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6Building
Construction
6
Objectives (1 of 3)
• Describe the characteristics of the following building materials: masonry, concrete, steel, glass, gypsum board, and wood.
6
Objectives (2 of 3)
• 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.
6
Objectives (3 of 3)
• Describe the function of each of the following building components: foundations, floors, ceilings, roofs, trusses, walls, doors, windows, interior finishes, and floor coverings.
• Describe how each of the five types of building construction react to fire.
6
Introduction (1 of 2)
• Building construction affects how fires grow and spread.– Fire fighters need to understand how each
type of building construction reacts when exposed to the effects of heat.
– Determines when it is safe to enter a burning building and when it is necessary to evacuate
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Introduction (2 of 2)
• Occupancy – How a building is used– Classifications indicate who is likely to be
inside, how many people, and what they are likely to be doing
• Contents – Vary, but usually related to building use
6
Construction Materials
• Key factors affecting combustibility:– Combustibility– Thermal conductivity– Decrease of strength at elevated
temperatures– Thermal expansion when heated
6
Types of Construction Materials
• Masonry
• Concrete
• Steel and other metals
• Glass
• Gypsum board
• Wood
• Plastics
6
Masonry
• Inherently fire-resistive
• Poor conductor• Openings can allow
fire to spread.• With prolonged
exposure to fire, masonry can collapse.
6
Concrete
• Naturally fire-resistive
• Poor conductor of heat
• Strong under compression
• Weak under tension
• Can be damaged through exposure to fire– Spalling
6
Steel (1 of 2)
• 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
6
Steel (2 of 2)
• Expands and loses strength when heated
• Any sign of bending, sagging, or stretching indicates immediate risk of failure.
6
Other Metals
• Aluminum– Siding, window and door frames, and roof
panels– Often melts and drips in fires
• Copper– Primarily used for piping and wiring
• Zinc– Used as a protective coating for metals
6
Glass
• Noncombustible, but not fire-resistive
• Ordinary (nontreated) glass will break when exposed to flame.
6
Gypsum Board
• 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.
6
Wood
• Most common building material
• Highly combustible
• Weakens when heated
• Fire-retardant chemicals can weaken wood.
6
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.
6
Types of Construction
• Type I: Fire-resistive
• Type II: Noncombustible
• Type III: Ordinary
• Type IV: Heavy timber
• Type V: Wood frame
6
Type I: Fire-Resistive (1 of 2)
• All structural components must be noncombustible.
• Used for:– Large numbers of
people– Tall or large area– Special occupancies
6
Type I: Fire-Resistive (2 of 2)
• Building materials should not provide fuel for a fire.
• Steel framing must be protected.
• Fires can be very hot and hard to ventilate.
• In extreme conditions Type I buildings can collapse.
6
Type II: Noncombustible (1 of 2)
• All structural components must be noncombustible.
• Fire-resistive requirements are less stringent than Type I.
6
Type II: Noncombustible (2 of 2)
• Structural components contribute little or no fuel.
• Fire severity is determined by contents.
• Most common in single-story warehouses or factories
6
Type III: Ordinary (1 of 2)
• 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
6
Type III: Ordinary (2 of 2)
• Two separate fire loads:– Contents– Construction materials
• Fire resistance depends on building age and local building codes.
• Exterior walls, floors, and roof are connected.
6
Type IV: Heavy Timber (1 of 2)
• Exterior masonry walls
• Interior structural elements, floors, and roof of wood
6
Type IV: Heavy Timber (2 of 2)
• 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.
6
Type V: Wood Frame (1 of 3)
• Most common type of construction in use
• All major components are wood or other combustible materials.
6
Type V: Wood Frame (2 of 3)
• 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
6
Type V: Wood Frame (3 of 3)
• Balloon-frame construction– Exterior walls
assembled with continuous wood studs.
• Platform-frame construction– Exterior wall studs not
continuous.
6
Building Components
• Foundation
• Floors and ceilings
• Roofs
• Trusses
• Walls
• Doors and windows
• Interior finishes and floor coverings
6
Foundation
• Transfer the weight of the building and its components to the ground
• Ensures building is firmly planted
• Weak or shifting foundations can cause collapse.
