Chapter 4 Flashcards
What is the most the most common building material used in North America?
wood
What 2 things affect how wood reacts to fire conditions?
size and moisture
What specific thing affects the rate at which wood burns?
moisture content
What is green wood?
wood with high moisture content
What is oriented strand board (OSB)?
a wooden structural panel formed by gluing and compressing wood strands together under pressure. This material has been replaced by plywood and planking in the majority of construction applications. Roof decks, walls, and subfloors are all commonly made of OSB.
What is masonry?
bricks, blocks, stones, and unreinforced and reinforced concrete products
What are veneer walls?
decorative covers; walls within a surface layer of attractive material laid over a base of common material
What is spalling?
expansions of excess moisture within masonry (concrete) materials due to exposure to heat of a fire, resulting in tensile forces within the material causing it to break apart.
What happens to stones and concrete when heated?
spalling
What are the two types of iron in buildings in North America?
cast iron and wrought iron
What is the primary material used for structural support in the construction of large modern buildings?
Steel
What is steel used for?
reinforce concrete floors, roofs, and walls, as well as stairs, wall studs, windows, and door frames
What happens to steel when it is heated?
it elongates
What happens when restrained steel is heated?
if retrained from movement at the ends, it buckles and fails somewhere in the middle
A 50 ft. steel beam may elongate as much as ___ inches when heated to 1000 degrees F.
4
What is the temperature that steel structures are anticipated to fail?
1000 degrees F
What will fail first? A lightweight steel truss or a large heavy I-beam?
a lightweight steel truss
What is a lightweight steel truss?
a structural support made from a long steel bar that is bent at a 90-degree angle with flat or angular pieces welded to the top and bottom
What happens to load-bearing walls when steel is heated?
elongated steel can push out load-bearing walls and cause collapse
What are decorative and functional uses of aluminum?
Roofing, flashing, gutters, downspouts, window and door frames, and exterior curtain wall panels
What are curtain wall panels?
a nonload-bearing wall, often of glass and steel, fixed to the outside of the building and serving especially as cladding
What has replaced wood in many commercial and residential buildings?
Aluminum studs
What is affected by heat more rapidly? Steel or aluminum?
Aluminum
What usually happens to metals that are exposed to excessive amounts of heat?
it fails
What is rebar?
short for reinforcing bar; a steel bar that is placed in concrete forms before the cement is poured; when the cement hardens the rebar within it adds considerable strength
What does reinforced concrete usually contain?
rebar
What two-forms of strength does reinforced concrete contain? Why?
compressive strength of the concrete and tensile strength of the steel
What is compressive strength?
the ability to withstand pressure on the surface
What is tensile strength?
the ability to withstand being pulled apart or stretched
What is gypsum also known as?
drywall or Sheetrock
What is gypsum?
an inorganic product from which plaster and wallboards are constructed
Why is gypsum unique?
it has high water content that absorbs a great deal heat as the moisture evaporates; the water content gives gypsum excellent heat-resistant and fire-retardant properties
What is lath and plaster?
a construction process rather an a single material; horizontal wood strips called lath are nailed to wall studs and covered with a mixture of plaster to form an interior wall finish
Is glass typically used for structural support?
No
What is fiberglass usually used for?
Insulation purposes
What is asbestos?
a mineral fiber that was used before 1970 for insulation and as a fire retardant; it has ben banned since 1989
What is hybrid construction?
a type of building construction that uses renewable environmental friendly or recycled materials; aka Natural of Green Construction
What are different types of insulation?
asbestos, urea formaldehyde foam insulation (UFFI), fiberglass, mineral wool, cellulose, cotton, straw, foam
What form of insulation is usually found in the exterior walls of hybrid or natural (green) construction?
straw
What are composite materials?
composite materials are manufactured by combining two or more distinctly different materials
What are types of composite materials?
finger-jointed limber, laminated timber, medium density fingerboard (MDF), particle board, synthetic wood
(pg 142)
What/who determines the type of building construction used in a structure?
the architect, structural engineer, or contractor
Who are building codes adopted by?
building codes are adopted by the AHJ and amended to meet local requirements
What are the two major building model codes in the US?
the NFPA 5000 and the International Code Council’s (ICC) International Building Code (IBC) building codes
What is NFPA 5000?
