Annex 2.A Resistance to fire
This annex provides guidance on how to establish the resistance to fire of a building element or component. Whilst it could be argued that occupants of a building only need minutes to reach relative safety such as a protected zone, it should be remembered that the fire tests used to establish fire resistance in terms of time, do not replicate a real fire. In order to ensure the safe evacuation of the building occupants and to ensure that fire-fighters are not placed at undue risk, it is necessary to apply certain factors of safety to the fire resistance for structural and non-structural fire protection.
Fire resistance durations are established from the guidance to Standards 2.1 to 2.15. Reference throughout this document to a short, medium or long fire resistance duration, will be satisfied by following the guidance in the table to this annex titled ‘Fire resistance duration for common building elements or components’. The designer is free to choose materials or products which satisfy either the British Standard Tests or the Harmonised European Tests.
Any test evidence or assessment used to substantiate the fire resistance rating of a wall, floor, ceiling, door or shutter should be carefully checked to ensure that is demonstrates compliance with appropriate fire tests and performance criteria contained in this handbook and is applicable to the complete installed assembly. For example, in the case of floors or ceilings small differences in details such as openings for lighting or ventilation can significantly affect the rating. Similarly, fire doors may also have small differences in detail such as glazing apertures, intumescent strips, door frames and ironmongery etc which may significantly affect the rating.
Transitional period - British and European fire tests will co-exist in use until the British Standard classifications are withdrawn.
The recommended fire resistance duration can be attained where the construction follows the guidance in the columns 3, 4 and 5 of the table below. The tests and specifications are:
Clause 10 of BS 476: Part 20: 1987, when read in conjunction with - for load-bearing elements, BS 476: Part 21: 1987 for non-load-bearing elements, BS 476: Part 22: 1987, for components, BS 476: Part 23: 1987, for ventilation ducts, BS 476: Part 24: 1987
for fire door assemblies with non-metallic leaves, BS 8214: 1990: Sections 1 and 2
for structural steelwork, BS 5950: Part 8: 2003 or ‘Fire Safe Design: A new approach to multi-storey steel framed buildings’ published by The Steel Construction Institute (within the limitations described in the SCI Publication P288)
for the structural use of timber, BS 5268: Part 4: Sections 4.1 and 4.2: 1990
for the structural use of concrete, BS 8110: Part 2: 1985, Section 4.3 ‘Tabulated data (method 1)’
an appropriate specification given in the Building Research Establishment Report BR 128 "Guidelines for the Construction of Fire Resisting Structural Elements" (BRE 1988).
The recommended fire resistance duration can be attained where the construction follows the guidance in Column 6 of the table above as specified in Commission Decision 2000/367/EC of 3/5/2000 implementing Council Directive 89/106/EEC as regards the classification of the resistance to fire of construction products, construction works and parts thereof.
BS EN 13501-2: 2007, Fire classification of construction products and building elements, Part 2- Classification using data from fire resistance tests (excluding products for use in ventilation systems).
BS EN 13501-3: 2005, Fire classification of construction products and building elements. Classification using data from fire resistance tests on products and elements used in building service installations: fire resisting ducts and fire dampers (other than smoke control systems).
BS EN 13501-4: 2007, Fire classification of construction products and building elements, Part 4 - Classification using data from fire resistance tests on smoke control systems.
The tests and specifications are:
BS EN 1363-1: 1999, Fire resistance tests, Part 1- General requirements.
BS EN 1363-2: 1999, Fire resistance tests, Part 2- Alternative and additional procedures.
BS EN 1363-3: 2000, Fire resistance tests, Part 3- Verification of furnace performance.
BS EN 1364-1: 1999, Fire resistance tests for non load-bearing elements - Part 1: Walls.
BS EN 1364-2: 1999, Fire resistance tests for non load-bearing elements - Part 2: Ceilings.
BS EN 1365-1: 1999, Fire resistance tests for load-bearing elements - Part 1: Walls.
BS EN 1365-2: 2000, Fire resistance tests for load-bearing elements - Part 2: Floors and roofs.
BS EN 1365-3: 2000, Fire resistance tests for load-bearing elements - Part 3: Beams.
BS EN 1365-4: 1999, Fire resistance tests for load-bearing elements - Part 4: Columns.
BS EN 1366-1: 1999, Fire resistance tests for service installations - Part 1: Ducts.
BS EN 1366-2: 1999, Fire resistance tests for service installations - Part 2: Fire dampers.
BS EN 1634-1: 2008, Fire resistance and smoke control tests for door and shutter assemblies, openable windows and elements of building hardware, Part 1 – Fire resistance tests for doors, shutters and openable windows.
BS EN 1634-2: 2008, Fire resistance and smoke control tests for door and shutter assemblies, openable windows and elements of building hardware, Part 2 – Fire resistance characterisation test for elements of building hardware.
