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Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
Ch 06 Wood Frame Construction
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Ch 06 Wood Frame Construction

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  • Courtesy of APA- The Engineered Wood Association
  • © DigitalVues/Alamy Images
  • © Steve Holderfield/ShutterStock, Inc.
  • Photo courtesy of Blaze-tech Fire Protection
  • Courtesy of the estate of Francis L. Brannigan
  • Transcript

    • 1. 6 Wood Frame Construction
    • 2. Objectives (1 of 3)
      • Identify and describe six types of wood frame structures classified as Type V construction
      • Identify and describe the specific fire protection differences between balloon frame and platform frame
      6
    • 3. Objectives (2 of 3)
      • Describe the construction of a platform-frame building
      • Understand how a truss is constructed and how it performs from a fire protection perspective
      • Explain the difference between firestopping and draftstopping
      6
    • 4. Objectives (3 of 3)
      • Describe the behavior of engineered and manufactured wood products under fire attack
      • Describe the different types of wood siding and roofing materials
      6
    • 5. Introduction
      • Most fires are fought on, in, or under wood.
      • Basic facts about wood
        • It is combustible
        • It creates combustible void spaces in which fire can hide and burst out
        • It can, in thin sections, have a very rapid flame spread
      6
    • 6. Definitions
      • Building terms are local in origin; different trades use different terms
        • Wood-framed
        • Wall-bearing
        • Curtain walls
        • Wooden-walled building
      6
    • 7. Wood Frame Terminology (1 of 2)
      • Chamfer
      • End matched
      • Engineered wood
      • Glued laminated timbers
      • Heavy timber
      • Joists
      6
    • 8. Wood Frame Terminology (2 of 2)
      • Lumber
      • Matched lumber
      • Oriented strand board (OSB)
      • Plywood
      • Rough lumber
      • Splines and studs
      • Wood and wood lath
      6
    • 9. Uses of Wood in Buildings
      • Structural
      • Non-load-bearing
      • Roofing
      • Interior trim
      6
    • 10. Types of Wood-Frame Buildings
      • Log cabin
      • Post and frame
      • Balloon frame
      • Platform frame
      • Plank and beam
      • Truss frame
      6
    • 11. Log Cabin
      • Constructed of entire tree trunks
      • Many older buildings, even multistory buildings, are concealed log cabins
      • Many carry unexpectedly heavy loads
      • Interior surfaces of log cabins might be boards or plywood
      6
    • 12. Post and Frame
      • Has an identifiable frame or skeleton of timber fitted together
      • Mortise and tenon
      • Trunnels
      • The walls are not structural or load-bearing.
      6
    • 13. Balloon Frame
      • Wall of ordinary studs nailed together
      • Almost universal construction method for multi-story wooden buildings until the middle of the 20 th century
      6
    • 14. Fires in Balloon-Frame Buildings (1 of 2)
      • Fire can spread through all the interconnected spaces
      • Interconnected voids are one big balloon
      • Installing firestopping in an old building is costly
      6
    • 15. Fires in Balloon-Frame Buildings (2 of 2)
      • Basement is usually the worst place for a fire to start
      • Fire fighters need to anticipate the spread.
      • Extension sector
      • Vermiculite
      6
    • 16. Platform Frame (1 of 2)
      • The first floor is built as a platform
      • Subflooring is laid on the joists
      • Frame for the first-floor walls is erected on the first floor
      • No continuity from top to bottom
      6
    • 17. Platform Frame (2 of 2)
      • Inherent barriers to limit the spread of fire through the walls
      • Open stairwell
      • Soffits
      • Kitchen fire can extend through soffits
      6
    • 18. Constructing a Platform-Frame Building (1 of 2)
      • Rough carpentry
      • Sill 
      • Subflooring 
      • Header or bond course 
      • Trimmer
      6
    • 19. Constructing a Platform-Frame Building (2 of 2)
      • Bottom plate 
      • Top plate 
      • Rafters 
      • Ridge boards
      • Hip 
      • Valley 
      6
    • 20. Plank and Beam (1 of 2)
      • Built with heavier beams
      • Thick, finished tongue and groove planks are used for flooring
      • Reduces the volume of concealed space
      • Interior finishes have high flame spread and smoke-developing characteristics
      6
    • 21. Plank and Beam (2 of 2)
      • Fire in high open spaces can spread rapidly and develop into a huge volume
      • Intermediate structures should be sprinklered or be of noncombustible construction
      6
    • 22. Lightweight Trusses and Other Wooden Members (1 of 2)
      • Fire service has gradually developed knowledge of trusses
      • Contribute to lighter-weight structures
      • Allow offsite prefabrication
      • Satisfy many building requirements
      6
    • 23. Lightweight Trusses and Other Wooden Members (2 of 2)
      • Lighter in weight than solid construction
      • Provides long clear spans
      • Can be delivered prefabricated
      6
    • 24. What Is a Truss?
