Building Construction Flashcards
Occupancy
- How bulding is used
- Firefighter can predict who is inside based on occupancy classification
Content
-Some buildings contain things that may be noncombustible, while others contain things that may be very combustible
Combustibility
-Whether or not a material will burn
Thermal Conductivity
-Descirbes how well a material will conduct heat
Thermal Expansion When Heated
-Some materials expand when heated
Steel Thermal Expansion
- 1” per 10’ at 1,000 degrees F
- 50’ section may elongate 4” at 1,000 degrees F
Masonry
- Stone, concrete blocks, brick
- Inherently fire resistive
- Poor conductor of heat, often used for fire wall
- Deteriorates when exposed to fire over time, can collapse
Concrete
- Naturally fire resistive
- Strong under compression
- Weak under tension
- Steel rods used to strengthen under tension, concrete acts as insulator for steel
Spalling
-Steam expanding in concrete because of heat that causes sections to break off
Steel
- Strongest common building material
- Can rust
- Conducts heat well, masonry, concrete, or gypsum often used to insulate from fire
- Bending, sagging, or stretching are considered warning of immediate risk of failure
Aluminum
-Used for siding, window frames, door frames, roof panels
Copper
- Electrical wiring
- Piping
Zinc
-Coating to protect metals from rust/corrosion
Glass
- Non-combustible but not fire resistive
- Ordinary glass will break when exposed to fire
Tempered Glass
- Stronger than ordinary glass
- Shatters into small pieces without sharp edges
Laminated Glass
- Thin sheet of plastic placed between two sheets of glass
- Likely to crack and remain in place when exposed to fire
Glass Blocks
- Limited strength, not load bearing
- Can usually withstand a fire
- Some approved for use with fire rated masonry walls
Wired Glass
- Tempered glass with reinforcing mesh wire
- Wire holds glass together under heat
- Often used in fire doors and windows
Gypsum
- Calcium sulfate and water molecules
- Good insulator, non-combustible
Gypsum Board
- Large sheets of compacted gypsum sandwiched between two layers of paper
- Limited combustibility
- Often used to create firestop
- Will fail over time
- If exposed directly to fire, should be replaced
Wood
- Most commonly used building material
- Fire retardant chemicals weaken wood
Laminated Wood
- Individual pieces of wood glued together
- Produces beams longer and stronger than solid lumber and makes curved beams
Wood Panels
- Thin sheets of wood glued together
- Plywood is most common type
Wooden Trusses
-Pieces of wood or wood/metal combinations used to support floors and roofs
Wooden Beams
- Efficient load-bearing members
- Wooden I-beam or box beam supports same load that solid wood beam could support
Fire-Retardant Wood
- Converts chemicals to h2o and carbon dioxide making a carbon char which insulates wood from fire
- Can reduce strength of the wood
Plastics
- Rarely used for structural supports
- Combustibility varies greatly
- Produce heavy, dense, dark smoke and toxic gases
- Most plastics made from petroleum products
Thermoplastic
-Melts/drips
Thermoset
-Loses strength but does not drip
Balloon-Frame Construction
- Popular between 1800’s-1940’s
- Continuous void spaces
- Prone to 90 degree collapse
Platform-Frame Construction
- Almost all modern wood-frame construction
- No continuous void spaces
- Exterior wall studs not continuous
Foundation
- Transfers weight of building/contents to the ground
- Ensures base of building planted firmly
- Usually concrete or masonry
- Most foundation problems not caused by fire
Dead Load
-Weight of building
Live Load
-Weight of contents
Fire-Resistive Floors
- Prevent fire from spreading vertically
- Concrete common in fire-resistive construction
- Fire can still spread quickly horizontally
Wood-Supported Floors
- Heavy timber can provide huge fuel load, but can also withstand fire for extended time without collapsing
- Conventional wood flooring can burn through in as little as 20 minutes
Pitched Roof
- Sloping or inclined
- Gabel, hip, mansard, and lean-to
- Usually supported by rafters or trusses
Rafters
-Solid wood joists mounted in an inclined position
Curved Roofs
- Buildings that require large, open interiors
- Supported by steel or wood bowstring trusses or arches
Flat Roofs
- Slightly sloped for drainage
- Wood support structure uses solid wood beams and joists
- Lightweight construction uses wood trusses or wood I-beams
- Usually covered in highly combustible materials
Truss
- Prefabricated wood/steel structural component composed of smaller components in a triangular configuration
- Parallel Chord Truss: Flat roof or floors
- Pitched Chord Truss: Sloping/pitched roof
- Bowstring Truss: Curved Roof
Load-Bearing Walls
- Provide structural support
- Supports both dead load and live load, transmitting loads to foundation
- Damaging or removing can cause collapse
- Exterior or interior
Nonbearing Walls
- Support only their own weight
- Can be breached or removed without compromising structure
Party Walls
- Shared line between two properties
- Almost always load bearing
- Often a firewall
Fire Partitions
-Interior walls extending from a floor to the underside of the floor above
Fire Enclosures
-Fire rated assemblies that enclose interior vertical openings, e.g. stairwells, elevator shafts
Curtain Walls
-Nonbearing exterior walls attached to the outside of a building.
Doors
- Entry/Exit, can be light/ventilation
- Most wood or metal
- Fire can usually burn through hollow core in a few minutes
- Metal doors more durable, fire resistant
Windows
-Light/ventilation, can be entry/exit
NFPA 80
-Standard for Fire Doors and Other Opening Protectives
NFPA 80 Designations for Fire Doors and Other Protective Openings
Class A: Openings in fire walls and in walls that divide a single building into fire areas
Class B: Openings in enclosures of vertical communications through buildings and in 2-hour-rated partitions providing horizontal fire separations
Class C: Openings in walls or partitions between rooms and corridors having a fire-resistance rating of 1 hour or less
Class D: Openings in exterior walls subject to severe fire exposure from outside the building
Class E: Openings in exterior walls subject to moderate or light fire exposure from outside the building
Manufactured Housing
- Lightweight building components
- Most parts combustible
- Death rate 3x higher than other single-family homes
Buildings Under Construction
-Particularly dangerous due to the fact that their fire prevention may not be in place.
Axial Load
-Straight Down The Middle
Eccentric Load
-Down and off to the side
Torsional Load
-Twisting