NFPA 5000 Building Construction and Safety Code
What are the 3 elements that every building is composed of?
structural frame, floor construction, roof construction
What is type 1 construction?
type 1 construction is also known as fire-resistive construction; type 1 provides the highest level of protection from fire development and spread as well as collapse
What is expected of type 1 construction?
type 1 is expected to remain structurally stable during a fire, and is considered to be the most collapse resistant
What meets the criteria for type I construction?
reinforced concrete, precast concrete, and protected steel frame construction
What is protected steel?
steel structural members that are covered with either a fire resistant stray-on fire proofing or fully encased in an approved system
What are type 1 structures usually incorrectly referred to as? Why?
the structure won’t burn, but the structure may degrade from the effects of fire as well as the addition of combustible materials within the structure
What is type II construction?
type II construction is also known as noncombustible of limited combustible construction; type II construction is composed of materials that will not contribute to fire development or spread;
What is true about steel components used in type II buildings?
steel components used in type II do not need to be protected for the same lengths of time of have the same fire-resistance rating as type I
What is the fire-resistance rating?
the fire resistance rating is the rating assigned to a material or assembly after standardized testing by an independent testing organization; identifies the amount of time a material or assembly will resist a typical fire, as measured on a standard time-temperature curve
What is the fire-resistance rating of type II compared to type I?
type II is generally half of type I, I-2 hours, depending on the component
What is the fire-resistance rating of type I structure?
3-4 hour burn
What is type III construction?
type III construction is also known as ordinary construction; commonly found in older schools and mercantile, business, and residential structures; requires that exterior walls and structural members be constructed of noncombustible material; interior walls, columns, beams, floors, and roofs are completely or partially constructed of wood
Which type of fire kills the most FF and why?
type III bc the fire travels through the walls and is concealed to FF; roofs in this structure also collapse faster
What is the condition that affects type III fire behavior the most in type III?
voids exist inside the wooden channels created by roof and truss systems and between wall studs that will allow for the spread of a fire unless fire stops are installed in the void
What are fire stops?
solid materials such as wood blocks used to prevent or limit the vertical and horizontal spread of fire and the products of combustion in hollow walls or floors, above false ceilings, in penetrations for plumbing or electrical installations, in penetrations of a fire-rated assembly, or in cocklofts and crawl spaces
What is a hazard that comes about due to renovations?
renovations to structures can change the interior arrangement, exit paths and structural integrity of a structure
What is type IV construction?
type IV constructions is also known as heavy timber/mill construction; it is characterized by the use of large-dimensioned lumber; these structural members will be greater than 8 in; fire rating of 2 hours; dimensions of all structural elements must adhere to minimum dimension sizing
What is the stability level of type IV construction?
type IV construction is very stable and resistant to collapse due to the sheer mass of their structural members; the lack of voids of concealed spaces help to prevent fire travel
What is the weakest part of type IV structure?
bolts and fasteners
What are two things that can cause a type IV structure to fail?
- failure of bolts/fasteners
- failure of Glulam beams
Glulam beams: small-dimensioned lumber that is glued together to form a laminated structure element; element is strong; commonly found in churches, barns, etc; fails bc glue holding elements together is affected by the heat
What are load-bearing walls?
walls of a building that by design carry at least some part of the structural load of the building in the direction of the ground or base
What is type V construction?
type V construction is commonly known as wood frame or stick frame; the exterior load bearing walls are composed entirely of wood
What is a veneer wall?
a veneer offers the appearance of type III construction while providing little additional fire protection or structural support to the structure
What does type V construction consist of?
framing materials that include wood 2x4” or 2x6” studs
What is an upright post in the framework of a wall for supporting sheets of lath and plaster, wallboard, or similar material?
stud
Does type V construction include the use of prefabricated wood truss systems or solid floor joists?
prefabricated wood truss system; system creates a large open void area between the floors of the structure, rather than the closed channel system found with solid wood floor joists
What is a manufactured home/structure?
a manufactured home is a structure that is built in a factory and shipped to the location where it is installed
Are manufactured homes required to conform to the model building codes?
no; they are required to conform to a US Dept. of Housing and Urban Development (HUD) standard that is similar to type V construction
What does the National Building Code of Canada (NBCC) define as the three types of building construction?
combustible construction, noncombustible construction, and heavy timber construction
In Canada, what are the residential dwellings built under the novoclimat standard?
a standard intended to make new homes more energy efficient and better insulated; airtight structure; more likely to fail rapidly under fire conditions bc heat is trapped within the structure; design makes vertical ventilation more difficult
What are occupancy classifications defined by?
the building code and life safety code adopted by the AHJ
What are the 3 primary model building codes in use in North America?
