purposes of meeting the Building Regulations, the following types of steel elements are deemed to have satisfied the minimum period of fire resistance of 15 minutes when tested to the European test method.
i. Beams supporting concrete floors, maximum Hp/A=230m-1 operating under full design load.
ii. Free-standing columns, maximum Hp/A=180m-1 operating under full design load.
iii. Wind bracing and struts, maximum Hp/A=210m-1 operating under full design load.
Guidance is also available in BS EN 1993-1-2.
Flats
1. Within the enclosures of a protected entrance hall or protected landing, or within fire resisting separation shown in Section 3, Diagram 3.4.
2. Within either:
a. the enclosures of a protected stairway
b. fire resisting separation shown in Diagram 2.2.
3. Within fire resisting separation either:
a. shown in Diagram 2.4
b. described in paragraph 2.16b.
4. Existing window between an attached/integral garage and the dwellinghouse.
5. Adjacent to an external escape stair (see paragraph 2.17 and Diagram 2.7) or roof escape route (see paragraph 2.13).
6. Between residential/sleeping accommodation and a common escape route (corridor, lobby or stair).
7. Between a protected stairway(1)and either:
a. the accommodation
b. a corridor that is not a protected corridor other than in item 6 above.
8. Between either:
a. a protected stairway(1)and a protected lobby or protected corridor
b. accommodation and a protected lobby other than in item 6 above.
9. Between the accommodation and a protected corridor that forms a dead end,other than in item 6 above.
10.Between accommodation and any other corridor, or sub-dividing corridors,other than in item 6 above.
11. Beside an external escape route.
Table B5
see Table B3
Table B5
12. Beside an external escape stair (see paragraph 3.68 and Diagram 3.11) or roof escape route (see paragraph 3.30).
NOTES:
Items 1 and 8 apply also to single storey buildings.
Fire resisting glass should be marked with the name of the manufacturer and the name of the product.
Further guidance can be found in A Guide to Best Practice in the Specification and Use of Fire-resistant Glazed Systems published by the Glass and Glazing Federation.
1. If the protected stairway is also a protected shaft or a firefighting stair (see Section 15), there may be further
restrictions on the use of glazed elements.
2. Measured vertically from the landing floor level or the stair pitch line.
3. The 100mm limit is intended to reduce the risk of fire spreading from a floor covering.
To restrict the use of materials which ignite easily, which have a high rate of heat release and/ or which reduce the time to flash over, maximum acceptable 'fire propagation' indices are specified, where the national test methods are being followed.
These are determined by reference to the method specified in BS 476-6:1981 or 1989 Method of test for fire propagation of products. Index of performance (I) relates to the overall test performance, whereas sub-index (i1) is derived from the first 3 minutes of test.
The highest national product performance classification for lining materials is Class 0. This is achieved if a material or the surface of a composite product 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.
Note: Class O is not a classification identified in any British Standard test.
Non-combustible materials are defined a. (National classes) when tested to BS 476: b. (European classes) when classified as class Table A6 identifies non-combustible products
in Table A6 either as listed products, or in terms
of performance:
Part 4:1970 Non-combustibility test for
materials or Part 11 :1982; or
A 1 in accordance with BS EN 13501-1 :2002
Fire classification of construction products
and building elements. Classification using
data from reaction to fire tests when tested
to BS EN ISO 1182:2002 Reaction to fire tests
for building products - Non-combustibility
test and BS EN ISO 1716:2002 Reaction to
fire tests for building products. Determination
of the gross calorific value.
and materials, and lists circumstances where
their use is necessary.
Materials of limited combustibility are defined in TableA7:
a. (National classes) by reference to the method specified in BS 476: Part 11 :1982; or
b. (European classes) in terms of performance when classified as class A2-s3, d2 in accordance with BS EN 13501-1 :2002, Fire classification of construction products and building elements, Part 1 Classification using data from reaction to fire tests when tested to BS EN ISO 1182:2002, Reaction to fire tests for building products -Non-combustibility test or BS EN ISO 1716:2002 Reaction to fire tests for building products -Determination of the gross calorific value and BS EN 13823:2002, Reaction to fire tests for building products - Building products excluding floorings exposed to the thermal attack by a single burning item.
Table A7 also includes composite products (such as plasterboard) which are considered acceptable, and where these are exposed as linings they should also meet any appropriate flame spread rating.
Much of the guidance in this document is given in terms of performance classifications in relation
to British or European Standards. In such cases, it will be necessary to demonstrate that a system
or product can meet the relevant performance classification. This will be achieved if the system or
product complies with one of the following.
a. They should be in accordance with a specification or design that has been shown by a specific
test to be capable of meeting that performance classification.
b. They should have been designed by using relevant design standards in order to meet that
performance classification.
c. They should have been assessed by applying relevant test evidence, in lieu of carrying out a
specific test, as being capable of meeting that performance classification.
