Annex E Types of Construction
This informative annex is not a part of the requirements of this NFPA document but is included for informational purposes only.
Table E.1 contains the fire resistance rating, in hours, for Types I through V construction. The five different types of construction can be summarized briefly as follows (see also Table E.2):
Type I is a fire-resistive construction type. All structural elements and most interior elements are required to be noncombustible. Interior, nonbearing partitions are permitted to be 1 or 2 hour rated. For nearly all occupancy types, Type I construction can be of unlimited height.
Type II construction has three categories: fire-resistive, one- hour rated, and non-rated. The number of stories permitted for multifamily dwellings varies from two for non-rated and four for one-hour rated to 12 for fire-resistive construction.
Type III construction has two categories: one-hour rated and non-rated. Both categories require the structural framework and exterior walls to be of noncombustible material. One-hour
rated construction requires all interior partitions to be one- hour rated. Non-rated construction allows nonbearing interior partitions to be of non-rated construction. The maximum permitted number of stories for multifamily dwellings and other structures is two for non-rated and four for one-hour rated.
Type IV is a single construction category that provides for heavy timber construction. Both the structural framework and the exterior walls are required to be noncombustible except that wood members of certain minimum sizes are allowed. This construction type is seldom used for multifamily dwellings but, if used, would be permitted to be four stories high.
Type V construction has two categories: one-hour rated and non-rated. One-hour rated construction requires a minimum of one-hour rated construction throughout the building. Non- rated construction allows non-rated interior partitions with certain restrictions. The maximum permitted number of stories for multifamily dwellings and other structures is two for non- rated and three for one-hour rated.
Table E.1 Fire Resistance Ratings for Type I Through Type V Construction (hr)
| Type I | Type II | Type III | Type IV | Type V | ||||||
| 442 | 332 | 222 | 111 | 000 | 211 | 200 | 2HH | 111 | 000 | |
| Exterior Bearing Walls aSupporting more than one floor, columns, or other bearing wallsSupporting one floor only Supporting a roof only | 4 | 3 | 2 | 1 | 0b | 2 | 2 | 2 | 1 | 0b |
| 44 | 33 | 21 | 11 | 0b 0b | 22 | 22 | 22 | 11 | 0b 0b | |
| Interior Bearing WallsSupporting more than one floor, columns, or other bearing wallsSupporting one floor only Supporting roofs only | 4 | 3 | 2 | 1 | 0 | 1 | 0 | 2 | 1 | 0 |
| 33 | 22 | 21 | 11 | 00 | 11 | 00 | 11 | 11 | 00 | |
| ColumnsSupporting more than one floor, columns, or other bearing wallsSupporting one floor only Supporting roofs only | 4 | 3 | 2 | 1 | 0 | 1 | 0 | H | 1 | 0 |
| 33 | 22 | 21 | 11 | 00 | 11 | 00 | H H | 11 | 00 | |
| Beams, Girders, Trusses, and ArchesSupporting more than one floor, columns, or other bearing wallsSupporting one floor only Supporting roofs only | 4 | 3 | 2 | 1 | 0 | 1 | 0 | H | 1 | 0 |
| 22 | 22 | 21 | 11 | 00 | 11 | 00 | H H | 11 | 00 | |
| Floor/Ceiling Assemblies | 2 | 2 | 2 | 1 | 0 | 1 | 0 | H | 1 | 0 |
| Roof/Ceiling Assemblies | 2 | 11∕2 | 1 | 1 | 0 | 1 | 0 | H | 1 | 0 |
| Interior Nonbearing Walls | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Exterior Nonbearing Walls c | 0b | 0b | 0b | 0b | 0b | 0b | 0b | 0b | 0b | 0b |
Source: Table 7.2.1.1 from NFPA 5000, Building Construction and Safety Code, 2012 edition. H: Heavy timber members.
aSee 7.3.2.1 in NFPA 5000.
bSee Section 7.3 in NFPA 5000.
cSee 7.2.3.2.12, 7.2.4.2.3, and 7.2.5.6.8 in NFPA 5000.
INFORMATIVE ANNEX E Annex E: Construction Types
Table E.2 Maximum Number of Stories for Types V, IV, and III Construction
Maximum Number of
In Table E.1 the system of designating types of construction also includes a specific breakdown of the types of construction through the use of arabic numbers. These arabic numbers follow the roman numeral notation where identifying a type of
Construction Type
Stories Permitted
construction [for example, Type I(442), Type II(111), Type III(200)] and indicate the fire resistance rating require‐
V Non-rated 2
V Non-rated, Sprinklered 3
V One-Hour Rated 3
V One-Hour Rated, Sprinklered 4
IV Heavy Timber 4
IV Heavy Timber, Sprinklered 5
III Non-rated 2
III Non-rated, Sprinklered 3
III One-Hour Rated 4
III One-Hour Rated, Sprinklered 5
Table E.3 Cross-Reference of Building Construction Types
ments for certain structural elements as follows:
- First arabic number — exterior bearing walls
- Second arabic number — columns, beams, girders, trusses and arches, supporting bearing walls, columns, or loads from more than one floor
- Third arabic number — floor constructionTable E.3 provides a comparison of the types of construction for various model building codes. [ 5000 : A.7.2.1.1]
NFPA 5000I (442)I (332)II (222)II (111)II (000)III (211)III (200)IV (2HH)V (111)V (000)UBC—I FRII FRII 1 hrII NIII 1 hrIII NIV HTV 1 hrV NB/NBC1A1B2A2B2C3A3B45A5BSBCIII—IV 1 hrIV UNPV 1 hrV UNPIIIVI 1 hrVI UNPIBC—IAIBIIAIIBIIIAIIIBIVVAVBSource: Table A.7.2.1.1 from NFPA 5000, Building Construction and Safety Code, 2012 edition. UBC: Uniform Building Code.FR: Fire rated.N: Nonsprinklered.HT: Heavy timber.B/NBC: National Building Code. SBC: Standard Building Code.UNP: Unprotected.IBC: International Building Code.
