Fire Safety and Performance of Wood in Multi-Residential and Commercial Buildings. Boris Iskra Forest & Wood Products Australia

Transcription

1 Fire Safety and Performance of Wood in Multi-Residential and Commercial Buildings Boris Iskra Forest & Wood Products Australia

2 This Presentation 1. Fire Hazard Properties Building Code of Australia Volume 1: Specification C1.10 (Floor, wall and ceiling linings) 2. MRTFC and Commercial Buildings Overview Timber properties during fire Connection performance during fire Calculation methods to predict timber capacity

3 Fire Resistance in the BCA BCA Reference Section C Fire Resistance Part C1 Fire Resistance and Stability Clause C1.10 Fire Hazard Properties Specification C1.10 Clause 3, 4 & 6 Fire Hazard Properties - Floors, Walls and Ceilings Specification C1.10 Clause 7 Fire Hazard Properties Other Materials Description Specifies community expectations regarding fire resistance of Class 2-9 buildings. Deemed-to-Satisfy (DTS) Provisions regarding fire resistance and stability DTS Provisions for Fire Hazard Properties of materials and assemblies used in the building construction industry A method of complying with the BCA requirements for floor coverings, walls and ceilings A method of complying with the BCA requirements for materials other than those used for floors, walls and ceilings

4 Topics 1. Fire Hazard Properties Clause C1.10: Specification C1.10 Clause 7 Clause C1.10: Specification C1.10 Clauses 3, 4 & 6 2. MRTFC and Commercial Buildings Overview Timber properties during fire Connection performance during fire Calculation methods to predict timber capacity

5 Clause C1.10 Class of Building? Class 1 or 10 No Clause C1.10 requirements Class 2-9 Clause C1.10 Timber-framed window? Solid timber handrail or skirting? Timber- faced solid core door or fire door? Joinery, cupboard shelving etc? Paints, varnishes, etc or adhesives yes No requirements Covering - Floor, Wall & Ceiling no Other Specification C Clauses 3, 4 & 6 Specification C Clause 7

6 Specification C1.10 Clause 7 Specification C1.10 Clause 7 sarking Other Materials 1? All other materials, including timber Flammability Index 5 Spread-of-Flame Index 9 and Smoke-Developed Index There are additional requirements for fire isolated exits, public entertainment theaters, public halls, refer BCA 2 Only for materials with a Spread-of-Flame Index > 5

7 Specification C1.10 Clause 7 Fire Hazard Properties of Timber More species can be found on:

8 Topics 1. Fire Hazard Properties Clause C1.10: Specification C1.10 Clause 7 Clause C1.10: Specification C1.10 Clauses 3, 4 & 6 2. MRTFC and Commercial Buildings Overview Timber properties during fire Connection performance during fire Calculation methods to predict timber capacity

9 Clause C1.10 Class of Building? Class 1 or 10 No Clause C1.10 requirements Class 2-9 Clause C1.10 Timber-framed window? Solid timber handrail or skirting? Timber- faced solid core door or fire door? Joinery, cupboard shelving etc? Paints, varnishes, etc or adhesives yes No requirements Coverings - Floor, Wall & Ceiling no Other Specification C1.10 Clauses 3, 4 & 6 Specification C1.10 Clause 7

10 Specification C1.10 Specification C Clause 3 Floor linings and floor coverings Floor Clause 3 Wall / Ceiling Lift yes Critical Radiant Flux Sprinklered? no Critical Radiant Flux and Smoke Development Rate 750 percent minutes Additional requirement for any portion of the floor covering that is continued more than 150 mm up a wall - Group number 1 or 2

11 BCA Requirements for flooring materials in a building not protected by a sprinkler system complying with specification E1.5, maximum smoke development rate of 750 percent-minutes is permitted. Class of building Class 2, 3, 5, 6, 7, 8 or 9b, Excluding accommodation for the aged Class 3 Accommodation for the aged Class 9a Patient care areas. Areas other than patient care areas. Class 9c Resident use areas. Areas other than resident use areas Sprinkler Status Fire No Sprinklers Sprinklers Isolated Exit EFT Consulting