BS EN 1634-3: 2004, Fire resistance and smoke control tests for door and shutter assemblies, openable windows and elements of building hardware, Part 3 – Smoke control test for door and shutter assemblies.
BS EN 81-58: 2003, Safety rules for the construction and installation of lifts – Examination and tests - Part 58: landing doors fire resistance test may be used in accordance with Council Directive 95/16/EC of 29/6/1995 implementing the Lifts Regulations 1997 (SI 1997/831).
Any reference to European Standards for Structure (Structural Eurocodes) must be taken to include the relevant UK National Annex:
BS EN 1991-1-2:2002, Eurocode 1: Actions on structures – Part 1-2: General actions – Actions on structures exposed to fire.
BS EN 1992-1-2:2004, Eurocode 2: Design of concrete structures – Part 1-2: General rules – Structural fire design.
BS EN 1993-1-2:2005, Eurocode 3: Design of steel structures – Part 1-2: General rules – Structural fire design.
BS EN 1994-1-2:2005, Eurocode 4: Design of composite steel and concrete structures – Part 1-2: General rules – Structural fire design.
BS EN 1995-1-2:2004: Eurocode 5: Design of timber structures – Part 1-2: General rules – Structural fire design.
BS EN 1996-1-2:2005: Eurocode 6: Design of masonry structures – Part 1-2: General rules – Structural fire design.
BS EN 1999-1-2:2007: Eurocode 9: Design of aluminium structures – Part 1-2: General rules – Structural fire design.
Table 2.7. Fire Resistance
|Construction||Fire resistance duration||British Standards Load bearing capacity (mins)||British Standards Integrity (mins)||British Standards Insulation (mins)||European Standards||Test exposure|
|1. Structural frame, column or beam||Short||30||None||None||R 30||Faces exposed on the inside|
|2. Separating floor or any other floor, used as a protected route of escape (2.0.6)||Short||30||30||30||REI 30||From the underside|
|3. Other than a floor in 2 or an intermediate floor within a flat or maisonette||Short||30||None||None||R 30||From the underside|
|4. Separating wall or an internal wall or screen used as a protected route of escape (2.0.6) [1, 2]||Short||30 ||30||30||REI 30 ||Each side separately|
|Medium||60 ||60||60||REI 60 |
|Long||120 ||120||120||REI 120 |
|5. Load-bearing wall, other than a wall in 4||Short||30||None||None||R 30||Each side separately|
|6. Fire door in a wall in 4||Short||None||30 ||None||E 30 Sa ||Each side separately, when fitted in frame |
|Medium||None||60 ||None||E 60 Sa |
|Long||None||120 [5,6]||None||E 120 Sa [5, 6]|
|7. External wall more than 1m from a boundary [1, 2]||Short||30 ||30||None||RE 30 ||From the inside only|
|Medium||60 ||60||30||RE 60 and I 30 |
|8. External wall not more than 1m from a boundary [1, 2]||Short||30 ||30||30||REI 30 ||From the inside only|
|Medium||60 ||60||60||REI 60 |
|9. Horizontal cavity barrier ||Short||None||30||None||E 30||From the underside|
|10. Vertical cavity barrier ||Short||None||30||None||E 30||Each side separately|
|11. Ceiling in place of a cavity barrier (see 2.4.2b, 2.4.2c, 2.4.3)||Short||None||30||30||EI 30||From the underside|
An external wall includes any external wall used to protect routes of escape (see clause 2.0.6) but excludes an unprotected area calculated in accordance with clauses 2.6.1 to 2.6.4.
Any door in an external wall, which is not included in the calculation of unprotected area, should have the same fire resistance and the same test exposure as the external wall.
In a timber stud wall or partition the following will also be deemed to have a short fire resistance duration:
polythene sleeved mineral wool, or mineral wool slab, in either case under compression when installed, or
calcium silicate, cement based or gypsum based board at least 12mm thick, or
steel at least 0.5mm thick, or
timber at least 38mm thick.
If the construction is non load-bearing, none in the case of column 3, and no load-bearing (R) in the case of column 6.
Medium fire resistance duration is sufficient for a fire door in the enclosing structure of a fire-fighting shaft.
Unless the fire door is in an external wall or a lift door or pressurisation techniques following the guidance in BS EN 12101: Part 6: 2005 are used, the fire door should also either:
in the case of column 4, have smoke seals fitted unless the leakage rate does not exceed 3 m³/m/hour, head and jambs only, when tested at 25 Pa according to BS476: Part 31: 1983 (Section 31.1) with AMD 8366/ November 1994, or
in the case of column 6, attain the additional classification of Sa when tested to BS EN1634-3: 2001.