1. Building Construction
CHAPTER 6
Building Construction 1

2. Knowledge Objectives
Explain how occupancy classifications affect fire suppression operations.
Explain how the contents of a structure affect fire suppression operations.
Describe the characteristics of masonry building materials.
Describe the characteristics of concrete building materials.
Describe the characteristics of steel building materials. 2

3. Knowledge Objectives
Describe the characteristics of gypsum building materials.
Describe the characteristics of wood building materials.
Describe the characteristics of engineered wood building materials.
Describe the characteristics of plastic building materials.
List the five types of building construction. 3

4. Knowledge Objectives
Describe the characteristics and effects of fire on Types I, II, III, IV, and V construction.
Describe the characteristics and effects of fire on balloon-frame and platform-frame construction.
Describe the challenges associated with fighting a fire in a hybrid building.
Describe the purpose of a foundation in a structure.
List the warning signs of foundation collapse. 4

5. Knowledge Objectives
Explain how floor construction affects fire suppression operations.
Describe the characteristics of fire-resistive floors, wood-supported floors, and ceiling assemblies.
List the three primary components of roof assemblies.
List the three primary types of roofs.
Describe the characteristics of trusses. 5

6. Knowledge Objectives List the types of trusses.
Describe the effects of fires on trusses.
Describe the characteristics of walls.
List the common types of walls in structures.
Describe the characteristics of door and window assemblies, fire doors, and windows.
Explain the effect that interior finishes have on fire suppression operations. 6

7. Knowledge Objectives
Explain the effect that exterior finishes and siding have on fire suppression operations.
Describe the hazards that buildings under construction or demolition pose to fire fighters.
Describe the factors that increase the chance of building collapse.
Describe how building construction factors into preincident planning and incident size-up. 7

8. Introduction Building construction affects how fires grow and spread.
Fire fighters need to understand how each type of building construction reacts when exposed to the effects of heat.
Fire fighters determine when it is safe to enter a burning building and when it is necessary to evacuate
Consider construction, but also occupancy and building contents. 8

9. Occupancy How a building is used
Classifications indicate who is likely to be inside, how many people, and what they are likely to be doing.
Occupancy classifications are used in conjunction with building and safety codes to establish regulatory requirements
Buildings constructed for one reason are often repurposed for another or used for a variety of occupancies. 9

10. Contents
Building contents must be considered when responding to a fire.
Contents vary widely, usually related to occupancy.
Whenever possible, fire fighters should prepare a preincident plan that accounts for buildings with special hazards.
Similar occupancies can pose different levels of risk. 10

11. Types of Construction Materials
The properties of these materials and the details of their construction determine the basic fire characteristics of the building itself.
Function, appearance, price, and compliance with building codes are all considerations.
Fire fighters’ chief concern is the behavior of the building under fire conditions.
A building method that is attractive to an architect may create deadly hazards for fire fighters. 11

12. Types of Construction Materials
Factors that affect the behavior of construction materials under fire conditions include:
Combustibility
Thermal conductivity
Decrease of strength at elevated temperatures
Thermal expansion when heated 12

13. Masonry Inherently fire-resistive Poor conductor
Can act as heat reservoir
Openings can allow fire to spread.
With prolonged exposure to fire, masonry can collapse.
© AbleStock; c Jones & Bartlett Learning. Photographed by Glen E. Ellman. 13

14. Concrete Naturally fire-resistive Poor conductor of heat
Used to insulate other materials
Often used for foundations, columns, floors, walls, roofs, and exterior pavement
Strong under compression
Weak under tension
Can be damaged through exposure to fire
Spalling can result in structural collapse.
Courtesy of Achim Hering. 14

15. Steel
Strongest material in common use, in both compression and tension
Will rust
Not fire-resistive
Will melt at extremely high temperatures
© Jones & Bartlett Learning. Photographed by Glen E. Ellman. 15

16. Steel Good conductor of heat Expands and loses strength when heated
Other materials are often used to protect steel.
Failure depends on the mass of the steel components, the loads placed on them, and the methods used to connect the steel pieces.
Any sign of bending, sagging, or stretching indicates immediate risk of failure. 16

17. Other Metals Copper Primarily used for piping and wiring Zinc
Used as a protective coating for metals
Iron: wrought iron and cast iron
Aluminum
Occasionally structural; used for siding, window and door frames, and roof panels
Often melts and drips in fires 17

18. Glass Ordinary glass will break.
Specially formulated glass can be used as a fire barrier in certain situations.
Thermal conductivity of glass is rarely a significant factor in the spread of fire.
Many different types of glass are available:
Ordinary window glass
Tempered glass
Laminated glass
Glass blocks
Wired glass

19. Glass © Sylvie Bouchard/Shutterstock, Inc. Courtesy of David Sweet.
© Jones & Bartlett Learning
© Jones & Bartlett Learning. Photographed by Glen E. Ellman.

