Saturday, August 10, 2013
VOCATION
TRAINING REPORT
•Building
Construction
•Material
used in construction
Objectives
- Describe the characteristics of the following building materials: masonry, concrete, steel, glass, gypsum board, and wood.
- List the characteristics of each of the following types of building construction: fire-resistive construction, noncombustible construction, ordinary construction, heavy timber construction, and wood-frame construction
- Describe how each of the five types of building construction react to fire.
- Describe the function of each of the following building components: foundations, floors, ceilings, roofs, trusses, walls, doors, windows, interior finishes, and floor coverings
Introduction
•Knowing building construction enables fire fighters to:
–Predict how a fire
will spread
–Make determinations
about structural integrity
–Recognize warning
signs of imminent collaps
•Fire risks also depend on occupancy and contents.
•Occupancy: how a building is used
•Contents: vary, but usually related to building use
Construction
Material Properties and Fire Behavior
•Key factors affecting combustibility:
–Combustibility
–Thermal conductivity
–Loss of strength when
heated
–Rate of thermal
expansion
Types
of Construction Materials
•Masonry
•Concrete
•Steel and other
metals
•Glass
•Gypsum board
•Wood
•Plastics
Masonry
•Inherently fire-resistive
•Poor conductor of heat
•Openings can allow fire to spread.
With prolonged
exposure to fire, masonry can collapse
Concrete
•Inherently fire-resistive
•Poor conductor of heat
•Strong under compression
•Weak under tension
•Can be damaged through exposure to fire
–Spalling
Steel
•Strongest material in common use
•Strong in both compression and tension
•Will rust if exposed to air and moisture
•Not fire-resistive
•Good conductor of heat
•Expands and loses strength when heated
Any sign of bending,
sagging, or stretching indicates immediate risk of failure
Other
Metals
•Aluminum
–Often melts and drips
in fires
•Copper
–Primarily used for
piping and wiring
•Zinc
–Primarily used as a
protective coating for metals
Glass
•Noncombustible, but not fire-resistive
•Ordinary (non-treated) glass will break when exposed to
flame.
Gypsum
Board
•Not a strong
structural material
•Used mainly for
finishing
•Very good insulator
•Limited
combustibility\
–Paper
will burn, but gypsum itself will not.
–Often
used as a firestop
•Prolonged exposure to fire will cause failure.
–Moisture in the
material will
evaporate causing deterioration.\
Wood
•Most common building material
•Highly combustible
•Weakens when heated
•Fire-retardant chemical can weaken wood.
Plastics
•Rarely used for structural support
•Combustibility varies
•Many plastics release dense, toxic smoke when they burn.
•Thermoplastic materials melt and drip.
•Thermoset materials lose strength but will not melt.
Construction
Type Determination
•Classification based
on combustibility and fire resistance
•Codes specify
construction type required based on:
–Height
–Area
–Occupancy
–Location
Types
of Construction
•Type I:
Fire-Resistive
•Type II:
Noncombustible
•Type III:
Ordinary
•Type IV: Heavy
Timber
•Type V: Wood
Frame
Type
I:Fire Resistive
•All structural components must be noncombustible.
•Used for:
–Large numbers of
people
–Tall or large area
–Special occupancies
•Building materials should not provide fuel for a fire.
–Contents may burn but
the building should not.
•Steel framing must be protected.
•Fires can be very hot and hard to ventilate.
•In extreme conditions Type I buildings can collapse.
Type
II: Noncombustible
•All structural components must be noncombustible.
•Fire-resistive requirements are less stringent than Type
I.
•Structural components contribute little or no fuel.
•Fire severity is determined by contents.
•Most common in single-story warehouses or factories
Type
III: Ordinary
•Used in a wide range of buildings
•Masonry exterior walls support floors and roof.
•Usually limited to no more than four stories
•Limited fire resistance requirements
•Two separate fire loads:
–Construction
materials
–Contents
•Fire resistance depends on building age and local
building codes.
•Exterior walls, floors, and roof are connected.
Type
IV: Heavy Timber
•Exterior masonry walls
•Interior structural elements, floors, and roof of wood
•No concealed spaces or voids
•Used for buildings as tall as eight stories
•Open spaces suitable for manufacturing and storage
•New Type IV construction is rare.
Type
V: Wood Frame
•Most common type of construction in use
•All major components are wood or other combustible
materials.
–Can rapidly become
fully involved
–Collapse frequently
•Most common type of construction in use
•Used in buildings of up to four stories
•Wooden I-beams and trusses
–Just strong enough to
carry required load
–No built-in safety
margin
–Collapse early and
suddenly
•Balloon-frame construction
–Exterior walls
assembled with continuous wood studs from the basement to the roof.\
•Platform-frame construction
–Exterior wall studs
not continuous.
