1. Building Construction Related to the Fire Service 4th Edition
Chapter 2 — Building Classifications and Structural Fire Resistance

2. Terminal Objective
Discuss the importance of fire resistance and its impact on building construction and classification types

3. Enabling Objectives
1. Describe building classifications used in the fire service. 2. Explain the function of occupancy classifications. 3. Describe ways that fire and fuel load are determined. 4. Explain methods for determining fire resistance.

4. Building codes classify structures by the materials used in their construction.
Type I – Fire-resistive
Type II – Noncombustible or protected noncombustible
Type III – Exterior protected (masonry)
Type IV – Heavy timber
Type V – Wood frame

5. Indicate degree of occupant safety provided by building’s construction
Building classifications are fundamental from both fire fighting and fire safety standpoints.
Help firefighters determine likelihood of structural collapse under fire conditions
Indicate degree of occupant safety provided by building’s construction

6. Building classifications are fundamental from fire fighting and fire safety standpoints.
Materials used
Fire resistance ratings required for structural components
Classifications in Building Codes Based On
Divided into subclassifications
Except Type IV (heavy timber)
Major Classifications
Type I construction
Highest Fire Resistance Requirements

7. Building classifications are fundamental from fire fighting and fire safety standpoints.
NFPA® 220, Standard on Types of Building Construction ______________
Building classification designated by a three-digit number code
First Digit
Fire resistance rating (in hours) of exterior bearing walls
Second Digit
Fire resistance rating of structural frames or columns and girders that support loads of more than one floor
Third Digit
Fire resistance rating of floor construction

8. Building classifications are fundamental from fire fighting and fire safety standpoints.
International
Building
Code®
Uses construction classifications similar to NFPA® 220
Requirements for individual structural components differ

9. Type I construction (fire-resistive) is classified by the presence of noncombustible structural components.
Fire resistance ratings within a specified range
Construction materials may be supplemented to attain necessary ratings
Addition of fire resistance increases structural integrity during a fire
Fire-resistive compartmentation provided by partitions and floors tends to limit/slow fire spread through a building, allowing time for evacuation and fire fighting

10. Steel is often used to increase the structural strength of concrete.
Type I buildings are most commonly constructed using a protected steel frame or reinforced concrete.
Steel is often used to increase the structural strength of concrete.

11. Contents contribute most of the fuel for a fire in Type I construction
Structural components do not contribute to combustible materials in Type I construction.
Contents contribute most of the fuel for a fire in Type I construction
Fire-resistive components do not contribute to fire extinguishment but do:
Collect heat from the fire
Give off radiant heat

12. Unprotected steel has no fire resistance.
Thickness of insulating material can be adjusted to meet fire ratings
Combination of steel strength and insulation produce a fire-resistive structural assembly
Steel must be protected by insulating material when used in fire-resistive designs

13. Degree of fire resistance will vary with type of concrete assembly
Concrete is an inherently noncombustible material with good thermal insulating properties.
Degree of fire resistance will vary with type of concrete assembly
Reinforced concrete can fail with an explosion or intense fire of long duration

14. Combustible materials that are typically permitted
Building codes usually permit a limited use of combustible materials in Type I construction.
Roof coverings
Interior floor finishes
Interior wall finishes and trims
Doors and door frames
Window sashes and frames
Platforms
Nailing and furring strips
Light-transmitting plastics
Foam plastics subject to restrictions
Combustible materials that are typically permitted

15. Glass and aluminum used with limited structural role
Type II (noncombustible) construction allows a wider range of materials than Type I construction.
Steel
Concrete
Glass and aluminum used with limited structural role
Building codes allow the use of combustible material in Type II construction for applications similar to those in Type I construction

16. Type II (noncombustible)construction allows a wider range of materials than Type I construction.
Some building codes contain a provision to omit fire-resistive rating for roof construction for some occupancy types when the roof is more than 20 feet (6.1 m) above the floor
Can cause a Type II construction building to be classified and inspected as Type I
Courtesy of McKinney (TX) Fire Department

17. Type II buildings can be protected or unprotected.
Require structural components to have one-hour fire resistance
Similar to Type I, but with a lower requirement for fire resistance
Provides a degree of structural fire protection similar to Type I, which will depend on the degree of fire resistance provided
Type II-A (Protected)