NFPA 5000, IBC, and the National Building Code of Canada (NBCC)
What 2 type of occupancies may structures be divided into?
single use or separated use
What is a single use structure?
must meet the building code requirements for its intended use; school meets school code requirements, business meets business code requirements, hospital meets hospital code requirements
What is a separated use structure?
a structure that contains multiple occupancies; must meet the requirements for each individual occupancy classification
What is an occupancy used for a gathering of 50 or more persons
assembly occupation
What are the components of a building?
foundation, floor/ceiling, walls, roof, stairs, doors, windows
What is designed to support the weight of the building and all its contents?
a building’s foundation; foundations may be shallow or deep
What defines the perimeter of the building as well as divides it into rooms?
walls
What are walls (usually interior) that only support their own weight?
non-load bearing walls
What is a partition wall?
an interior wall that separates a space into rooms
What may act as a partition wall?
non-load bearing walls
What materials are fire walls constructed of?
masonry materials bc they do not burn
What are fire walls?
intended to provide separation that mets the requirement of a specified fire-resistance rating; build of fire-resistive materials; designed to limit the spread of a fire within a structure or between adjacent structures
Fire walls may be used with ____ to separate two adjoining structures or two occupancy classifications within the same structure to prevent the spread of fire from one to the other
party walls
What are party walls?
load bearing wall shared by two adjacent structures
What are the most difficult to penetrate when attempting to force entry into or escape an area?
exterior walls and fire walls
What part of the house may be used to assist in vertical ventilation during a fire?
roof
What are 3 prevalent types of roof shapes?
flat, pitched, and arched
What type of roofs are commonly found on commercial, industrial, single/multifamily residencies?
flat roofs
What may flat roofs be surrounded wall?
parapet walls
What are parapet walls?
portion of the exterior wall of a building that extends above the roof (to facilitate drainage)
What is the most common type of pitched roof?
roofs elevated in the center along a ridge line with a roof deck that slopes down to the eaves along the roof edges
What is a ridge?
a horizontal line at the junction of the top edges of two sloping roof surfaces
What is the edge of a pitched roof? This overhands the outside wall
Eave
What is skip sheathing?
decking that consists of boards or planks set with a small space between them
How do type of roof contributes to FF casualties?
the rapid collapse of arched roofs involved in fire has contributed to many FF injuries and fatalities making them one of the most dangerous type of roof construction
What are the 3 main components that make up a roof?
roof supporting structure, roof deck/sheathing, roof covering
What are the two general types of roof supports used in residential and commercial construction?
beams and truss assemblies
What are the sections of lumber location directly under the roof decking?
beams
What is the included beam that supports a roof? This beam runs parallel to the slope of the roof and the roof deck is attached to it
rafter
What are wood trusses assembled using?
Gusset plates (also called gang nails)
How deep to gang nails penetrate into the wood?
3/8”
What are gusset plates?
metal or wooden plates used to connect and strengthen the joints of two or more separate components (such as metal or wooden truss components or roof or floor components) into a load-bearing unit
What are the different type of trusses?
parallel chords, pitched chord, arched truss, bowstring truss
What is a parallel chord truss?
a truss constructed with the top and bottom chords parallel; used as floor joists in multistory buildings and as ceiling joists in buildings with flat roofs
What are parallel chord truss’ generally used to support?
flat roofs and floor assemblies
What happens to wood joists when they are exposed to fire?
they lose their strength; the roof becomes soft of spongy before failure, especially with a wood plank roof deck
What is a joist?
a horizontal structural member used to support a ceiling or floor; drywall materials are nailed or screwed the ceiling joists and the subfloor is nailed or screwed to the floor joists
How will a truss system handle fire?
the slender members used to manufacture a truss are susceptible to early failure; the open web design of truss joints permit the rapid spread of fire in directions perpendicular to the truss joint (fire-ceililng; truss-horizontal)
What are lightweight wood trusses connected by?
gusset plates made of wood or metal
What are lightweight wooden trusses?
structural supports constructed of 2x3” or 2x4” members that are connected by gusset plates
What is the portion of the roof between the roof supports and the roof covering?
