Building Construction

With the renewed emphasis on topics of fire behavior and building construction, realizing what makes up the environment we work in is — and has always been — important to firefighter safety. Recognition of general styles of construction, the materials used, and generic qualities of each enables firefighters and command officers to make better fireground decisions. Having some form of recognition-primed decision-making based on some forms of information is essential to basic fireground operations (tactical objectives) and command strategy development. Generally there arefive types of building construction agreed upon between the International CodesCouncil (ICC) and the National Fire Protection Association (NFPA) 220 –Standard on Types of Construction.· Type I – FireResistive· Type II – Noncombustible· Type III – Ordinary,· Type IV – Heavy Timber· Type V – Wood FrameEach has its ownpositives and negatives. All can be faced by those in the trenches at some timeor another. Now coming into view, in regard to building construction, is greenconstruction, using renewable materials within and on the structure.Type I — Fire ResistiveWith Fire Resistiveconstruction, we see several factors that have the ability to assistfirefighters. This style of construction does have some flaws that need to benoted. The definition we all learned at one time or another has been“Structural members including walls, partitions, columns, floor and roofconstructed of noncombustible material.” What does that mean? It simply meansthat the major structural components, floors, walls and roofs will not lendthemselves to the fire (as fuel). These buildings “consist of mainly reinforcedconcrete with structural members (walls, columns, beams, floors and roofs)being protected by blown-on insulation or automatic sprinklers.”The walls and floorstend to compartmentalize the fire and hold it in one area. The primary firehazard in this, as with all the others, is the contents — the stuff we put intothe structure. As the insulation is knocked off/scraped off, exposure of the structuralsteel components to the heat leads to elongation and collapse.Other troublesomeissues for us are access — some forms of forcible entry and structuralbreaching are time-consuming and very tough. Large debris masses fromstructural collapse cause these buildings to hold lots of heat due to thematerials used in the contents, as well as some construction features. Oneother note on these buildings: the fire-resistance ratings on floors, walls andstructural supports are under laboratory conditions — not the real world. Thehour ratings of these assemblies “measure how long assemblies maintainload-bearing ability under fire conditions — NOT how difficult it is to fightthe fire.” It buys time for the occupants to leave and firefighters to mount aninterior attack — if possible.Type II – NoncombustibleNoncombustibleconstruction has the same materials as Fire Resistive; the difference isNoncombustible construction has no form of fire-resistance protecting thestructural steel components. These buildings have lower fire resistance ratings— remember these are done in labs. Now that the steel is unprotected, we canexpect the structural steel to elongate — four inches for every 100 feet. Ifthe steel can’t elongate, it will warp, twist and fall down, which equalsstructural collapse. If there are serious dead loads, live loads or any otherloads the building is under, it will lead into a very bad day.Contents are still aproblem. These buildings are common construction and relatively cost-effectivefor the owner. Other problems are the metal decking flat or pitched roofs. Flatroofs are several layers of insulation, roofing paper, neoprene liners forweather resistance, tar and gravel and not easy ventilation tasks. The pitchedroofs may have lightweight panels for lighting and that equals burn through, orventilation along with firefighter step through. Remember to sound your roofs.These buildings also hold heat...

Today, these five construction types are no longer as clear-cut as they used to be because of the addition of lightweight and manufactured lumber materials, as well as the use of materials that were formerly found only in Type II or I construction. Building code officials consider these to be "hybrids," and will classify them according to the most combustible components that are used. A lightweight truss and wood frame building supported on structural steel is a hybrid, and will be classified as Type V. The distinction between the building construction "types" is further blurred because of remodeling and renovation. Buildings are usually remodeled using the lightest and least expensive materials that meet the building code, rather than matching the new materials to those used in the original construction. This leads to the introduction of unprotected structural steel into Type II and IV buildings; and the introduction of manufactured wood, I-joists, and wood trusses into century-old Type III and V buildings. These "hybridized" buildings will no longer have the behavior that we expect of them under fire conditions. The behavior of the fire itself will change: it is likely to spread faster and burn hotter than we might anticipate in a building of this age and type.Rather than focusing on the type of construction that we see from the street upon our arrival, we need to focus on what we know of fire behavior in buildings, the probable routes of fire spread, and the probable speed with which it will spread.The key points to this approach are:• Combustible: To what extent are load-bearing assemblies combustible? These will be found in Types III, IV, and V. If in doubt, we should assume that load-bearing assemblies are combustible.• Lightweight: To what extent are materials "lightweight" I-joists, wood trusses, manufactured wood, or steel stud and truss assemblies? These can be found in any Type. If in doubt, assume that load-bearing assemblies are lightweight, with no inherent fire resistance.• Hybrid: Any type of building except for Type I can be a hybrid. If in doubt, assume that it is a hybrid.• Concealed (void) spaces may be present in any type of construction except for true Type IV. If in doubt, we should assume that concealed spaces are present, and that they are interconnected.• Sprinklered: A true Type IV built since 1880 has an automatic fire sprinkler system. Any other type may have sprinklers. This note is a "must" on our preincident plan.• Rated wall or floor-ceiling assemblies will be present in a true Type IV built since 1880. Any other type may also have these. If the building has been remodeled (what building hasn't?) these rated assemblies may have been penetrated, and may no longer be reliable.Photo 3 shows the above information in a chart. The key to using this approach is to use it in preincident planning, so that we can best predict the paths of fire extension, the routes that the products of combustion will follow, and the best locations at which to stop the fire.If we arrive at a fire in an unfamiliar structure for which we have no preincident plan, for the protection and safety of firefighters we must assume that the structure is:• Combustible, of lightweight and manufactured materials, with hybrid components• Surrounded with interconnected concealed spaces• Unsprinklered• Constructed without rated walls and floor-ceiling assemblies As these assumptions are found to be not true, we will have more options available to us in fighting the fire.When these assumptions are found to be true, we will have the same options for fighting the fire that we used in our original incident action plan, and we will have exposed our personnel to no unnecessary risk.

TYPE IA (ISO 6): The main structural elements are noncombustible. Examples of these materials would be masonry and concrete.Basically, all concrete construction. TYPE IB (ISO 5): The main structural elements are noncombustible. Examples of these materials are heavy steel with spray-on insulation or enclosed in double layers of sheetrock. Basically, protected steel construction. TYPE IIA (ISO 4): The main structural elements of the walls are masonry or concrete. The roof support is unprotected metal beams or bar joists. TYPE IIB (ISO 3): The main structural elements of the walls and roof are unprotected steel. These are lightweight metal buildings like “Butler Buildings” and Quonset Huts. Caution - if metal siding is affixed to wood members, construction is TYPE VB. TYPE IIIA (ISO 2): A combination of building construction comprised of exterior walls of masonry or concrete and roof/floors of combustible material that has been treated to have at least a 1-hr fire resistance rating. TYPE IIIB (ISO 2): Same as TYPE IIIA, except that the roof/floors of combustible materials have no fire resistance rating. This is the most common of ISO 2 construction where the underside of the roof is seen with wood construction but the walls are masonry or concrete. TYPE IV (ISO 2):Known as heavy timber or mill construction in which the exterior walls are of noncombustible materials. Interior building elements utilize wood structural members and heavy wood decking. Building elements do not contain concealed spaces and contain systems that prevent a fire from the exterior into unprotected openings. TYPE VA (ISO 1): A wood-framed building. Protected construction having all major building elements with at least a 1-hour fire-resistance rating. Exception: non-load bearing interior walls and partitions having no rating. TYPE VB (ISO 1): A wood-framed building having no fire-resistance ratings. This is the most commonly seen ISO 1 construction.­­­­