18. Type II buildings can be protected or unprotected.
Major structural components have no fire resistance
Use of unprotected steel
Cannot be expected to provide structural stability under fire conditions
Failure of unprotected steel must be anticipated
Speed at which unprotected members will fail depends on ceiling height, size of unprotected steel members, intensity and duration of fire
Type II-B (Unprotected)

19. The use of unprotected steel is the most common characteristic of unprotected construction.
Courtesy of McKinney (TX) Fire Department

20. Frequently masonry construction
Type III construction is commonly referred to as “ordinary construction.”
Exterior Walls
Frequently masonry construction
Any noncombustible material with the required fire resistance can be used
Courtesy of Dave Coombs

21. Type III construction is commonly referred to as “ordinary construction.”
Interior Structural Components Permitted to be Partially or Wholly Combustible
Walls
Columns
Beams
Floors
Roofs

22. Type III construction is commonly referred to as “ordinary construction.”
Two subclassifications for interior structural components
Protected
When required to have a fire rating, can be protected by several means
Unprotected
Unprotected steel is sometimes used to support combustible members

23. Gypsum is an extremely common interior covering.
Type III construction is commonly referred to as “ordinary construction”
Gypsum is an extremely common interior covering.

24. A fundamental fire concern with Type III construction is combustible concealed spaces.
Concealed spaces must contain fire stops
Fire can enter these spaces when:
Openings exist in interior finish materials
Fire has sufficient magnitude to destroy the material
Combustible concealed spaces are created between
Floor and ceiling joists
Studs in partition walls covered with interior finish materials

25. Firefighters cannot assume any level of structural stability where the structural components are combustible.
Combustible materials involved in fire will be consumed and collapse
Without interior supports, exterior masonry walls may collapse

26. Type IV construction is commonly known as heavy-timber or “mill” construction.
Like Type III Construction
Exterior walls are normally of masonry construction
Interior structural components are combustible

27. Important Distinctions Between Type III and IV Construction
Type IV construction is commonly known as heavy-timber or “mill” construction.
Important Distinctions Between Type III and IV Construction
Type IV has beams, columns, floors and roofs made of solid or laminated wood with greater dimensions than in Type III
Concealed spaces not permitted between structural components in Type IV

28. Type IV construction uses a designation of 2HH instead of A and B subdivisions.
Courtesy of McKinney (TX) Fire Department
In Type IV construction, concealed spaces are not permitted between structural members.

29. The structural components of Type IV construction are made of heavy timber.
Type IV uses wood components with greater mass and dimensions than Type III/Type V construction
Greater structural endurance under fire conditions
Slower to ignite and burn
If not exposed to a prolonged fire, may be cleaned of charring and remain in place after a fire

30. The structural components of Type IV construction are made of heavy timber.
Heavy timber components are combustible and ultimately will be consumed in a fire
Exterior masonry walls can become unstable and collapse due to loss of interior bracing
Require minimum nominal dimensions of
6 inch x 10 inch
(150mm x 250 mm)
for floor construction

31. Modern Type IV construction is used primarily for aesthetic purposes.
Not common in new construction for multi-story buildings
Many buildings of this type remain in use
Many buildings built in the 19th/early 20th centuries have been converted to residential use

32. Uses a wood frame to provide primary structural support
Type V construction allows all major structural components to be of combustible construction.
Uses a wood frame to provide primary structural support

33. Type V construction allows all major structural components to be of combustible construction.
Many Type V structures are required to have a 1-hour fire resistance for structural components
Plaster and fire-rated gypsum board typically provide enough protection

34. Type V construction allows all major structural components to be of combustible construction.
Limitations of Type V Construction
Presence of extensive concealed voids
Can become totally involved and completely destroyed in a fire
Heavily involved wood-frame building presents an exposure threat to adjacent structures
Building codes impose restrictions on maximum heights/areas and may require a separation distance between building and property line

35. Several different methods can be used to construct a Type V building.
In modern practice, Type V is most often constructed using light-frame construction
1830’s introduced in U.S.
Eliminated heavy posts and beams
Made use of smaller studs, joists, and rafters
Permitted a building to be erected faster and cheaper

36. Mixed construction occurs when a new structure is built on an existing structure of a different construction type.
Mixed structures may present special challenges for emergency responders

37. REVIEW QUESTION
What are the five basic building classifications used to classify structures by the materials used in their construction?

