fire science chapter 4 building construction

common building materials

wood, masonry, metals, reinforced concrete, gypsum, lath and plaster, glass/fiberglass, plastic, composite materials

wood

wood is the most common building material in North America and is the main component of a variety of structural assemblies. size and moisture content affect how wood reacts to fire conditions. the smaller the dimensions of the wood, the easier it is to ig

oriented strand board (OSB)

a wooden structural panel formed by gluing and compressing wood strands together under pressure. this material has replaced plywood and planking in the majority of construction applications. roof decks, walls, and subfloors are all commonly made of OSB

masonry

masonry includes bricks, stones and concrete blocks. Brick and stone are generally used to create veneer walls, which are decorative covers for wood, metal, and concrete-block load-bearing walls. masonry is minimally affected by fire and exposure to high

spalling

expansion of excess moisture within masonry materials due to exposure to the heat of a fire, resulting in tensile forces within the material, causing it to break apart. the expansion causes sections of the material's surface to violently disintegrate, res

metals - iron

two types of iron can be found in buildings in N America:
-cast iron - commonly used in the 19th century for structural support, beams and columns, for stairs, balconies, railings, and elevators, and for the facades of buildings. facades consisted of larg

metals -steel

Steel is the primary material used in the construction of large modern buildings. Steel is also used for stairs, wall studs, window and door frames, and for balconies and railings. It is also used to reinforce concrete floors, roofs and walls. Steel struc

lightweight steel truss

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

Metals - aluminum

The use of aluminum increased throughout the 20th century. Initial uses included decorative and functional uses including roofing, flashing, gutters, downspouts, window and doorframes, and exterior curtain wall panels. Aluminum is used in the construction

Curtain wall

A nonload-bearing wall, often of glass and steel, fixed to the outside of a building and serving especially as a cladding.

other metals

Tin - has been used to produce metal ceiling tiles and is used as a roof covering
Copper - found in wiring, pipes, gutters and other decorative elements
lead - still found in pipes, flashing, and as a component of stained glass of leaded glass windows.
th

reinforced concrete

reinforced concrete is internally fortified with steel reinforcement bars (rebar) or wire mesh. this gives the material the compressive strength (ability to withstand pressure on the surface) of concrete along with the tensile strength (ability to withsta

gypsum

aka drywall or Sheetrock, is an inorganic product from which plaster and wallboards are constructed. it is unique because it has a high water content that absorbs a great deal of heat as the moisture evaporates. the water content gives gypsum excellent he

lath and plaster

process in which horizontal wood strips called lath are nailed to wall studs and covered with a mixture of plaster to form an interior wall finish. generally found in building constructed prior to the 1950s. wire mesh was also used to replace the lath for

glass/fiberglass

glass is not typically used for structural support. conventional glass is not a barrier to fire extension. heated glass may break and shatter when it is struck by a cold fire stream.
fiberglass is typically used for insulation purposes and is located betw

types of insulation

asbestos - mineral fiber used before 1970 for insulation and as a fire retardant. it is a known carcinogen.
urea formaldehyde foam insulation (UFFI) - originally used in the 1970s for insulating walls, this material caused high levels of formaldehyde emis

plastic

used in many forms as a building material. on the exterior of buildings, vinyl sliding is used over older sliding, foam insulated panels, or other materials. water and sewer pipes are made from varying sizes of plastic pipe and fittings and are used to re

composite materials

being used more frequently than in the past. generally, composite materials are manufactured by combining two or more distinctly different materials. this process results in lightweight materials with high structural strength, resistance to chemical wear,

construction classifications

the type of building construction used in a structure is determined by the architect, structural engineer, or contractor. locally adopted building codes regulate the type of construction based on the intended use (referred to as occupancy classification),

