08 building construction fdny

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Probationary Firefighters Manual

Chapter 8

BUILDING CONSTRUCTION

OBJECTIVE: To introduce members to some of the different types of buildingconstruction and their relation to fire spread.

Familiarize members with basic building collapse.CONTENTS: Building illustrations

Construction features Glossary of terms

FDNY SOURCE:

Firefighting Procedures:o Volume One: Books 1 6o Volume Three: Book 3

Safety Bulletinso No. 85

OTHER REFERENCES:

1. Brannigan, F. (1992). Building Construction for the Fire Service, (3rded.). Quincy, MA:National Fire Protection Association

2. Captain Murphy, D. & Firefighter Molle, H. (2000, 3rd). More on gypsum roof decksystems, With New York Firefighters (WNYF), p. 25.

3. Dunn, V. (1988) Collapse of Burning Buildings: A Guide to Fireground Safety. SaddleBrook, NJ: Fire Engineering Books & Videos: a Division of Penn Well PublishingCompany

4. International Fire Service Training Association (1999)Building Construction: Related tothe Fire Service (2

nded.). Oklahoma: Fire Protection Publications, Oklahoma State

University.5. International Fire Service Training Association (1998).Essentials of Firefighting (4th ed.).

Oklahoma: Fire Protection Publications, Oklahoma State University.

6. TenanetNet (2005).NYS Multiple Dwelling Law, Retrieved October 15, 2006, fromhttp://tenant.net/Other_Laws/MDL/mdltoc.html

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http://tenant.net/Other_Laws/MDL/mdltoc.htmlhttp://tenant.net/Other_Laws/MDL/mdltoc.htmlhttp://tenant.net/Other_Laws/MDL/mdltoc.html


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BUILDING CONSTRUCTION

TITLE PAGE

BEAMS....................................................................................................................1

BUILDING CODES ....................................................................................................4

COLLAPSE ..............................................................................................................6

BULKHEAD..............................................................................................................8

FIRE ESCAPES.........................................................................................................14

FRAMING ..............................................................................................................17

GYPSUM ..............................................................................................................24

LIGHTWEIGHT CONSTRUCTION...............................................................................26

LOADS ..............................................................................................................30

ROOFS ..............................................................................................................32

STAIRS ..............................................................................................................33

STAIRWAYS.34

STRUCTURAL STEEL................................................................................................38

TRUSSES ..............................................................................................................43

WALLS ..............................................................................................................48

WINDOWS ..............................................................................................................49


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FDNY Probationary Firefighters ManualChapter Eight BUILDING CONSTRUCTION

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AIR SHAFT A space between buildings or between rooms within a building,provided for the purpose of admitting air and light to rooms.

AUTO

EXPOSURE

The extension of fire in or on the exterior of a building from fire

originating in the same building

BASEMENTA story partly underground but having at least one-half its height,measured from finished floor to finished ceiling, above the curb level.

CELLAR A story having more than one-half its height from finished floor tofinished ceiling below the curb level.

BEAMS

BEAM A horizontal member used to carry loads perpendicular to its length.

FIRE

-CUT

A bevel cut at the end of roof beams in brick walls, leaving the beams

free to fall if burned through without causing the walls to fall.

JOIST Closely spaced beams supporting a floor or ceiling.

OPEN SHAFTS ENCLOSED SHAFTS


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Beams/joists can be supported by bearing walls in numerous ways:


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Beams/joists can also be supported by other beams, known as girders.

GIRDER A horizontal structural member used to carry loads perpendicular to itslength but larger in size to beam.

Girder


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BUILDINGCODES

1938 Building Code

Class 1: Fireproof Structure

Class 2: Fire-Protected Structure

Class 3: Non-Fireproof StructureClass 4: Wood Frame Structure

Class 5: Metal Structure

Class 6: Heavy Timber Structure

1968 Building Code

Construction Group I - Noncombustible Construction Group II - Combustible

I-A: 4 Hour Protected II-A: Heavy TimberI-B: 3 Hour Protected II-B: Protected Wood Joist

I-C: 2 Hour Protected II-C: Unprotected Wood Joist

I-D: 1 Hour Protected II-D: Protected Wood FrameI-E: Unprotected II-E: Unprotected Wood Frame

CLASS A

MULTIPLE

DWELLING

A building housing three or more families in which residency is

permanent in nature

CLASS B

MULTIPLE

DWELLING

A multiple dwelling which is occupied transiently.