38. Building construction and occupancy classifications are used together in building codes.
Establish limitations on permissible heights and open areas of buildings
Reflect life safety issues inherent to specific types of occupancies
Facilitates the administration of a code
Allows for the use of less cumbersome language
Assign building occupancies into groups with broadly similar fire risks

39. International Building Code® (IBC®) Occupancy Classifications
Building codes group building occupancies into occupancy classifications.
Ten major occupancy classifications is a relatively small number to group all the potential uses for a building
26 Subgroups
International Building Code® (IBC®) Occupancy Classifications
Assembly Group A
Business Group B
Educational Group E
Factories Group F
High Hazard Group H
Institutional Group I
Mercantile Group M
Residential group R
Storage Group S
Utility/Miscellaneous Group U

40. Considerable variation of hazards can exist within the International Building Code® classifications.
Courtesy of McKinney (TX) Fire Department
A parking garage with noncombustible construction may shelter combustible materials, which would alter the hazards within the space.

41. NOTE
The IBC® also separately addresses one- and two-family dwellings not more than three stories high. Although these buildings are classified as R in the IBC®, they are governed by a separate code, the International Residential Code (IRC).

42. NFPA® 5000 and NFPA® 101 identify 12 major occupancy classifications.
NFPA® Occupancy Classifications
Assembly
Educational
Day care
Health care
Ambulatory health care
Detention and correctional
Residential
Residential board and care
Mercantile
Business
Industrial
Storage

43. Required separations can range from 1-3 hours
Buildings frequently contain occupants that represent more than one occupancy classification.
Building codes may require fire-resistive separations between various occupancies
Specific requirements for occupancy separation will depend on the local building code
Required separations can range from 1-3 hours
May permit reduction in required occupancy separation, if a building is sprinklered
Different occupancies present different types and levels of hazards to each other

44. Buildings frequently undergo a change in occupancy.
A change of occupancy can create serious problems when safety features required by the new occupancy are not fully implemented

45. REVIEW QUESTION
What is the purpose of occupancy classifications?

46. Fuel load is a critical factor when determining the fire safety requirements of a space.
Total quantity of combustible material in a compartment
Contributes to the calculation of the fire load
Fuel Load
Maximum amount of heat that can be released if all fuel is consumed
Will vary depending on the heat of combustion of the fuel load
Fire Load

47. Expressed in pounds per square foot (kg/m²)
Fire load is the product of the weight of the combustibles multiplied by their heat of combustion.
Expressed in pounds per square foot (kg/m²)
Used as an estimate of total potential heat release or thermal energy to which a building may be subjected if all combustibles become fully involved in fire
Buildings with combustible structural components have a greater fire load

48. A variety of materials are used in building construction
The difference between noncombustible products and materials that support combustion must be clearly established.
A variety of materials are used in building construction
Especially important when materials are used in combination or treated to alter their properties

49. The International Building Code® definition of a combustible material
Building codes contain explicit criteria for determining what constitutes a combustible material.
The International Building Code® definition of a combustible material
“In the form in which used and under the conditions anticipated, will not ignite, burn, support combustion, or release flammable vapors, when subjected to fire or heat”
ASTM E 136, Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750°C
Most commonly used test for determining combustibility

50. Rate at Which Fuel Burns
A fire load may not directly translate into an equivalent structural load.
Fire Load
Rate at Which Fuel Burns
Severity of a Fire

51. A fire load may not directly translate into an equivalent structural load.
Faster the available fuel burns
Greater the heat release rate (HRR)
Greater release rate results in a faster developing fire

52. Resulting in a higher heat release rate
A fire load may not directly translate into an equivalent structural load.
Materials that have a high exposure surface to oxygen will burn more rapidly
Resulting in a higher heat release rate

53. REVIEW QUESTION
What is the purpose of occupancy classifications?

54. Fire resistance describes several properties of a material.
Combustibility
Thermal Conductivity
Chemical Composition
Density
Dimensions

55. Fire-resistive construction is not prone to structural failure under fire conditions.
In the case of walls, partitions, and ceilings, means the ability to act as a barrier to fire
Fire resistance indicates the ability of a structural assembly to maintain its load-bearing capacity and structural integrity under fire conditions