      • A framed structure consisting of a triangle or group of triangles arranged in a single plane
      • Loads applied at intersections of the members will cause direct stresses in the members
      • Loads applied between these points cause flexural stresses
      6
    • 25. Rigidity (1 of 2)
      • Geometric principle
      • Triangle is inherently stable
      • Economy
      • Chords
      6
    • 26. Rigidity (2 of 2)
      • Struts
      • Ties
      • Panel points
      • Web
      6
    • 27. Principle Types (1 of 2)
      • Parallel-Chord Truss
        • The bottom and top chords are parallel.
        • Steel bar joist
        • Long-span parallel-chord roof trusses have a slight upward pitch to the center.
        • Are being used for floors and roofs
      6
    • 28. Principle Types (2 of 2)
      • Triangular Trusses
        • Triangular in shape in order to provide a peaked roof
        • Must be closely spaced
      6
    • 29. Connectors
      • A problem in truss design
      • Connectors now capable of transmitting heavy loads
      6
    • 30. Compression vs. Tension (1 of 2)
      • Normal truss:
        • Top chord in compression and bottom chord in tension
      6
    • 31. Compression vs. Tension (2 of 2)
      • Cantilever is reversed:
        • Top chord in tension and bottom chord in compression
      • In sketches, compression members are often shown as thick lines, while tension members are shown as thin lines
      6
    • 32. Truss Principles, Case #1
      • A building span of 20 feet
      • Two 10-foot ­I-beams extend from the walls.
      • Assume each beam can carry 1000 pounds.
      • If column is removed, beam would have to be 20 feet long but carry only 500 pounds
      6
    • 33. Truss Principles, Case #2 (1 of 2)
      • The column is cut off and a stub remains at the junction of the beams
      • A triangle restores the load­carrying capacity of the beam
      6
    • 34. Truss Principles, Case #2 (2 of 2)
      • A truss with single compression member extending downwards is called an inverted king post truss
      • A truss with two compression members is called a queen post truss
      6
    • 35. Problems with Trusses
      • Failure
      • Multiple truss failures
      • Rising roofs
      • Tables of allowable design stresses
      • Defective design
      • Competition in the supply business
      6
    • 36. Truss Failure in Fires
      • Economy of the truss
      • Bottom chord: under compression
      • Top chord: in tension
      • Compressive load
      • Ties
      • Large triangular trusses
      6
    • 37. Wood Truss Floors
      • Are a hazard to fire fighters
      • Heating of the gusset plate will decompose tensioned wood fibers
      • No outward indication of their presence
      • May be disclosed by smoke or fire pushing through the wall at the floor line
      6
    • 38. Truss Void (1 of 2)
      • Found within a truss roof system, this void space is between the top floor ceiling and the roof
      • Represents a large area in which explosive carbon monoxide can accumulate
      • Voids are interconnected horizontally and vertically
      6
    • 39. Truss Void (2 of 2)
      • The National Fire Protection Association (NFPA) Fire Protection Handbook
      • Concentration (in parts per million [ppm]) x duration (minutes) = 35,000 is likely to be dangerous
      • The flammability range of carbon monoxide is from 12.5 to 74 percent
      6
    • 40. Catastrophe Potential (1 of 2)
      • Lateral extension of truss
        • May support a balcony that is the only exit for occupants
      6
    • 41. Catastrophe Potential (2 of 2)
      • Truss passes through outside wall
        • Only firestopping is typically gypsum “buttered” in place with cement
        • Firestopping is penetrated by lighting circuits
      • Stairway exits with truss voids
        • If involved in fire, can collapse before the occupants have escaped
      6
    • 42. Automatic Sprinklers and Truss Voids
      • NFPA 13R
        • Purpose to prevent flashover and save lives
        • Code describes partial systems that should not be expected to provide full fire suppression
      6
    • 43. Lightweight Wooden I-Beams
      • Wooden beam
      • Sawn beam
      • Steel I-beam
      • Sawn wooden beam
      • Wooden I-beams
      • Web of the I-beam
      6
    • 44. Truss Frame (1 of 2)
      • The roof and floor trusses and studs are tied into a unitized frame
      • The small dimension lumber will burn faster than larger solid lumber
      • Unsupported spans in trussed structures are subject to total collapse
      6
    • 45. Truss Frame (2 of 2)
      • Loss of a stud could precipitate the collapse of the integral roof or floor truss
      • Design assumes that every truss member will remain in its assigned position under load
      6
    • 46. Firestopping
      • Fire spreads through hidden voids
      • No tested standards for wood firestopping or draftstopping
      6
    • 47. Differences: Firestopping and Draftstopping
      • Both limit the spread of fire
      • Firestops typically limit vertical movement
