Assembly
Two or more interconnected structural components combined to meet a specific function or design requirement. (Roof Trusses, Wall Frames, Doors including their frames)
Attic
An open space between the roof and ceiling of a building. Providing an open space for fire to burn undetected or spread throughout a structure.
Balloon Frame
A type of wood-frame construction in which the studs in exterior walls extend from the basement or foundation to the roof. This type of construction allows fires to spread undetected from the basement to the attic through the hollow walls.
Bar Joist
A joist constructed of steel with bars in the vertical web space. A Common structural component in office buildings and other commercial structures. Very high strength to weight ratio except when exposed to heat, in which early failure is likely.
Beam
A horizontal structural component subjected to vertical loads. Typical beams are steel or large dimension wood members.
Bowstring Truss
A roof assembly with a curved (Arched) top chord and a horizontal bottom chord. These assemblies are very strong except when exposed to direct flame contact when catastrophic failure with out warning may occur.
Butterfly Roof
A V-Shaped roof in which the two sides slope toward a valley in the middle. An unusual type of roof that is rarely seen in cold climates where snow load is a factor.
Cantilever
A beam that is unsupported at one or both ends. typically used to support balconies or apartments and some office buildings.
Chord
The main structural members of a truss as distinguished from diagonals. Chords span open space between the upper and lower diagonal members in a truss assembly.
Cockloft
An open space between the roof and ceiling of a commercial or industrial building. Usually found under flat or nearly flat roofs. In a fire, these spaces act in much the same way as attics.
Column
A vertical supporting member. Columns may be wooden or steel posts. Steel posts often support lightweight roof assemblies and if unprotected by surface insulation, steel posts may fail quickly in a fire.
Compression
Force that tends to push the mass of a material together. Bearing walls in a building are under compression from the weight of the roof and other materials above.
Course
Horizontal layer of masonry units. A row of bricks is an example of a course.
Curtain Board
Nonload-bearing interior wall extending down from a roof or ceiling to limit the horizontal spread of fire and heat. If curtain walls are penetrated by unprotected openings, fire can spread unchecked.
Decking
Planks or panels of plywood or oriented strand board (OSB) that form the substrate of a roof assembly. In vertical ventilation through a roof, the decking must be removed from the ventilation opening to realize the full effect of the opening.
Drywall or Gypsum Wall Board
Fire resistive wall covering also called sheetrock
Eave
The edge of a pitched roof that overhangs an outside wall. Attic vents in typical eaves provide an avenue for an exterior fire to enter the attic.
Engineered I-Beam
Wooden I-Beam consisting of continuous wooden upper and lower chords separated by a web of OSB or similar sheet rock
Fire Door
A rated assembly consisting of a solid-core door, door frame and hardware. Fire doors are used to confine a fire to one room or section of a building by closing a communicating opening when triggered by fire. If fire doors are to function as designed, the
Flat roof
A roof that is flat or nearly flat relative to the horizon. Many commercial buildings have flat roofs covered with tar and gravel or other weatherproof material. Flat roofs lend themselves to being opened for vertical ventilation.
Gable Roof
A pitched roof characterized by square-cut ends and sides that slope down from the ridge line to the eaves. These are the most common roof style on homes and other small buildings.
Gable Wall
A wall rising to meet a gable roof at the end of a building. these walls are found only at the ends of gable roofs and they often include an attic vent near the top of the wall.
Gambrel Roof
A roof characterized by a single ridge line from which roof sections on both sides of the ridge descend at two different pitches. These roofs are common on barns and other farm buildings. Because of the different angles of the slopes, gambrel roofs can ma
Girder
A horizontal structural member used to support beams or joists. Girders are almost always of larger dimension than the members they support.
Glue-Lam Beam
A wooden structural members composed of relatively short pieces of lumber glued and laminated together under pressure to form a long, extremely strong beam. Because of the mass of most glue-Lam beams, they resist fire extremely well compared to other mate
Gusset Plate
Wooden or metal plate used to connect structural members that are butted together; most often used in the construction of trusses. Many metal gusset plates are simply pressed into the wood and are subject to early failure if the plates warp from the heat
Gypsum Board
Interior finish material consisting of calcinated gypsum, starch, Water, and other additives sandwiched between two sheets or specifically treated paper
Header Course
Course of bricks laid with the ends facing outward. Because the ends of the bricks are smaller than the sides, a header course is easy to identify. Header courses are only used in un-reinforced masonry, and this makes that type of construction easy to ide
Hip Roof
A pitched roof in which the ends are all beveled so that there are no gable walls. A common roof style on many newer residences. Unlike gable roofs, in hip roofs the attic vents are only under the eaves or on the roof.
