Chapter 3 - Building Construction Flashcards
AHJ
Authority having jurisdiction. Adopts and amends building codes to meet local requirements.
Type 1 Fire Resistive
Provides highest level of protection from from spread as well as structural collapse. Structural members have highest fire-resistive rating thus they do not add to the fuel load. Reinforced concrete, precast concrete, and protected steel frame. Structure will not burn but can degrade from effects of fire.
Compartments can retain heat leading to potential for rapid fire development. Roofs can be extremely hard to penetrate. Windows may be inoperable or hard to access.
Type 2 Non-combustible
Will not contribute to fire development or spread. Materials do not meet the stricter requirements of those used in type 1. Materials include metal framing, metal cladding, or concrete block wall and unprotected open web joists supporting metal roof decks. More prone to collapse than type 1 due to lighter-weight materials with lower fire-resistive ratings.
Type 3 Ordinary
Common in mercantile, business, residential, and older schools/churches. Exterior walls and structural members constructed of non-combustible or limited combustible materials. Interior walls, columns, beams, floors, and roofs are completely or partially constructed of wood. Void spaces less protected than type 1 and 2. Fire will spread through these spaces unless fire stops are installed. Prefabricated wood truss systems similar to those found in type 5 are found in this type sometimes (fail quickly).
Type 4 Heavy Timber
Use of large-dimensioned lumber or laminated wood. Extremely stable and resistant to collapse due to the sheer mass. Exterior walls constructed of non-combustible materials. Interior building elements have no concealed spaces. This lack of void spaces or concealed spaces helps prevent unseen fire travel. Glue laminated beams may fail when exposed to fire because the heat may affect the glue holding the laminates together.
Type 5 Wood Frame
Exterior load bearing walls are composed entirely of wood. Veneer of stucco, brick, or stone may be constructed over the wood framing. Common in single family residences and multistory apartment buildings. Studs 2 x 4 or 2 x 6. Modern vinyl siding adds another petroleum based fuel to the fire load which produces dense, dark, oily, toxic smoke and melts away. Prefabricated wood truss systems in place of solid floor joists.
Factory built homes
Modular, prefabricated, manufactured (most common factory built home), and industrialized housing. Partially or completely built in factory and shipped to location. Manufactured homes are not required to conform to the model building codes. Fire can spread more quickly due to fewer internal walls to create compartments.
Panelized homes
Assembled on site from pre constructed panels made of foam insulation between sheets of plywood.
Floors and ceilings
Floors at ground level may consist of concrete slab or a floor assembly made up of joists and decking over a crawl space or basement. Upper floors consist of joists and decking with the ceiling attached over the bottom. Be aware of duct work, electrical, water or natural gas pipes, pipes for suppression systems.
Walls
Consist of bottom plate, top plate, vertical studs, and horizontal braces sandwiched between 2 surfaces made of gypsum or lath and plaster.
Basements
Fires can damage floor joists and load bearing walls that support the upper floor and structure. Stairs can provide a flow path and can be a fall danger. Can be partially underground, fully, or walk out (daylight). Absence of drywall reduces the fire resistance of the studs and joists.
Access or convenience stairs
Not required to be a part of the means of egress system and typically connect no more than 2 levels
Protected stairs
Enclosed with fire-rated construction, usually with either a 1 or 2 hour rating. Generally serve 2 stories or more and are part of the required means of egress.
Unprotected stairs
Not enclosed with fire-rated construction and they may serve as a flow path for the fire and smoke.
Roofs
Protect structure and contents from effects of weather. Shape and construction intended to provide drainage, and support weight of snow and resist effects of wind.
3 prevalent types of roof; flat, pitched, and arched.
Flat roofs
Common on commercial, industrial, and multistory. Be aware of water tanks, antennas, signs, hvac equipment, solar panels.
Parapet walls
Low walls that surround flat roofs, extend from exterior walls.
Pitched roofs
Ridge line with roof deck that slopes down to the eaves along the roof edges. Involved beams or trusses which can be wood or metal. Roof decking or sheathing material usually plywood or oriented strand board (OSB). Open gable and box gable.
Arched roofs
Common in late 1800s to mid 1900s. Exterior walls support weight of the roof. (ie bowstring)
Roof supports
Beams (box beams and I-beams) and truss assemblies.
Gusset plate
Wood trusses assembled using metal plates. As wood burns, plates fall out and no longer a structural support for the truss.
Parallel chord truss
Usually constructed of wood or metal and used to support flat roofs and floor assemblies.
Roof deck
Portion of the roof between the roof supports and the roof covering.
Purlin
Horizontal member between trusses that support the roof.
2 common concrete roofs
Cast-in-concrete and pre-cast.
Roof covering
Part of the roof that is exposed to the weather.
Cocklofts
Concealed space between the top floor and the roof of a structure.
Green roof
Use of the roof surface of a building for a rooftop garden. Increase load on structure called dead load. Can interfere with ventilation and fire location indicators.
Cold roofs
Generally found in cold climates to prevent ice damming and icicle formation at the eaves. Prevent interior heat from escaping into the attic space. Can interfere vertical ventilation.
