Chapter 3: Building Construction Flashcards
Building codes
regulate: the type of construction
Building codes regulate: the type of construction based on
o intended use,
o structure size,
o the prescence or lack of an automatic fire suppression system
what determine the type of building construction
The construction materials and their resistance to fire exposure
what code does Canada follow
Canada uses National model construction codes
5 types of construction
Type I through V which are further divided into subcategories depending on code and construction type
what defines each type of building type
The construction materials and performance when exposed to fire define each construction type
Type I and purpose
(fire resistant)
- Provides highest level of protection from fire spread as well as structural collapse
- Composed of noncombustible or limited combustible materials with high fire resistive rating
- Can be expected to remain structurally stable longer during fire and most collapse resistant
type I composed of
reinforced concrete
precast concrete
protected steel
Reinforced concrete
concrete that is internally fortified with steel reinform=cement bars or mesh placed within the concrete before it hardens
precast concrete
concrete building member is poured and set according to specification in a controlled environment and is then shipped to the concrete site for use
protected steel
steel structural members that are covered with either spray on fire proofing or fully encased in an underwiters laboratories tested and approved system
type I is often incorrectly reffered to as being…. but isn’t because….
fireproof
o While the structure wont burn it may degrade from the effects of fire
o Additional coimbustible materials in the building can generate sufficient heat over time to weaken buildings integrity
During a fire in a Type I structure firefighters may experience the following:
o Compartments can retain heat, contributing to the potential for rapid fire development
o Roofs may be extremely difficult to penetrate for ventilation purposes due to construction material and design
o Windows may be nonoperating causing them to be very difficult to open for ventilation
Type II and purpose
- Composed of materials that will not contribute to fire development or spread
- Do not meet the stricter requirements of those materials used in Type I building classification but still do not add to fuel load
materials used in Type II
metal framing members,
o metal cladding, or concrete block wall construction
o unprotected open web joists supporting metal roof decks
Type III and purpose
(ordinary construction)
- Commonly found in mercantile, business and residential structures and older schools
- Requires that exterior walls and structural members be constructed non combustible or limited combustible materials
type III materials
exterior walls and structural members be constructed non combustible or limited combustible materials
- Interior walls, collums, beams, floors and roofs completely or partially constructed of wood
type III - May contain a number of conditions that can influence fire behaviour including:
o Void channels inside the wooden channels that roof and truss systems create between wall studs are less protected than in type I and II construction
Fire will spread through these spaces unless fire stops are installed in the void
o Prefabricated wood truss systems
These systems may fail quickly when exposed to fire
type IV and purpose
Heavy Timber)
- Characterized by use of large dimesnsioned lumber or laminated wood
- Extremely stable and resistant to collapse due to the sheer mass of their structural members
o When involved in a fire it’s the timbers’ own char that reduces heat penetration to the inside of the beam
Type IV material
- Exterior walls are constructed of non combustible materials
- Interior building elements are constructed of solid or laminated wood with no concealed spaces, helping prevent unseen fire travel
- Glue laminated beams
- Glue laminated beams are part of what type of building and caution of them and where they are found
Type IV
- Glue laminated beams may fail when exposed to fire because the heat may affect the glue holding the laminates together
o Found in churches, auditorium, and other large facilities with vaulted or curved ceilings
Type IV buildings may contain the following conditions that can affect their behaviour during a fire
o The high concentration of wood can contribute to the intensity of a fire once it starts
o Collapse of masonary walls can be caused by the loss of structural integrity of timbers
Type V and purpose
- Examples: single family residences, some multistory apartment buildings
cheap
Type V materials
- Exterior load bearing walls are composed entirely of wood
- A venner of stucco, brick or stone may be constructed over the wood framing making it look like Type III
Depending on siding material, it may ——- to —- —- —- or —- —– —–
o Modern siding such as vinyl adds another petroleum based fuel to the structural fire load producing dense, dark, oily, toxic smoke
o The siding covers combustible insulation which becomes exposed when the siding melts away and may contribute to rapid fire development on the exterior and may extend to interior
- Depending on siding material, it may contribute to exterior fire spread or help minimize fire spread
Use of prefabricated wood truss sytem in place of solid floor joists create….