12 Specification C1.10 Clause 3: Floors - Fire Hazard Properties of Timber More species can be found on:

13 Specification C1.10 Specification C Clause 4 Wall and ceiling linings Floor Wall / Ceiling Clause 3 Clause 4 Lift Sprinklered? Sprinklered? yes no yes no Critical Radiant Flux Critical Radiant Flux and Smoke Development Rate 750 percent minutes Group Number Group Number and smoke growth rate index 100 or average specific extinction area < 250 m²/kg

14 NCC PERMITTED WALL AND CEILING LINING MATERIALS GROUPS Class of building Sprinkler Protection Fire Isolated Exits & Fire Control Rooms Public corridors Specific areas Other areas Walls Ceilings Walls Ceilings Walls Ceilings Walls Ceilings Class 2 Residential Apartments Class 3 Short term Accommodation Class 3 Accommodation for Aged, disabilities and children Class 5 Office Class 6 Retail Class 7 Carpark Class 8 Factory or laboratory Class 9a Health-care Class 9b Schools Class 9b Assemble buildings other than schools Class 9c Aged Care No 1 1 1, 2 1, 2 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 Yes 1 1 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 No 1 1 1, 2 1, 2 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 Yes 1 1 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 No , 2 1, 2 1, 2, 3 1, 2, 3 Yes 1 1 1, 2 1, 2 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 No 1 1 1, 2 1, 2 1, 2, 3 1, 2 1, 2, 3 1, 2, 3 Yes 1 1 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 No 1 1 1, 2 1, 2 1, 2, 3 1, 2 1, 2, 3 1, 2, 3 Yes 1 1 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 No 1 1 1, 2 1, 2 1, 2, 3 1, 2 1, 2, 3 1, 2, 3 Yes 1 1 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 No 1 1 1, 2 1, 2 1, 2, 3 1, 2 1, 2, 3 1, 2, 3 Yes 1 1 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 No , 2 1, 2 1, 2, 3 1, 2, 3 Yes 1 1 1, 2 1, 2 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 No 1 1 1, 2 1, 2 1, 2, 3 1, 2 1, 2, 3 1, 2, 3 Yes 1 1 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 No , 2 1, 2 1, 2, 3 1, 2, 3 Yes 1 1 1, 2 1, 2 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 Yes 1 1 1, 2 1, 2 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 Lift Cars N/A , 2 1, 2

15 Specification C1.10: Walls / Ceiling Fire Hazard Properties of Timber More species can be found on:

16 Clause Specification C1.10: Lift Cars Specification C1.10 Clause 6 Lift cars Floor Wall / Ceiling Lift Cars Clause 3 Clause 4 Clause 6 Sprinklered? Sprinklered? Floor, Wall/Ceiling? yes Critical Radiant Flux no Critical Radiant Flux and Smoke Development Rate 750 percent minutes yes Group Number no Group Number and smoke growth rate index 100 or average specific extinction area < 250 m²/kg floor Critical Radiant Flux 2.2 kw/m² wall/ceiling Group Number 1 or 2

17 Specification C1.10 Clause 6: Floors - Fire Hazard Properties of Timber More species can be found on:

18 Topics 1. Fire Hazard Properties Clause C1.10: Specification C1.10 Clause 7 Clause C1.10: Specification C1.10 Clauses 3, 4 & 6 2. MRTFC and Commercial Buildings Overview Timber properties during fire Connection performance during fire Calculation methods to predict timber capacity

19 MRTFC - Overview M R T F C Multi Residential Timber Frame Construction

20 Maximum storey height for timber DTS complying buildings Australia Number of Storeys Without Sprinklers Storey Max floor area (m 2 ) Single family Unlimited Unlimited Multi-residential 3 Unlimited Office 2 8,000 Retail 2 5,000 Industrial 2 18,000 Public (Assembly) 1 8,000