      • Draftstops limit horizontal movement
      6
    • 48. Types of Firestopping
      • Inherent firestopping results from normal building construction
      • Legal firestopping meets the requirements of a code
      6
    • 49. Effectiveness of Firestopping (1 of 2)
      • The lack of firestopping in one stud channel is sufficient to transmit fire
      • In older houses, sides of the chimney-like stud channels are combustible
      • Lack of firestopping is particularly critical in balloon-frame buildings
      6
    • 50. Effectiveness of Firestopping (2 of 2)
      • Not all building inspectors are familiar with the basic gas law:
        • If the temperature rises and the volume remains the same, the pressure rises
      6
    • 51. Cutoff Ends of Joists
      • Used as firestopping
      • No seal because the wood “cut out” creates a space
      6
    • 52. West and East Coasts
      • Uniformly unsatisfactory practices
      • Sheet of gypsum board “buttered” into place
      • Thin plywood or flake board poorly fitted
      6
    • 53. Removal of Firestops
      • Removed for the installation of such items as heat ducts, electrical cables, sprinkler systems, and central vacuum cleaner systems
      • Unlikely to be replaced
      6
    • 54. Draftstopping and Truss Floors
      • Truss voids in each floor
      • Truss proponents argue that firestopping will mitigate the problem
      • Severe backdraft explosion can provide a significant collapse
      6
    • 55. Protecting Wood from Ignition
      • Sobering News
        • Most fires are fought by fire fighters standing on, in, or under a combustible structure
        • Encasing wood in concrete promotes decay
      6
    • 56. Impregnation
      • Wood can be impregnated in a variety of way: pressure- or chemically-treated.
      • Wood cannot be made fireproof or noncombustible
      • It can be made fire retardant
      • Impregnated wood is not noncombustible wood
      6
    • 57. Pressure Treatment
      • Can reduce wood’s flame spread
      • Pressure treatment can reduce the hazard of wood construction
      • Treated wood will burn, although at a slower rate
      6
    • 58. Underwriters Laboratories, Inc. (UL)
      • Provides various classifications of treated lumber
      • Consult “Lumber, Treated (BPW)”
      6
    • 59. Chemicals
      • Previously used ones impregnated the wood but leached out and corroded metal connectors
      • New products cite noncorrosive materials
      6
    • 60. Bad Practices
      • Fire retardant plywood (FRT), one sheet wide, on both sides of a firewall
      • Plywood delaminates with fire exposure
      • Plywood treated with certain chemicals decays from heat
      6
    • 61. Surface Coatings
      • Intumescent coatings swell up when heated
      • People spread it thinner than recommended
      • Applying to existing installations leaves the unexposed surface untreated
      6
    • 62. Dangerous Treated Wood
      • Pressure treated plywood and lumber treated has been used for basement walls
      • Widely used for exterior structures
      • Still combustible and might cause a collapse
      • Fumes are toxic
      6
    • 63. Plywood
      • Plywood was seen as answer to wood’s lack of shear strength
      • Plywood exposed to fire delaminates
      • Plywood can be impregnated to render it fire retardant
      6
    • 64. Spliced Timbers
      • Are joined by metal connectors to transfer loads
      • Acts as a single member
      • Heated metal connections can destroy the wood and the timber may fail
      6
    • 65. Laminated Timbers
      • Plank-like sections of nominal two-inch boards are glued under pressure
      • Burn like solid heavy timbers and do not delaminate like plywood
      • Laminated wooden beams are not the same thing as wooden I-beams
      6
    • 66. Paper Wrapping
      • Laminated timbers are shipped in a protective paper wrapper
      • Paper is hemp-reinforced and coated with a bituminous moisture repellant
      • Paper ignites readily and has a high flame spread
      6
    • 67. Planks
      • Fabricated by gluing three boards together with the center board protruding on one side and indented on the other
      • A sample ignited burned like a solid piece of wood
      6
    • 68. Finger Joints
      • Made by cutting a series of long points into the end of each piece
      • The joints are glued together
      6
    • 69. Chipboard
      • Wood chips are often glued together to make flat sheets
      • Sometimes used for the floors of mobile homes
      • Some is water soluble
      6
    • 70. Flitch Plate Girders
      • A composite of a steel plate or plywood sandwiched between two beams
      • Failure of the connection between the wood and steel could cause failure
      6
    • 71. Wood and Plastic Roof Panels
      • Large plywood roof panels with a gypsum board interior surface sandwiched a thick plastic foam core to create panels
      • Panel used as a roof support
      • Dangerous to vent such a roof
      6
    • 72. Sheathing
      • Covering applied to the studs or framing of a structure
      • Exterior surface covers the sheathing.