- Use of prefabricated wood truss sytem in place of solid floor joists create open void between floors
Wood i-beams and what happens to them during fire conditions
are usually constructed of a central piece of thin plywood, have numerous holes cut in for wires to pass through
o Under fire conditions these fail and burn much more rapidly than solid lumbar
adhesives and industrial glues
used more frequently in type V
used to engineered structural members
no more or less reliable than other construction methods
Truss
structural member used to form a roof or floor framework trusses form triangles or combinations of triangles to provide maximum load bearing capacity with a min amount of material
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 fire rated assembly or in cocklofts and crawl spaces
Factory Built Homes
Structures that are partially or completely built in factory and shipped to location on which they are to be installed
Manufactured (mobile) homes
- Most common type of factory built homes
Manufactured (mobile) homes follow what rules
- Required to conform to US department of housing and Urban Development standard
-Not required to conform to the model building codes
Constructed before —–have ——- fire resistance
1976 have less
After 1976 mobile homes include:
Factory installed smoke and CO alarms
Use of flame retardant materials in interior finishes
Use of lame retardant materials aound heating and cooking equipment
Installation of safer heating and cooking equipment
Installation of gypsum board rather than wood paneling in interior finishes
Factory installed fire suppression systems (sprinklers)
mobile homes in fire conditions
- Some lightweight building materials in some factory built homes are susceptible to early failure in a fire
o Does not make forced entry` easier because can breach walls - May be anchored directly to concrete slab or have open crawl space beneath them which provides an additional source of oxygen during fire
- Fire may spread quicker because of fewer internal walls
Other types of factory built homes
Modular homes
Panelized homes
Pre cut homes
Hybrid modular structure
Modular homes
Modular section is transported to site then attached to permanent foundation which may include full basement
must comply with same local building codes as site built homes
o Only 6% of factory built homes are modular
o Sections can be stacked vertically and connected horizontally in numerous ways
Panelized homes
assembled on site from pre constructed panels made of foam insulation sandwiched between sheets of plywood
o Panels are self supporting so framing members are unnecessary
Pre cut homes
consist of individual parts that are custom cut and must be assembled on site.
examples of pre cut homes
Variety of styles including:
o Pole houses
o Post and beam construction
o Log homes
o A-frames
o Geodesic domes
Hybrid modular structure
includes elements of both modular design and panelized design
o Modular core units such as bathrooms or mechanical rooms are constructed in factory, moved to the site and assembled. Pre constructed panels are then added to the modules
Floors at ground level may consist of
a concrete slab or a floor assembly made up of joists and deck over a crawl space or basement
Upper floors of a multistory consist of
joists and decking with ceiling attatched to the bottom
Top level consists of
ceiling, joists or rafters and the roof above
The space between the floor/ceiling or ceiling/roof may contain:
o Duct work or open air plenum
o Electrical or communications wiring
o Water or natural gas pipes
o Pipes for a fire suppression system
o Recessed lighting and audio speakers
o Fiberglass, cellulose, or foam insulation beneath the roof or under the floors to act as sound proofing
Floor assemblies may be constructed of a combination of materials. Floors may be:
o Poured reinforced concrete
o Cellular concrete over metal decking
o Finished wood, tile, or carpet surface over a wood subfloor attatched to metal or wood joists
ceiling assemblies may be constructed of a combination of materials
o Gypsum board
o Tin tiles
o Lath and plaster attatched joists, roof trusses or beams
Ceilings in corridors that are designated as exit or egress passageways will have what kind
have the same fire resistance rating as the walls in that corridor
Walls
- Define the perimeter of the building as well as divide it into compartments or rooms
Exterior walls may be wood or metal siding attatched to:
o Studs
o A single layer of concrete
o Concrete blocks
o Logs
Wall assemblies consist of
a bottom plate, top plate, vertical studs and horizontal braces and sandwhiched between two surfaces made of gypsum or lath and plaster
o The cavity that the two surfaces form may have insulation
