0. Building Construction Related to the Fire Service
Chapter 2 — Structural Fire Resistance and Building Classifications

1. Building Construction
Learning Objective 1
Define fire resistance.
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2. Building Construction
Fire Resistance
Function of the properties of all materials used; includes combustibility, thermal conductivity, chemical composition, density, and dimensions
Ability of a structural assembly to maintain load-bearing and structural integrity under fire conditions
(Continued)
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3. Building Construction
Fire Resistance
Ability of walls, partitions, and ceilings to act as a fire barrier
Fire resistance rating
Expressed in hours and fractions of hours
Incorporated into construction classifications and building codes
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4. Building Construction
Learning Objective 2
Discuss methods of determining fire resistance and the limitations of each method.
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5. Determination of Fire Resistance
Conducting standard fire resistance testing in a laboratory
Performing analytical calculations to determine the resistance to a standard fire test exposure
Employing analytical structural fire engineering design methods based on real fire exposure characteristics
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6. Fire Resistance Test Method
Laboratory test is most commonly used method
Component subject to heat of a standard fire in test furnace
Primary points of failure for test
Fire resistance ratings expressed in standard intervals
(Continued)
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7. Fire Resistance Test Method
Factors impacting fire resistance ratings from standard test
Standard fire test evaluates ability of structural assemblies to carry a structural load and act as a fire barrier
Information NOT provided by test
Assemblies may be penetrated
(Continued)
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8. Building Construction
Learning Objective 3
Identify fire testing organizations and discuss the significance of fire test results.
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9. Fire Testing Organizations
Testing for fire resistance ratings is beyond capability of local fire and building departments
Several laboratories are equipped to conduct testing
Some organizations use furnaces primarily for research and product development
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10. Building Construction
Fire Test Results
Published by testing laboratories
Deviation from materials or dimensions specified alters test results
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11. Building Construction
Learning Objective 4
Recognize the role of analysis in determining fire resistance.
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12. Analytical Design Using Real Fire Exposures
NFPA® 251 test
Most commonly used
May be too severe or not severe enough
Ratings determined analytically using a different time-temperature curve must be interpreted cautiously
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13. Noncombustible Materials
Building codes contain explicit criteria for determining combustible material
Incapable of supporting combustion under normal circumstances
Most common test for determining combustibility – ASTM E 136
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14. Building Construction
Learning Objective 5
Discuss the basic building classifications as they relate to fire resistance.
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15. Building Construction
Classifications
Type I, Fire-Resistive
Type II, Noncombustible
Type III, Masonry (Exterior protected)
Type IV, Heavy timber
Type V, Wood frame
(Continued)
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16. Building Construction
Classifications
In building codes, based on materials used in construction and hourly fire resistance ratings required for structural components
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17. Building Construction
Type I Construction
Structural members are noncombustible construction with a specified fire resistance
Combustible material typically permitted in certain components
Most common methods of construction
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18. Building Construction
Type II Construction
Noncombustible – Can be either protected or unprotected
Material other than steel can be used
Building codes allow combustible material similar to that in Type I
(Continued)
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19. Building Construction
Type II Construction
Unprotected, noncombustible building cannot be expected to provide structural stability under fire conditions
Point at which unprotected members will fail depends on several factors
Protected, noncombustible structural fire protection is similar to Type I
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20. Building Construction
Type III Construction
“Ordinary construction”
Exterior walls frequently masonry, but can be any noncombustible material with required fire resistance
Interior members
Partially or wholly combustible
Protected or unprotected
(Continued)
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21. Building Construction
Type III Construction
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22. Building Construction
Type IV Construction
“Mill construction”
Difference from Type III
Used in older factories, mills, and warehouses
Primary fire hazard – Massive amount of fuel from large structural members
Courtesy of McKinney (TX) Fire Department
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23. Building Construction
Type V Construction
All structural components may be combustible
Two subclassifications
Differences from Type III
Threat to adjacent structures if heavily involved in fire
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24. Building Construction
Mixed Construction
Some buildings are allowed a mixed construction type
May result in special challenges for emergency responders
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25. Building Construction
Learning Objective 6
Discuss the concept of fire load and its impact on building construction types.
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26. Building Construction
Fire Load
Maximum heat released if all available fuel in a building was consumed
Product of weight of combustibles multiplied by their heat of combustion
Expressed in lb/sq ft (kg/sq m)
Varies depending on heat of combustion of fuel
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27. Building Construction
Heavy Fire Load
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28. Fire Load and Construction Type
Buildings with combustible structural components have greater fire load than Type I and II
Fire load does not translate into equivalent structural load
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29. Building Construction
Learning Objective 7
Explain occupancy classifications as they relate to fire risks.
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30. Occupancy Classifications
Assign building occupancies into groups with broadly similar fire risks
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31. Building Construction
IBC® Classifications
Group A – Assembly
Group B – Business
Group E – Education
Group F – Factories
Group H – High Hazard
Group I – Institutional
Group M – Mercantile
Group R – Residential
Group S – Storage
Group U – Utility and Misc.
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32. Building Construction
Mixed Occupancies
Buildings may contain more than one occupancy classification
Codes require fire-resistive separations between various occupancies
Requirements depend on local code
Reduction in occupancy separation may be permitted if building is sprinklered
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33. Building Construction
Change of Occupancy
Frequently occurs
Can create problems
May require expensive renovations that owner not willing to pay
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34. Building Construction
Summary
Fire behavior in buildings is determined largely by construction materials and structural fire resistance.
Structural fire resistance is determined most often through laboratory testing.
(Continued)
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35. Building Construction
Summary
Building codes classify construction into types based on construction material, structural fire resistance, and occupancy.
Occupancies within individual occupancy groups present roughly similar fire risk factors.
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36. Building Construction
Review Questions
1. What is fire resistance?
2. What is the value of standard fire tests?
3. What is a noncombustible material?
4. What considerations do firefighters need to take into account when they encounter dropped ceilings?
(Continued)
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37. Building Construction
Review Questions
5. What are the major occupancy classifications contained in the International Building Code® (IBC®)?
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