Fire Safety and Performance of Wood

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This presentation demonstrates how the fire performance requirements in the Building Code of Australia (BCA) for Class 1a, Class 2, 3 & 9c as well as Class 5,6 9a & 9b buildings can be met. In this …

This presentation demonstrates how the fire performance requirements in the Building Code of Australia (BCA) for Class 1a, Class 2, 3 & 9c as well as Class 5,6 9a & 9b buildings can be met. In this context, the presentation provides verified construction details that utilise the BCA's deemed-to-satisfy provisions.

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  • 1. Fire Safety and Performance of Wood
    In Multi-Residential and Commercial Buildings
  • 2. Learn more about wood at UTAS
    Centre for Sustainable Architecture with Wood
    Graduate Certificate in Timber (Processing & Building)
    4 units, part time, online
    Areas covered include:
    Wood science
    Design for durability and service for life
    Timber as a renewable resource
    Sustainable design and construction
    Engineered wood products
    International technologies and developments
    Plus, selected topics of individual interest
    More information: Associate Professor Greg Nolan
    (03) 6324 4478 or enquiries@arch.utas.edu.auwww.csaw.utas.edu.au
  • 3. Learning Objectives
    After this presentation you should be able to:
    Identify which Fire Hazard Properties apply in various situations
    Understand how to use timber in multi-residential and commercial buildings
    Outline the effectiveness of timber members and timber connections during fire
    For architects - AACA Competencies:
    Design
    Documentation
  • 4. This Presentation
    Fire Hazard Properties
    Specification C1.10
    Specification C1.10a
    MRTFC and Commercial Buildings
    Overview
    Timber properties during fire
    Connection performance during fire
    Calculation methods to predict timber capacity
  • 5. Fire Resistance in the BCA
  • 6. Topics
    Fire Hazard Properties
    Clause C 1.10: Specification C1.10
    Clause: C1.10: Specification C1.10a
    MRTFC and Commercial Buildings
    Overview
    Timber properties during fire
    Connection performance during fire
    Calculation methods to predict timber capacity
  • 7. Clause C1.10
    Class 1 or 10
    No Clause C1.10
    requirements
    Class of Building?
    Class 2-9
    Clause C1.10
    • Timber-framed window?
    • 8. Solid timber handrail or skirting?
    • 9. Timber- faced solid core door or fire door?
    • 10. Joinery, cupboard shelving etc.?
    • 11. Paints, varnishes, etc. or adhesives
    yes
    No requirements
    no
    Covering - Floor, Wall & Ceiling
    Other
    Specification C1.10
    Specification C1.10a
  • 12. Specification C1.10
    Specification C1.10
    Materials1?
    All other materials, including timber
    sarking
    Flammability Index
    ≤ 5
    Spread-of-Flame Index
    ≤ 9
    and
    Smoke-Developed Index2
    ≤ 8
    1 Additional requirements apply to fire isolated exits, public entertainment theaters, public halls etc. refer to BCA for details
    2 Only for materials with a Spread-of-Flame Index > 5
  • 13. Specification C1.10 – Fire Hazard Properties of Timber
    More species can be found on: www.woodsolutions.com.au
  • 14. Topics
    Fire Hazard Properties
    Clause C1.10: Specification C1.10
    Clause C1.10: Specification C1.10a
    MRTFC and Commercial Buildings
    Overview
    Timber properties during fire
    Connection performance during fire
    Calculation methods to predict timber capacity
  • 15. Clause C1.10
    Class 1 or 10
    No Clause C1.10
    requirements
    Class of Building?
    Class 2-9
    Clause C1.10
    • Timber-framed window?
    • 16. Solid timber handrail or skirting?
    • 17. Timber- faced solid core door or fire door?
    • 18. Joinery, cupboard shelving etc.?
    • 19. Paints, varnishes, etc. or adhesives
    yes
    No requirements
    no
    Coverings - Floor, Wall & Ceiling
    Other
    Specification C1.10
    Specification C1.10a
  • 20. Specification C1.10a
    Specification C1.10a
    Wall / Ceiling
    Floor
    Lift
    Sprinklered?
    yes
    no
    Critical Radiant Flux
    Critical Radiant Flux
    and
    Smoke Development Rate
    ≤ 750 percent minutes
  • 21. Specification C 1.10a: Floors -Fire Hazard Properties of Timber
    More species can be found on: www.woodsolutions.com.au
  • 22. Specification C1.10a
    Specification C1.10a
    Wall / Ceiling
    Floor
    Lift
    Sprinklered?
