Fire Performance - Gyproc Ireland

1 fire PerformanceLEGISLATION AND GUIDANCEI rish Building Regulations fire SafetyTechnical Guidance Document B published by theDepartment of the Environment, Heritage and LocalGovernment is part of a series of documents forming theBuilding Regulations. The document specifies the minimum periods of fireresistance to be achieved by building elements dependingupon their classification, which vary according to thebuildings size and use. Generally, the greater the designatedrisk within a building, the greater the defined period of fireresistance required to protect the elements within thebuilding. The document also sets out criteria relating to thematerials used to form the internal surfaces of the buildingto control and reduce the risk of fire Protection for Structural Steel in buildings,ASFP Yellow BookThis publication which is prepared by the Association forSpecialist fire Protection (ASFP), sets out the theory andprovides guidance on the methods of fire protectingstructural steel to comply with the Building OF fire PERFORMANCEFire growthWhilst they may not be the materials first ignited in a fire ,the materials used in the construction of separating wallsand ceilings can significantly affect the rate of fire spreadand its growth within a building.

2 The materials used forsuch building elements are of particular importance wherelinings constitute the boundaries of circulation spaces andmeans of prevent the rapid spread of fire , which could trapoccupants within a building, and also reduce the chances ofa fire becoming large, the spread of fire can be restrictedby sub-dividing a building into can relate to any element of a building,typically walls and floors, that can offer fire resistancebetween two defined areas for a designated periodof appropriate level of sub-division depends upon, The use and fire loading of the building The height and scale of the building in relation toappropriate evacuation provisionStructural fire precautionsPremature failure of a building can be prevented byensuring loadbearing elements of the structure have aminimum period of fire resistance to failure of theirloadbearing capacity. fire limit stateFor the purposes of structural design, fire is considered tobe an accidental limit state in which the structure must notcollapse.

3 Within this manual where load bearing systemsare referenced, 100% loadbearing capacity may beassumed unless their loadbearing capacity is quoted withrespect to a stated load members that are designed to be fully stressedunder normal conditions may be subject to reduced loadratios under fire state behaviour of timber in fireTimber has a low thermal expansion coefficient and a lowthermal conductivity. The combination of these propertiesenables the charring that occurs around the exterior of thetimber in a fire situation to provide an inherent level ofself protection, with the timber below the charred layermaintaining a level of structural strength. The amount ofundamaged timber can be assessed for structural stabilityusing standard design guides in conjunction with stressmodification behaviour of steel in fireSteel generally begins to start losing strength attemperatures above 300 C, eventually melting atapproximately 1500 C.

4 For the purposes of structuraldesign, the greatest loss of strength occurs between 400 Cand 600 determining the level of fire protection required toprevent steel from structural failure, a critical designtemperature of 550 C is typically used unless otherwisestated. The level of protection required is assessed basedon the relevant section factor A/V (Hp/A) of the steel. It isthe responsibility of a qualified design engineer to specifythe appropriate limiting steel loss of strength from cold-formed steel at elevatedtemperatures exceeds that of hot-rolled steel and specialistadvice is recommended in determining the strengthreduction factor at the limiting PerformanceCharred timber joists after a test7T 00353 1 629 8400 F 00353 1 623 7054 E PerformanceFIRE TEST STANDARDSThe Irish Building Regulations and its supporting technicalguidance documents require certain elements of structureand other building elements to provide minimum periodsof fire resistance, which are typically expressedin minutes, and generally based on the occupancy and sizeof the building.

5 BS fire resistance standardsUnder the British test standards (BS) the fire resistance ofloadbearing and non-loadbearing elements are assessedagainst the procedures set out in the relevant sections ofBS 476. The fire resistance of an individual buildingelement may relate to its loadbearing capacity, fireintegrity and/or fire insulation Performance capacityA loadbearing element must support its test load or astated ratio of the test load. For horizontal elements , roof, and beams, allowable levels of verticaldeflection may be separating element must resist collapse, the occurance ofholes, gaps or fissures through which flames and hot gasescould pass, and sustained flaming on the unexposed separating element must restrict the temperature rise ofthe unexposed face to below specified fire resistance standardsWhen compared against British Standards, the newharmonised standards have lead to an increase in severityof the test furnaces, particularly in the first 30 minutes of atest.

