1. Chapter 9 Ordinary Construction

2. Objectives Understand the details of ordinary construction.
Understand how the structural stability of a masonry wall is compromised.
Identify specific wall and wall component problems.
Recognize collapse indicators.

3. Objectives
Identify the problems associated with interior structural elements.
Identify fire hazards associated with roofs.
Explain how masonry walls and fire doors act as fire barriers.
Understand fire spread through void spaces of ordinary construction.

4. Introduction
Is this chapter primarily concerned with hazards “back East”?
Many of the best examples were taken west of the continental divide.
Learn from the bad experiences of others.

5. Classifying Ordinary Construction
Common characteristic of ordinary construction is exterior walls made of masonry.
Cast-iron front buildings
© Robert Crum/ShutterStock,Inc.

6. Classifying Ordinary Construction
Exterior walls are noncombustible or limited combustible, but the interior floors and walls are made of combustible materials.
Today, the term has multiple meanings.

7. Know the Pronunciation
Masonry (not masonARY)
Lintel (not LENtil)
Spalling (not spalDING)

8. Classification Type III construction
Can be described as “Main Street, USA”
Strip mall with lightweight wood roof trusses and concrete block walls

9. Masonry Walls
May consist of brick, stone, concrete block, terra-cotta tile, adobe, precast, or cast-in-place concrete
Cast-in-place concrete includes different types of concrete.
May or may not be of one material

10. New Load-Bearing Walls
Utilize open cell polystyrene panels
Wood joists are hung from these panels.
Add fire safety problems for fire fighters

11. Fire Limits
Older code provision that would not allow a structure to be built without the use of exterior masonry walls
Wood-frame buildings were banned inside the fire limits.

12. Exclusive Classes
Codes and standards divide buildings into various classes.
Sometimes, what was used was what was available.
Often, little or no thought was given to types of construction.

13. Characteristics of Ordinary Construction
Masonry bearing walls
Wood joists
Roof often similar to the floor in construction
Cockloft
Courtesy of Glenn Corbett.

14. Bearing and Nonbearing Walls
Use similar construction materials
Often identical in appearance
© Kanwarjit Singh Boparai/ShutterStock, Inc.

15. Wood Beam Floor
Wider buildings need a column, girder, and beam system.
Connection systems come in many forms.
Connection weakness creates collapse potential.

16. Void Spaces Inherent part of ordinary construction
Fire protection included embossed metal or tin ceilings.
Ceilings can be fire fighter barriers once fire penetrates the void space.

17. Effective Fire Separation
Not within an ordinary construction building
Often is imperfect or nonexistent in attic spaces

18. Height of Masonry Buildings
Inherent limits
Need to increase the thickness of the wall as the height increases

19. Monadnock Building in Chicago
Tallest old-style masonry-bearing wall building in the United States
15 stories high
Masonry walls at base are several feet thick.
Photo courtesy of David K. Staub.

20. Newer Buildings
High-rise buildings with no wall thicker than 12 inches
Medium-rise brick buildings with no wall thicker than 8 inches

21. Masonry Construction Terms
Adobe
Ashlar masonry
Cantilever wall
Cavity walls
Composite wall
© Photos.com

22. Masonry Construction Terms
Concrete masonry unit (CMU)
Cornice
Coping
Course
Cross wall
Flying buttress
Courtesy of Glenn Corbett.

23. Masonry Construction Terms
Header or bond course
Hollow masonry walls
Masonry columns
Courtesy of Glenn Corbett.

24. Masonry Construction Terms
Parging (or pargetting)
Rubble masonry
Rubble masonry wall
Courtesy of Glenn Corbett.

25. Masonry Construction Terms
Solid masonry walls
Stretcher course
Courtesy of Glenn Corbett.

26. Masonry Construction Terms
Terra-cotta tiles
Unreinforced masonry
Wythe
Courtesy of Glenn Corbett.

27. Renovation and Restoration of Ordinary Construction
Modifications
Most old buildings have undergone extensive modifications.
Modifications usually have a detrimental effect on the fire suppression.