    Sprinklered?
    yes
    no
    yes
    no
    Group Number
    Critical Radiant Flux
    Critical Radiant Flux
    and
    Smoke Development Rate
    ≤ 750 percent minutes
    Group Number
    and
    smoke growth rate index
    or
    average specific extinction area
    < 250 m²/kg
  • 23. Specification C 1.10a: Walls / Ceiling Fire Hazard Properties of Timber
    More species can be found on: www.woodsolutions.com.au
  • 24. Clause Specification C1.10a: Lifts
    Specification C1.10a
    Wall / Ceiling
    Floor
    Lift
    Floor, Wall/Ceiling?
    Sprinklered?
    Sprinklered?
    yes
    no
    yes
    no
    floor
    wall/ceiling
    Group Number
    Critical Radiant Flux
    Critical Radiant Flux
    and
    Smoke Development Rate
    ≤ 750 percent minutes
    Group Number
    and
    smoke growth rate index
    or
    average specific extinction area
    < 250 m²/kg
    Critical Radiant Flux
    ≥ 2.2 kW/m²
    Group Number
    1 or 2
  • 25. Topics
    Fire Hazard Properties
    Specification C1.10
    Specification C1.10a
    MRTFC and Commercial Buildings
    Overview
    Timber properties during fire
    Connection performance during fire
    Calculation methods to predict timber capacity
  • 26. MRTFC - Overview
    – Multi
    – Residential
    – Timber
    –Frame
    –Construction
    M
    R
    T
    F
    C
  • 27. MRTFC and Performance Requirements
    • MRTFC deals with:
    • 28. Class 1 buildings (houses or dwellings attached side by side)
    • 29. Class 2 buildings (flats and units above one another as well as side by side)
    • 30. Class 3 buildings (residential parts of hotels, motels, accommodation for students, aged and disabled)
    • 31. Class 9c buildings (buildings for the aged)
    • 32. Performance criteria in these classes focuses on:
    • 33. Fire resistance
    • 34. Sound resistance
    • 35. This presentation focuses on Fire Resistance
  • 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 for “other property”:
    • 36. A SOU is a part of a building that is occupied by one owner, lessee or other occupant
    • 37. SOUs must be designed to restrict fire and sound from affecting adjoining SOUs
  • 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
  • 38. Measuring Fire Resistance Levels
    • The BCA requires protection to be provided at the boundaries between compartments or SOUs
    • 39. The walls, floors and ceilings bounding compartments are constructed to meet “Fire Resistance Levels” (FRLs) to prevent the spread of fire
    • 40. 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
    • 41. Partition walls are the exact opposite: barriers but non-loadbearing so typically have a FRL of -/30/30 or -/60/60
  • General Framing Requirements
    • MRTFC details focuses on meeting the combined requirements of fire, sound and structural requirements for designated wall, floor and ceiling elements in Class 1, 2 and 3 buildings
    • 42. A systems approach is used to meet needs which can be broken up into:
    • 43. Wall framing systems
    • 44. Floor/ceiling framing systems
    • 45. Each system uses a number of common concepts to maintain continuity at intersections between elements and at penetrations, including:
    • 46. Fire resistant joints
    • 47. Cavity barriers
    • 48. Fire stops
  • Double Stud Walls in More Detail
    • The system features two stud walls with a separating cavity
    • 49. Load bearing frames are typically made from 90x45 timber framing
    • 50. The frames can be prefabricated as required
    • 51. The system is easy to handle and erect onsite
    • 52. Insulation is used extensively between studs or in the cavity
    • 53. It must be non-combustible (BCA Requirement)
    • 54. Fire grade plasterboard is built up in layers to meet fire requirements
    • 55. Fibre cement sheet can be used in combination with plasterboard
    • 56. Other cladding or linings can be used over these components
  • 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
    • 57. walls may be single skin (not double) because sound resistance isn’t required in the roof or eaves areas
  • Floor/Ceiling Systems
    • Floor/ceiling systems are required between sole occupancy units (SOUs)
    • 58. These systems consist of floor coverings, platform flooring, floor joists, sound insulation, resiliently mounted ceiling battens and ceiling linings
  • Summary of Floor/Ceiling System Components
    • Timber joists dictate the load and spanning capacity of the floor
    • 59. Non-combustible sound insulation is placed within the joist depth
    • 60. Resiliently mounted ceiling battens are fixed transversely to the joists to isolate sound from the structure above
    • 61. 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)
  • Continuity of Systems
    • Care must be taken to ensure weak spots don’t occur at the interfaces between systems (e.g. intersections and penetrations)
    • 62. Methods of doing this include:
    • 63. Fire resistant joints
    • 64. Cavity barriers
    • 65. Fire stops at gaps and penetrations (caulking)
  • 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
    • 66. Some structural framing remains protected by the plasterboard and by the slow charring of the other framing at the junction.