Photovoltaic (PV) system
Solar energy. Even if power is off to building, panels can retain significant amount of electricity and if light is available, panels can continue to produce power.
Rain or snow roof
Pitched roofs built over flat roofs. Void can created can conceal a fire and allow it to burn undetected. Hvac units can also be hidden. Increase dead load. Ventilation problems. FF should not enter the void area to cut a hole in the original roof (can become trapped, overcome by heat and smoke, fall through weakened roof, caught in extreme fire condition).
Doors
Constructed of wood, metal (aluminum, carbon steel, stainless steel, bronze, copper), and glass.
Swinging doors
Can be single or double leaf. Usually required as exit doors in a means of egress.
Sliding doors
Used for elevators, power operated doors in storefront entrances, and fire doors to protect openings that are not a part of the means of egress. Sliding doors are never allowed as part of a means of egress because they slow the travel of people through the opening.
Vertical doors
Loading dock, garage, freight elevator, fire doors protecting openings that are not part of the required means of egress.
Revolving door
Designed to minimize air floor through a door opening to reduce building heating or cooling losses. Wings of the revolving door are designed to collapse under pressure and provide an unobstructed opening.
Wood panel and flush door
Common type of swinging door. Panel, solid core, or hollow core. Flush door (also called slab door) consists of flat face panels which can be attached to a solid or hollow core.
Solid core door
Interior core of laminated blocks of wood, particleboard, or mineral composition. Core is covered with 2 or 3 layers of surface material, usually plywood. If intended for exterior application, later of sheet metal may be attached. Better fire barrier than panel doors or hollow core doors.
Hollow core door
Grid or honeycomb of wood, plastic, or fibreboard.
Glass door
Building codes require glass doors to be made of tempered glass that resists breakage.
Metal door
Common door is a hollow door made from steel or aluminum. A door made with 2 corrugated sheets has an interior core material such as Styrofoam.
Fire doors
Protect openings in fire rated walls and block the spread of fire within a structure.
Horizontal sliding fire door
Often found in old industrial buildings and usually held open by a fusible link. Cannot be used to protect openings in walls that are required parts of a means of egress.
Swinging fire door
Common in stairwell enclosures or corridors. Fusible link. Slower to operate than devices that react to smoke or rate of temperature increase. A significant amount of smoke may flow through before fusible link can release the door.
Windows
Consist of a frame, one or more sashes (fixed or moveable framed unit that may be included within a window frame). Frame composed of the sill, side jambs, and head jamb. Sill is the lowest horizontal member of the window frame and supports the weight of the hardware and sash.
Glazing
All windows contain glass, known as glazing. Can be single, double or tripled glazed.
Fixed windows
Display windows, picture windows, or deadlights.
Double hung
2 sashes that can move past each other in a vertical plane
Single hung
Only 1 moveable sash.
Casement
Side hinged sash that is usually installed to swing outward. Can be 1 or 2 sashes
Awning
Has 1 or more top-hinged, outward swinging sashes that are opened by unlatching and pushing or using mechanical crank. Can be open during rain.
Jalousie
Large number of narrow overlapping glass sections swinging outward (same concept as awning).
Security windows
Security bars or grills can prevent the escape of trapped occupants or FF and can slow the access time for FF. Must be removed when interior ops begin.
Deadload
Weight of the structure, structural members, building components, and any other features permanently attached to the building that are constant and immobile.
Eave
Edge of a pitched roof that overhangs an outside wall. Attic vents in typical eaves provide an avenue for an exterior fire to enter the attic.
Joists
Horizontal structural members used to support a ceiling or floor. Drywall materials are nailed or screwed to the ceiling joists and the subfloor is nailed or screwed to the floor joists.
Masonry
Bricks, blocks, stones, and unreinforced and reinforced concrete products.
Rafter
Inclined beam that supports a roof, runs parallel to the slope of the roof, and to which the roof decking is attached.
Load forces
Safety factors
The purpose of a Safety Factor is to allow for unexpected loading, workmanship deficiencies, and material defects. Safety Factors range from at least 2:1 up to as high as 6:1 depending on the structure.
Floor materials
Poured reinforced concrete
Cellular concrete over metal decking
Finished wood, tile, or carpet over wood subfloor attached to metal or wood joists
Ceiling materials
Gypsum board Tin tiles
Lath and plaster attached to joists, trusses, or beams
Floor And Ceiling Fire Resistance
Ceilings in exit or egress passageways
Same fire-resistance rating as walls in that corridor
Material used to cover floors in high occupancy structures. Rated to limit flammability. Ratings indicated in hours.
Building Collapse Signs
- Cracks in external walls constructed of brick, concrete, block, stucco, etc.
- Bulging or leaning of walls.
- Sounds of structural movement
- Smoke or water leaking through exterior walls
- Flexible (spongy) floors or roof
- Distorted roof lines
- Bearing walls or support components bending or
distorting - Heavy spalling of concrete members and exposure of reinforcing steel
Construction, Renovation, Demolition Hazards
- Occupants may remain in the building
- Fire alarm and detection systems may be out of service or damaged
- Construction materials and debris may accumulate
- Contractors or owners/occupants may not follow local building codes
