The "Anatomy & Physiology" Of the Structural Fireground

What type of construction? You may be surprised. An important feature of a pre-incident plan is the classification of building construction. Classifying the type of building should be simple, quick and strategically relevant. The classification of a...


What type of construction? You may be surprised. An important feature of a pre-incident plan is the classification of building construction. Classifying the type of building should be simple, quick and strategically relevant. The classification of a building should capture important strategic...


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  • Type I (442 or 332) — "Shall be those types in which the fire walls, structural elements, walls, arches, floors, and roofs are of approved noncombustible or limited-combustible materials."

    Author comments: This type of construction is referred to as "Fire Resistive." The three-digit numbers refer to hours of fire resistance. The first number of the three-digit series refers to exterior bearing walls; the second number refers to columns, beams, girders, trusses and arches, supporting bearing walls, columns or loads from more than one floor; and the third number refers to floor construction. For example, in a 442 building, columns that support more than one floor must be protected with four hours of fire resistance and the floor assembly with two hours of fire resistance. Of strategic significance is the fact that non-load-bearing walls within a Type I (442) building are not required to have any degree of fire resistance.

  • Type II (222, 111 or 000) — Author comments: The same NFPA 220 description as Type I (above), but as you can see the fire resistance requirements (222, 111 or 000) are less rigorous. This means that unprotected structural components can fail when exposed to high temperatures during a contents fire.
  • Type III (211 or 200) — "Shall be that type in which exterior walls and structural elements that are portions of exterior walls are of approved noncombustible or limited-combustible materials, and in which fire walls, interior structural elements, walls, arches, floors and roofs are entirely or partially of wood of smaller dimensions than required for Type IV construction or are of approved noncombustible, limited-combustible or other approved combustible materials."

    Author comments: Keep things simple: Type III usually features a non-combustible exterior (walls) and a combustible interior (roof and floors).

  • Type IV (2HH) — "Shall be that type in which fire walls, exterior walls, and interior bearing walls and structural elements that are portions of such walls are of approved noncombustible or limited-combustible materials. Other interior structural elements, arches, floors and roofs shall be of solid or laminated wood without concealed spaces and shall comply with the allowable dimensions of 4.5.5."

    Author comments: The letter H represents "heavy timber members." Examples: timber columns supporting a floor must be eight inches in their smallest dimension. However, timber columns supporting a roof are allowed to be somewhat smaller, six inches in their smallest dimension.

  • Type V (111 or 000) — "Shall be that type in which structural elements, walls, arches, floors, and roofs are entirely or partially of wood or other approved material."

    Author comments: In other words, the entire load-bearing structural system can contribute fuel to the fire (burn).

MARK EMERY, EFO, is a shift battalion chief with the Woodinville, WA, Fire & Life Safety District. He is a graduate of the National Fire Academy's Executive Fire Officer program and an NFA instructor specialist. Emery received a bachelor of arts degree from California State University at Long Beach and is a partner with Fire Command Seattle LLC in King County, WA. He may be contacted at fci@usa.com or access his website www.competentcommand.com.

Building Construction Types Cross-Reference (provided for comparison)
NFPA 5000 is the Building Construction and Safety Code
UBC: Uniform Building Code
NBC: National Building Code
SBC: Standard Building Code
IBC: International Building Code
FR: Fire Rated
N: Non-sprinklered
HT: Heavy Timber
UNP: Unprotected
NFPA 5000 I I II II II III III IV V V
(442) (332) (222) (111) (000) (211) (200) (2HH) (111) (000)
UBC I II II II III III IV V V
FR FR 1-hr. N 1-hr. N HT 1-hr. N
NBC 1A 1B 2A 2B 2C 3A 3B 4 5A 5B
SBC I II IV IV V V III VI VI
1-hr. UNP 1-hr. UNP   1-hr. UNP
IBC IA IB IIA IIB IIIA IIIB IV VA VB