20. Gypsum Board Very good insulator Limited combustibility
Paper will burn, but gypsum itself will not.
Often used as a firestop
Commonly covers interior
Prolonged exposure to fire will cause failure.
© Jones & Bartlett Learning. Photographed by Glen E. Ellman. 20

21. Wood Most common building material
Most important characteristic is combustibility.
Weakens when consumed by fire
Ignites, burns, decomposes based on:
Ignition, moisture, density, preheating, size, and form
High temperatures decrease strength via pyrolysis. 21

22. Engineered Wood Products
Includes plywood, fiberboard, oriented strand board, and particle board
Produced from small pieces of wood held together with glue or adhesive
Preferred over natural wood for many reasons
Drawbacks include that it warps, contains toxic products, burns quickly, and fails quickly.

23. Fire-Retardant-Treated Wood
Wood is impregnated with mineral salts.
Makes it difficult to ignite
Slows rate of burning
Fire-retardant chemicals can weaken wood.
Dangerous to stand on roofs made of fire- retardant plywood

24. Plastics Rarely used for structural support Combustibility varies
Many plastics release smoke when they burn.
Thermoplastic materials melt and drip.
Thermoset materials lose strength but will not melt.
© AbleStock. 24

25. Types of Construction Types I through V
Buildings are classified based on the combustibility of the structure and the fire resistance of its components.
Fire resistance (in hours) refers to the length of time that a building or building component can withstand a fire before igniting.
Building codes specify type of construction to be used based on the height, area, occupancy classification, and location of the building. 25

26. Type I: Fire-Resistive
Most fire-resistive
All structural components must be noncombustible.
Used for:
Large numbers of people
Tall or large area
Special occupancies
© John Foxx/Alamy Images 26

27. Type I: Fire-Resistive
Reinforced concrete and steel-frame construction
Building materials should not provide fuel for a fire.
Fires can be very hot and hard to ventilate.
In extreme conditions, can collapse.
© Michael Doolittle/Alamy Images. 27

28. Type II: Noncombustible
All structural components must be noncombustible.
Fire-resistive requirements are less stringent than Type I.
Steel is most common structural material.
© Jones & Bartlett Learning 28

29. Type II: Noncombustible
Fire walls are sometimes used to subdivide these buildings and prevent catastrophic losses.
Fire severity is determined by contents.
Structural components contribute little or no fuel.
Little interior finish is utilized.
Automatic sprinklers should be used to protect combustible and valuable contents. 29

30. Type III: Ordinary Used in a wide range of buildings
Usually limited to no more than four stories
Masonry exterior walls support floors and roof.
Limited fire- resistance requirements
© Brandon Bourdages/Shutterstock, Inc. 30

31. Type III: Ordinary Two separate fire loads: Contents
Construction materials
Fire resistance depends on building age and local building codes.
Void spaces allow a fire to spread horizontally and vertically.
Exterior walls, floors, and roof are connected. 31

32. Type IV: Heavy Timber Exterior masonry walls
Interior structural elements, floors, and roof of wood
Heavier wood than Type III
No concealed spaces or voids
© Helen Filatova/Shutterstock, Inc. 32

33. Type IV: Heavy Timber Used for buildings as tall as eight stories
Open spaces suitable for manufacturing and storage
New Type IV construction is rare.
Automatic sprinkler systems were developed to protect mill construction.
Conversions of these buildings tend to divide open spaces into smaller compartments and create void spaces. 33

34. Type V: Wood Frame Most common type of construction in use
All major components are wood or other combustible materials.
© Jones & Bartlett Learning 34

35. Type V: Wood Frame Does not have any fire-resistive components
Often collapses and suffers major destruction
Usually creates voids and channels that allow fire to spread quickly
Can easily extend to nearby buildings
Smoke detectors are essential.
Modern construction techniques rely on wooden I- beams and wooden trusses.
These buildings collapse early and suddenly. 35

36. Type V: Wood Frame
Might be covered with wood, vinyl, aluminum siding, brick veneer, or stucco
Just because you see a brick covering does not mean the building has solid brick walls.
Structural fires cause veneer to collapse or peel away as the wall behind it burns.
A collapse zone should be set up around a burning building. 36