56. The fire resistance rating can be evaluated quantitatively.
Expressed in units of time (hours)
Fire resistance ratings in building codes include minimum requirements for structural components

57. Other Methods of Determining Fire Resistance
Laboratory testing is the most common method used to determine fire resistance.
Standard Test ASTM E-119
Also known as NFPA® 251, Standard Method of Tests of fire Endurance of Building Construction and Materials
Other Methods of Determining Fire Resistance
Mathematical models based on data collected during nonstandard testing
Statistical data to determine probability of fire resistance based on standard test results

58. Earliest Known Fire Tests on Building Materials
Laboratory testing is the most common method used to determine fire resistance.
Earliest Known Fire Tests on Building Materials
Germany
United States
Denver, CO 1890
New York City, 1896

59. The ASTM-119 fire-resistance test is used to establish required performance standards in building codes.
Component is subjected to the heat of a fire regulated to maintain a standard temperature in a laboratory test furnace
Temperature in the test furnace is raised along a time scale

60. Test results are classified
The fire resistance of structural systems is affected by the manner in which they are used in the field.
Test results are classified
Load bearing
Nonload bearing
In the test, structural components are loaded to approximate expected working stresses in the design
Before the test, the company testing its materials ensure that the item is properly aligned and placed for best results.

61. The fire resistance of structural systems is affected by the manner in which they are used in the field.
End restraints affect the extent to which an assembly may expand or rotate at its ends when exposed to high temperatures, affecting its ability to support a load
Fire resistance ratings are developed for restrained and unrestrained floor and ceiling assemblies

62. The fire resistance test continues until the specimen fails or the required time reached.
Assemblies are not normally tested beyond four hours — the maximum time the building code requires
During the test, sensors indicate the temperature on the nonexposed side of the door.

63. The failure criteria are specific to the specimen being tested.
Primary Points of Failure
Failure to support an applied load
Temperature increase on the unexposed side of wall, floor, and roof assemblies of 250°F (121°C) above ambient temperatures
Passage of heat or flame through the assembly sufficient to ignite cotton waste
Excess temperature on steel members

64. NOTE
The failure point temperature of steel will depend on the application of the component. Other factors include maximum temperatures indicated for identified points in the assembly, and the average overall temperature.

65. Certain wall, partition and door assemblies are subjected to the application of a hose stream.
Duplicates the impact and thermal shock of water that may occur during firefighting operations during a prolonged fire

66. Number is rounded down to the nearest interval
An assembly may fail at any time during the test for any number of reasons.
For more accurate and useful data, fire resistance ratings for test specimens are expressed in standard intervals
- 15 minutes
- 30 minutes
- 45 minutes
- 1 hour
- 1 ½ hours
- 2 hours
- 3 hours
- 4 hours
Number is rounded down to the nearest interval

67. Fire resistance ratings are established using a standardized laboratory test fire.
In uncontrolled conditions, rated assemblies may perform satisfactorily for longer or shorter periods of time than in laboratory conditions due to:
Workmanship
Variation in materials from test specimens
Specific conditions used during testing

68. Specific conditions and limitations of laboratory testing may affect fire resistance ratings.
Standard time-temperature curve maintained in laboratory may not duplicate uncontrolled fires
Laboratory size restrictions do not permit testing entire buildings
Behavior of identical materials or assemblies in larger configurations may be different because of the effects of thermal expansion in larger members

69. The E-119 test is the only standardized test method currently universally accepted by building codes.
The use of fire ratings developed over the years has contributed significantly to:
Safety of individual buildings
Fire safety of communities

70. The standard test evaluates the ability of assemblies to carry a structural load and to act as a fire barrier.
Does NOT Provide
Information about performance of assemblies constructed with components or lengths other than those tested
Evaluation of the extent to which the assembly may generate smoke, toxic gases, or other products of combustion
Measurement of the degree of control or limitation of the passage of smoke or products of combustion

71. The standard test evaluates the ability of assemblies to carry a structural load and to act as a fire barrier.
Does NOT Provide
Measurement of flame spread over the surface of tested material
Effect on fire endurance of openings in an assembly such as electrical outlets and plumbing openings, unless specifically provided for in the construction tested
Fire behavior of joints between building elements

72. Another limitation of E-119 is when the continuity of an assembly is destroyed, it cannot function as a fire barrier.
Over time, particularly during renovation, fire-resistive assemblies may be penetrated and not adequately fire-stopped
Ductwork
Plumbing
Electrical
Communication

73. Testing laboratories use very large furnaces with high temperatures to determine fire resistance ratings.
Certified laboratories have equipment that is unavailable to local fire and building departments.