Heating, Ventilating, Air Conditioning (HVAC)
Unless automatically protected with automatic fire dampers, the duct work associated with these systems can allow smoke and fire to spread throughout a building.
Interstitial Space
An accessible or inaccessible space between layers of building materials; an attic or cockloft sometimes used to house HVAC and other machinery. Like attics and cock lofts, unless properly protected, these spaces can allow fire to burn undetected or to sp
Joists
Horizontal structural members used to support a ceiling or floor. Drywall materials are nailed or screwed to the ceiling joists, and the sub-floor is nailed or screwed to the floor joists.
Lamella Arch
An arch constructed of short wooden members connected in a specific geometric pattern. Wile rare in modern construction, these roof assemblies can still be found in many older buildings.
Mansard Roof
A roof characterized by steeply sloped facets surrounding a flat or nearly flat center section. Many remodeled buildings have false mansard roofs that consist of a fascia added to an existing flat roof. in some cases, the fascia forms a concealed space in
Mortar
A mixture of sand, cement, and water used to bond masonry units into solid mass. The joints between bricks are filled with mortar. Mortar joints are sometimes the easiest to penetrate when a masonry wall must be breached.
Open Web Joist
A joist constructed with a web composed of materials such as bars or tubes that not fill the entire web space. These are very common building assemblies because of their strength compared to their cost. When exposed to fire they lose their strength quickl
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 sub-floors.
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.
Parapet
A wall at the edge of some roofs. Most parapet walls range from a few inches to a few feet in height, but they can be high enough to require a ladder to reach the roof from the top of the wall. At night, parapet walls can be significant trip hazards for f
Party Wall
A wall shared by two adjoining buildings; usually a load-bearing wall that is also a fire wall. the failure of a roof assembly attached to a party wall can affect the structural integrity of the adjoining building.
Pitch
The ratio of rise-to-span of a roof assembly. The steeper the pitch, the greater the slip hazard unless roof ladders are used.
Pitched Roof
A roof that is sloped to facilitate runoff. Pitched roofs range from those that are flat to those that are extremely steep, common on some churches.
Plate
The top or bottom horizontal members of a frame wall. The sole plate is nailed or screwed to the sub-floor, and the top plate is what the roof assembly rests on.
Platform Construction
Frame-type construction in which each floor interrupts the exterior studs forming an effective fire-stop at every floor. This is the most common type of construction used to frame modern residences and other small buildings.
Plywood
A wooden structural panel formed b gluing and laminating very thing sheets of wood together under pressure. Plywood is still used in some applications but has been replaced in construction by OSB.
Rafters
Beams that span from a ridge board to an exterior wall plate to support roof decking. While it is important to cut away roof decking during vertical ventilation operations, cutting rafters can seriously weaken a roof and should be avoided whenever possibl
Rated Assembly
Two or more construction components combined to form an assembly that has a specific fire resistance rating. A fire door is an example of a rated assembly as well as a woof-frame wall covered with a specified thickness of gypsum drywall.
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.
Reinforced Concrete
Concrete that has been poured into forms that contain an interconnected network of steel rebar.
Sawtooth Roof
A roof with a profile of vertical and sloping surfaces that resemble a saw blade. These roofs are common on older industrial buildings, but many are still in existence. The vertical walls in the roofs usually include man windows to allow light in. In some
Sheathing
Plywood, OSB, Or wooden planking (Sometimes called Sheeting) applied to a wall or roof over which a weather-resistant covering is applied. Most sheathing is relatively easy to penetrate forcible entry or ventilation.
She Roof
A pitched roof that slopes in one direction only from the ridge.
Spalling
Degradation of concrete due to prolonged exposure to high heat. Water trapped within the concrete is vaporized the heat and expands, causing the concrete to break apart. While spalling concrete can sounds like gun fire, in most cases is it relatively harm
Stud
A vertical structural member in a frame wall. Stud walls are the assemblies to which wall coverings are nailed or screwed. Studs can be made of either wood or light-gauge steel.
Tension
Force that tends to pull the mass of a material apart. Tension is what causes some roof assemblies to pull away from walls and fall inward.
Truss
A wooden or metal structural unit made up of one or more triangles in a flat pane. Because of the inherent strength of the triangle within its structure, when a truss is intact it is much stronger than the individual members of which it is made.
Load-Bearing Walls
Wall that is used for structural support.
Non load-bearing walls.
Wall, usually interior, that supports only its own weight.
Partition wall
Interior non-load bearing wall that separates a space into rooms.
Green Wood
Wood with high moisture content
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
Masonry
Bricks, Blocks, Stones, reinforced and non-reinforced concrete products. Acceptable fire wall construction, minimally affected by high heat exposure. Look for signs of spalling to check for integrity.