FIRE PARTITION A partition provided for the purpose of protecting life by furnishing anarea of exit, or refuge, and having a fire resistive rating of at least three

hours.

*1938 Building Code

FIREPROOF

CONSTRUCTION

A building in which the walls, floors, structural members andstairway enclosures are made of incombustible materials with

fire resistive ratings as required by the Building Code,

FIRE RETARDING any material or substance that is used to hold back the spread offire for a rated period of time


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FIRE STOPPING the closing of all concealed draft openings to form an effectualfire barrier at floors, ceilings and roofs with brick, concrete,

gypsum, asbestos, mineral wool, rock wool, metal lath with

cement or gypsum plaster, or other approved incombustiblematerials.

FIRE WALL A wall provided primarily for the purpose of resisting thepassage of fire from one structure to another or from one area of

a structure to another, and having a fire resistive rating of at least

four hours.

*1968 Building Code

RENOVATED

BUILDING

Any alteration to the original structural components, major orminor, that may effect fire fighting operations.

Alteration," as applied to a building or structure, shall mean any

change or rearrangement in the structural parts or in the egress

facilities of any such building or structure, or any enlargementthereof, whether by extension on any side or by any increase inheight, or the moving of such building or structure from one

location or position to another.

SINGLE ROOM

OCCUPANCY

A multiple dwelling in which the apartments, which wereformerly rented to families, are now rented as single rooms to

unrelated people. These occupants use the kitchen and bathroom

facilities in common.

VARIATION Permission given by the Department of Buildings and/or Boardof Standards and Appeal to construct a building in variation withthe existing Building Code.


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COLLAPSE

A collapse is one of the most dangerous operations a firefighter will encounter. The FDNYmight be dispatched to a report of a collapse or one may happen during firefighting

operations. Injured or disoriented people may require assistance, while others may still be

trapped in the rubble.

COLLAPSE ZONE The expected ground area a falling wall will cover when it collapses.It is at least the distance away from the wall which is equal to theheight.

Horizontal Collapse Zone width of the structure

Vertical Collapse Zone height of the structure

PRIMARY

STRUCTURAL

MEMBER

A structure that

supports another

structural member inthe same building,

such as a bearing wall,a column, or a girder.The collapse of a

primary structural

member will oftencause the collapse of

the structural member

it supports.

SPALLING Loss of surface material when concrete (or stone) is subjected to heat.It is due to the expansion of moisture in the concrete. Explosive

spalling occurs violently, throwing bits of concrete projectiles(Brannigan 331.).

CAUSES OF

COLLAPSE

Structural Weakness:

Accumulation of snow orrain on the roof

Overloading of floors Backdrafts/Smoke Explosions Fires

Excavations Improper Renovations Weather earthquakes,

winds etc.

Impact load from a collision

WARNING SIGNS Plaster sliding or falling off of walls Prolonged burning Sagging floors due to excessive

water

Traveling cracks Walls/columns bulging

out of alignment

Sounds e.g. creaking,rumbling, etc.


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TYPES OF COLLAPSES


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BULKHEAD Any structure on the roof of a building enclosing stairways, tanks,elevator machinery or other accessories to a structure.

WALK

THROUGHBULKHEAD

A structure at the uppermost portion of interior stairs that may isolate

the front section of the roof from the rear. One must walk through thebulkhead to reach the other section of the roof.


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CANTILEVER a horizontal structural member supported on one end only

COAMING A raised frame around a floor or roof opening or scuttle to keep waterfrom running in.

COCKLOFT The space between the roof and the top floor ceiling. Fire may enterthe cockloft through recesses, voids and ducts.

COMMON

COCKLOFT

Open all the way from one end of a row of houses or stores to the

other end.

COCKLOFT AREA


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CORBELLING Course of brick built out from the face of a wall, as steps in reverse.*See definition of parapet for illustration

CANOPY A supported, roof likecovering which projects from

a wall as an ornamentalfeature.

MARQUEE A permanent hood which projects over an entrance to a building and isnot supported by posts or columns.


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COLUMN A vertical member instructural frame used to

transfer floor and roof

loads to the foundation.

CORNICE Decorative trim at the roof line. Made of metal, wood or masonry,which tops the front wall & projects from it (Brannigan 194.).


