Building Construction Flashcards
NFPA # for Building Construction
NFPA Standard 220
Building Construction Types
Types 1-5
Type 1
Fire-resistive
Type 2
Noncombustible or limited combustible
Type 3
Ordinary construction
Type 4
Heavy timber
Type 5
Wood frame
Type 1 443 (numbers after #1 mean what?)
First number is hours resistant to fire (i.e. 4 hours) of EXTERIOR bearing walls
Second number is the fire resistance rating of STRUCTURAL frames/columns
Third number is the fire resistance rating for the FLOOR construction
Examples of Type 1 Construction
High-rises, jails/prisons, hospitals (protected steel infrastructure)
Type 1 Strengths
- Resists direct flame impingement
- Confines fire well
- Little collapse potential (from fire effect alone)
- Impervious to water damage
Type 1 Weaknesses
- Difficult to breach
- Difficult to ventilate
- Massive amounts of debris
- Floors, ceilings, walls retain heat
Type 2 make-up
Unprotected steel is most common characteristic
Materials with no fire-resistance ratings (i.e. untreated wood) may be used in small quantities
Open-web bar joist is very common w/ type 2
Examples of Type 2 Construction
Warehouses, restaurants, etc. (Walmart, malls, mechanic shop)
Type 2 Strengths
- Almost as fire resistive as Type 1
- Confines fire well
- Almost as structurally stable as Type 1
- Easier to vertically ventilate than Type 1
Type 2 Weaknesses
- Difficult to breach for access/escape
- Unprotected steel structure components can fail due to high heat
- Roof systems are less stable than Type 1
- Steel components may weaken by fire
- May weaken by rust or corrosion
- Massive debris following collapse
Type 3
Ordinary construction
May also be called brick and joist
Type 3 make-up
- Exterior walls and structural members made up of noncombustible or limited combustible material
- Interior walls, beams, floors, and roof are made completely or partially of small-dimension wood
Type 3 primary fire hazard
Smoke and fire spread through concealed spaces (i.e. cockloft or suspended ceiling) VOID SPACES
Type 4
Heavy timber
Rarely used today other than churches (used to be warehouses, mills, etc.)
Type 4 Primary Fire Hazards
- Massive amounts of combustible materials
- Heavy timbers remain stable for a long period under fire conditions
Type 5
Wood-frame construction aka residential (also lots of restaurants and convenient stores)
Type 5 makeup
Small-dimension wood and other materials (commonly used in single-family residence)
Balloon wood-frame vs. Platform wood-frame
Balloon is older victorian-style homes w/o firebreak (fire spreads very quickly) vs. Platform wood-frame is more modern construction, one floor built at a time with a firebreak in-between floors (slows down spread of fire)
Type 5 Primary Fire Hazards
- Almost unlimited potential for fire extension w/in a structure
- Fire extension to nearby structures
- Fire extension from doors and windows to exterior structure
Fire Conditions on wood factors
- Size of wood
- Moisture content
- Smaller pieces of wood may be protected by drywall to increase their fire-resistance
Fire conditions on wood (types of wood)
- Green wood does NOT burn as fast as dried/cured wood
- Wood impregnated w/ fire retardant material does NOT burn as fast as untreated wood
Fire conditions on masonry factors
- Bricks rarely show signs of loss of integrity/deterioration
- Stones may spall
NFPA Standard
NFPA Standard 220 covers Types of Building Construction
Construction Classifications dictated by…
Architect, Structural Engineer, and/or Contractor
Type 1 Primary Fire Hazards (Fire-resistive)
Contents of structure (because structure is fire-resistive, aka parking garages, hospitals, etc.)
Type 2 Primary Fire Hazards (Noncombustible or limited combustible)
- Contents of structure
- Heat buildup causing failure of structural support
- Failure of flat, built-up roofs
Type 3 Primary Fire Hazards (Ordinary Construction)
- Smoke and fire spread through concealed spaces (between the walls, floors, and ceilings)
- Fire spread can be reduced by placement of fire stops inside concealed spaces
Type 4 Primary Fire Hazards (Heavy Timber)
- Massive amount of combustible contents (HEAVY TIMBER) in addition to structural contents
- Heavy timbers remain stable for a long period of time under fire conditions, but when combusting they give off an incredibly high amount of BTU’s and serious exposure to heat problems
Type 5 Primary Fire Hazards (Balloon wood-frame vs. Platform wood-frame)
- Almost unlimited potential for fire extension w/in structure
- Fire extension to nearby structures (particularly other Type 5 structures)
- Fire extension from doors and windows to exterior of structure
Occupancy Classifications
- Single-Use: Must meet the building code requirements for its intended use
- Separated-Use: Contains multiple occupancies or use groups and must meet the requirements for each individual occupancy classification
Variables that Affect Building Behavior
- Age
- Occupancy
- Exposures
- Configuration
- Type of Construction
- Building Access
- Fire or Fuel Loads
- Fire Protection
Fire Effects on Wood
Depends on size of wood and moisture content
The smaller the size of the wood, the more likely it is to lose its structural integrity.
“Green” wood does NOT burn as fast as dried or cured wood and wood impregnated with fire retardants does NOT burn as fast as untreated wood.
Fire Effects on Masonry
- Bricks rarely show signs of loss of integrity/deterioration
- Stones may spall or lose portions of their surface
- Blocks may crack, but usually retain most of their strength
Fire Effects on Steel
- Strongest of structural materials
- Steel is non-rotting, resistant to aging, and dimensionally stable
- Steel elongates when heating and can push out load-bearing walls
- May elongate as much as 4 inches when heated to about 1,000 degrees Fahrenheit
Fire Effects on Reinforced Concrete
- May lose their strength and crack/spall under fire conditions
- May separate concrete from reinforcement material
Fire Effects on Gypsum Building Materials
- Gradually breaks down under fire conditions
- Has high water content (so when it burns and this water content evaporates, that takes most of the heat with it)
- That makes gypsum building materials excellent heat-resistant and fire retardant material
Fire Effects on Glass/Fiberglass Building Materials
- Fiberglass insulation may be combustible and difficult to extinguish
- They do NOT significantly add to the fire load
- Glass cracks when suddenly cooled with water after fire
Loads Placed on a Building
- Dead load
- Live load
- Design load
- Undesigned load
- Distributed load
- Concentrated load
- Fire load
- Impact load
- Compression load
- Tension load
- Shear load
- Static load
- Dynamic load
- Axial load
- Eccentric load
- Torsion load