21 Maximum Storey Height by Building Classification Rise in storey Type of Construction Class 2 Class 3 Class 5 Class 6 Class 9a Class 9b Apartments Hotels Office Shops Healthcare Schools & public buildings 4 or more A A A A A A 3 A A B B A A 2 B B C C B B 1 C C C C C C

22 Maximum Storey Height by Building Classification Rise in storey Type of Construction Class 2 Class 3 Class 5 Class 6 Class 9a Class 9b Apartments Hotels Office Shops Healthcare Schools & public buildings 4 or more A A A A A A NCC A A B B A A 2 B B C C B B 1 C C C C C C

23 MRTFC and Performance Requirements MRTFC commonly deals with: Class 1 buildings (houses or dwellings attached side by side) Class 2 buildings (flats and units above one another as well as side by side) Class 3 buildings (residential parts of hotels, motels, accommodation for students, aged and disabled) Class 9c buildings (buildings for the aged) Performance criteria in these classes focuses on: Fire resistance Sound resistance This presentation focuses on Fire Resistance

24 SOU Concept In Class 2 and 3 residential buildings there is extensive use of Sole occupancy units (SOUs). This separates buildings into manageable units and provides protection to other property : A SOU is a part of a building that is occupied by one owner, lessee or other occupant SOUs must be designed to restrict fire and sound from affecting adjoining SOUs

25 Type of Construction The extent of fire resistant construction required by the BCA depends on the Type of Construction: Type A provides the highest level of passive protection e.g. structural elements must withstand burnout of the building contents Type B provides lower passive protection e.g. less of the structure must be able to withstand burnout of the contents Type C provides the lowest passive fire resistance e.g. only some elements have specified fire resistance intended to mainly restrict horizontal spread of fire to adjoining dwellings

26 Measuring Fire Resistance Levels The BCA requires protection to be provided at the boundaries between compartments or SOUs The walls, floors and ceilings bounding compartments are constructed to meet Fire Resistance Levels (FRLs) to prevent spread of fire FRLs are expressed in minutes as follows: FRL: 60 / 60 / 60 structure integrity insulation Columns have a FRL of 60/-/- or 120/-/- etc as they are not barriers Partition walls are the exact opposite: barriers but non-loadbearing so typically have a FRL of -/30/30 or -/60/60

27 General Framing Requirements MRTFC details focus on meeting the combined requirements of fire, sound and structural performance for designated wall, floor and ceiling elements in Class 1, 2 and 3 buildings A systems approach is used to meet needs which can be broken up into: Wall framing systems Floor/ceiling framing systems Each system uses a number of common concepts to maintain continuity at intersections between elements and at penetrations, including: Fire resistant joints Cavity barriers Fire stops

28 Double Stud Walls in More Detail The system features two stud walls with a separating cavity Load Bearing frames are typically made from 90x45 timber framing The frames can be prefabricated as required The system is easy to handle and erect on-site Insulation is used extensively between studs or in the cavity It must be noncombustible (BCA Requirement) Fire grade plasterboard is built up in layers to meet fire requirements Fibre cement sheet can be used in combination with plasterboard Other cladding or linings can be used over these components

29 Treatment of Roof and Eave Cavities Depending on the type of construction, fire rated walls may need to continue through the roof and eaves cavities. In these areas: walls must extend at least to the underside of the roof walls may be single skin (not double) because sound resistance isn t required in the roof or eaves areas

30 Floor/Ceiling Systems Floor/ceiling systems are required between sole occupancy units (SOUs) These systems consist of floor coverings, platform flooring, floor joists, sound insulation, resiliently mounted ceiling battens and ceiling linings

31 Summary of Floor/Ceiling System Components Timber joists dictate the load and spanning capacity of the floor Non-combustible sound insulation is placed within the joist depth Resiliently mounted ceiling battens are fixed transversely to the joists to isolate sound from the structure above Plasterboard is fixed to the sound resilient supports. A build up of layers is used to achieve sound and fire requirements (fire grade board required)