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COPING STONE Top masonry tile or stone of a parapet wall, designed to carry offrainwater. Sometimes called a capstone, it weighs between five and

fifty pounds (Dunn 18.).

COMPACTOR A device for crushing garbage and trash into a small space prior toremoval from the premises

DUMBWAITER A device for collecting garbage from apartments by means of awooden car which is raised and lowered in a vertical shaft by

means of a rope and a pulley. In most buildings having these

dumbwaiters they are no longer used


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EXPOSURES A system of designating the areas or buildings which are adjacent tothe fire building. When facing the main entrance to the fire building,

exposure #1 is in front of the building, #2 is on the left, #3 is to the

rear of the fire building and #4 is on the right.


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FIRE ESCAPE An emergency means of egress from a building consisting of metalbalconies on the outside of a building connected by ladders to each

other and to the ground. Some fire escapes have a ladder from the top

floor balcony to the roof.

DROP LADDER A vertical ladder normally held in the "up" position at the second floorbalcony of the fire escape by a hook. When this ladder is to be used,the hook is released and the drop ladder is lowered or dropped to the

ground. Care must be exercised to make certain that no one is struck

by this ladder when it is lowered or dropped to the ground.


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PARTY WALL

BALCONY

A structure built as an emergency means of egress from a buildingwhich will afford lateral access to an adjoining building or apartment

separated by a fire wall. They do not have ladders to ascend or

descend from floor to floor or the roof.

COUNTER

BALANCED

STAIRWAY


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GOOSENECK

LADDER

A vertical ladder, the side rails of which are curved at the top. Thistype of ladder is sometimes used between the top floor balcony of a

fire escape and the roof.

WOOD (YANKEE)

GUTTER

Found on most Brownstones. They can be dangerous, since they

are made of wood and then tarred over many times. Usually

rotted.

Yankee Gutter


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FRAMING

BAYS The open area between either studs, in a wall, or beams in a flooror a roof

FIRE STOP

(CATS)

A strategically located structural component designed to prevent

the horizontal and/or vertical spread of fire in walls, partitions,floor, roof and other areas of a building.

HEADER A beam which carries the ends of beams which are cut off inframing around an opening.

LALLY COLUMN A vertical structural member consisting of a steel pipe filled withconcrete.

LINTEL A horizontal building member, supporting the weight above anopening, such as a window or a door.

When overhauling, lintels shouldnot be removed, regardless of

charring, as they support a considerable amount of brickwork.*See definition of parapet for illustration

NOGGING Brick filling between studs

RAFTER Closely spaced beams supporting the roof and running parallel tothe slope of the roof.

RIDGE The horizontal line at the junction of the top edges of twosloping roof surfaces.

RIDGE BOARD

(POLE)

The board at the ridge to which the rafters of both slopes of the

roof are nailed.

SLEEPER Wood strips imbedded in concrete to provide a nailing base forthe under flooring

SOFFIT (EAVES) The underside of subordinate structural members.

STUD Vertical structural elements in a wall or partition arranged inrows and used for the support of lath, plaster wall board, etc.

TAIL BEAM A beam which frames into the header instead of spanning theentire distance between supports.

TRIMMER A beam at the side of an opening and carrying one end of aheader.

FURRING

(LATH)

A light frame of wood or metal strips applied to a surface to

support plaster, stucco or other surfacing materials.


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BASIC TYPES OF WOOD FRAMING


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BALLOON

FRAMING

In balloon framing construction, fire can easily extend vertically. Studs

and corner posts are continuous from the sill to the top plate. The side

wall studs, at a point of the upper floors, are notched out and a 1 x 4 is

fitted and nailed into the studs. This is known as the ledger board. The

ledger board supports the floor joists of the upper floor.


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PLATFORM

FRAMING

Each level is completed separately. The floor beams and deck for the next

higher level are constructed on top of the lower story.

From a fire protection standpoint, platform construction is superior to

balloon, because there are no concealed wall voids extending for more

than one floor level (Dunn).


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GYPSUM PLANK

ROOF DECKING

Gypsum planks are normally 2 inches thick, 2 feet wide and 8 feetlong and factory-laminated of two gypsum panels. Each plank

weighs approximately 135lbs.