US construction

both the IBC (international building code) and the NFPA classify buildings in five types of construction defined by the construction materials and their performance when exposed to fire. every building is composed of the following elements:
structural fra

type I (fire resistive)

provides the highest level of protection from fire development and spread as well as collapse. all structural members are composed of noncombustible or limited-combustible materials with a high fire-resistive rating. structural components such as walls, f

protected steel

steel structural members that are covered with either a fire-resistant spray-on fire proofing or fully encased in an Underwriter Laboratory (UL) tested and approved system

type II (noncombustible or limited combustible)

composed of materials that will not contribute to fire development or spread. steel components used in type II do not need to be protected for the same lengths of time or have the same fire-resistance rating as type I. structures with metal framing member

fire-resistance rating

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

type III (ordinary construction)

commonly found in older schools and mercantile, business and residential structures. requires that exterior walls and structural members be constructed of noncombustible materials. interior walls, columns, beams, floors, and roofs are completely or partia

fire stop

solid materials such as wood blocks, used to prevent or limit the vertical and horizontal spread of fire and the products of combustion

type IV (heavy timber/mill construction)

characterized by the use of large-dimensioned lumber. as a general rule, these structural members will be greater than 8in in dimension with a fire-resistance rating of 2 hours. the dimensions of all structural elements must adhere to minimum dimension si

type V (wood or stick frame)

the exterior load-bearing walls are composed entirely of wood. a veneer of stucco, brick or stone may be constructed over the wood framing which gives the appearance of type III construction while providing little additional fire protection or structural

manufactured structures

home built in a factory and shipped to the location where it is installed. make up 25% of all housing sales in the US.
they are not required to conform to the model building codes; they are required to conform to a US Dpt of housing and urban development

factory-built homes

-manufactured homes: most common type. almost completely prefabricated prior to delivery and is the least expensive. the HUD code preempts all local building codes and is more stringent than model building codes
-modular homes: must comply with the same l

canadian construction

the National Building Code of Canada (NBCC) defines three types of building construction:
1. combustible construction - does not meet the requirements for noncombustible construction
2. noncombustible construction - the degree of fire safety is attained b

occupancy classifications

structures are also classified by their intended use or occupancy. occupancy classifications are defined by the building code and life safety code adopted by the AHJ. the three primary building codes in use in N America are NFPA 5000, IBC, and the Nationa

single use

a single-use structure must meet the building code requirements for its intended use. for instance, an office building must meet requirements found in the Business Occupancy Classification while an elementary school must meet the requirements of an Educat

separated use

structures that contain multiple occupancies or use groups must meet the requirements for each individual occupancy classification. that is, in a strip mall, each space is classified by its use and separated from the other units by a fire-rated wall, as r

building components - foundations

designed to support the weight of the building and all its contents. may be shallow or deep. a shallow foundation extends a few feet into the earth around the perimeter of the structure. the foundation sits on a footing made from poured, reinforced concre

building components - floors/ceilings

floors at ground level may consist of a concrete slab or a floor assembly made up of joists and decking over a crawl space or basement. upper floors of a multistory building consist of the joists and decking with the ceiling attached to the bottom. the to

building components - walls

exterior wall may be wood or metal siding attached to studs, a single layer of concrete blocks or logs. internal wall assemblies may be rated for a specified fire resistance time depending on the local building code.
because masonry materials do not burn,

fire wall

fire-rated wall with a specified degree of fire resistance, built of fire-resistive materials and usually extending from the foundation up to and the through the roof of the building, that is designed to limit the spread of a fire within a structure

building components - roofs

the shape and construction of the roof is intended to provide drainage, support the weight of accumulations of snow, resist the effects of wind, and insulate the interior from external temperature changes. therefore, the geographic location of the structu

flat roofs

commonly found on commercial, industrial, multifamily residential structures, and some single-family residences. generally has a slight slope toward the outer edge to facilitate drainage. the roof may be surrounded by parapet walls or divided by fire sepa

parapet

portion of the exterior walls of a building that extends above the roof. a low wall at the edge of the roof

pitched roofs

among the most common styles are thoe elevated in the center along a ridge line with a roof deck that slopes down to the eaves along the roof edges. most pitched-roof construction involves rafters or trusses made of wood or metal that run from the ridge l

ridge

horizontal line at the junction of the top edges of two sloping roof surfaces

eave

the edge of a pitched roof that overhangs an outside wall.

