When the type of construction of the building is used in the building code, the
reference is to one of five categories of construction, based on the relative fire
safety of each type. Currently, the classifications of construction types are ranked
on the combustibility of the entire assembly, versus the fire-resistivity of the basic
materials. Note that each type is not specific to a specific material. In actuality,
concrete and steel may be used in any of the types of construction, but the use of wood is
in construction types I and II.
|Types of Construction - 2018
||Assembly Fire Resistivity
|Type I - Non-combustible Fire-Resistive Construction
||Concrete columns, beams and floors
|Type II - Non-Combustible
||Steel columns, beams and decks/floors
|Type III - “Hybrid” Non-Combustible / Combustible
||Concrete tilt-up construction with wood glulam (subdiaphragm) roof
|Type IV - “Heavy Timber”
||6x10 wood beams / 8x8 wood columns / cross-laminated timbers
|Type V - Wood Frame Construction
||Wood or metal stud construction
Type IA and IB - Non-combustible construction (i.e., typically steel or concrete)
requiring high to moderate levels of fire protection. These structures are often
reinforced concrete structures or steel structures with a high degree of fire-resistance
detailing using either concrete encasement or
spray applied fireproofing
Type IIA and IIB - Non-combustible construction requiring either low (“one-hour”) or no
fire-resistant construction. This type of construction is typically heavy steel
construction using moment frames or brace frames as a lateral force resisting system.
Interior partitions are typically framed from light-gauge metal studs. Spray applied
fireproofing systems are often used to provide the requisite fire-resistivity to the
primary and secondary framing systems.
Type IIIA and IIIB - Non-combustible exterior walls with a combustible (i.e., typically
wood-framed) roof requiring either low or no fire resistant construction. Construction
of this type is often either tilt-up warehouse type of construction with a wood
subdiaphragm type roof. Type III construction has also become more common in mid-rise
multifamily construction, using fire-retardant treated wood for exterior wall
Type IV - Heavy Timber and Mass Timber
Type IV - Heavy timber construction with moderate levels of fire-resistant construction
Type IV A/B/C - Mass timber construction, allowing mid-rise and
construction from wood products. These types of construction will be found in the next
edition of the building code, and earlier in some states.
Type V - Combustible
Type VA and VB - Constructed of any allowable material, including wood construction,
with low or no fire-resistant construction. Type V-A requires one-hour fire resistant
construction throughout. Both Type V-A and Type V-B construction is typically
constructed of light-frame wood or metal stud and joist framing. In North America,
these systems are typically platform framed but can be balloon framed as well.
Building Elements within Types of Construction
Each type of construction has assigned to it various
for various building elements, such as structural frame, bearing and nonbearing walls,
floor assemblies, etc. For each type of construction and its subtype, there are minimum
requirements for the hourly fire-resistance rating for each element. Regarding
subtypes, subtype B is generally non-rated construction (except for in Type I) and
subtype B is generally at least one hour rated. It should be mentioned that the ratings
are minimum ratings, and when ratings of a greater value are required elsewhere in the
code, those higher ratings will govern. In addition, as the type of construction
increases, generally the cost of construction will increase as well.
Types of Construction: the relationship to building areas and automatic fire sprinkler systems
The Type of Construction directly affects the amount of allowable floor area that a
building may have.
shows how the allowable floor area varies depending on the sprinkler system installed,
the number of stories the building has and the type of construction assigned. This
table can either be used to analyze if a design correctly:
- Specifies the proper automatic fire sprinkler system based on
If the building is within the
fire area limits
based on the sprinkler system provided for, and
If the correct type of Construction has been assumed for the building.
In addition, the building
tables must also be consulted to similarly verify if the building is within the
allowable heights and number of stories.
If these items are left to verify later into the design, the cost to the budget can be
disastrous if a full redesign of the building is required, because the incorrect Type of
Construction was selected. Alternatively, using these tables in an iterative manner can
be time consuming if the building is not clearly a particular type of construction (such
as a single family home or a tall high rise building).
Types of Construction: Two tools to provide efficiency in design and analysis
UpCodes provides multiple tools for assessing proper types of construction. One tool is
the Construction Type Guide, found in the Project Input page of the code calculators.
This guide will allow you to quickly try a number of different options in regards to
sprinkler types and occupancy groups and areas to see which types of construction would
be candidates for the building in question. If a more detailed analysis is needed, the
building composition of single or mixed occupancy, single or multi-story buildings can
be provided in the project input, and the Guide will show the various types of
construction that may be allowed for that particular building type. Another tool, the
Code Calculators, can provide detailed information about the compliance of a design.
In the following example, a
Group B Occupancy
building of 77,000 square feet with 3 stories and that has a building height of 45 feet
with an NFPA 13 sprinkler system can use any type of construction. However, if the
sprinkler system were to be eliminated, construction types IIB, IIIB, VA or VB could not
History of Types of Construction from the UBC to IBC.
Ever since the early days of the Uniform Building Code, buildings have been classified
as one of five general types of construction to account for the relative fire safety
inherent in various types of construction methods. In the United States, buildings are
generally constructed of one of a few types of materials: concrete, steel, masonry or
wood. While each of these materials with the exception of wood are considered
non-combustible, each material has methods of construction that lend themselves to being
more or less fire-resistant. In the building code, the types of construction are
labeled types 1 through 5, denoted by roman numerals I, II, III, IV and V. The origins
of this is found in the 1927 Uniform Building Code, the first edition of the building
code developed for use on the United States west coast. The original classifications
|Type Of Construction - 1927 UBC
||Structural Element Fire Resistivity
|Type I - Fire-Resistive Construction
|Type II - Heavy Timber Construction
|Type III - Ordinary Masonry Construction
|Type IV - Metal Frame Construction
|Type V - Wood Frame Construction
The types were ranked by overall fire resistivity of the basic materials. Even though
heavy timber is itself a combustible material, while metal frame is not, the inherent
fire-resistivity of a large timber beam or column is much higher than an unprotected
steel beam or column. After the 1949 Uniform Building Code, the types of construction
then started moving to become ordered by combustibility of the material, with new fire
resistivity ratings shown by 1-hour or non-rated sub-categories.
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Please note we’ve used the Wyoming Building Code for the examples above as it shares much in common with many other state and city codes. Please reference your jurisdiction’s codes
for amendments specific to your project.