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 well.Type III – OrdinaryOrdinary constructionis traditionally considered “Main Street, USA” where buildings built on themain street of the town are constructed of masonry walls and timber within,usually three to five stories. Cast iron fronts, beams and some girders arefound in these buildings. Wood components are smaller than heavy timbercomponents, but larger than most wood frame components. Most of these buildingswere used as retail spaces at the street level, with offices or apartmentsabove. These buildings are aging — 100 years old, and in some places, older.Some serious modifications have happened in their lifetimes.Key factors are theload-bearing walls; two are load-bearing and they hold the joists, two arenon-load-bearing. Look for vent openings between the joists — cockloft/atticspace indicator — that usually run with the street direction, but not always.Void spaces are rampant in these buildings with all the changes they’ve seen.When fires enter thesespaces, it quickly takes control of the building. These buildings can bevertically vented, although it may take a little time with the layers ofroofing material or the rain roof (roof over an existing roof) added later inlife.Type IV – Heavy TimberHeavy Timberconstruction is also known as mill construction. These buildings wereoriginally built for heavy machinery and processing of materials. Originallybuilt with thick masonry walls, big pieces of wood (larger than eight x eightinches) as the structural components and several layers of wood flooring, theyoffer some values. Without full automatic sprinkler coverage, be prepared to dobattle quickly and hope for a quick knockdown. If not, defensive operationswith lots and lots of water for an extended period of time can be expected.These buildings mayalso have the floor joists fire-cut. A fire-cut is where the ends of the beamsare cut at an angle inside the masonry wall to allow the floor(s) to fall intothe building to maintain wall stability. We may also find bowstring trusses inthe roof or arched roofs. Heavy timber construction happens today in somechurch sanctuaries using laminated lumber to get the heavy timber look, orassembly occupancies looking for a natural feel to their structures. As thesebuildings age as well, the modifications made include unprotected steelassisting the structural components already there. Some components may beremoved as well, and that leads to structural collapse.This building is atrue double-edged sword — it will take some time to get going and staystructurally sound for a long period of time, but when the fire takes over —heat generated by those timbers creates problems for any exposures in the area.Type V – Wood FrameWood Frameconstruction is the most familiar to all of us. A large part of our living,training and learning occurs in these structures. It’s where we’ve “cut ourteeth” and learned our trade, for the most part. Besides, residentialstructures outnumber everything else. The evolution here came from log cabins,to balloon-frame, then platform, and now lightweight construction. Smalldimension lumber used for most frame houses. We now find wooden I-beams used infloor assemblies; although they are a strong weight-bearing material, they failmiserably under fire conditions.Documented cases showwhere houses are collapsing as the first-due apparatus arrives on scene. Nowfound are aluminum studs, laminated timbers, aluminum joist hangers, gussetplates and all kinds of truss assemblies. Be aware that air handling units arein attic spaces, adding to the dead load the trusses have to support —especially with fire burning underneath. Outer skins range from wooden groovedplywood siding, wooden siding with boards, Masonite® siding, aluminum or vinylsiding and finally brick.One of the most commonsize-up mistakes I hear is a “residential structure with masonry construction.”Masonry is a component — not a style of construction. The brick you see is aveneer — a single layer of brick for looks only. Although there are some TypeIII - Ordinary construction single family buildings, knowing your buildings isvital to you and your crew’s lives.Now added to all thisbasic information are more changes: green construction with reusable materials,hybrid construction methods where several of the different types ofconstruction are melded within a single building and construction methods thatget lighter and cheaper. Add to that buildings under construction, renovationand demolition — those are hazards on their own. With all this, how is itpossible to keep up? Diligence and study — on duty and off — allows us toperform at our best. Knowledge is one of the best tools to have.This is only the tipof the proverbial iceberg. We all have to keep up with changes, and buildingconstruction is no different. Take time to really look at the buildings youprotect, already standing and under construction. The more we learn about thebattleground we fight on, the better we will survive and pass on thatinformation to the next generation of firefighters.

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.­­­­