arched roofs

are ideal for some types of occupancies because they can span large open areas unsupported by columns, pillars, or posts. the rapid collapse of arched roofs involved in fire has contributed to many FF injuries and fatalities making them one of the most da

roof construction

made up of three main components including the roof supporting structure, the roof deck or sheathing and the roof covering

roof supports

two general types used in residential and commercial construction:
-beams are the sections of lumber located directly under the roof decking. on a pitched roof they extend from the ridge line or pole at the peak to each side wall.
-roof truss assemblies m

rafter

inclined beam that supports a roof, runs parallel to the slope of the roof and to which the roof decking is attached

parallel chord truss

a truss constructed with the top and bottom chords parallel. these trusses are used as floor joists in multistory buildings and as ceiling joists in buildings with flat roofs

lightweight wood truss

structural supports constructed of 2x3in or 2x4in members that are connected by gusset plates

roof decks

the portion of the roof between the roof supports and the roof covering. types of roof decks include:
plywood sheathing, oriented strand board (OSB), wood tongue and groove, corrugated metal, sprayable concrete encapsulated polystyrene, reinforced concret

purlin

horizontal member between trusses that supports the roof

roof coverings

the roof covering is the part of the roof exposed to the weather. materials include:
wooden shingles or shakes, molded metal or rubber imitation shingles or tiles, asphalt shingles, asphalt sheets, terra-cotta or concrete tile, blown-on foam, built-up tar

roof penetrations and openings

include a variety of items that provide light, ventilation, access, vapor exhausts, or are part of the plumbing or HVAC systems. penetrations can indicate the location of some types of rooms such as bathrooms or mechanical spaces. monitors, smoke and atti

cockloft

concealed space between the top floor and the roof of a structure

roof obstructions - green roofs

involves the use of the roof surface of a building for a rooftop garden. this increases the insulating effects between the building interior and the outside and it increases the air quality.
a rooftop garden constitutes a dead load on the roof structural

roof obstructions - cold roofs

generally found in cold, snowy climates to prevent ice damming and icicle formation at eaves. it is designed to prevent interior heat from escaping into the attic space thus melting the snow on the roof. the cold roof layering system design can create sig

roof obstructions - photovoltaic roofs

a photovoltaic (solar energy) system produces clean and reliable energy that can be used in a wide range of applications. cells can be laid on top of a roof or embedded in the roof.
the electricity generated by the operation of the solar system represents

roof obstructions - rain roof

may be found on commercial buildings, schools and residential structures. generally, they are pitched roofs placed over older flat roofs for aesthetic purposes, to prevent leaks, channel moisture off the roof and as a more cost-effective alternative to re

roof obstructions - security

in many communities, metal security bars or grilles are mounted over doors and windows to prevent illegal entry. this type of security will slow entry, create emergency exit hazards, and reduce the effectiveness of ventilation tactics

roof obstructions - permitted structural modifications

construction requirements are intended to provide occupants with the highest level of fire and life safety possible. over the life of a structure you can expect that modifications will be made to improve and update it. the modifications must meet the loca

roof obstructions - non permitted modifications

even though permits and inspections are required by local ordinance, owners or occupants may make unapproved or non permitted modifications during construction or renovation that can inhibit effective ventilation and increase the risk of fire extension an

roof obstructions - roof-mounted equipment

most commercial, industrial, institutional, educational, and some residential structures have equipment mounted on the roofs. this is particularly true of structures with flat roofs. these items add a live load to the dead load distributed on the roof, in

live load

(1) items within a building that are movable but are not included as a permanent part of the structure; merchandise, stock, furnishings, occupants, FFs and the water used for fire suppression are examples of live loads
(2) force placed upon a structure by

stairs

stairs that are a part of the required means of egress must provide protection for the occupants as they travel to safety. stairs meeting these requirements are called protected or enclosed because they are built to resist the spread of fire and smoke.
st

means of egress

continuous and unobstructed way of exit travel from any point in a building or structure to a public way, consisting of three separate and distinct parts: exit access, exit and exit discharge

protected stairs

interior protected stairs are critical components of the life safety system of a building. protected stairs are enclosed with fire-rated construction, usually with either a 1 or 2 hour rating. also, protected stairs generally serve two stories or more and

exterior stairs

exterior stairs may either be open to the air or enclosed. enclosed exterior stairs must comply with requirements similar to those of interior protected stairs

fire escapes

building codes have not permitted fire escapes in new construction for many decades.
fire escapes that have been in place for many years may not be able to support the required live load created during an emergency evacuation or fire suppression operation

