Chapter 4 - Building Construction (MINE)

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, firefighters, and the water used for fire suppression are examples of live loads. (2) Force placed upon a structure by the addition of people, objects, or weather.

Party Wall

A load-bearing wall shared by two adjacent structures. A fire wall may be used as one of these.

Curtain Wall

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

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.

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 made of this.

National Building Code of Canada

Aka the NBCC, it has three types of building construction: Combustible, Noncombustible, and Heavy Timber

Stud

An upright post in the framework of a wall for supporting sheets of lath and plaster, wallboard, or similar material.

Types of Insulation

Asbestos, urea formaldehyde foam, fiberglass, mineral wool, cellulose, cotton, straw, foam.

Wide Flange Beams

Box Beams or I-beams manufactured from plywood and wood truss joists used to support flat roofs and floors. They provide adequate strength but the thin web on I-beams makes them susceptible to early failure in a fire.

Cockloft

Concealed space between the top floor and the roof of a structure.

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.

Spalling

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

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 through the roof of a building, that is designed to limit the spread of a fire within a structure or between adjacent structures. Often made of masonry

Roof Types

Flat, pitched, arched

Purlin

Horizontal member between trusses that support the roof.

Joists

Horizontal structural members used to support a ceiling or floor. Drywall materials are nailed or screwed to the ceiling joists, and the subfloor is nailed or screwed to the floor joists. Tend to lose their strength gradually when exposed to fire.

Defining Construction Types

IBC AND NFPA BOTH DEFINE CONSTRUCTION BY 5 TYPES BASED ON THE MATERIAL'S PERFORMANCE WHEN EXPOSED TO FIRE Each building is composed of structural frames, floor construction, and roof construction.

Steel Failure

If this type of material is restrained from the sides, it will fail somewhere in the middle. Its failure can be anticipated near or above 1000˚F. ITS CRITICAL FAILURE POINT CAN BE REACHED AT CEILING LEVEL FROM RISING HEAT AND SMOKE IN THE ROOM. Its failure depends on the size, carrying load, composition of the material, and geometry of the member. Fireproofing is sprayed on members to reduce the effect of heat on it

Rafter

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

Partition Wall

Interior non-load bearing wall that separates a space into rooms.

Gusset Plates

Metal or wooden plates used to connect and strengthen the joints of two or more separate components (such as metal or wooden truss components or roof or floor components) into a load-bearing unit.

Glass/Fiberglass

Not typically used for structural support. Used in sheet form for doors/windows, block form for non-load bearing walls. The second type is used for insulation purposes between exterior/interior walls and in roofs. Not a significant fuel for fires but can be combustible.

Parapet

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

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. Lower ratings are permitted for roof systems and flood. However, combustible insulation may be used in these members that may cause a fire.

Rebar

Short for reinforcing bar. These steel bars are placed in concrete forms before the cement is poured. When the concrete sets (hardens) the rebar within it adds considerable strength. It gives the material compressive strength as well as tensile strength. It can perform well in fires but lose strength through spalling.

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 in hollow walls or floors, above false ceilings, in penetrations for plumbing or electrical installations, in penetrations of a fire-rated assembly, or in cocklofts and crawl spaces.

Protected Steel

Steel structural members that are covered with either spray-on fire proofing (an insulating barrier) or fully encased in an Underwriters Laboratories Inc. (UL) tested and approved system.

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.

Lightweight Wood Truss

Structural supports constructed of 2- x 3-inch or 2- x 4-inch (50 mm by 75 mm or 50 mm by 100 mm) members that are connected by gusset plates.

Doors

THESE ARE CLASSIFIED BY THE WAY THE OPERATE. They vary widely in design and construction. There are 5 types.

Security Bars/Grilles

THESE ARE MOUNTED OVER DOORS AND WINDOWS TO PREVENT ILLEGAL ENTRY. It can however prevent emergency exit and proper ventilation.

Access or Convenience

THESE TYPES OF STAIRS ARE NOT REQUIRED FOR THE MEANS OF EGRESS SYSTEM AND TYPICALLY CONNECT NO MORE THAN TWO LEVELS. These stairs are not enclosed with fire-rated construction. They are also known as unprotected stairs.

Foundations

THIS BUILDING COMPONENT IS DESIGNED TO SUPPORT THE WEIGHT OF THE BUILDING AND ALL ITS CONTENTS. They may be shallow or deep and sits on a footing. Shallow foundations may be used for single-story dwelling while deep ones may be used to support the mass of a large area or tall building.