GYPSUM PLANK DECKING SYSTEM

GYPSUM CONCRETE

ROOF DECKING

Gypsum concrete is mill formulated and composed of calcinedgypsum and wood chips or shavings. It is usually poured to a

2 inch thickness and weighs approximately 17.5 lbs. per square

foot (280lbs compared to the size of a Gypsum plank).

GYPSUM CEMENTERY ROOF SYSTEM

Deck With Ceiling


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SAFETY CONCERNS OF GYPSUM ROOF SYSTEMS:

Gypsum plank and concrete decking is of lightweight construction which spans largewide spaces. The main drawback, from a firefighting operational stand point, is that

this type of construction is extremely vulnerable to moisture causing a deterioration of

the system.

The above characteristic, along with truss construction, are conducive to an earlycollapse under fire operations. Members shall not be committed to roof operationswhen this type of roof construction is found.

Interior firefighting operations shall be conducted from areas of safety due to theweight of such decking materials. Hose streams should be operated well in advance of

members.

The presence of a Gypsum RoofDeck will be indicated by a whitepowdery residue during saw

operations. Upon this

observation, members shall make

immediate notification to theIncident Commander and proceed

to evacuate the roof.

However, a field unit discovered that white powdery residue will only be present on aroof not subjected to moisture. Theyfurther discovered that a gypsum roof

that had been penetrated by moisture will

produce a brownish, clay-typesubstance, that will fill the shroud of the

saw during cutting operations.

o It should be stressed that thiscondition exists in roofs thatalready are degraded by moisture.


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LIGHTWEIGHTCONSTRUCTION

LAMINATED

WOOD "I" BEAMS

Consist of a top and

bottom chord and web.

The chords are made of2" x 3", 2"x 4", or two-

" CDX or pressed

plywood glued together.

The web is usually made

of " plywood.

Contractors may have

bore holes to route

electric, plumbing etc.,

compromising the strength of this beam. If not properly sealed,

fire can extend from one bay to another.

METAL "C"

JOISTS

are constructed of lightweight steel, approximately 1/16" thick,

and may have predrilled holes for plumbing and electric lines.

Cross braces may prevent twisting.


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LIGHTWEIGHT

WOOD TRUSSES

Made of 2"x3"s or 2"x4"s, which are held together with sheetmetal gang nails or gusset plates.

o Gang nails (gusset plates) penetrate only " to ". When exposed to high heat, fire, or prolonged moisture, gang

nails may pull away causing the failure of that truss. The failureof one truss may initiate a domino effect on adjoining trusses.

When light weight wood trusses are used as joists, fire canspread horizontally unimpeded.

Tests have shown truss failure rates a low as 1 minute, 20seconds. Failure of one truss can cause a structure to totally

collapse.


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OPEN WEB

STEEL BAR

JOIST

No fire resistance rating, protection from firedepends on the ceiling finish and finish

roofing.

Used to span long distances (up to 60 feet). Unprotected open web steel joists are particularly vulnerable to

elevated temperatures of a fire and may collapse after only 5 or 10

minutes.

May be covered with various roof decks:o Solid woodo Cementitious roof plank (wood fibers chemically processed and pressure

bonded with portland cement)

o Pre-cast concrete or gypsum planko Gypsum concrete (factory controlled mixture of gypsum and wood chips)

poured over form boards and steel wire mesh; usually 2" minimum thickness.

o Most common decking is corrugated steel, with the joists spaced from four tosix feet apart.

Roofs with this type of roof support system must not cut. Vertical ventilation should be limited to removal of skylights & scuttle covers if

present.

Emphasis should be placed on any and all horizontal ventilation points.


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ANYBUILDINGWITHLIGHTWEIGHTCONSTRUCTION

SHOULDBEENTEREDINTOTHECIDSPROGRAM.


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LOADS

AXIAL LOAD is a force perpendicular to the supportingmember. An axial load is straight and true

and is evenly applied to the bearing structure.

DEAD LOAD the weight of all permanent stationary construction entering into astructure and includes the weight of walls, floors, roofs, structuralmembers, etc.

ECCENTRIC LOADis a force whose resultant is perpendicular to

the supporting member but does not pass

through the center of the mass. The load isnot evenly applied to the supporting or

bearing member.

LATERAL LOAD are loads that are exerted outwardly on a horizontal plane. Theseforces may take place during a collapse or an explosion. Walls are

not usually designed to withstand severe lateral loads.