smokeproof stair enclosures

building codes require a smoke proof stair enclosure under certain circumstances such as stairs serving a high-rise building. stair enclosures using either active or passive smoke control may be defined as smoke proof. a mechanical ventilation system, act

unprotected stairs

because unprotected stairs are not enclosed with fire-rated construction, they may serve as a path of spread for fire and smoke. building codes typically allow the use of unprotected stairs in buildings when they connect only two adjacent floors above the

doors - swinging doors

rotates around a vertical axis by means of hinges secured to the see jambs of the doorway framing. generally, swinging doors are required as exit doors as a means of egress, although other types of doors can be used under very specific conditions

doors - sliding doors

sliding doors are never allowed as a means of egress because they slow the travel of people through the door opening.

doors - folding doors

may be found in residential occupancies, in places of assembly to divide large conference areas into smaller rooms, and as horizontal fire doors. horizontal fire-door assemblies must meet very specific requirements and be tested and listed for use as a me

doors - vertical doors

a door that opens in a vertical plane is known as an overhead door and is often found in industrial occupancies for applications such as loading dock doors, garage doors, freight elevator doors, and fire doors protecting openings that are not part of the

doors - revolving doors

designed to minimize the flow of air through a door opening to reduce building heating or cooling losses.
a revolving door prevents the movement of hose or equipment into a building which can present a problem for FFs. furthermore, a crowd of people attem

door construction/materials

the construction material of a door influences its effectiveness as a fire barrier and the degree to which it can be forced open during an emergency.
doors are constructed from wood, metal and glass. aluminum and carbon steel are the metals most commonly

wood panel and flush doors

a very common type of swinging door is the wood panel door. a panel door consists of vertical and horizontal members that frame a rectangular area. thin panels of wood, glass, or louvers are placed within the framed rectangular area.
a flush door consists

glass doors

most commonly used in office and mercantile buildings. building codes require glass doors be made of tempered glass that resists breakage. in addition, various plastics such as Lexan or Plexiglas are often used in framed doors to provide additional securi

metal doors

a common type of metal door is a hollow metal door made from steel or aluminum

fire doors

fire doors protect openings in fire-rated walls. the use of fire doors to block the spread of fire is an established fire-protection technique. when properly maintained and operated, fire doors are very effective at limiting the spread of fire and total f

rolling steel fire doors

commonly used to protect an opening in a fire wall in an industrial occupancy or an opening in a wall separating buildings into fire areas. this type of door cannot be used on any opening that is required to be part of the means of egress.
this type of do

horizontal sliding fire doors

often found in old industrial buildings and are usually held open by a fusible link, and slide into position along a track either by gravity or by use of a counterweight. also cannot be used to protect openings that are required as means of egress.
a comm

swinging fire doors

commonly used in stairwell enclosures or corridors that require a fire door. fire doors can either be automatic or self-closing. an automatic door is normally held open and closes automatically when an operating device is activated. a self-closing door is

windows

modern buildings often rely on their HVAC system for ventilation and artificial lighting for illumination. elimination of windows that can be opened enhances energy efficiency in buildings because it reduces air infiltration around windows. consequently,

fixed windows

consists only of a frame and a glazed stationary sash. the large windows found in mercantile occupancies and high rise office buildings are common examples of fixed windows

movable window configurations

-double-hung: has two sashes that can move past each other in a vertical plane
-single-hung: has only one sash openable
-casement: has a side-hinged sash that is usually installed to swing outward
-horizontal sliding: has two or more sashes of which at le

security

a common method for providing window security is to fasten metal bars or screens to the exterior of the window frame or to the building itself.
when interior firefighting operations begin, security bars and grilles must be removed or disabled to ensure FF

sizing up existing construction

when sizing up a building, look for the following:
-age of the building
-construction materials
-roof type
-renovations or modifications
-dead loads
-number of stories
-windows
other items are important to observe during size-up, such as occupancy type ad

dangerous building conditions

there are two types of dangerous conditions that may be posed by a particular building:
-conditions that contribute to the spread and intensity of the fire
-conditions that make the building susceptible to collapse

dangerous building conditions - fuel loading

fuel load is the maximum heat that can be produced if all the combustible materials, both contents and building materials, in a given area burn. heavy fuel loading is the presence of large amounts of combustible materials in an area of a building. proper