Floors/Ceilings

THIS BUILDING COMPONENT'S CONSTRUCTION VARIES DEPENDING ON THE LEVEL ITS AT. At ground level it may consists of concrete while at upper levels it may consist of joists and decking with the ceiling attached at the bottom. Some jurisdictions require warnings to be placed indicating the type of floor or ceiling truss system used.

Type of Building Construction

THIS IS DETERMINED BY THE ARCHITECT, STRUCTURAL ENGINEER, OR CONTRACTOR. It is regulated by local building codes.

Wood

THIS IS THE MOST COMMON BUILDING MATERIAL USED IN NORTH AMERICA. Size and moisture affects how it reacts to fire conditions. (Smaller = easier to ignite and faster to lose structural integrity). Moisture content of this affects the rate at which it burns.

Roof Covering

THIS PART OF THE ROOF IS THE ONE THAT IS EXPOSED TO THE WEATHER. Materials include wood/asphalt/metal/rubber shingles, sheets, terracotta, foam, tar/gravel, composite materials

Cold Roofs

THIS ROOF OBSTRUCTION IS GENERALLY FOUND IN COLD, SNOWY CLIMATES TO PREVENT ICE DAMMING AND ICICLE FORMATION AT EAVES. It prevents interior heat from escaping into the attic. The design of it (multiple layers of material) can prove to be difficult for fire fighters during vertical ventilation.

Masonry

THIS TYPE OF MATERIAL INCLUDES BRICKS, BLOCKS, STONES, AND UNREINFORCED CONCRETE PRODUCTS. It is minimally affected by fire and exposure to high temps. It usually maintains fair structural stability.

Separated Used

THIS TYPE OF OCCUPANCY CONTAINS MULTIPLE OCCUPANCIES OR USE GROUPS WHICH MUST MEET REQUIREMENTS FOR EACH INDIVIDUAL OCCUPANCY CLASSIFICATION. Example: strip malls

Single-Use

THIS TYPE OF OCCUPANCY MUST MEET THE BUILDING CODE REQUIREMENTS FOR ITS INTENDED USE. (Office bldg = business occupancy, elementary school = educational occupancy)

Smokeproof Stair Enclosures

THIS TYPE OF STAIR USES A MECHANICAL VENTILATION SYSTEM WHICH IS ACTIVATED BY AUTOMATIC FIRE/SMOKE DETECTION EQUIPMENT, TO KEEP SMOKE OUT OF THE AIR ENCLOSURE AND PRESSURIZE THE SHAFT.

Lightweight Construction Support System

THIS TYPE OF SYSTEM IS MANUFACTURED FROM SMALLER PIECES OF WOOD OR LIGHT GAUGE STEEL. It forms trusses that weigh less than traditional systems. It is becoming more common in buildings today other than type I and II construction.

Green Wood

THIS TYPE OF WOOD HAS A HIGH MOISTURE CONTENT, affecting rate at which it burns. It does not ignite as readily or burn as fast as wood that has been dried or dehydrated over time.

Roof

The primary function of this building component is to protect the structure and its contents from the effects of weather. THE SHAPE OF IT IS INTENDED TO PROVIDE DRAINAGE, SUPPORT THE WEIGHT OF SNOW, RESIST WIND, AND INSULATE THE INTERIOR FROM EXTERNAL TEMPERATURE CHANGES.

Aluminum

The use of this material increased in the 20th century. It has been used as decorative pieces in the Empire State Building. It is also used for roofing, flashing, gutters, window/door frames, exterior curtain wall panels, and studs. Also used in residential structures. IT IS MORE RAPIDLY AFFECTED BY HEAT THAN STEEL.

Permitted Structural Modifications

These are made to older structures to update and provide higher fire and life safety. THEY MAY INCLUDE ADDITIONS TO THE STRUCTURE, REMOVAL OF NON-LOAD-BEARING WALLS OR PARTITIONS, REPLACEMENT OF FIRE ESCAPES WITH ENCLOSED STAIRWAYS, OR SEALING WINDOWS/DOORS THAT ARE NOT REQUIRED FOR EMERGENCY EXITS. They must follow local building codes.

Building Codes

These are regulated by the AHJ Two Major ones in the US: NFPA 5000 and IBC FACTORY-BUILT HOMES (MOBILE HOMES) ARE EXEMPT FROM LOCAL BUILDING CODES Federal/state owned buildings (offices, courthouses, university bldgs, post offices may also be exempt.

