24 SPRING • 2011
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Carolina Fire Rescue EMS Journal
Building construction: how it effects your firefighting By Mike Coffey 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 decisionmaking based on some forms of information is essential to basic fireground operations (tactical objectives) and command strategy development. Generally there are five types of building construction agreed upon between the International Codes Council (ICC) and the National Fire Protection Asso-
ciation (NFPA) 220 – Standard on Types of Construction. • Type I – Fire Resistive • Type II – Noncombustible • Type III – Ordinary, • Type IV – Heavy Timber • Type V – Wood Frame Each has its own positives and negatives. All can be faced by those in the trenches at some time or another. Now coming into view, in regard to building construction, is green construction, using renewable materials within and on the structure.
Type I — Fire Resistive With Fire Resistive construction, we see several factors that have the ability to assist firefighters.This style of construction does have some flaws that
need to be noted.The definition we all learned at one time or another has been “Structural members including walls, partitions, columns, floor and roof constructed of noncombustible material.”What does that mean? It simply means that the major structural components, floors, walls and roofs will not lend themselves to the fire (as fuel).These buildings “consist of mainly reinforced concrete with structural members (walls, columns, beams, floors and roofs) being protected by blown-on insulation or automatic sprinklers.” The walls and floors tend to compartmentize the fire and hold it in one area.The primary fire hazard in this, as with all the others, is the contents — the stuff we put into the
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structure. As the insulation is knocked off/scraped off, exposure of the structural steel components to the heat leads to elongation and collapse. Other troublesome issues for us are access — some forms of forcible entry and structural breaching are time-consuming and very tough. Large debris masses from structural collapse cause these buildings to hold lots of heat due to the materials used in the contents, as well as some construction features. One other note on these buildings: the fire-resistance ratings on floors, walls and structural supports are under laboratory conditions — not the real world.The hour ratings of these assemblies “measure how long assemblies maintain load-bearing ability under fire conditions — NOT how difficult it is to fight the fire.” It buys time for the occupants to leave and firefighters to mount an interior attack — if possible.
Type II – Noncombustible Noncombustible construction has the same materials as Fire Resistive; the difference is Noncombustible construction has no form of fire-resistance protecting the structural steel components.These buildings have lower fire resistance ratings — remember these are done in labs. Now that the steel is unprotected, we can expect the structural steel to elongate — four inches for every 100 feet. If the steel can’t elongate, it will warp, twist and fall down, which equals structural collapse. If there are serious dead loads, live loads or any other loads the building is un-
der, it will lead into a very bad day. Contents are still a problem. These buildings are common construction and relatively costeffective for the owner. Other problems are the metal decking flat or pitched roofs. Flat roofs are several layers of insulation, roofing paper, neoprene liners for weather resistance, tar and gravel and not easy ventilation tasks.The pitched roofs may have lightweight panels for lighting and that equals burn through, or ventilation along with firefighter step through. Remember to sound your roofs. These buildings also hold heat well.
Type III – Ordinary Ordinary construction is traditionally considered “Main Street, USA” where buildings built on the main street of the town are constructed of masonry walls and timber within, usually three to five stories. Cast iron fronts, beams and some girders are found in these buildings. Wood components are smaller than heavy timber components, but larger than most wood frame components. Most of these buildings were used as retail spaces at the street level, with offices or apartments above.These buildings are aging — 100 years old, and in some places, older. Some serious modifications have happened in their lifetimes. Key factors are the load-bearing walls; two are load-bearing and they hold the joists, two are non-load-bearing. Look for vent openings between the joists — cockloft/attic space 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 these spaces, it quickly takes control of the building.These buildings can be vertically vented, although it may take a little time with the layers of roofing material or the rain roof (roof over an existing roof) added later in life.
Type IV – Heavy Timber Heavy Timber construction is also known as mill construction.These buildings were originally built for heavy machinery and processing of materials. Originally built with thick masonry walls, big pieces of wood (larger than eight x eight inches) as the structural components and several layers of wood flooring, they offer some values. Without full automatic sprinkler coverage, be prepared to do battle quickly and hope