Informative Annex F Availability and Reliability for Critical Operations Power Systems; and Development and Implementation of Functional Performance Tests (FPTs) for Critical Operations Power Systems
This informative annex is not a part of the requirements of this NFPA document but is included for informational purposes only.- Availability and Reliability for Critical Operations Power Systems. Critical operations power systems may support facili‐ ties with a variety of objectives that are vital to public safety. Often these objectives are of such critical importance that system downtime is costly in terms of economic losses, loss of security, or loss of mission. For those reasons, the availability of the critical operations power system, the percentage of time that the system is in service, is important to those facilities. Given a specified level of availability, the reliability and main‐ tainability requirements are then derived based on that availa‐ bility requirement.Availability. Availability is defined as the percentage of time that a system is available to perform its function(s). Availability is measured in a variety of ways, including the following:(3) The logistics provided to support maintenance of the system. The number and availability of spares, mainte‐ nance personnel, and other logistics resources (refueling, etc.) combined with the system’s level of maintainability determine the total downtime following a system failure.Reliability. Reliability is concerned with the probability and frequency of failures (or lack of failures). A commonly used measure of reliability for repairable systems is MTBF. The equivalent measure for nonrepairable items is MTTF. Reliabil‐ ity is more accurately expressed as a probability over a given duration of time, cycles, or other parameter. For example, the reliability of a power plant might be stated as 95 percent proba‐ bility of no failure over a 1000-hour operating period while generating a certain level of power. Reliability is usually defined in two ways (the electrical power industry has historically not used these definitions):
- The duration or probability of failure-free performance
where:Availability MTBF MTBF MTTRunder stated conditions - The probability that an item can perform its intended function for a specified interval under stated conditions [For nonredundant items, this is equivalent to the
Availability Hours of Downtime*
0.9 876
0.99 87.6
0.999 8.76
0.9999 0.876
0.99999 0.0876
0.999999 0.00876
0.9999999 0.000876*Based on a year of 8760 hours.
Availability of a system in actual operations is determined by the following:- The frequency of occurrence of failures. Failures may prevent the system from performing its function or may cause a degraded effect on system operation. Frequency of failures is directly related to the system’s level of relia‐ bility.
- The time required to restore operations following a system failure or the time required to perform mainte‐ nance to prevent a failure. These times are determined in part by the system’s level of maintainability.preceding definition (1). For redundant items this is equivalent to the definition of mission reliability.]Maintainability. Maintainability is a measure of how quickly and economically failures can be prevented through preventive maintenance, or system operation can be restored following failure through corrective maintenance. A commonly used measure of maintainability in terms of corrective maintenance is the mean time to repair (MTTR). Maintainability is not the same thing as maintenance. It is a design parameter, while maintenance consists of actions to correct or prevent a failure event.Improving Availability. The appropriate methods to use for improving availability depend on whether the facility is being designed or is already in use. For both cases, a reliability/availa‐ bility analysis should be performed to determine the availability of the old system or proposed new system in order to ascertain the hours of downtime (see the preceding table). The AHJ or government agency should dictate how much downtime is acceptable.Existing facilities: For a facility that is being operated, two basic methods are available for improving availability when the current level of availability is unacceptable: (1) Selectively adding redundant units (e.g., generators, chillers, fuel supply) to eliminate sources of single-point failure, and (2) optimizing maintenance using a reliability-centered maintenance (RCM) approach to minimize downtime. [Refer to NFPA 70B-2010, Recommended Practice for Electrical Equipment Maintenance.] A combination of the previous two methods can also be imple‐ mented. A third very expensive method is to redesign subsys‐ tems or to replace components and subsystems with higher reliability items. [Refer to NFPA 70B.]New facilities: The opportunity for high availability and relia‐ bility is greatest when designing a new facility. By applying an
- The duration or probability of failure-free performance
- Availability and Reliability for Critical Operations Power Systems. Critical operations power systems may support facili‐ ties with a variety of objectives that are vital to public safety. Often these objectives are of such critical importance that system downtime is costly in terms of economic losses, loss of security, or loss of mission. For those reasons, the availability of the critical operations power system, the percentage of time that the system is in service, is important to those facilities. Given a specified level of availability, the reliability and main‐ tainability requirements are then derived based on that availa‐ bility requirement.Availability. Availability is defined as the percentage of time that a system is available to perform its function(s). Availability is measured in a variety of ways, including the following:(3) The logistics provided to support maintenance of the system. The number and availability of spares, mainte‐ nance personnel, and other logistics resources (refueling, etc.) combined with the system’s level of maintainability determine the total downtime following a system failure.Reliability. Reliability is concerned with the probability and frequency of failures (or lack of failures). A commonly used measure of reliability for repairable systems is MTBF. The equivalent measure for nonrepairable items is MTTF. Reliabil‐ ity is more accurately expressed as a probability over a given duration of time, cycles, or other parameter. For example, the reliability of a power plant might be stated as 95 percent proba‐ bility of no failure over a 1000-hour operating period while generating a certain level of power. Reliability is usually defined in two ways (the electrical power industry has historically not used these definitions):