Roof Trusses

These components are assemblies of framing constructed on site or in a factory and shipped to site. There are a variety of these ranging from parallel chords pitched chord or arched.

Beams

These components are sections of lumber directly under roof decking. They extend from ridge line at the peak of pitched roofs to the walls on each side. ON FLAT ROOFS, THEY EXTEND FROM WALL TO WALL. They may be exposed or concealed in a ceiling.

Roof Obstructions

These may be located on the roof and are basically things that block areas or are installations on the roof.

Nonpermitted Modifications

These may be made during updates that are unapproved and can actually inhibit ventilation and increase fire risk/structural collapse. They are primarily the removal of load-bearing components, increased dead load, or modifying venting/fire suppression systems.

Renovations

These may cause old buildings to be upgraded and increase their fire-resistance. Added sprinkler/alarm systems will improve the fire and life safety of older buildings. It is possible to add living spaces, or change wiring without permits that may create hazards for fire fighters.

Stairs

These provide access to, or egress from, levels of a structure.

Roof-mounted Equipment

These roof obstructions are usually equipment located on flat roofs. They add live load to the roof and can increase potential for collapse. Examples are HVAC units, water towers, generators, etc.

Flat Roof

These types of roofs are commonly found on commercial, industrial, and multi family residences as well as some single family dwellings. It generally has a slight slope for drainage. IT IS FREQUENTLY PENETRATED BY CHIMNEYS, VENT PIPES, SHAFTS, SCUTTLES, AND SKYLIGHTS.

Protected or Enclosed

These types of stairs are a part of the means of egress system and are built to resist fire spread and smoke. They are critical components of the life safety system. They are fire-rated with a 1-2 hour rating. Usually serve over 2 stories.

Walls

This building component defines the perimeter of the building, as well as divides it into compartments or rooms. Exteriors may be made of wood or metal siding attached to studs or concrete. THEY MAY ALSO BE AN ASSEMBLY OF STUDS WITH THE EXTERIOR MATERIAL ON THE OUTSIDE AND AN INTERIOR COVERING ON THE INSIDE.

Other Metals Used in Construction

This includes tin (metal ceiling tiles, roof coverings), copper (wiring, pipes, gutters), lead (pipes, flashing, windows). These metals will all fail when exposed to excessive heat.

Lath and Plaster

This is a construction process rather than a material. Wood strips (lath) are nailed into wall studs and covered with plaster to form an interior wall finish. Generally found in buildings prior to 1950s. Wire mesh has been used for lath as well. Can be difficult to penetrate and conceal/add fuel to the fire from the studs and lath.

Gypsum

This is an inorganic product from which plaster and wallboards are constructed. IT HAS A HIGH WATER CONTENT ENABLING IT TO ABSORB HIGH AMOUNTS OF HEAT AS THE MOISTURE EVAPORATES. It is excellent to resisting heat and retarding fires. Commonly used to insulate steel/structural members Commonly referred to as drywall or Sheetrock

Occupancy Classification

This is defined by the building code and life safety code adopted by the AHJ. Structures are divided into single-use or separated use.

Roof Deck

This is the portion of roof between roof supports and the covering. Can be made from plywood heating, OSB, wood tongue and groove, corrugated metal, concrete.

Plastic

This is used in many forms as a building material. Used as vinyl siding, foam insulation panels, water and sewer piping and fittings, wall coverings, mantel pieces. Most of this will melt and can add to the fuel load in a structure.

Steel

This material is the primary material used for structural support in the construction of large buildings as well as stairs, wall studs, windows, etc. It also is used to reinforce concrete. This material lengthens when it is heated. A 50 FOOT MEMBER MAY LENGTHEN AS MUCH AS 4" WHEN HEATED FROM ROOM TEMP. TO 1,000˚F (538˚C) Lengthening can actually cause structural collapse

Roof Penetrations and Openings

This part of the roof include a variety of items that provide light, ventilation, access, HVAC, etc. THEY CAN INDICATE THE LOCATION OF SOME TYPES OF ROOMS SUCH AS BATHROOMS OR MECHANICAL SPACES.

Green Roofs

This roof obstruction is designed to protect the environment and conserve energy. It creates increased insulating effects and provides better air quality in urban areas. It is considered as a dead load. The increased load can accelerate structural failure in event of a fire.