Cantilever walls
Walls that extend beyond the structure that supports them
Veneer Walls
Walls with a surface layer of attractive material laid over a base of common material.
Cast Iron
Rarely used in modern construction, typically found in older buildings. Commonly used as an exterior surface cover fastened to the masonry wall on the front of the building. May crack or shatter when heated and rapidly cooled. Primary concern for firefigh
Steel
Primary material used for structural support in construction of large modern buildings. Steel structures enlongate when heated. If steel is restrained at the ends, it will buckle and fail in the middle. Failure imminent nearing 1000 degrees F.
Reinforced concrete
Concrete that is intentionally fortified with steel reinforcement bars, or wire mesh. Look for signs of spalling and cracks as an indication of damage occurring and that overall strength may be reduced.
Gypsum
inorganic product from which plaster and wall bpards are constructed. Due to its high water concentration when exposed to fire, the water evaporates, making gypsum an excellent heat absorbing agent. Areas where gypsum has failed, structural members behind
Glass
Not typically used for structural support. Glass is not not an effective barrier to fire extension. Heated glass may crack and shatter when exposed to a cold fire stream.
Fiber Glass
Insulation purposes mainly. Glass component is non-combustible, but the material it is bound to may be combustible and can be difficult to extinguish.
Type 1 Construction, AKA Fire Resistive Construction
Maintains its structural integrity during a fire and is intended to allow occupants time to exit the building. Materials mainly consist of Reinforced Concrete, with structural members protected by blown on insulation and automatic sprinklers. Fire resista
Type 1 Construction: Strengths and Weaknesses
Strengths: Resists direct flame impingement, Confines Fire Well, Little Collapse Hazard, Impervious to Water Damage. Weaknesses: Difficult to breach, Difficult to Ventilate, Massive Debris Following Collapse, Floors Ceilings and walls retain heat.
Type 2 Construction AKA Non-Combustible
Same building construction as type 1 but lacking fire resistant blown on insulation. All building materials are fire rated. "All metal" buildings fall into this category. Primary fire attack is room and contents. Heat build up can cause structural members
Type 2 Construction: Strengths and Weaknesses
Strengths: Almost as resistive to fire as Type 1, Confines Fire Well, Almost as structurally stable as type 1, easier to vertically ventilate than type 1. Weaknesses: Difficult to breach, Unprotected steel structural components can fail due to heat, Roof
Type 3 Construction: AKA Ordinary Construction
Structural members must be made of noncombustible materials. Interior structures however are almost entirely made of wood in smaller dimensions than heavy timber. Primary fire concern is smoke and heat spreading through hidden concealed spaces.
Type 3 Construction: Strengths and Weaknesses
Strengths: Resists Fire Spread from the outside, Relatively Easy to vertically ventilate. Weaknesses: Interior structural members vulnerable to fire involvement, Fire Spread potential through concealed spaces, Susceptible to water damage.
Type 4 Construction: AKA Heavy Timber Construction
Outside and structural materials be made from non-combustible or minimally combustible materials. Interior structures are made of solid or laminated wood with NO CONCEALED SPACES. Wood dimensions large enough to be heavy timber. Used in old factories, Mil
Type 4 Construction: Strengths and Weaknesses
Strengths:Resists collapse due to flame impingement of heavy beams. Structurally Stable, Relatively easy to vertically or horizontally ventilate. Relatively easy to breach, Manageable debris following collapse. Weaknesses: Susceptible to fire spread from
Type 5 Construction: AKA Wood Frame Construction
outside, and inside, structural and finished materials almost entirely made of wood in smaller dimensions than that of heavy timber. Presents almost unlimited potential for fire spread interior and fire spread to near by structures. Fire spread can move f
Type 5 Construction: Strengths and Weaknesses
Strengths: Easily breached, Easy to ventilate, Resistant to collapse from earthquakes due to light weight and flexibility. Collapse debris relatively easy to manage. Weaknesses: Susceptible to fire spread fro outside, Susceptible to rapid flame spread ins
Fire Load
Maximum heat that can be produced if all the combustible materials in the area burn. Heavy loading, is the presence of large amounts of combustible materials, arrangement of the materials directly affects fire loading.
Collapse Zone
The area extended horizontally from the base of the wall to one and one half the height of the wall.
Reinforcement Stars "Star Bolts
May mean that the structure is of questionable stability. Connected by tension rods to the opposite side of the building to support from the outside.
Rain Roof
A second roof constructed over an older roof.
Gang Nail
Form of gusset plate. These thin steel plates are punched with acutely V-shaped holes that form sharp prongs on one side that penetrate wooden members to fasten them together.