28. Historical Case Example: Brown Merrill Building
1890 fire
Some interior walls on the first floor had been removed.
Iron poles supported the upper floors.
An arch in the basement had been removed.

29. Renovations in Existing Buildings
Result of alterations
One part of a building can be different from another.
Interior alterations and finish can make determining the true nature of the building difficult.
© Stephen Aaron Rees/ShutterStock, Inc.

30. Preservation Undeniable historic value Architectural heritage
Fire safety seems a low priority
Original walls maintained

31. The Owner’s Rights Fundamental right anchored in our legal system
Only clear public danger will force repair or demolition.
Alterations may prove deadly for fire fighters.

32. Fire Resistance Building development is evolutionary.
Piecemeal provisions of fire-resistive features are less than ideal.
Concrete topping creates dead weight.

33. Recent Construction Departs from ordinary construction
Not necessarily an improvement
Noncombustible voids
Lightweight wood trusses and wooden I- beams can contribute to the accumulations of explosive carbon monoxide.

34. Wood Flourishes
Use of flourishes over masonry has left few truly noncombustible buildings.

35. Desire for Wider Spans
Widespread use of unprotected steel for roof framing

36. General Problems of Ordinary Construction
Structural stability of the masonry wall
Stability of the interior column, girder, and beam system
Void spaces
Masonry wall as a barrier to fire extension

37. Discovery of Hazard Indications of building failure
Smoke or water flowing through walls
Soft floors
A small partial collapse
Walls out of plumb
Time since arrival on scene

38. Discovery of Hazard
Key texts
Construction Failures
Building Failures

39. Ordinary Constructed Buildings
In most cities, have been around a long time
Ample opportunity to study buildings and establish preplanned tactics

40. Clues to Disaster Some are evident from the street.
Others require detailed examination.

41. Problems with Types of Walls and Wall Components in Ordinary Construction
Hollow or cavity walls
Limited penetration by rain

42. Problems with Types of Walls and Wall Components in Ordinary Construction
Carbon monoxide could accumulate in the hollow space or cavity and explode disastrously.

43. Sheet or Foamed-In-Place Plastic Insulation
Often placed in hollow walls
Has various ignition characteristics
Produces large quantities of smoke

44. Hollow Walls of Terra-Cotta Tile
Present a special hazard
Exterior and interior wythes connected with steel ties
If wythes move, clay tile has no tensile strength.

45. Masonry Walls Used to be built only of bricks
Now made using concrete block
Uneven settlement
Masonry wire trusses

46. Cast Iron
Cast-iron columns and wrought- or cast- iron arches or lintels
Allowed walls to be made of prefabricated cast-iron sections
Front may separate from side walls.
Columns may transmit fire vertically.

47. Lintels Arches and beams carry the wall above an opening.
The steel “L” lintel is common today.
Steel lintels are tied into the masonry wall.

48. Lintels When heated, they elongate and the masonry can fail.
Wood lintels
© Naomi Marois/ShutterStock, Inc.

49. Imitation Brick Made by spreading a coat of gray concrete on lath
Coat of red concrete is then applied.
Another method is to cement thin slices of brick onto panels of gypsum board.

50. Structural Stability of Exterior Masonry Walls
Little in traditional firefighting training on this subject
Flying bricks are hazardous.
© REUTERS/Chip East/Landov

51. General Collapse Indicators
Inherent structural instability
Failure of a nonmasonry supporting element
Increase in the live load
Collapse of a floor or roof

52. General Collapse Indicators
Impact load of an explosion
Collapse of a masonry unit
Collapse of another building onto the building in question

53. Bricks and Mortar Poorly made bricks deteriorate readily.
Mortar can force masonry out of alignment.
Sand-lime mortar is water-soluble.
Parging may cover brick defects.
Restored buildings are still suspect.
© MitarArt/ShutterStock, Inc.