LIVE LOAD All loads other than dead loads. These loads are not permanent orstationary and include the weight of merchandise, office fixtures,

furnishings and all free standing material and persons.

IMPACT LOAD Are loads delivered, in a short time, on structural members andproduce stresses on structural members that may not have beenprovided for in design and may cause collapse.


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PARAPET That portion of a wall continued above the roof line.

RETURN The interior surface of a scuttle or skylight between the roof andthe top floor ceiling

SCUTTLE An opening in the roof or a floor of a house fitted with a lid.


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ROOFS

BUILT UP

ROOF

is the roofing material applied in sealed water-proof layers on thestructural members of the roof.

MEMBRANE

ROOF

Roofing material in roll form, consisting of asphalt materials,

(bituminous) polymers of plastics and synthetics for strength. Thicknesscan vary. Roofs covered with this type of materials are susceptible to

ignition and rapid flame spread when exposed to flame.

RAISED

(INVERTED)

ROOF

A roof which is raised above the roof beams and supported by 2 x 4"s.

The extent to which it is raised varies so as to provide proper drainage on

the roof. The result is a large open cockloft where fire can spread easily.


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STAIRS

TREAD: the horizontal part of a step onwhich the foot is place.

the vertical part of a step whichextends from the tread of a step to

the nosing of the next higher step

that part of the tread which

extends past the riser.

Vertical post at each landing

supporting handrails

RISER:

NOSING:

NEWEL

POST:


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STAIRWAYS

ACCESS

STAIRS

A stairway, usually open, serving a number of floors of a commontenant. Also known as convenience stairs.

ATTACK

STAIRWAY

A fire stair being used by the Fire Department to gain access to the fire

area, where the door between the stairway and the fire area is being

maintained in an open position.

EVACUATION

STAIRWAY

Fire tower or a fire stairs, designated by the Fire Department or a pre-

existing building fire plan, that is remote from the fire area and used for

the evacuation of the building occupants. A fire tower is the preferred

evacuation stairs.

FIRE TOWER An enclosed stairway connected at each story by an outside balcony orfireproof vestibule vented to the outside.

Required by NYS building code in high-rise buildings,built between 1938 and 1968.


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RETURN

STAIRS

Breaks up the stair climb at the middle of the stair rise with anintermediate landing; here, the climber reverses direction before starting

the second half of the stair rise.

TERRAZZO A polished floor covering made of small marble chips set in severalinches of cement. A terrazzo floor is a collapse hazard: it adds weight to

floor beams, conceals the heat of a serious fire below, and, because it is

watertight, allows water to accumulate and build up to dangerous

proportions. In 1966, A fire burning in a cellar below a terrazzo floorburned away the floor beams, although little heat and smoke penetrated

the floor itself. The floor suddenly collapsed, killing 12 firefighters(Dunn 32).


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SCISSOR

STAIRS

Two stairs constructed side by side in the core of a building in whichtheir doors alternate the point of exit to opposite sides of the core.


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LAYOUTS-STAIRWAYSANDPUBLICHALLS

TRANSVERSE STAIRSLocated at points remote from eachother but a person can go from one

stairway to another via public hall onall floors of the building.

An asset to fire operations

WING STAIRS

These stairs, one or two in a building,are located in each wing. There is no

connection to the other wing. Thediagram represents half a building

showing each type.

ISOLATED STAIRSUsually have individual entrance.

Floor landings are limited. Noconnection to other.


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STRUCTURALSTEEL

Older buildings generally only have two structural elements to support the structure,

masonry and wood. The introduction of a third element, steel, had the following advantages:

It allowed girders to support floors instead of a costly bearing wall of brick The consistency of steel structural characteristics allowed a fairly exact amount of

failure to be determined, thereby eliminating costly overbuilding required by the use

of safety factors when using less predictable materials such as masonry and wood.

And finally, the ability of steel to be connected permitted the coupling of severalbuilding sections, e.g. the H type design of residential housing.

Structural Steel creates three concerns to the fire service:

1. Steel when heated expands, and substantial elongation can occur at a fire. This

elongation can cause a wall to bulge, move, or even collapse if the steel is set within

the wall.

2. Steel when heated to higher temperatures during a fire may fail. Floor beams

supported by such failing steel will fall to the floor below.