Fire wall assemblies
include the wall structure, doors, windows and any other protected openings meeting the required protection rating criteria
Materials used to cover floors in high occupancy structures
o Rated to limit flammability
o Ratings indicated in hours
fire walls may be used to
separate two ajoining structures and can also divide large structures into smaller portions and contain a fire to a particular portion of the structure
how are fire wall protection reduced
o When home owners and contractors make unprotected hoes for wires,pipes etc the protection of the fire wall can be reduced or eliminated
most difficult walls to penetrate
Exterior walls and fire walls are the most difficult to penetrate when attempting forced entry
general dangers of basements and stairs
- Fire in basements can damage floor joists and load bearing walls supporting upper floor
- Stairs can provide a fall danger in low visibility
- Stairs can provide a flow path for the movement of air, fire gases, and smoke throughout a structure
Basement
- A floor of a structure that is either partially or fully below grade level
Fire in basements may be more hazardous than in other compartments because
limited means of ingress/egress and limited ventilation
in basements -Absence of dry wall reduces fire resistance of
the studs and joints making the structural members part of the fuel load in the space
Protected or enclosed stairs
Stairs in commercial or multifamily residential buildings are required to have called this because they are built to resist the spread of fire and smoke
Access or convenience stairs
stairs that are not required to be a part of egres system and typically connect no more than two levels
Stairs can be classified as either
interior or exterior stairs
Interior protected stairs
are critical components of the life safety system of a building
- - enclosed with fire rated construction, usually with either a 1- or 2- hour rating, depending on building height
Firefighters should control the doors on protected stairs because
to maintain the integrity of the stairwell
o May facilitate either ventilation of the structure or evacuation of occupants
Exterior stairs
May be either open to the air or enclosed
Enclosed exterior stairs must comply with
requirements similar to those of interior protected stairs
Open stairs are naturally
ventilated but may be partially enclosed from the weather
Types of basements
o Partially underground (windows)
o Fully underground (no windows)
o Walkout or daylight (door to basement)
Unprotected stairs
- They may serve as a flow path for fire abd smoke
- Will not protect anyone from exposure to the products of combustion
- typically allowed to only to connect two adjacent floors above basement level
exterior fire escapes, escalators, and ladders are …
no longer aproved means of egress
Penetrations or openings in the roof are indications of
the general arrangement of the rooms within and may be used to assist in vertical ventilation during a fire
Building owners or occupants may make —— —– ——–to roofs during construction or renovations
Building owners or occupants may make unapproved or nonpermitted modifications to roofs during construction or renovations
3 prevalent types of roof
flat, pitched and arched
common combination of three roof designs
o Pitched (gable end)
o Gambrel
o Mansard
o Sawtooth
o Hip
o Shed
o Lantern
o Butterfly
less common roof styles
o Saw tooth
o Butterfly
Shape and construction of roofs intended to:
o Provide drainage
o Support weight of snow
o Resist effects of wind
disadvantage of combination of roofs
May have a combination which can contribute to voids underneath and limit the ability of firefighters to access areas under the roof
Flat roofs Commonly found on
commercial, industrial, multifamily residential structures
flat roof characteristics
- Generally have a slight slope to facilitate drainage
- Chinmenys, vent pipes, shafts, scuttle and skylights are common
- Parapet walls (2 ft-encases what’s on roof) may surround flat roofs
- Fire separation walls may divided the roof
- Obstuctions that may be on flat roofs include
o Water tanks
o Antenas
o Signs
o HVAC equipment
o Solar panels
Pitched roofs
Elevated in the center along ridge line with a roof deck that slopes down to the eaves along the roof edges
- Pitched roofs usually have a covering of roofing paper applied before the finish surface is laid
The finish of pitched roofs may consist of the following
o asphalt shingles
o Asphalt roll on roofing
o Metal panels
o Slate
o Tile
Arched roofs
They can spend large open areas and supported by columns, pillars, or posts
primarily constructed from late 1800s-mid1900s
Roof are made up of Three main components including
o the roof supporting structure,