Rain Roof

This roof obstruction is found on commercial buildings, schools, and residential structures. They are usually placed over old roofs to prevent leaks and remove moisture. They may create voids that can allow fires to burn undetected. VENTILATING THIS TYPE OF ROOF WILL NOT REMOVE SMOKE FROM THE STRUCTURE UNTIL THE ORIGINAL ROOF IS PENETRATED.

Photovoltaic Roofs

This roof obstruction produces clean and reliable energy. It has cells in panels that are laid or embedded on the roof. EVEN IF BUILDING POWER IS SHUT OFF, THE PANELS WILL RETAIN A SIGNIFICANT AMOUNT OF ELECTRICITY. Significantly hazardous to fire fighters (tripping, breaking, falls, shock).

Novoclimat Standard

This standard is intoned to make new homes more energy efficient and better insulated. They are almost airtight, constructed of smaller dimension lumber, and use HVAC systems. However, they are more likely to fail rapidly under fire conditions because of the airtight-ness of the structure. Ventilation is also more difficult.

Type V Construction

This type of construction is commonly known as wood frame or stick frame. EXTERIOR LOAD-BEARING WALLS ARE CONSTRUCTED ENTIRELY OF WOOD WITH A VENEER AS ITS SURFACE. Most common types are single family dwellings or apartment buildings. Consists of wood stud construction less than 8". With coverings on the exterior ranging from aluminum siding to plastic to wood and veneers attached by nails, screws, or glue. IT NOW INCLUDES THE USE OF PREFABBED WOOD TRUSSES IN PLACE OF SOLID FLOOR JOISTS. THIS CREATES A LARGE VOID AREA BETWEEN FLOORS OF A STRUCTURE.

Type I Construction

This type of construction is known as fire-resistive construction. It provides the highest level of protection from fire as well as from collapse. All members are composed of noncombustible or limited-combustible materials with a high fire-resistive rating. STRUCTURAL MEMBERS MUST BE ABLE TO RESIST FIRE FOR A PERIOD OF 3-4 HOURS. Often incorrectly referred to as being fireproof. During a fire, interior components may add fuel, compartments may retain heat, roofs may be hard to penetrate, and windows may be non operating posing difficulties for fire fighters.

Type IV Construction

This type of construction is known as heavy timber/mill construction. It is characterized by the use of large lumber. Structural members are usually greater than 8" and have a fire resistance rating of 2 hours. Any other materials used must have a rating of at least 1 hour. These structures are stable and resistant to collapse. THEY ARE COMPOSED OF SOLID OR LAMINATED WOOD AND HAVE NO CONCEALED SPACES/VOIDS WHICH PREVENTS FIRE TRAVEL. Modern uses include Glulam beams which are strong but may fail when exposed to fire because of the glue. The high concentration of wood may contribute to a fire once it starts, collapse of masonry walls may be caused by loss of structural integrity of timbers.

Type II Construction

This type of construction is known as noncombustible or limited-combustible construction. IT IS COMPOSED OF MATERIALS THAT WILL NOT CONTRIBUTE TO FIRE SPREAD. Members do not need to meet the strict requirements of Type I Construction. Most common form includes metal framing/cladding, masonry, metal deck roofs. The fire resistance rating is 1-2 hours (half of Type 1) depending on the component. More prone to structural collapse that type I. It is normally used when fire risk is expected to be low or when fire suppression/detection systems are designed to meet the fuel load of the contents

Type III Construction

This type of construction is known as ordinary construction. It is commonly found in older schools and mercantile, business, and residential structures. IT REQUIRES THAT EXTERIOR WALLS AND STRUCTURAL MEMBERS BE COMPOSED OF NONCOMBUSTIBLE MATERIALS. Interior walls, columns, beams, floors and roofs may be made of wood. These structures may have voids inside wooden channels in roof/truss systems that could allow for the spread of fire, have renovations made to them, change in building use, prefabbed truss systems that could easily fail in a fire.

Combustible Construction (NBCC)

This type of construction under the NBCC does not meet requirements for noncombustible construction

Heavy Timber Construction (NBCC)

This type of construction under the NBCC is one in which a degree of fire safety is attained by placing limitations on wood size for structural methods and thickness/composition of wood floors and roofs. IT AVOIDS CONCEALED SPACES UNDER FLOORS AND ROOFS.

Noncombustible Construction (NBCC)

This type of construction under the NBCC is one in which the degree of fire safety is attained by the use of noncombustible materials for structural members and other building assemblies.