dangerous building conditions - furnishings and finishes

besides the fuel load, the furnishings and interior finishes can contribute to fire spread and smoke production. the interior finishes include the window, wall, and floor coverings such as drapes, wallpaper, and carpet

dangerous building conditions - roof coverings

the combustibility of a roof's surface is a basic concern to the fire safety of an entire community.
wood shakes in particular, even when treated with fire retardant, can significantly contribute to fire spread

dangerous building conditions - large, open spaces

large, open spaces contribute to the spread of fire throughout. in facilities with these, proper vertical tactical ventilation is essential for slowing the spread of the fire. in concealed spaces, fire can travel undetected, feeding on combustible exposed

engineered and truss construction

FFs must be aware of the danger posed by the increased use of engineered or lightweight construction and trussed support systems. experience has shown that unprotected engineered steel and wooden trusses can fail after 5-10min of exposure to fire. for ste

construction, renovation and demolition hazards

for a variety of reasons, the risk of fire rises sharply when construction, renovation, or demolition is being performed in a structure. contributing factors are the additional fuel loads and ignition sources brought by building contractors and their asso

structural collapse

structural failure of a building or any portion of it resulting from a fire, snow, wind, water, or damage from other forces. collapse potential should be considered during preincident surveys and throughout the size-up process until the situation is mitig

structural collapse factors - construction type

in N America, examples of structural collapse involving high-rise buildings or type I construction buildings are very limited.
church steeples, water tanks, chimneys, and false facades that extend above the top of the structure must be viewed as a potenti

hazards of truss systems

FF should take the following steps to minimize the risk of injury or death during structural fire fighting operations involving a roof or truss system:
-know how to identify roof and floor truss construction
-immediately report the presence of truss const

-open ceilings and other concealed spaces immediately whenever a fire is suspected of being in the overhead space. apply the following tactics:

-when responding to any structure where a fire has been reported, always check the ceiling prior to entering the building.
-as you advance into the building, check the ceiling at intervals of ~20ft
-when you enter another portion of the building, repeat t

hazards of truss systems - at the emergency indecent, use the following procedures to protect FFs:

-evacuate FFs performing operations under or above trusses as soon as it is determined that the trusses are exposed to fire, and move to a defensive mode
-after extinguishing a fire in a building containing truss construction, use defensive overhauling pr

structural collapse factors - length of time a fire burns

the longer a fire burns, the greater the temperature of the fire gases in the upper levels of the structure or compartment. using the time-temperature curve, applying an estimate of the length of time a fire has been burning to the type of construction, y

structural collapse factors - stage of fire

the stage of the fire can easily indicate the quantity of heat that the structure has been exposed to and the potential for structural collapse.
in the decay stage, and during post suppression activities, collapse becomes very likely due to the weakened s

structural collapse factors - contents

the contents may contribute to collapse in three ways:
-generating higher temperatures and rapid combustion that will weaken the structure due to a higher fuel load
-causing collapse more rapidly due to added dead weight
-increasing stress on structural m

structural collapse factors - amount of water used to extinguish a fire

every gallon of water that is used to suppress the fire adds 8.33 pounds of weight to floors that may already be weakened. as an estimated 250gpm adds one ton of water per minute to the structure.
indicators of potential or imminent collapse include:
-roo

actions taken when collapse is imminent

first, as you and the rest of your crew are exiting the building, inform Command and all others inside the building of the situation.
second, establish and clear the collapse zone as soon as possible. no personnel or apparatus should be allowed to operate

determining collapse zone

a collapse or safety zone must be established adjacent to any exposed exterior walls of the structure. traditionally, collapse zones have been estimated by taking the height of the structure and multiplying it by a factor of 1.5. as the structure increase

guidelines for determining a collapse zone:

-type I construction high rise buildings are not as likely to collapse, making the primary concern the hazard of flying glass from windows or curtain walls. in type I construction, it is the contents of the building burning, not the structure itself
-type

balloon frame construction

a construction method using long continuous studs that run from the sill plate (located on the foundation) to the roof eave line. all intermediate floor structures are attached to the studs. requires the use of long lumber and generally lacks any type of

platform frame construction

a construction method in which a floor assembly creates an individual platform that rests on the 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 fir