74. Many organizations perform fire-resistance testing.
Underwriters Laboratories
Underwriters Laboratories of Canada
Building Research Division of the National Research Council of Canada
Southwest Research Institute
Intertek Testing
University of California at Berkeley
Armstrong Cork Company
National Gypsum Company

75. Testing laboratories publish results of fire-resistance testing.
Underwriters Laboratories
Annual Fire Resistance Directory
lists tested assemblies and
resistance ratings
Any deviation from the materials or dimensions specified will alter the test results
Field inspections must enforce correct conditions to ensure performance of assemblies

76. Mathematical equations have been developed to predict the behavior of materials under test conditions.
No need for direct testing
Testing materials in a furnace is costly
Structural members may not match those previously tested
Equations have evolved into models that utilize mechanical and thermal properties of materials at high temperatures

77. The most common method used to satisfy building code requirements for structural fire-resistance is NFPA® 251.
Standard time-temperature curve may not reflect conditions in an uncontrolled structure fire
Updates to testing methodology include calculations of fire resistance based on a time-temperature curve that reflects a more realistic fire occurrence for a given set of circumstances
In some cases, this will be a less severe fire exposure than provided in NFPA® 251
Fire-resistance ratings determined analytically using a different time- temperature curve must be interpreted cautiously

78. Fire resistance of structural elements can be calculated using standard ASCE/SFPE 29.
In 1997, American Society of Civil Engineers (ASCE) and the Society of Fire Protection Engineers (SFPE) jointly developed
ASCE/SFPE 29, Standard Calculation Methods for Structural Fire Protection
Provides methods for calculating fire resistance ratings that are equivalent to the results obtained from the standard fire test

79. Fire resistance of structural elements can be calculated using standard ASCE/SFPE 29.
These methods may not provide accurate results when applied to materials that have not been used in the actual tests
These calculation methods are limited to use with the following materials:
Structural steel
Plain and reinforced concrete
Timber and wood
Concrete masonry
Clay masonry

80. Fire endurance can be calculated in minutes using standard units.
Fire Endurance (Standard Units): R = {[(C1 x M) + C2] x I} ÷D
R = Fire endurance in minutes
M = Mass of the member in lbs/ft
D = Heated perimeter in inches
I = Thickness of protection in inches
C1 = 1200 ÷ r, r is the insulating material density in pounds per cubic foot
C2 = 30 for low-density insulating materials such as mineral fibers, vermiculite, and perlite
(C1 and C2 are constants that are empirically derived for the insulating units and are the same for U.S. and metric units)

81. Fire endurance can be calculated in minutes using metric units.
Fire Endurance (Metric Units):
R = {[(0.672 x C1 x M) + (0.039 x C2)] x I} ÷ D
R = Fire endurance in minutes
M = Mass of the member in lbs/ft
D = Heated perimeter in inches
I = Thickness of protection in inches
C1 = 1200 ÷ r, r is the insulating material density in pounds per cubic foot
C2 = 30 for low-density insulating materials such as mineral fibers, vermiculite, and perlite
(C1 and C2 are constants that are empirically derived for the insulating units and are the same for U.S. and metric units)

82. REVIEW QUESTION
What methods are used to determine and calculate fire resistance of building materials?

83. Summary
Depending on the construction material used and the structural fire resistance, building codes classify construction into major types.
Building codes also classify buildings according to the occupancy and how many people are inside, as well as how the building is being used.

84. Summary
Occupancies within the individual occupancy groups present roughly similar fire risk factors.
The fire behavior in a building is largely determined by the building’s materials and fire resistance.

85. Summary
The structural fire resistance of building components is determined most often through laboratory testing.

86. Building Construction Related to the Fire Service 4th Edition
Chapter 2 — Building Classifications and Structural Fire Resistance