roof deck
The components of roof decks include:
sheathing, roof plank/slabs, and purlins
What is a purlin?
a horizontal member between trusses that support the roof
What is the main problem with concrete roofs?
they are extremely difficult to penetrate, causing a ventilation problem
Monitors, smoke and attack vents, scuttle hatches, and skylights may be used to gain access to attics and _____ and may be used to provide an exit point for some types of ventilation.
cockloft
What is a cockloft?
a concealed space between the top floor and the roof of a structure
What type of roof benefits energy conservation?
green roofs/vegetative roof systems
What is the greatest benefit of green roofs?
the increase in air quality due to the oxygen-carbon dioxide exchange of growing plants, particularly in urban areas
What type of load is a rooftop garden? Dead or live
dead
What is a dead load?
weight of the structure, structural members, building components, or any other features permanently attached to the building that are constant and immobile
What happens to a load under fire conditions?
structural failure is accelerated, particularly if the roof is combustible
Aside from being a dead load, what other problem can green roofs cause?
ventilation problems
What issue can a thick and insulated “cold roof” cause to FF?
ventilation problems
What is a photovoltaic (solar energy) roofing system?
a system that provides clean and reliable energy that can be used for a wide range of applications
What roofs may be found on commercial buildings, schools, and residential structures?
rain roofs
What is a rain roof?
a second roof constructed over an existing roof
What is a problem with rain roofs?
the void created by the rain roof can conceal a fire and allow it to burn undetected
What problems can unapproved or non permitted modifications during construction/renovation pose to FF?
they can inhibit effective ventilations and increase the risk of fire extension and structural collapse
What is a live load?
items within a building that are movable but are not included as a permanent part of the structure; merchandise, stock, furnishings, occupants, FF, and the water used for suppression are examples of live load;
What do stairs that are part of the required means of egress require?
they must provide protection for the occupants as they travel to safety; stairs meeting these requirements are called protected/enclosed bc they are built to resist the spread of fire and smoke
What does “means of egress” mean?
continuous and unobstructed way of exit travel from any point in a building or structure to a public way, consisting of 3 separate and distinct parts: exit access, exit, and exit discharge
What is a mechanical ventilation system designed to do?
keep smoke out of the stair enclosure by pressurizing the air shaft
How is a mechanical ventilation system activated?
by automatic fire/smoke detection equipment
What are the 5 types of doors?
swinging, sliding, folding, vertical, revolving
What is a swinging door?
a door that rotates around a vertical axis by means of hinges secured to the side jambs of the doorway framing
What is the use of swinging doors in means of egress?
exit doors
What door is suspended from an overhead track and may use rollers as well as floor guides/tracks?
sliding door
What is the main advantage of sliding doors?
it eliminates door swing that might interfere with the use of interior space
What is the use of sliding doors in means of egress?
no use; slow the travel of people through the door opening
What door is hung from an overhead track with rollers or glides similar to those used by a sliding door?
folding door
What door opens in a vertical plane?
vertical door/overhead door; found in loading dock doors and garage doors
What is a revolving door?
a door that is constructed with 3 or 4 sections or wings that rotate in a circular frame; designed to minimize flow of air through a door opening to reduce building heating or cooling losses
What is the use of revolving doors in means of egress?
prevents movement of hose or equipment into a building which is a problem for FF; hinders exit bc a crowd of people attempting to flee can’t move through quickly
What are doors constructed of?
wood, metal, and glass
What is a common type of swinging door?
wood panel door
What is a solid-core door?
formed with an interior core of laminated books of wood, particleboard, or a mineral composition
What is a hollow-core door?
a door constructed with spacers between the face panels to provide lateral support
What are better fire barriers? Solid-core doors or hollow-core doors?
solid-core doors
____ doors are used for both exterior and interior applications
glass
What to building codes require glass doors to be made of?
tempered glass that resists breakage
What are common hollow metal doors made out of?
steel or aluminum
What is a fire door?
fire doors protect openings in fire-rated walls and block the spread of fire
Can a rolling steel fire door be used on an opening that is required to be part of the means of egress?
no
Can horizontal sliding doors be used to protect openings in walls that are required parts of a means of egress?
no
Which fire doors are commonly used in stairwell enclosures or corridors that require a fire door?