37. Type V: Wood Frame Balloon-frame construction
Exterior walls assembled with continuous wood studs
Top-to-bottom fire spread
Check void spaces
© Jones & Bartlett Learning 37

38. Type V: Wood Frame Platform-frame construction
Exterior wall studs not continuous
Floors are platforms, slowing vertical fire spread
© Jones & Bartlett Learning 38

39. Hybrid Building Construction
Does not fit entirely into any of the construction types because it incorporates building materials of more than one type.
Renovated building can give the impression that it is one construction type when it is really a mixture.
Courtesy of Jennifer Schottke. 39

40. Building Components
Understanding how various components of a building function will improve a fire fighter’s safety.
Some building construction features are safer for fire fighters. 40

41. Foundations
Transfer the weight of the building and its components to the ground
Ensure building is firmly planted
Modern foundations are usually constructed of concrete or masonry.
© Dorn1530/Shutterstock, Inc. 41

42. Foundations Weak or shifting foundations can cause building collapse.
Causes of weak or shifting foundations:
Improper construction
Shifting soil
Earthquakes
Look for cracks that indicate movement.
If the building has been modified or remodeled, look for places where support could be compromised. 42

43. Floors and Ceilings
Fire fighters working inside must rely on the integrity of the floor to support their weight.
Floor failure can drop a fire fighter onto a lower floor.
In a multistory structure, fire fighters may be working below a floor, which would fall on them if it collapsed.
The floor system influences whether a fire spreads vertically from floor to floor or is contained on a single level. 43

44. Fire-Resistive Floors
Floor-ceiling system designed to prevent collapse and vertical fire spread
Void space contains building systems and equipment
If space above ceiling is not partitioned or protected, fire can extend horizontally.
© Lourens Smak/Alamy Images 44

45. Wood-Supported Floors
Common in non-fire-resistive construction
Heavy-timber floors can often contain a fire for an hour or more.
Conventional wood flooring burns readily and can fail in as little as 20 minutes.
Modern, lightweight wood I-beams and trusses offer little fire resistance. 45

46. Floors It is impossible to tell how a floor is constructed from above.
Building’s age and local construction methods can provide significant clues.
Older buildings may have been renovated.
Preincident surveys should be used to gather essential structural information.

47. Ceiling Assemblies
From a structural standpoint, the ceiling is considered to be part of the floor assembly.
May conceal heating, ventilation, and air- conditioning distribution systems, as well as wiring and fire sprinkler systems
Can be part of the fire-resistive package
Hollow spaces between the floor and the ceiling can contribute to the horizontal spread of fire.

48. Roofs Protect building from weather Can be vital to stability
Three major components:
Supporting structure
Decking
Covering
© Jones & Bartlett Learning 48

49. Roofs Most common types of supports are solid beams, composed of:
Girders
Beams
Rafters
Trusses
Roof decking is the portion of roof between the supports and covering.
Roof materials may be combustible, noncombustible, or both.

50. Pitched Roofs Sloped or inclined
Can be gable, hip, mansard, gambrel, or lean-to
Usually supported by rafters or trusses
Require some sort of roof covering
© Jones & Bartlett Learning 50

51. Pitched Roofs Slope means danger of falls.
Roof ladders and aerial apparatus are used.
Usually supported by either rafters or trusses.
Pitched roofs require a covering.
A: Paul Springett/Up the Resolution/Alamy Images; B: Ron Chapple/Thinkstock/Alamy Images; C: TH Photo/Alamy Images. 51

52. Curved Roofs
Used for large buildings that require large, open interiors
Usually supported by steel or wood bowstring trusses or arches
Decking material in use must be identified before ventilation openings can be made. 52

53. Flat Roofs Have a slight slope for drainage
Wood support structures use solid wood beams and joists.
Highly combustible materials
Present unique ventilation problems
Courtesy of Captain David Jackson, Saginaw Township Fire Department 53

54. Trusses Triangular geometry creates a strong, rigid structure.
Widely used in new construction
Usually prefabricated wood or steel
Can be exposed or enclosed
© M Stock/Alamy Images. 54

55. Parallel Chord Truss
Two parallel horizontal members connected by a system of diagonal or vertical members
Used for flat roofs and floors
Wood truss
Steel bar joist is another example
© Jones & Bartlett Learning. Photographed by Glen E. Ellman. 55

56. Pitched Chord Truss Used for sloping roofs
Roof deck is supported by the top chords, and ceilings are attached to the bottom chords.
© Jones & Bartlett Learning 56

57. Bowstring Truss Same shape as an archery bow
Compressive vs. tensile forces
Usually quite large and widely spaced
Used for curved roofs
c Jones & Bartlett Learning
Courtesy of Captain David Jackson, Saginaw Township Fire Department. 57