  • Fire Resistant Floor Junctions
    • Needed at intersections between wall/wall elements such as when one element has a lower FRL than the other
    • 67. The joint is made by adding extra pieces of timber to the joint between the elements
    • 68. 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
    • 69. In general, the more pieces of timber added to the joint, the longer the joint will last.
    • 70. In some cases light gauge steel angles are also used to slow char at corners
  • Cavity Barriers
    • Cavity barriers restrict the passage of flame, smoke and gasses in cavities that bypass wall/floor/ceiling intersections
    • 71. Typical example: intersection between a wall separating SOUs and a non-fire rated external brick veneer wall
    • 72. Cavity barriers can be made by:
    • 73. timber battens
    • 74. appropriate sheet linings
    • 75. moisture repellent mineral wool
    • 76. Light gauge steel profiles
    Cavity barrier using sheet lining
    Example prior to brick veneer being laid
  • 77. Fire Rated Shafts
    Use fire shafts to avoid services in fire/sound rated walls
  • 78. Topics
    Fire Hazard Properties
    Specification C1.10
    Specification C1.10a
    MRTFC and Commercial Buildings
    Overview
    Timber properties during fire
    Connection performance during fire
    Calculation methods to predict timber capacity
  • 79. Unprotected Timber Exposed to Fire
  • 80. Protected Timber Exposed to Fire
    • Char can also occur within a wall or floor when protected by linings.
    • 81. Experiments show it commences later and is at a slower rate
    • 82. Distribution of char is different
  • Topics
    Fire Hazard Properties
    Specification C1.10
    Specification C1.10a
    MRTFC and Commercial Buildings
    Overview
    Timber properties during fire
    Connection performance during fire
    Calculation methods to predict timber capacity
  • 83. Connections
    • Connections usually limit the capacity of a timber element
    • 84. AS1720.4-2006 – Fire Resistance and Structural Adequacy of timber members also provides guidance for the design of connections
  • Connections and AS 1720.4
    • Unprotected metal fasteners may limit FRLs of unprotected timber
    • 85. Protection of fixings is required and can be via:
    • 86. surface protection or
    • 87. embedding fixings under plugs
    • 88. Other protection measures need test data to support their use
  • Topics
    Fire Hazard Properties
    Specification C1.10
    Specification C1.10a
    MRTFC and Commercial Buildings
    Overview
    Timber properties during fire
    Connection performance during fire
    Calculation methods to predict timber capacity
  • 89. Charring Rate for Unprotected Timber
  • 90. Depth of Char for Unprotected Timber
  • 91. Examples of the Fire Resistance of Unprotected Solid Hardwood
    • Calculated based on load-bearing capacity of residual section
    • 92. Depends on density / magnitude of applied load / timber grade / dimensions
    • 93. FRLs for typical unprotected 3-sided exposed hardwood beams are shown opposite
  • Narrow section timber directly exposed to fire has a low FRL in accordance with AS 1720.4
    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
    Interpretation of AS 1720.4 design rules
  • 94. Alternative Method
    Protect the timber with plasterboard
  • 95. Timber can be effectively used in buildings that are exposed to fire
    The key to the correct use of timber is detailing in accordance with relevant Australian standards and industry manuals (e.g. Timber Design Guides)
    Conclusions
  • 96. More Information
    • WoodSolutions Technical Design Guides
    • 97. Updates include details for columns in walls and improved junction details
    • 98. Available by registering at www.woodsolutions.com.au
  • Learn more about wood at UTAS
    Centre for Sustainable Architecture with Wood
    Graduate Certificate in Timber (Processing & Building)
    4 units, part time, online
    Areas covered include:
    Wood science
    Design for durability and service for life
    Timber as a renewable resource
    Sustainable design and construction
    Engineered wood products
    International technologies and developments
    Plus, selected topics of individual interest
    More information: Associate Professor Greg Nolan
    (03) 6324 4478 or enquiries@arch.utas.edu.auwww.csaw.utas.edu.au
  • 99. More Information