32 Continuity of Systems Care must be taken to ensure weak spots don t occur at the interfaces between systems (e.g. intersections and penetrations) Methods of doing this include: Fire resistant joints Cavity barriers Fire stops at gaps and penetrations (caulking)

33 Fire Resistant Floor Junctions Fire resistant joints are used at intersections between floor/ceiling elements e.g. where one element has a lower FRL than the other Some structural framing remains protected by the plasterboard and by the slow charring of the other framing at the junction.

34 Fire Resistant Floor Junctions Needed at intersections between wall/wall elements such as when one element has a lower FRL than the other The joint is made by adding extra pieces of timber to the joint between the elements The extra timber adds fire resistance because when it burns it forms an insulative char layer on the surface this slows burning in the core of the timber and in doing so provides fire resistance for a period of time In general, the more pieces of timber added to the joint, the longer the joint will last. In some cases light gauge steel angles are also used to slow char at corners

35 Cavity Barriers Cavity barriers restrict the passage of flame, smoke and gasses in cavities that bypass wall/floor/ceiling intersections Typical example: intersection between a wall separating SOUs and a non-fire rated external brick veneer wall Cavity barriers can be made by: timber battens appropriate sheet linings moisture repellent mineral wool Light gauge steel profiles Cavity barrier using sheet lining Example prior to brick veneer being laid

36 Fire Rated Shafts Use fire shafts as a means of avoiding services in fire/sound rated walls

37 Topics 1. Fire Hazard Properties Specification C1.10 Specification C1.10a 2. MRTFC and Commercial Buildings Overview Timber properties during fire Connection performance during fire Calculation methods to predict timber capacity

38 Unprotected Timber Exposed to Fire

39 Protected Timber Exposed to Fire Char can also occur within a wall or floor when protected by linings. Experiments show it is at a slower rate and commences later Distribution of char different

40 Topics 1. Fire Hazard Properties Specification C1.10 Specification C1.10a 2. MRTFC and Commercial Buildings Overview Timber properties during fire Connection performance during fire Calculation methods to predict timber capacity

41 Connections Connections usually limit the capacity of a timber element AS Fire Resistance and Structural Adequacy of timber members also provides guidance for the design of connections

42 Connections and AS Unprotected metal fasteners may limit FRLs of unprotected timber Protection of fixings is required and can be via: o surface protection or o embedment of fixings under plugs Other protection measures need test data to support their use

43 Topics 1. Fire Hazard Properties Specification C1.10 Specification C1.10a 2. MRTFC and Commercial Buildings Overview Timber properties during fire Connection performance during fire Calculation methods to predict timber capacity

44 Charring Rate for Unprotected Timber

45 Depth of Char for Unprotected Timber

46 Example of the Fire Resistance of Unprotected Solid Hardwood Calculation to achieve effective load-bearing capacity of the section Dependant on timber density FRLs achieved using effective depth of charring for a typical unprotected 3-sided exposed hardwood beams (650 kg/m 3 ) are shown opposite FRL Effective depth of charring- mm 30/-/ /-/ /-/ /-/- 78

47 Interpretation of AS design rules Narrow section timber directly exposed to fire has a low FRL in accordance with AS Large member sections can have significant FRLs however the connections are sometimes not protected or embedded to the same degree, hence limit the FRL to potentially a relatively low values. Protection may be needed for these connections.

48 Alternative Method Protect the timber with plasterboard

49 Conclusions Timber can be effectively used in buildings that are exposed to fire The key to the correct use of timber is the detailing in accordance with relevant Australian standards and industry manuals (e.g. Technical Guides)

50 woodsolutions.com.au The knowledge building website.

51 More Information WoodSolutions Technical Guides Improvements include details for columns in walls and improved junction details Available for free by registering at