58. Trusses Under fire, provide little margin of safety
High surface-to-mass ratio
Failure at one point produces failure for the entire truss.
Wooden trusses constructed with metal gusset plates are especially prone to failure.
Steel trusses are prone to failure during fire.
A 100-ft-long beam/truss can elongate as much as 9” (23 cm) when heated to 1000ºF (540ºC). 58

59. Trusses Truss spaces can also contribute to the spread of fires.
Be alert for a fire burning under you or a rapid collapse of the roof trusses.
Some jurisdictions have passed laws requiring buildings constructed with trusses be marked.
Identifying trusses enables you to better predict the behavior of a particular building and evaluate the risk and benefit of different approaches to fire suppression. 59

60. Walls Most visible part of a building
Constructed of masonry, wood, steel, aluminum, glass, and many other materials
Walls are:
Load-bearing
Nonbearing
Specialized 60

61. Load-Bearing Walls Provide structural support
Either interior or exterior
Support both “dead load” and “live load”
Damaged wall can result in collapse.
© Jones & Bartlett Learning 61

62. Nonbearing Walls Support only their own weight
Can be breached or removed without compromising structural integrity
Either interior or exterior
© Jones & Bartlett Learning 62

63. Specialized Walls Party walls Common to two properties
Almost always load-bearing
Often a fire wall
Fire walls
Designed to limit horizontal fire spread
Extend from foundation through roof
Constructed of fire-resistant materials 63

64. Specialized Walls Fire-barrier walls
Interior walls that extend from a floor to underside of floor above
Fire separations
Fire-rated assemblies for vertical openings
© Jones & Bartlett Learning. Photographed by Glen E. Ellman. 64

65. Specialized Walls Curtain walls
Nonbearing exterior walls attached to the outside of the building
Often serve as the exterior skin of a steel-framed high- rise building
Courtesy of Glenn Corbett. 65

66. Walls
Wood framing is used to construct walls in most houses and small commercial buildings.
Vertical wooden studs support the walls and partitions inside the building.
Solid, load-bearing masonry walls can reach six stories high; nonbearing masonry walls can reach almost any height.
Modern masonry walls are typically reinforced.
Often used as fire walls 66

67. Doors and Windows Generally have differing functions:
Doors provide entry and exit.
Windows provide light and ventilation.
In an emergency, doors and windows are almost interchangeable. 67

68. Door Assemblies Mostly constructed of wood or metal
Hollow-core wood doors offer little fire resistance.
Solid-core doors provide some fire resistance.
Metal doors are more durable and fire resistant. 68

69. Window Assemblies Used for light, ventilation, entry, and exit
Window type depends on a variety of factors.
Know whether a window type is difficult to open or does not open.
Modern design may make forcible entry more difficult.
© Jones & Bartlett Learning 69

70. Fire Doors and Fire Windows
Constructed to prevent the spread of flames, heat, and smoke
Must meet NFPA 80
Rating includes all items required to operate the door or window as a combined system.
Fire doors must automatically shut.
Courtesy of Securalldoors.com. 70

71. Interior Finishes and Floor Coverings
Exposed interior surfaces of a building
Considerations include
How easily a material will ignite
How quickly a flame will spread
How much energy it will release
How much smoke it will produce
Which components the smoke will contain
Fire fighters should know the hazards posed by different interior finishes.
Most are plastic derived from petroleum products. 71

72. Exterior Finishes and Siding
The outside of buildings may be covered with a wide variety of metals.
Siding may or may not ignite or burn under ordinary circumstances.
Some materials may help prevent fire spread:
Stucco
Brick veneer
Metal, wood, plastic or vinyl siding
Some siding is bonded with insulation
Courtesy of Glenn Corbett. 72

73. Buildings Under Construction or Demolition
Construction or demolition sites pose special problems for fire fighters.
Built-in fire protection features are often missing.
Fire-resistive enclosures can be missing.
These sites often have large quantities of building materials stored close to these buildings, which can add to the fire load.
All of these factors can enhance fire spread, leading to quick structural failure. 73

74. Buildings Under Construction or Demolition
Many fires are inadvertently caused by workers using torches to weld or take apart structures.
Flammable gases and combustible materials might be left where they could add fuel to fire.
Buildings under construction or demolition are often unoccupied for many hours, resulting in delayed discovery and reporting of fires.
In some cases it might prove difficult for fire apparatus to approach the structure or for fire fighters to access working hydrants. 74