o the roof decking or sheahing,
o and the roof covering
There are two general types of roof supports
o beams
o truss assemblies
arched roof types
- bowstring, pleated barrel, ribbed, lamella
Beams
the sections of lumber located directly under the roof decking
Beams on:
o on pitched roofs
o on flat roofs
o on pitched roofs they extend from the ridge line or pool at the peak of each side wall
o on flat roofs the beam extends from wall-to-wall the beam may be exposed or concealed behind a ceiling
Box beams and I-beams (wide flange beams):
manufactured from plywood and are often used in conjunction with wood joist to support flat roofs and floors
o these beams provide adequate structural strength under normal conditions but the thin web portion of plywood I – beams makes them susceptible to early failure and fire
Roof truss assemblies may be
conventional framing constructed on site or pre-manufactured in a factory and shipped to the site
Wood trusses are assembled by using
what happens to them during fires
metal gusset plates that only penetrate about 3/8 inch into the wood as wood burns away from the plates.
o during a fire the plates fall out and are no longer a structural support for the truss
Trusses created from engineered materials are also susceptible to early failure because
the open Web design of truss joist permits the rapid spread of fire in directions perpendicular to the truss joist instead of simply along the long dimension of the member
truss types include
o parallel cords,
o pitched chords,
o arched chords (not to be confused with boastring trusses)
o bowstring truss
Parallel chord truss
constructive wood or metal is generally used to support flat roofs and floor assemblies
Lightweight steel trusses
are made from long steel cords that are either straight or bent up to 90° with either flat or tubular members in the web space
o Unprotected lightweight open Web joists can be expected to fail quickly in a fire
Roof deck
: the portion of roof between the roof supports and the roof covering
Types of roof decks found in North America include:
o Plywood sheathing
o Oriented strand board OSB
o Wood tongue and groove
o Corrugated metal
o Sprayable concrete encapsulated polystyrene
o Reinforced concrete
o Double Tee performed concrete
The components of roof decks include:
o Sheathing
o roof planks or slabs
o purlins
Corrugated steel decking is frequently used in applications where
it serves as both the deck and the exterior roof covering
There are two basic types of concrete roofs common in North America
cast in place and precast
Cast in Place concrete
is placed into forms at the building site as a wet mass and hardens in prepared forms
o Permits the designer to cast the concrete in a wide variety of shape
o Does not develop its design strength until after it has been placed in the location where it will be used
Precast concrete:
widely used because they can be fabricated offsite and hauled to the construction site ready for use
o Lightweight concrete roofs are one particular variety of precast construction
o Time corrosion moisture or exposure to heat may cause concrete to separate from metal reinforcement and degrade its structural integrity
The roof covering is
the part of the roof exposed to the weather
Roof covering materials include:
o Shingles:- asphalt, wooden or shake, fiberglass, rubber, solar
o Asphalt sheets
o Tiles: Terra-cotta, concrete, slate, or synthetic membrane tiles
o Blown on foam
o Built up tar and gravel surface
o Metal roof systems or sheets
o Composite materials
Roof penetrations and openings:
items that provide light, ventilation, access, vapour exhaust, or a part of plumbing or HVAC systems
Roof penetrations and openings include:
scuttle hatches, skylights, monitors, automatic smoke vents, ventilation shaft, ventilation fans, penthouse or bulkhead doors, chimneys, HVAC exhausts, bathroom vent pipes, attic vents, dormers
Roof modifications include
Green roofs, cold roofs, photovalactic roofs, rain or snow roofs, security, structural modifications, roof mounted equipment
Green roof:
use of the roof surface of a building for a rooftop garden
green roof under fire conditions
Under fire conditions the increased load can accelerate structural failure particularly if the roof is combustible
green roof concerns
interfere with ventilation practises and fire location indicators
o Other concerns include:
The effects of high velocity winds and uplift wind pressur
Roof drainage which can add weight to the roof creating a collapse hazar
The exposure hazard that drive agitation on the roof may create
The need for a clear space between vegetation and firewalls that penetrate the roof
Cold roofs
generally found in cold, snowy climates to prevent ice damaging an icicle formation at eaves.