6 In addition, the new EN fire resistance classificationsalso impose strict rules governing the use of tests to coverspecific end use scenarios. Therefore, different specifications may be required to meetEN standards compared to those required to meet BSstandards, often with additional limitations imposed on apartitions maximum recommended , under the current Irish Building Regulations, thetwo testing systems are operating concurrently and fireresistances may still be based on the relevant parts ofBS 476. Designers therefore have the choice on thestandards they adopt for their TO fire TEST STANDARDSF lame spread over wall and ceiling surfaces is controlled byspecifying materials that are either classified as non-combustible or of limited combustibility. Non-combustibilityWhere maximum fire safety is required, certain buildingelements need to be constructed of non-combustiblematerials.

7 A building material is designated as non-combustible if it satisfies the Performance criteria whentested in accordance with BS 476: Part 4:1970 (1984) Non-combustibility test for materialsand BS 476: Part 11:1982(1988) Method for assessing the heat emission frombuilding F Multiboard and Glasroc F FireCase are classified asnon-combustible in accordance with BS 476: Part resistance test - integrity testing on 3m high partitionLoaded timber stud wall failing in respect of loadbearing capacitySurface spread of flameWhen tested to either BS 476: Part 7: 1997 Surface spreadof flame test for materialsor BS 476: Part 7: 1987 Methodfor the classification of the surface spread of flame ofproducts, combustible materials(or certain materials oflimited combustibility) are classified as Class 1, 2, 3, or 4with Class 1 providing the greatest resistance to surfacespread of exposed plasterboard surfaces of Gyproc plasterboardsare all designated Class PropagationIn addition to a materials contribution to the surfacespread of flame in a fire , consideration must also be givento the amount and rate of heat evolved by these materialswhen used in areas requiring maximum safety.

8 Within the Irish Building Regulations, circulation areas androutes of escape are typically required to be constructedusing materials classified as either Class B-s3,d2 (EuropeanClass) or Class 0 (National Class) Please note, although Class 0 is the highest performanceclassification for lining materials within the BuildingRegulations, Technical Guidance Document B ( fire Safety),it is not a classification identified in any British StandardA Class 0 material is defined within the Irish BuildingRegulations as either:(a) composed throughout of materials of limitedcombustibility (including non-combustible materials) or(b) a Class 1 material that has a fire propagation index (I)of not more than 12 and a sub-index (i1) of not morethan surfaces of Gyproc plasterboards and the exposedplasterboard surface of Gyproc thermal laminates aredesignated Class 0. European test standardsThe Construction Products Directive (CPD) within Europeanlegislation is designed to enable free trade across Europe inconstruction products.

9 EN test standards can be split intotwo main parameters; reaction to fire and fire Reaction to FireEN reaction to fire classifications also run concurrently withthe national standards which are classified under BS EN Reaction to fire classifications, in accordance withBS IS EN 520 are the manufacturing standards by which allGyproc board products are classified. The Euroclass test methodology which is based around theSingle Burning Item (SBI) test method (BS EN 13823: 2002),along with the non-combustibility test (BS EN ISO 1182:2002), heat of combustion test (BS EN ISO 1716: 2002) anddirect flame impingement test (BS EN ISO 11925-2: 2002),predicts the Performance of building materials in a real firemore accurately than the old BS 476 EN standards, a materials classification is defined byBS EN 13501-7: 2002 to give a Euroclass rating. The ratingsrange from A1 (non-combustible) through to F.

10 The tablebelow compares the EN classifications with the previouslyused national is subject to classification without furthertest . This assessment means that any type of plasterboardcan be classified as A2 so long as the grammage of thepaper liner does not exceed 220g/m2. All Gypsum IndustriesGyproc plasterboard products manufactured in accordancewith BS IS EN 520 are designated Euroclass PerformanceSurface spread of flame testNational EuroclassSafety levelclassificationcategoryNon-combustib leA1 Material of limited combustibilityA2 Class 0 BClass 1 CClass 3DN/AEN/AFdecreasing fire safetyComparison of Technical Guidance Document Bcategories and relevant EN test requirements9T 00353 1 629 8400 F 00353 1 623 7054 E Performanc