NOTE: Some products are subject to Classification Without Further Testing (CWFT). For the purposes
of this approved document, such products can be considered to have been shown to be
able of meeting a performance specification as per paragraph B1a.
This document uses the European classification system for reaction to fire set out in BS EN 13501-1;
however, there may be some products lawfully on the market using the classification system set
out in previous editions. Where this is the case, Table B1 can be used for the purposes of this
document.
NOTE: The national classifications do not automatically equate with the transposed classifications
in the ‘BS EN 13501-1 classification’ column, therefore products cannot typically assume a European
class unless they have been tested accordingly.
NOTE: A classification of s3, d2 indicates that no limit is set for production of smoke and/or
flaming droplets/particles. If a performance for production of smoke and/or flaming droplets/
particles is specified, then only the European classes can be used. For example, a national class may
not be used as an alternative to a classification which includes s1, d0.
Thermoplastic material is any synthetic polymeric material that has a softening point below 200°C if tested to BS EN ISO 306 Method A120. Products formed from these materials cannot always be classified in the normal way. In those circumstances the following approach can be followed.
Thermoplastic materials used for window glazing, rooflights and lighting diffusers within suspended ceilings do not need to meet the criteria within paragraph B19 onwards, if the guidance to requirements B2 and B4 is followed.
For the purposes of requirements B2 and B4, thermoplastic materials should be classified as TP(a)
rigid, TP(a) flexible or TP(b), as follows:
a. TP(a) rigid
i. rigid solid uPVC sheet
ii. solid (as distinct from double- or multi-skinned) polycarbonate sheet a minimum of 3mm
thick
iii. multi-skinned rigid sheet made from uPVC or polycarbonate that has a class 1 rating when
tested to BS 476-7
iv. any other rigid thermoplastic product, a specimen of which (at the thickness of the
product as put on the market), when tested to BS 2782-0 Method 508A, performs so that
both:
• the test flame extinguishes before the first mark
• the duration of flaming or afterglow does not exceed 5 seconds following removal of
the burner.
b. TP(a) flexible
Flexible products a maximum of 1mm thick that comply with the Type C requirements
of BS 5867-2 when tested to BS 5438 Test 2 with the flame applied to the surface of the
specimens for 5, 15, 20 and 30 seconds respectively, but excluding the cleansing procedure; and
c. TP(b)
i. rigid solid polycarbonate sheet products a maximum of 3mm thick, or multi-skinned
polycarbonate sheet products that do not qualify as TP(a) by test
ii. other products which, when a specimen of the material between 1.5 and 3mm thick is
tested in accordance with BS 2782-0 Method 508A, have a maximum rate of burning of
50mm/minute.
NOTE: If it is not possible to cut or machine a 3mm thick specimen from the product, then a 3mm
A thermoplastic material alone when used as a lining to a wall or ceiling cannot be assumed to protect a substrate. The surface rating of both thermoplastic material and substrate must therefore 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 needs to meet the required classification.
Performance of the resistance of roofs to external fire exposure is measured in terms of penetration through the roof construction and the spread of flame over its surface.
Roof constructions are classified within the European system as BROOF(t4), CROOF(t4), DROOF(t4), EROOF(t4) or FROOF(t4) in accordance with BS EN 13501-5. BROOF(t4) indicates the highest performance and FROOF(t4) the lowest.
BS EN 13501-5 refers to four separate roof tests. The suffix (t4) used in paragraph B16 indicates that Test 4 is to be used for the purposes of this approved document.
This document uses the European classification system for roof covering set out in BS EN 13501-5; however, there may be some products lawfully on the market using the classification system set out in previous editions. Where this is the case, Table B2 can be used for the purposes of this document.
Common to all of the provisions of Part B of the Building Regulations is the property of fire
resistance. Fire resistance is a measure of one or more of the following.
a. Resistance to collapse (loadbearing capacity), which applies to loadbearing elements only,
denoted R in the European classification of the resistance to fire performance.
b. Resistance to fire penetration (integrity), denoted E in the European classification of the
resistance to fire performance.
c. Resistance to the transfer of excessive heat (insulation), denoted I in the European
classification of the resistance to fire performance.
Any test evidence used to demonstrate the fire performance classification of a product or system should be carefully checked to ensure that it is applicable to the intended use. Small differences in detail, such as fixing method, joints, dimensions, the introduction of insulation materials and air gaps (ventilated or not), can significantly affect the performance.