Revolving Door

This type of door is constructed with three or four wings that rotate in a circular frame. THIS TYPE OF DOOR PREVENTS THE MOVEMENT OF HOSE OR EQUIPMENT INTO A BUILDING WHICH CAN BE PROBLEMATIC FOR FIREFIGHTERS.

Glass Door

This type of door is for both exterior and interior applications. They are most commonly used in office or mercantile buildings. THEY ARE REQUIRED BY BUILDING CODES TO BE MADE OF TEMPERED GLASS THAT RESISTS BREAKAGE.

Folding Door

This type of door is hung from an overhead track and is usually made to divide large conference areas into smaller rooms. They may also be used as horizontal fire doors.

Vertical Door

This type of door is known as an overhead door and is mainly used in garages and freight elevators.

Sliding Door

This type of door is suspended from an overhead track. ITS MAIN ADVANTAGE IS THAT IT ELIMINATES A DOOR SWING THAT MIGHT INTERFERE WITH USE OF INTERIOR SPACE. They are never allowed as use in the means of egress because they slow exit time.

Wood Panel Flush Door

This type of door is very common and consist of flat face panels that span the full height of the door. They can have solid or hollow cores.

Swinging Door

This type of door rotates around a vertical axis. They are generally required as exit doors in a means of egress.

Cast Iron

This type of iron was commonly used in the 19th century for structural support beams and columns, stairs, balconies, facades of buildings, etc. IT STANDS UP WELL TO FIRE BUT IT MAY CRACK OR SHATTER WHEN RAPIDLY COOLED. Failure is usually caused by its bolts and connections.

Wrought iron

This type of iron was used in buildings in the early 1800's for nails, tie rods, balconies, and railings. After 1850 it was used for rail, I-beams, columns, channels. Today it is used for decorations in fences, gates, and railings. It is usually welded together or riveted.

Metal

This type of material includes cast iron, steel, aluminum, etc. Provides structural support and decorative coverings. The effect of fire and heat on it depends on the type and its exposure or covering

Composite Materials

This type of material is manufactures by combining two or more different materials. Results in lightweight materials with high strength, resistance to chemicals/corrosion and heat as well. They are cost effective and easy to make. It is being used more commonly due to a shortage of high quality, large diameter timber. SUCH MATERIALS INCLUDE FINGER-JOINTED TIMBER, LAMINATED TIMBER, MEDIUM DENSITY FIBERBOARD, PARTICLE BOARD, SYNTHETIC WOOD, OSB. They may be highly combustible and can produce toxic gases and deteriorate under fire conditions.

Pitched Roof

This type of roof has many different styles. They involve rafters or trusses that run from the ridge line to the top of the outer wall made of wood or metal with decking and heating on the top. Shingles are placed on top of that.

Arched Roof

This type of roof is ideal for some occupancies because they span large open areas unsupported by columns or posts. THE DESIGN OF THESE ROOFS DEPENDS PRIMARILY ON THE EXTERIOR WALLS TO SUPPORT THE WEIGHT OF THE ROOF.

Fire Escape

This type of stair is open and made of metal with landings. It is attached to the side of a building. They are not normally used in modern construction because of its inability to support live loads in an emergency and its anchors are subject to the freeze/thaw cycle.

Exterior Stairs

This type of stair may be either open to the air or enclosed. They must comply to similar requirements to interior protected stairs.

Manufactured Home

This type of structure is built in a factory and shipped to locations for installation. They are not required to conform to model building codes. They conform to the HUD standard similar to Type V construction. THOSE BUILT BEFORE 1976 HAVE LESS FIRE RESISTANCE THAN THOSE OF CURRENT CONSTRUCTION. Amount fo fires in these homes has decreased since 1980. Possibly due to smoke alarms, flame-retardant materials, safe heating/cooking equipment, gypsum board, sprinkler systems.

Roof Supports

Two general types of these are beams and trusses

Hybrid Construction

Type of building construction that uses renewable, environmentally friendly or recycled materials. Also known as natural/green construction.

Non-load bearing wall

Wall, usually interior, that supports only its own weight.

Load-Bearing Wall

Walls of a building that by design carry at least some part of the structural load of the building in the direction of the ground or base. THESE WALLS SUPPORT THE WEIGHT OF THE STRUCTURE OR STRUCTURAL COMPONENTS.

Veneer Walls

Walls with a surface layer of attractive material laid over a base of common material. Decorative covers for wood, metal, and concrete block load-bearing walls.

Dead Load

Weight of the structure, structural members, building components, and any other features permanently attached to the building that are constant and immobile.