3. Steel columns or girders, generally in an "I" beam shape, transmit fire and heat. The

"I" beam or channel rail, as it is sometimes called, when in the form of a column

located in the inner framework of a building may extend from the first floor up into

the roof space or cockloft area. The space between the enclosing wood framework

and "I" beam, when in the form of a vertical column, leads up into the cockloft and

many times spreads to this roof space.


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"I" beams will absorb heat from the fire at a rate dependent on many factors, such as, the

temperature of the fire, the extent of the fire, and the mass (weight and size) of the beam. A

large, heavy "I" beam will be able to absorb more heat and its temperature will rise more

slowly than a lightweight beam.

Because of the conductivity of the steel, this temperature will diffuse into the beam

causing its expansion. An average 50 foot long steel beam, heated uniformly over its length

to 970F will extend in length approximately four inches. A longer "I" beam will expand a

proportionately greater distance, and as the temperature increases, the rate of expansion

increases. At 1000 F a 100-foot long beam will have extended in length nine-and-a-half

inches.

When these steel beams are heated from 1000 F to 1500 F, their yield strength drops

dramatically and they start to soften and fail. This temperature can be reached in five to ten

minutes at a fire and it is only a matter of time at an uncontrolled fire (thirty minutes for the

smaller beam sections), until these beams can be heated beyond their strength limitations.

There is a false impression that hot steel beams or columns cooled by hose streams

will crack or fail. Tests have shown that cooling a steel member will cause it to regain its

strength and load carrying ability, and under normal circumstances, there should be no

hesitation in cooling these members. If the beam has already sagged under the weight of

floors or roof, firefighters should not be allowed in the possible collapse zone, whether these

beams are cooled or not. The steel will contract to its original length as it is cooled and if the

beam has sagged, this shortening may pull the end of the beams off their supports or twist

the beam allowing the joists to drop.

UNPROTECTED

STEELSteel structural components of a building which do not have any

fire resistive covering such as concrete, brick, asbestos, etc.


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SUSPENDED(DROP)CEILINGS

They are suspended by lightwood strips, steel wire or

steel bars, all of which are

quickly affected by fire.

Suspended ceilings offertheir own collapse potentialwhen loaded with water or

weakened by fire and are

sometimes blown down by abackdraft in the cockloft.

Special care must beexercised when these ceilings are constructed of heavy wire lath and plaster or tin, as

these ceilings often fail and fall in one piece over the entire area of a store.

Besides inflicting injury, these ceilings can trap members beneath, if they fall intact.

These ceilings should be "punched" with a hook for water detection, to checkconstruction and fire conditions.

Multiple layers of tin, sheetrock or tiles may have been affixed together on supportswhich were not intended to carry such weight.

A slight amount of water or fire can cause failure and the weight of such a ceilingincreases chance of entrapment and injury.

When initially pulling suspended ceilings members should be in a safe area in case oftotal failure.

Light fixtures offer another hazard as they may swing down if the support breaks at oneend. The void area created by suspend ceilings is referred to as the Plenum,which may

allow for fire travel. Also, in this area are installed pipes, wiring, air handling ducts and

recessed lighting fixtures.

Plenum


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THROAT Part of a building that connects the wings of the building.


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TRUSSES

BEWARE OF T HE TRUSS

Truss roof construction is used to span large areas, free of support columns, and can bemade of wood or steel. Most roof trusses are designed just to provide the span andsupport of the roof system.

Basically, the truss is composed of two major members, chords and webs. There is atop and bottom chord connected by shorter members called webs. The webs are placed

vertically and diagonally, forming triangular configurations with the chord members.

There are many variations but all are essentially the same; a combination ofinterdependent components used to span large distances through the use of smaller

pieces fastened together.

In any truss frame, every part of the truss is important to its stability. The failure ofany element may lead to the failure of the entire truss. Because of the wide spans and

the interdependence of trusses, one with another, the failure of a truss may have seriousconsequences far from the point where the initial failure occurs.

Truss roofs are not designed nor constructed to be used as a Fire Department workingplatform. Early collapse of the roof must be anticipated in a heavy fire condition andmembers should not be committed to roof operations.

Members operating on the roof must immediately inform their officer and IncidentCommander of the type of roof system and the presence of any heavy equipment.

Members should also be aware that light-weight wood trusses and wood I-beams arebeing used as floor supports, creating the same potentially dangerous collapse

conditions within the interior of the structure.