The standards of fire resistance necessary for a particular building 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 similar for buildings with the same use.
Because the use of buildings may change, a precise estimate of fire severity based on the fire load due to a particular use may be misleading. Therefore if a fire engineering approach of this kind is adopted, the likelihood that the fire load may change in the future needs to be considered.
Performance in terms of the fire resistance to be achieved by elements of structure, doors and
other forms of construction is classified in accordance with one of the following.
a. BS EN 13501-2.
b. BS EN 13501-3.
c. BS EN 13501-4.
Fire resistance is measured in minutes. This relates to time elapsed in a standard test and should not be confused with real time.
The fire resistance necessary for different circumstances is set out in the following tables.
a. Table B3 gives the specific requirements for each element of structure.
b. Table B4 sets out the minimum periods of fire resistance for elements of structure.
c. Table B5 sets out limitations on the use of uninsulated fire resisting glazed elements.
The following guidance should be used when applying the fire resistance standards in Table B4.
a. If 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). In some circumstances, it
may be reasonable to vary this principle, for example:
i. if the supporting structure is in the open air and is not likely to be affected by the fire in
the building
ii. if the supporting structure is in a different compartment, with a fire-separating element
(that has the higher standard of fire resistance) between the supporting and the separated
structure
iii. if a plant room on the roof needs greater fire resistance than the elements of structure
that support it.
b. If an element of structure forms part of more than one building or compartment, that element
should be constructed to the standard of the higher of the relevant provisions.
c. If, due to the slope of the ground, one side of a basement is open at ground level (allowing
smoke to vent and providing access for firefighting) for elements of structure in that storey
it may be appropriate to adopt the standard of fire resistance that applies to above-ground
structures.
d. Although most elements of structure in a single storey building may not need fire resistance,
fire resistance is needed if one of the following applies to the element.
i. It is part of, or supports, an external wall, and there is provision in the guidance on
requirement B4 to limit the extent of openings and other unprotected areas in the wall.
ii. It is part of, or supports, a compartment wall, including a wall that is common to two or
more buildings.
iii. It supports a gallery.
For the purposes of this paragraph, the ground storey of a building that has one or more basement storeys and no upper storeys may be considered as a single storey building. The fire resistance of the basement storeys should be that specified for basements.
Assessments should not be regarded as a way to avoid a test where one is necessary. Assessments should only be carried out where sufficient relevant test evidence is available. Relevant test evidence is unlikely to be provided by test standards which have different classification criteria.
Tests and assessments should be carried out by organisations with the necessary expertise. For NOTE: Standard fire tests do not directly measure fire hazard. They measure or assess the response
example, organisations listed as ‘notified bodies’ in accordance with the European Construction Products Regulation or laboratories accredited by the United Kingdom Accreditation Service (UKAS)
for the relevant test standard can be assumed to have the necessary expertise.
of a material or system to exposure to one or more aspects of fire conditions. Performance in fire
tests is only one of a number of factors that should be taken into account.
Reaction to fire relates to the degree to which a product will contribute, by its own decomposition, to a fire under specified conditions. Products, other than 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 BS EN 13501-1. Class F is assigned when a product fails to attain class E. Untested products cannot be classified in accordance with BS EN 13501-1. Materials covered by the Classification Without Further Testing (CWFT) process can be found by accessing the European Commission's website https://eur-lex.europa.eu/.
The classes of reaction to fire performance of A2, B, C, D and E are accompanied by additional
classifications related to the production of smoke (s1, s2, s3), with s1 indicating the lowest
production, and/or flaming droplets/particles (d0, d1, d2), with d0 indicating the lowest
production.
NOTE: When a classification includes s3, d2 this means that there is no limit set for smoke
production and/or flaming droplets/particles.
To reduce the testing burden on manufacturers, BS EN 13238 defines a number of standard substrates that produce test results representative of different end use applications. The classification for reaction to fire achieved during testing is only valid when the product is used within this field of application, i.e. when the product is fixed to a substrate of that class in its end use. The standard substrate selected for testing should take account of the intended end use applications (field of application) of the product and represent end use substrates that have a density of a minimum of 75 of the standard substrate's nominal density.
Standard substrates include gypsum plasterboard (BS EN 520) with a density of 700+/-100kg/m3,
calcium silicate board (BS EN 14306) 870+/-50kg/m3 and fibre-cement board 1800+/-200kg/m3.
NOTE: Standard calcium silicate board is not representative of gypsum plasterboard end use (due
to the paper layer), but would be representative of most gypsum plasters (with densities of more
than 650kg/m3).
NOTE: Classifications based on tests using a plasterboard substrate