      • Many old houses were built without sheathing
      6
    • 73. Low-Density Black Fiberboard
      • Moisture and vermin proof
      • Carries the warning, “Combustible. May burn or smolder if ignited.”
      • Plumber’s torch
      6
    • 74. Plywood and Gypsum
      • Both are used for sheathing
      • Combined with brick veneer surfacing and gypsum interior surface, gypsum is used to provide rated fire-resistive exterior walls
      6
    • 75. Foamed Plastic
      • Also used for sheathing
      • May or may not be flame-inhibited
      • In a fire, may degrade and give off noxious fumes
      6
    • 76. Siding (1 of 2)
      • Novelty siding 
      • Batten 
      • Plywood siding 
      • Shingle and shake 
      • Asbestos cement shingle 
      6
    • 77. Siding (2 of 2)
      • Asphalt felt siding
      • Vinyl siding 
      • Metal siding 
      • Corrugated metal siding 
      • Stucco 
      6
    • 78. Brick Veneer
      • Is laid up from the foundation in one wythe
      • Such a wall is unstable because it is thin
      • Galvanized steel anchors are nailed to the studs
      • Pyrolytic decomposition can be an issue
      6
    • 79. Stone Veneer
      • Natural or artificial stone and cast concrete
      • Permastone is one trade name
      6
    • 80. Wood Shingle Roofing (1 of 2)
      • Fire hazard
        • Some of the greatest fire disasters in history have been due to the spread of fire by wood shingle roofs
        • The conflagration hazard presented by wood shingles is a serious consideration
      6
    • 81. Wood Shingle Roofing (2 of 2)
      • A Strong Comeback
        • Many areas have wood-shingled roofs.
        • Permitted wherever frame buildings are permitted
      6
    • 82. Testing Laboratories
      • Rate wood shingles in accordance to NFPA 256
      • Elements considered include flame exposure, spread of flame, and resistance to burning
      • Roofing materials are classified as A, B, or C
      6
    • 83. Tile Roofs
      • Heavy tile roof
        • Collapse of thousands of pounds of tile
        • Truss-supported tile failure
      6
    • 84. Imitation Timber
      • Watch for the following:
        • Unprotected steel beams or columns boxed in wood
        • Unprotected steel encased in plaster
        • False wood beams
        • Polyurethane imitation wood beams
      6
    • 85. Making Wood Construction Safe
      • Wood is a uniquely renewable resource
      • Unfortunately it is combustible
      • Combustibility can be dealt with only by complete automatic sprinkler protection
      6
    • 86. Summary (1 of 2)
      • Type V construction has six types of wood frame structures
      • In a balloon-frame building, fire can spread through all the interconnected spaces from cellar to attic and across the ceiling
      • Firestopping is often required by code to be installed to prevent the spread of fire
      6
    • 87. Summary (2 of 2)
      • Trusses and specially treated or constructed wood materials create unique challenges for fire protection
      • Wood cannot be made fireproof or noncombustible
      • Combustibility can be dealt with only by complete automatic sprinkler protection
      6

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