This document discusses construction types as defined by building codes. It outlines the five main construction types - Type I (fire-resistant non-combustible), Type II (non-combustible), Type III (combustible exterior/non-combustible interior), Type IV (heavy timber), and Type V (combustible). The construction type determines the building's allowable height, area, and fire resistance of structural elements based on occupancy and materials used. Non-combustible materials like steel and concrete provide the highest fire resistance while combustible wood is the least fire resistant.

1. CONSTRUCTION TYPES

2. CODE ANALYSIS
 Decision on Construction type based on a give
occupancy
 Allowable building area and height per construction type
 Economics and Utility – least costly and complicated
construction allowed by code
 Provide sufficient area for intended use
 Speculative for profit buildings
 Sustainability
 GOAL – maximize allowable height and area given a
construction type

3.  Building elements
 Columns, floor/ceiling systems, interior walls, and
vertical shafts
 Structural elements
 Support the weight of the building

4.  Fire resistance principle based on desire to limit
spread of fire from:
 One building to another
 One area to another
 One floor to another

5.  Codes define construction types by defining the
kinds of materials to be used for building and
construction elements
 Establishes the minimum hourly fire rating of
building elements
 Materials categorized as noncombustible, limited
combustible, and combustible

6.  Fire rating – Hourly fire endurance rating not
fireproof
 Non combustible – ‘material of which no part will
ignite and burn when subjected to fire’ – 1997 UBC
 Masonry, concrete, steel
 Combustible – wood and plastics

7.  A protected – additional covering must be added
to add the fire resistance of the material
 B unprotected – nothing added

9.  Required ratings for specific structural elements may
vary
 Construction types divided into subcategories
 Protected (A) – structural components must have
added fire protective enclosure that adds to the fire
resistance of the material
 Unprotected (B) – no additional treatment or
covering required to be added to the structural
components

10.  Every building must have a construction type
classification
 If even one of the construction type criteria is failed
to be met, it then falls into the next least resistive
category
 Interior project modifications must make sure that
any modifications to the building or structural
elements does not change their construction type
requirements

11.  Use of performance codes may be allowed
 Older buildings where construction type is not easily
determined
 Structural material fire ratings impossible to classify
 Matching existing construction will result in below
standard requirements
 Requires ‘appropriate’ fire resistance for the
structural member, potential exposure to fire, height
and use of the building

12.  Hour fire rating represents length of time material or
assembly must resist fire
 How easily they ignite
 How long they burn once ignited
 How quickly flames spread
 How much heat the material generates
 Higher hour rating indicates noncombustible materials
are required
 Low hour ratings indicates that fire-resistant or limited
combustible materials are allowed (amount may be
limited)

13.  Noncombustible materials – will not ignite, burn,
support combustion, or release flammable vapors
when subject to fire or heat
 ASTME136 Standard Test Method for Behavior of
Materials in a Vertical Tube Furnace at 750
degrees Celsius
 Steel
 Iron
 Concrete
 Masonry

14.  Combustible materials – will ignite and continue to
burn once flame source is removed
 Wood
 Can be chemically treated to achieve some fire
resistance
 Fire-retardant treated wood FRTW
 Fire treated wood can be used in most rated walls
 Can also be used as finish material – trims

15.  Fire resistant if cross section is large enough –
Heavy timber
 Builds a layer of char during a fire that helps
protect the rest of the timber
 Columns 8x8”
 Beams 6x10”

16.  Fire resistant and limited combustible materials can
be used in combination with other materials to
create rated assemblies
 Wood studs with gypsum board on both sides – 1
hour rated wall

17. TYPE I AND II CONSTRUCTION
 Steel and concrete – considered noncombustible
 Difference between types is the required fire rating of the structural
elements
 High rise and large buildings
 Type IA construction – highest level of fire-resistance-rated
construction – passive protection for all elements of the structure
 Type IB – permits reduction of 1 hr. in structural frame and ½ hr. in
roof construction
 Type IIA – allows active or passive protection on all members
 Type IIB – allows unprotected noncombustible building elements
 Combustible materials of limited quantity and used in conditions
where they will not contribute or compromise the resistance of
structural members

18. TYPE III CONSTRUCTION
 Mixed combustible and noncombustible elements
 Exterior is non combustible – masonry
 Interior structural and roof may be wood
 Small office building or urban buildings adjacent to each other
 Type III buildings have mix of combustible and noncombustible
construction – construction type resulted from prevention of
fires between buildings by igniting the exterior walls – interior
allowed to be combustible

19. TYPE IV CONSTRUCTION
 Heavy timber
 No concealed spaces such as soffits, plenums or suspended
ceilings
 Type IV address safety in manufacturing and storage buildings
– exterior walls of noncombustible construction and interior
structure and floors made up of heavy timber members
 No concealed spaces in building elements
 Floor framing minimum nominal thickness 3” and held away
from exterior wall and must have fire blocking

20. TYPE V CONSTRUCTION
 Most combustible
 All wood
 Exterior may be brick veneer, siding or stucco
 Typically small buildings – residential house,
dentist’s office, convenience store
 Allows any material permitted by codes
 Fire resistance is provided by adding fire resistant
materials to encapsulate the structural members

21. EXAMPLE
 You are asked to design an office in a floor of an
existing building
 Before deciding on the rating and materials of
interior walls and ceilings. Identify building
construction type
 Is the frame wood, steel, concrete block or other
masonry?
 What are the exterior walls?
 Are the floors wood or concrete?

22.  It is possible to have two construction types in the same
building
 Construction types must be separated from each other
 Vertical separation – Fire Wall
 Party Wall is similar – shared lot line between two parcels of
land
 Must extend from foundation through the roof to the parapet
 Must remain stable even if one side of the wall collapses during fire
 Horizontal separation – horizontal assembly
 Must extend over the entire floor to the exterior or another
vertical fire wall

23.  Stricter construction types is linked to large
occupancies, thus allowing more evacuation time
 Assembly
 Hazardous
 Institutional

24.  Sustainability requirements
 Steel and concrete – typical structural material
 Steel often made of 100% recyclable content and
recyclable afterwards
 Concrete can be made up of recycled content and
recyclable afterwards
 Wood – renewable material
 Must come from sustainably managed forests

25.  Height and Area of a building limited by
 Occupancy type
 Construction type
 Whether or not building is sprinklered
 Whether there are adjacent buildings