54. Wood Beams Can carry an amazing load
Construction is not apparent from the exterior.
Heavy masonry walls are carried over openings on wooden beams.
Check basement and attic for clues.

55. Cracks Indicate weakness in a wall Horizontal cracks
Knickerbocker Theater
© zastavkin/ShutterStock, Inc.

56. Arches A brick or stone may fall out of an arch.
If any arch unit is out, there is no arch.

57. Wall Weaknesses All walls are inherently unstable.
Often, front and side walls are designed to brace one another.
Different materials expand and contract at different rates.

58. Wall Weaknesses Stabilization of walls
Holes cut through walls create a serious weakness.
Construction of additional openings should be supervised by a structural engineer.

59. Steel Lintels Used without any protection for the steel
Steel lintels can deform and throw bricks.
Reinforced-concrete lintels are commonly used in masonry walls.
Bottom concrete may spall off, exposing the reinforcing rods.

60. Bracing Can be a sign that a wall is in distress
Braces are not always an indication of instability, especially if used with spreaders in a regular pattern.
Bracing upgrades the earthquake resistance of unreinforced masonry walls.
© tatiana sayig/ShutterStock, Inc.

61. Eccentric Loads Must be counterbalanced
Know what is at the other end of a cantilevered beam.
© Thomas Nord/ShutterStock, Inc.

62. Unvented Voids
Carbon monoxide gas in unvented voids can detonate violently.
Masonry walls are not designed to resist lateral impact loads.

63. Planes of Weakness Floor beams are difficult to level.
Leveling with a wood beam creates a plane of weakness.
Horizontal planes of weakness
Vertical planes of weakness

64. Effects of Interior Structural Elements and Building Contents on an Exterior Wall
Pushing down a wall
Tightly fitted wooden floor beams may act as a series of levers.
Floor beams placed with an upward camber or rise.

65. Effects of Interior Structural Elements and Building Contents on an Exterior Wall
Pushing down a wall (cont’d)
Beams can be corbelled out from the wall.
Be wary of curtain walls.

66. Cause of Wall Collapses
Cold water hitting a hot wall has little effect.
Wooden components are more significant in the collapse.
A heavy stream can penetrate brick veneer.
Heavy streams can rip loosened bricks.
Very heavy streams can smash brick walls.

67. Interior Structural Stability
Interior collapse of an overloaded floor can cause the walls to collapse.
Collapse of an exterior wall may cause an interior collapse.

68. Planning for Collapses
Design connections to permit easy collapse of girders
Design easy collapse of floors to prevent collapse of walls with fire-cut joists
There is opposition to these points of view.

69. Fire-Resistive Combustible Assemblies
Combustible floor and wall assemblies have achieved fire-resistance ratings.
Used to produce code-classified protected combustible structures

70. Interior Structural Support Systems of Columns, Beams, and Girders
Inherent defects
Balloon-frame wall-carrying interior loads
Stone walls and interior walls

71. Interior Structural Support Systems of Columns, Beams, and Girders
Inherent defects (cont’d)
Adjustable steel jack posts
Water pipe used incorrectly
Openings in interior masonry bearing walls
© Boston Globe/Getty Images.

72. Deficiencies of Material
Addition of unprotected steel
Sometimes apparent, but is often fully concealed
Steel bar joists can be installed between each pair of wood joists to strengthen a building.

73. Deficiencies of Material
Wood beams
May be trussed initially or at a later date
Strut or rods may fail first.

74. Connections in Ordinary Construction
Beam-to-girder
Beam-to-beam
Beam-to-column
Cast-iron columns
Interior suspended loads

75. Beam-to-Girder Connections
Set the beams atop the girder
Add height to the walls
Connection methods reduce the size of the wood.
Effective strength is determined by the size of the thinnest portion.