Designed to prevent into your heat from escaping into the attic space thus melting the snow on the roof
Photovoltaic roofs (solar energy)
produces clean and reliable energy useful for many applications
Photovoltaic roofs (solar energy) dangers and hazards for firefighters
o The electricity that the system generates presents a significant hazard for firefighters
o The panels retain a significant amount of electricity if light is available the panels will continue to produce power and produce electricity even if they are fire damaged
Rain or snow roofs
pitched roofs built over older flat roofs for aesthetic purposes, leak prevention, directing moisture off the roof, an alternative to repairing or resurfacing the original roof
o Built over mobile homes to provide a more permanent appearance
dangers of Rain or snow roofs
o The void that the rain roof creates can conceal a fire and allow it to burn undetected
o HVAC units may also be hidden from view under the rain roofs, adding to the collapse potential
o Ventilating a rain roof will not remove smoke from within the structure until the original roof is penetrated
Firefighters should not enter the void area to cut a hole in the original roof because they can:
become trapped in the void,
be overcome by the heat and smoke trapped in the void,
fall through a weekend original roof,
be caught in an extreme fire condition as a heated gases mix with fresh air
roof security
wired glass may be installed for security purposes in rooftop skylights
o This type of glass is difficult to penetrate and takes time to remove
Roof mounted equipment
: most commercial industrial institutional educational and some residential structures have equipment mounted on the roofs especially on flat roofs
o Roof mounted equipment includes
HVAC units, water towers, telecommunication equipment, advertising signs or billboards, recreation areas, wind generators, electrical transformers, derricks hoists and cranes, Winchester, steeples minarets spires and crosses, electrical lines and weatherhead’s
Doors
are a tool for fire and Flo path control
Doors can be classified by
style and construction material
Material of a door influences its
its effectiveness as a fire barrier in the degree to which you can be forced open
Doors are constructed from
wood metal and glass
most commonly used metals for doors
o Aluminum and carbon steel are the most commonly used metals but stainless steel, bronze, and copper are also used
Swinging doors
- Rotates by means of hinges secured to the side jambs of the doorway or on pivot posts supported at the top and bottom
- Can be single or double leaf
- May also be single acting swinging in one direction, or double acting swimming into directions
Sliding doors are never allowed to be used as
Never allowed as a part of a means of egrass because they slow the travel of people through the door opening
Sliding doors:
Suspended from an overhead track and uses steel or nylon rollers
Used for Elevators, power operated doors in storefront entrances, and fire doors to protect openings that are not a part of the means of aggres
Folding doors
- Hung from an overhead track with rollers or glide similar to those used by a sliding door
- Bifolding or multi folding and may be found in residential occupancies
- Horizontal fire door assemblies must meet specific requirements and be tested and listed for used as a means of egress
Vertical doors
- A door that opens in a vertical plane is known as an overhead door
- often found in industrial occupancies for application such as:
o Loading dock doors
o Garage doors
o Freight elevator doors
o Fire doors protecting openings that are not part of the required means of egress
Revolving doors
- Constructed with three or four sections or wings that rotate in a circular frame
- Designed to minimize the airflow through a door opening to reduce building heating or cooling losses
- Revolving doors can prevent the movment of hose or equipment into a building
- The wings are Design to collapse under pressure and provide an unobstructible opening
Panel door
consists of vertical and horizontal members that frame a rectangular area
o Common type of swing door
Flush door
consists of flat face panels that are the height and width of the door
o The panels are attached to a solid or hollow core
o Can be designed with openings to accommodate glass vision panels or ventilation louvres
Solid core door
formed with an interior core of laminated blocks of wood, particleboard, or a mineral composition
o The court is covered with two or three layers of surface material which is usually plywood
o Better fire barriers then panel doors or hollow core doors