Truss construction should be suspected on all new or renovated taxpayer/commercialstructures as well as all large span building spaces. When found, these structures

should be the subject of a CIDS card.


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BOWSTRING

TRUSS

Can be made of heavy timber or metal or a combination of both. Wooden bowstrings are found in older commercial structures in NYC, e.g.

supermarkets, bowling alleys, lumberyards, auto storage garages, and in buildings thatoriginally housed such occupancies.

Characteristic hump-like roof profile the longer the span, the higher the bow. This easily recognized silhouette, if not obscured by signs, built up parapets or smoke

conditions, gives notice of truss construction. Other types of truss construction are not

as easily discerned from the exterior of the building.

Trusses may be spaced 10 or 20 feet apart with roof beams installed between thetrusses to support the roof coverings.

Also, in the older wooden truss roof buildings, there is a possibility of rotting at theends of the trusses where they rest on the walls, due to water leaking through the roof

covering. To prevent this leakage, building owners, may place a small section ofroofing at an angle between the wall and the roof to form a trough for drainage.

Wood truss roofs appear to fail without warning. The roof does not sag or get"spongy." Steel trusses tend to "stretch" when losing their strength because of elevated

temperatures, but wood tends to "snap".

Trusses are composed of smaller and lighter weight members and they span greaterdistances than the conventional roof beam construction. Fire will affect them more

rapidly.

If a serious fire involves the roof portions then firefighters should not be committed tocut such roofs. Fire conditions must be closely monitored and the firefighters on theroof must be removed when roof stability is in doubt.


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VERTICAL

VOIDS

Created by pipe recess (water & vent pipes), channel rails, electricalconduits, dumbwaiter shafts, etc. Can spread fire throughout the

building by convection or burning embers dropping down these voids

and starting a fire on a lower floor.

Soil pipe, water pipe and electrical line found in a rear closet.


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If heat is detected at BASE OF of soil pipe,

inspection holes shall be cut.

If heat is detected in walls,

inspection holes shall be cut.

Firefighter makes inspection

hole in the wall.

Officer communicates via Handie-Talkie to

Office on floor above. Fire extending up pipe

recess, between kitchen and bathroom.


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WALLS

BEARING

WALL

A wall of a building which carries any load other than its own weight.

KNEE WALL A wall used to box out a finished attic. This creates large voids andoccupants usually store combustibles behind it.

PARTITION A non-bearing wall one story or less in height

VENEER

WALL

Single thickness of masonry or brick-designed to improve exterior

appearance of the building, it lends no structural support.

MORTAR A material composed of sand and cement (and possibly other additives)used to build brickwork.


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WINDOWS

WINDOW

BARS

The location of window security bars will vary. However, it is notuncommon to find these installations on all floors and all sides.

The construction of these bars will vary from thin aluminum childguards to heavy wrought iron and steel.

Some bars may be set in mortar or brick. Others may be bolted orscrewed into the wooden frame of the window or door.

Civilians may becometrapped with no means

of escape.

Firefighters maybecome trapped when

going above the fire

for a search. Window bars are

heavy and difficult to

remove.

CASEMENT

WINDOWS

A metal framed window which opens outward. This type of window is

usually found in high rise multiple dwellings.


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ENERGY

EFFICIENT

WINDOW

(EEW)

A window designed to maintain air tight insulation, and will containmore than one pane of glass with an air tight space in-between.

*SPECIAL NOTE ON ENERGY EFFICIENT WINDOWS*

EEWSHAVEAMAJORIMPACTONTHEVENTILATIONPROCEDURE

These windows maintain their integrity longer than ordinary single pane windows in a fire

environment with the following effects:

A. High heat buildup in fire apartment and floor above.B. Possibility of a backdraft/flashover.C. Difficult to vent properly.D.

Cause rapid extension.

E. Discoloration due to high heat is not readily apparent.F. Difficulty in determining the fire apartment, room or floor area.

Energy Efficient Windows can cause extreme heat and smoke conditions to develop in the

fire apartment and apartment above the fire. The potential for flashover and backdraft isincreased. Uncontrolled horizontal ventilation can seriously jeopardize member safety.

Fire showing out failed Energy Efficient Windows is indicative of high heat and fire in an

advanced stage.


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WINDOW

GATE

A folding gate placed at a window to preventintruders from entering. The type that is

approved by the Board of Standards &

Appeals does not have any locks.

08 building construction fdny

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