swinging fire doors
What have been relied upon as means of light, ventilation, access, and rescue?
windows
What term refers to a framed unit that may be included within a window frame? This may be fixed or movable
sash
What do fixed windows consist of?
frame and a glazed stationary sash; examples of this are high-rise office building windows
What are the types of windows?
double hung, single hung, casement, horizontal sliding, awning, jalousie, projecting, and pivoting
While preventing unlawful entry is the primary reason for installing security bars or grilles, they also have a ____ effect on fire and life safety.
negative
What factors should on look for when sizing up a building?
age of the building, construction materials, roof type, renovations or modifications, dead loads, number or stories, and windows
What are two primary types of dangerous conditions that may be posed by a particular building?
conditions that contribute to the spread and intensity of fire and conditions that make the building susceptible to collapse
What is the fuel load?
the maximum heat that can be produced if all the combustible materials, both contents and building materials, in a given area burn
What is the presence of large amounts of combustible materials in an area of a building?
heavy fuel loading; one of the most critical hazards bc the fire can overwhelm the capabilities of a fire suppression system and make it hard for FF to gain access during fire suppression operations
Besides fuel load, what else can contribute to fire spread and smoke production?
furnishings and interior finishes (ex. tables sofas desks beds and other items found in occupancies)
How long does it take for steel and wooden trusses to fail?
5-10 min of exposure to fire
Do steel or wooden trusses need tone exposed to flames to fail?
no; these trusses can fail from exposure to heat alone without any flames
What part of the truss system can warp and fail quickly when exposed to heat?
gusset plates (unless they are corner nailed)
What is a significant design deficiency of the truss system?
the tensile strength placed on the bottom chord
Why is the risk of fire increased when construction, renovation, or demolition is being performed?
additional fuel loads/ignition sources
The structural failure of a building or any portion of it resulting from a fire, snow, wind, water, or damage from other forces is referred to as ______
structural collapse
What is structural collapse?
structural failure of a building or any portion of it resulting from a fire, snow, wind, water, or damage from other force
What factors should be considered when determining the potential for structural collapse?
construction type, length of time fire burns, stage of the fire, contents, and amount of water used to extinguish the fire
The longer the fire burns, the _____ the temperature of the fire gases in the upper levels of the structure or compartment?
greater
Will unprotected steel or wood frame construction collapse during the incipient stage or a fire?
no
At what point during a fire is collapse very likely? Why?
the decay stage and during post suppression activities bc of the weekend state of structural members and the buildup of water
Building contents may contribute to structural collapse in 3 ways because:
generating higher temperatures and rapid combustion will weaken the structure due to a higher fuel load, dead weights added and will cause collapse more rapidly, and stress is increased due to increased weight from water retention
How much weight does every US gallon of water that is used to suppress add?
8.33 lbs; 250 gallons = 1 ton
3 steps to take when collapse is imminent:
exit and inform Command and all others of the situation, establish and clear the collapse zone ASAP, and PAR
How do you determine a collapse zone for type I construction?
type I construction high-rise buildings are not as likely to collapse; primary concern is the hazard of flying glass; the building won’t burn just the contents inside, so the structural collapse will be localized and not structure wide
How do you determine a collapse zone for type II construction?
when exposed to temperatures of 1,000 dg F, metal will begin to expand causing floors and walls to collapse
How do you determine a collapse zone for type III construction?
determine it regularly (1 1/2xH); masonry walls can collapse in one piece or crumble in many parts
How do you determine a collapse zone for type IV construction?
one of the least likely to collapse but establish it normally if the fire is that intense; most members will resist collapse
How do you determine a collapse zone for type V construction?
depends whether the style is platform frame (collapse inward) or balloon frame (collapse outward)
How long will it take for lightweight trusses to fail when exposed to direct heat?
5 min
What construction method uses long continuous studs that run from the sill plate (located at the foundation) to the roof eave line? This style requires the use of long lumber and generally lacks any type of fire stopping within the wall cavity
balloon frame construction
What is the problem with balloon frame construction?
the wall cavities between the studs are open from the ground floor to the attic and a fire could extend throughout that distance, within the walls
Which construction method will a floor assembly create an individual platform that rests on the new foundation? Wall assemblies the height of one story are placed on this platform and a second platform rests on top of the wall unit. Each platform creates fire stops at each floor level restricting the spread of fire within a wall cavity
platform frame construction