Hollow core door
constructed with spacers between the face panels to provide lateral support
o Less expensive and lighter than solid core doors
Glass doors
- Use them both exterior and interior locations they are found in almost all occupancies but they are most commonly used in office and Mercantile buildings
- Framed or frameless
- Building code require glass doors to be made of tempered glass that resists breakage
Hollow metal door
can either be panel or flush and his normally 1¾ inches thick
- A flush door consists of smooth sheet metal face panels 1/20 inch thick
Fire doors
- Protect openings in fire rated walls and block the spread of fire within a structure
- When properly maintain an operated fire doors are very effective at limiting the spread of fire and total fire damage
Special types of fire rated fire doors are available for
freight and passenger elevators, security, chute openings, service counter openings, dumbwaiters
Overhead rolling steel fire doors
commonly used to protect a firewall opening in an industrial occupancy or an opening in a wall separating buildings into fire areas
o Maybe used on one or both sides of a doorway or other wall opening
o Door cannot be used on any opening that is required to be part of the means of egress
o This type of door ordinarily closes under the force of gravity
Horizontal sliding fire doors
often found in old industrial buildings, are usually held open by a fusible link and slide into position
o Horizontal sliding doors cannot be used to protect openings in walls that are required parts of means of egress
Swingimg fire doors
commonly used in stairwell enclosures or Corridor’s that require a fire door
o A swinging fire door must be closed during a fire in order to perform its functi
o Fire doors can either be automatic or self closing
o For a swinging fire door to close some type of detection device must first sense of fire or the smoke from a fire the oldest and simplest detection device is a fusible link that melts from the heat of a fire
windows
Means of light, ventilation, access and rescue
A window consists of
a frame, one or more sashes, and all necessary hardware to make a complete unit
Sash
refers to a fixed or moveable frame to you know that may be included within a window frame
o The frame is composed of cells, side jambs, and head jamb
The glass of windows may be
single, double or triple glazed
o there may be one thickness of glass, two thicknesses separated by an inner gas, or three thicknesses separated by voids filled with gas
fixed windows
- Consist only of a frame and glazed stationary sash
- Can be used alone or in combination with moveable windows
Moveable windows several common configurations
- Double hung
- Single hung
- Casement:
- Horizontal sliding
- Awning
- Jalousie
- Projecting
- Pivoting
Double hung moveable windows
has two sashes that can move past each other in a vertical plane
o Commonly used in residential occupancies because it permits circulation through the top and bottom of the window opening
- Single hung moveable window
has only one openable sash
Casement moveable window
has a side hinged sash that is usually installed to swing outward
o Can be open fully by unlatching and pushing or using the mechanical window crank for ventilation
Horizontal sliding moveable window
has two or more sashes of which at least one moves horizontally within the window frame
Awning moveable window
has one or more top hinged, outward swinging sashes that are open by unlatching and pushing or using the mechanical window crank
o This arrangement permits the window to be open during rain
Jalousie moveable window
includes a large number of narrow overlapping glass section swing outward
Projecting moveable window
swings outward at the top or bottom and slides upward or downward and grooves
Pivoting moveable window
has a sash that pivots horizontally or vertically on central axis
Common window security method
is to fasten metal bars or screens to the exterior of the window frame or the building itself
window security - Negative affect on fire and life safety
as they can prevent the escape of trapped occupants or firefighters and can slowly access time for firefighters
Rolling steel shutters
- Much like overhead rolling steel fire doors
- Rolling steel shutters may also be used to protect a firewall opening in an industrial occupancy or an opening in a wall separating buildings into fire areas
- Rolling steel shutters block interior window openings
Fire walls may be used to
Seperate two adjoining structures or two occupancy classifications within the sane structure to prevent fire spread