76. Beam-to-Beam Connections
Made when an opening is made in wooden floor
Mortise and tenon joints
Metal joist hangers
Lightweight hangers
© WilliamRobinson/Alamy Images

77. Beam-to-Column Connections
Self-releasing floors
Girders
Dog iron
Transfer beams

78. Cast-Iron Columns Pintles transfer loads of columns on upper floors.
Use of pintles and cast-iron columns can cause a collapse due to unsafe connections.

79. Interior Suspended Loads
Balconies and mezzanines are hazardous.
Interior designers like to hang heavy loads from the overhead.
© iStockphoto/Thinkstock.

80. Floors
When a stairway is relocated, old opening is usually covered over
Closure is lighter than the floor
Opening can cause collapse
Sheet of metal over the opening can also collapse.

81. Light Well
Vertical shaft with windows that provides light and ventilation to enclosed rooms

82. Flooring Construction
Used to consist of subflooring and a finished floor
Now often a single thickness of plywood and carpeting

83. Floor Collapse
Can occur early in the fire

84. Roofs Equipment failure can cost lives, but roof also can fail.
A roof is not designed or constructed as a fire department working platform.

85. Fire Characteristics of Conventional Wood Roofs
Roofs supported on solid sawn rafters and beams
Structural characteristics must be known, not just “type.”
Solid-sawn wood contains “fat” wood.

86. Fire Characteristics of Conventional Wood Roofs
Beam gradually weakens in a fire, and the roof becomes spongy.

87. Roof Hazards Best roof is one in which the roof beams rest on girders.
Hangars or other metal connections make the roof more vulnerable to failure.
Courtesy of Frank Bellina.

88. Roofs Supported on Heavy Wood Beams
Can be much less reliable than they appear
Apparent long beams are often several beams spliced together.

89. Energy Conservation and Rapid Completion
Important considerations in today’s buildings
Foamed plastic is sandwiched between sheets of plywood.
Plastic may melt away in a fire, allowing the roof panel to fall.

90. Making Use of Natural Light
Corrugated glass-fiber-reinforced plastic panels are made to the same dimensions as corrugated steel.
Fire fighter could easily step through the plastic.

91. Ventilation Tactics Can accelerate collapse
No such thing as zero impact

92. Excess Live Loads Can accelerate collapse
Water trapped on a flat roof can cause a collapse.

93. Equipment Often mounted on roofs Grillage is affected by the fire.
Supporting beams should be watched for overheating.

94. Modern Roofs
Have little or no inherent fire resistance to early failure
Typical non-fire-resistive roof has elements that are susceptible to failure.
Additional roofs are built over an original roof, causing additional failure risks.

95. Lightweight Wood Truss Roofs
Case Study: Fire in the gable end of a truss roof restaurant
Heavy equipment had been on the roof.
The construction made the fire impervious to an interior attack.

96. Lightweight Wood Truss Roofs
Case Study: Collapse of a lightweight wood truss church roof in Lake Worth, Texas
Heavy fire involvement of the trussloft led to extremely rapid failure of the trusses.

97. Bowstring Truss Roofs
Name comes from the curved shape of the top chord.
Tied arches
Popular during the mid-20th century
Hackensack, NJ, fire
Courtesy of David G. De Vries/Library of Congress.

98. Treated Plywood Roofs
Builders object to the cost and leakage problems.
Many accepted the use of fire-resistant treated plywood (FRTP) roofing extending to the underside of the roof.
Some chemicals used in FRTP react and deteriorate in ordinary temperatures.

99. Void Spaces
Voids or concealed spaces are an inherent part of buildings of ordinary construction.
Requirements for firestopping may not have existed or may have been ignored.
Major firefighting problem
NFPA 13

100. Interior Sheathing
A protective interior sheathing or finish for a structure contributes to a building’s fire safety.
True as long as the sheathing keeps fire out of the structure

101. Light Smoke Showing A misleading expression
Light smoke often signals a disaster.
Tremendous fire threat can be concealed in voids.