75. Building Collapse
Partial or complete building collapse has the potential to kill or injure people.
Courtesy of Glenn Corbett. 75

76. Building Collapse
Each department should have information about the local types of building construction and hazards.
Often obtained through preincident planning
Should be available to fire fighters who are dispatched to an emergency scene.
Should include characteristics of the building that might lead to building collapse. 76

77. Building Collapse
To fully understand the potential for building collapse, you must first understand the forces that act on every building.
Once a collapse begins, the results are unpredictable.
It is important that fire fighters do everything possible to anticipate collapse. 77

78. Signs of Collapse Cracks in walls Leaning walls
Pitched, sagging, or stuck doors
Moaning, groaning, or cracking sounds
Movement or shifting of water on the floor
Smoke pushing through cracks
Lack of water runoff
© monbibi/ShutterStock, Inc. 78

79. Building Collapse: Factors
Environmental
Building occupancy
Existing structural instability
Fire and explosion damage
Lightweight construction
© photoslb/ShutterStock, Inc. 79

80. Preincident Planning and Incident Size-Up
Preincident planning allows fire departments the ability to:
Determine the type of construction 80

81. Preincident Planning and Incident Size-Up
The best way to gather necessary information
Allows personnel to determine the type of building construction and to survey the specific characteristics of that building.
© Steven Townsend/Code 3 Images. 81

82. Preincident Planning and Incident Size-Up
You can document the characteristics of a building before a fire starts
It is not possible to preplan every property in your department.
Keep up with the changes in building construction. 82

83. Summary
It is vital for fire fighters to understand the basic types of building construction and to recognize how it affects fire growth and spread.
Based on a structure’s occupancy classification, a fire fighter can predict who is likely to be inside the building.
Building contents usually are related to the occupancy of the structure. For example, a warehouse is likely to store goods or chemicals. 83

84. Summary
The most commonly used building materials are wood, engineered wood products, masonry, concrete, steel, aluminum, glass, gypsum board, and plastics.
The key factors that affect the behavior of each of these materials under fire conditions are combustibility, thermal conductivity, decrease in strength at elevated temperatures, and thermal expansion when heated. 84

85. Summary
Masonry includes stone, concrete blocks, and brick. It is fire-resistive and a poor conductor of heat. Even so, a masonry structure can cause excessive heat to be held in a building after a fire is extinguished or can collapse under fire conditions if the roof or floor assembly collapses.
Concrete is a fire-resistive material that does not conduct heat well. It often is used to insulate other building materials from fire. 85

86. Summary
Steel is used in the structural framework of buildings. It is strong and resistant to aging, but it is not fire-resistive and conducts heat. The risk of failure of a steel structure depends on the mass of the steel components, the loads placed on them, and the methods used to connect the components. 86

87. Summary
Glass is noncombustible but not fire-resistive. Ordinary glass will usually break when exposed to fire. Tempered glass is stronger and more difficult to break. Laminated glass is likely to crack and remain in place when exposed to fire. Glass blocks have limited strength and are not intended to be used as part of a load- bearing wall. Wired glass incorporates wires that hold the glass together and prevent it from breaking when exposed to heat. 87

88. Summary
Gypsum board is commonly used to cover the interior walls and ceilings of residences. It has limited combustibility and does not conduct or release heat to contribute to fire spread. It may fail if exposed to fire for extended periods.
The most important characteristic of wood is its high combustibility. The rate at which wood ignites, burns, and decomposes depends on several factors: ignition, moisture, density, preheating, and the size and form. 88

89. Summary
Engineered wood products are manufactured from small pieces of wood that are held together with glue or adhesives. Engineered wood products may warp under high humidity and release toxic fumes during a fire.
Wood cannot be treated to make it completely noncombustible, but it can be made to be more difficult to ignite and burn through application of a fire-retardant treatment. 89

90. Summary
Plastics are rarely used for structural support but may be found throughout a building. The combustibility of plastics varies greatly. Many plastics produce quantities of heavy, dense, dark smoke and release high concentrations of toxic gases.
There are five types of building construction: Types I - V 90

91. Summary
Hybrid buildings consist of more than one type of construction. This may occur during initial construction or because of later renovations.
Every building contains the following major components:
Foundation
Floors and ceilings
Roof and trusses
Walls
Doors and windows
Interior and exterior finishes 91

92. Summary
Buildings under construction or demolition often lack fire protection features and present additional hazards to fire fighters.
Factors related to building collapse include the environment, building occupancy, existing structural instability, fire and explosion damage, and lightweight construction. Once a collapse begins, the results are unpredictable.
The preincident plan should contain information on the structure’s type of building construction. 92