6
Floors and Ceilings (1 of 2)
• Fire-resistive floors– Floor–ceiling system
designed to prevent vertical fire spread
– If space above ceiling is not partitioned or sprinklered, fire can quickly extend horizontally across a large area.
6
Floors and Ceilings (2 of 2)
• Wood-supported floors– Heavy-timber floors can often contain a fire
for an hour or more.– Conventional wood flooring burns readily and
can fail in as little as 20 minutes.– Modern, lightweight wood I-beams and
trusses
6
Roofs
• Not designed to be as strong as floors
• Three primary designs:– Pitched roofs– Curved roofs– Flat roofs
6
Pitched Roofs
• Sloped or inclined• Can be gable, hip,
mansard, gambrel, or lean-to
• Usually supported by rafters or trusses
• Require some sort of roof covering
6
Curved Roofs
• Used for large buildings that require large, open interiors
• Usually supported by bowstring trusses or arches
6
Flat Roofs (1 of 2)
• Have a slight slope for drainage
• Wood support structures use solid wood beams and joists.
6
Flat Roofs (2 of 2)
• Open-web steel trusses (bar joists) often used for support
• Most coverings highly combustible
• Ventilation may involve cutting through many layers of roofing.
6
Trusses (1 of 2)
• Triangular geometry creates a strong, rigid structure.
• Usually prefabricated wood or steel
• Three types:– Parallel chord– Pitched chord– Bowstring
6
Trusses (2 of 2)
6
Walls
• Most visible part of a building
• Constructed of a variety of materials
• Walls are:– Load-bearing– Nonbearing– Specialized
6
Load-Bearing Walls
• Provide structural support
• Either interior or exterior
• Support both “dead load” and “live load”
• Damaged wall can result in collapse.
6
Nonbearing Walls
• Support only their own weight
• Can be breached or removed without compromising structural integrity
• Either interior or exterior
6
Specialized Walls (1 of 2)
• Party walls– Common to two properties– Almost always load-bearing– Often a fire wall
• Fire walls– Designed to limit horizontal fire spread– Extend from foundation through roof– Constructed of fire-resistant materials
6
Specialized Walls (2 of 2)
• Fire partitions– Interior walls that extend from a floor to
underside of floor above
• Fire enclosures– Fire-rated assemblies for vertical openings
• Curtain walls– Nonbearing exterior walls attached to the
outside of a building
6
Doors
• Can be used for entry, exit, light, and ventilation
• Mostly constructed of wood or metal– Hollow-core wood doors offer little fire
resistance.– Solid-core doors provide some fire resistance.– Metal doors more durable and fire resistant.
6
Window Assemblies
• Used for light, ventilation, entry, and exit
• Window type depends on a variety of factors.
6
Fire Doors and Fire Windows(1 of 3)
• Constructed to prevent the spread of flames, heat, and smoke
• Must meet NFPA 80
• Labeled according to approved use
6
Fire Doors and Fire Windows(2 of 3)
• Class A• Class B• Class C• Class D• Class E
6
Fire Doors and Fire Windows(3 of 3)
• Fire windows are used when a window is needed in a required fire-resistant wall.
6
Interior Finishesand Floor Coverings
• Finishes and coverings are exposed interior surfaces of a building.
• Different interior finish materials contribute in various ways to a building fire.
6
Manufactured Housing
• Mobile and modular homes
• Lightweight building components
• Most components are combustible
• Death rate in mobile home fires is three times that of other types of single-family homes
6
Buildings Under Construction or Demolition
• Construction or demolition sites pose special problems for fire fighters.
• Built-in fire protection features are often missing.
• Fire-resistive enclosures can be missing.
• Often unoccupied for long periods
6
Preincident Planning and Incident Size-Up (1 of 2)
• Preincident planning allows fire departments the ability to:– Determine the type of
construction
6
Preincident Planning and Incident Size-Up (2 of 2)
• It is not possible to preplan every property– Incident size-up– Learn the general
characteristics of building types in your area
6
Summary (1 of 2)
• Many materials are used in building construction, and each material reacts differently to heat and fire.
• The five types of building construction each have their own strengths and weaknesses and differing levels of resistance to fire.
6
Summary (2 of 2)
• Buildings contain a variety of parts or components. These components are made from several materials, and each react differently to fire.