102. Ceiling Spaces
Older buildings have higher ceilings than those built today.
False ceilings conserve heating and cooling.
Lowering the ceiling rarely includes firestopping.
Usual construction methods create a huge three-dimensional void across the ceilings.

103. Joist Spaces
Protected from hose streams by their construction and the ceiling below
Wood truss floors have immeasurably increased this problem.

104. Combustible Gases in Void Spaces
Can provide the fuel for a devastating explosion
Generation of carbon monoxide

105. Large Voids Public buildings often include vast void spaces.
Access for heavy-caliber streams is limited.
Fire-loaded upper floors become inaccessible concealed spaces.
Require sprinkler protection if above first floor

106. Fire Extension
Rarely is provision made to prevent the extension of fire through the stairways and halls.
Often there are many bypasses
Interconnected voids provide fire paths.

107. Interior Walls Balloon-frame construction in older buildings
Masonry walls do load-carrying.
Walls are not carried into attic, creating combustible space.

108. Voids in Mixed Construction
Some buildings are composites of older sections and newer sections.
Any new fire­-resistive addition may be at the mercy of the old building.

109. Cornices and Canopies
Cornice is a structure that tops the wall and projects from it.
Collapse of cornices has caused many fire fighter fatalities and injuries.

110. Cornices and Canopies Coming back into style Sidewalk canopy
Decorative cornices
© iStockphoto/Thinkstock.

111. Fire Barriers Masonry bearing walls as fire barriers
Conditions make a bearing wall less than a fire wall.
If buildings have a 12- or 16-inch unpierced bearing wall, these walls form a barrier to the passage of any fire.

112. Fire Doors
Additional openings are often made without proper protection.
Fire fighters need to be trained to inspect a fire door for proper operation.
Courtesy of Lawrence Doors.

113. Protection from Exposures
Adjacent buildings
Fire coming through the lower roof may extend to the adjacent building.
Burning material may fall out of the upper windows onto the adjacent roof.

114. Protection from Exposures
Windows
Side windows may provide fire path to adjacent building.
Hidden windows may provide a surprise path for fire to travel.

115. Protection from Exposures
Narrow alleys
Present difficult defense problems against exposures
Windows facing the alley are usually protected.
Wired glass is of limited value against radiant heat.

116. Protection from Exposures
Outside sprinklers or spray systems
Installed to protect against exposure fires
Fire department should be fully familiar with their operation.
Courtesy of Tim Scroggins.

117. Party Walls Structural walls that are common to two buildings
Established by mutual contract between the owners
Are thinner than two separate walls

118. Fire-Ground Safety Fire fighter safety is critical.
Set up a Board of Building Review.
Survey major buildings.
Establish time limits for staying in buildings.
Prefire planning helps determine the boundary between building stability and instability.

119. Summary
Ordinary construction describes an almost infinite variety of buildings.
In simpler days, ordinary construction was generally known as brick and wood-joisted construction. Today, this construction uses a variety of walls and interiors.
The chief common characteristic of ordinary construction is that the exterior walls are made of masonry with combustible frame members.
Ordinary construction is classified as Type III construction.
Modifications can have a detrimental effect on the structure.

120. Summary
Many buildings constructed in recent years depart from simple ordinary construction; this is not necessarily an improvement.
In modern construction, a noncombustible void can accumulate explosive carbon monoxide gas as readily as a combustible void.
The problems presented to the fire department by ordinary construction can be divided into:
The structural stability of the masonry wall
Stability of the interior column, girder, and beam system
Void spaces
Masonry wall and fire wall as barriers

121. Summary
Many fire texts cite indications of building failure that may be observed on the fire ground.
The interior structure may push down a wall in several ways.
Fire departments are concerned about equipment because equipment failure can cost lives.
Fire fighter safety at the scene is a critical factor that all departments must face.