The changing nature of fires

Opinion

Hey there, time traveller!
This article was published 15/03/2016 (2572 days ago), so information in it may no longer be current.

The recent number and severity of fires in Winnipeg is of great concern, not only to the citizens of Winnipeg, but also to its professional firefighters. A vicious basement fire on Bruce Avenue saw two firefighters declare a “mayday” when they became entangled in fallen wires. They just managed to survive and got out as the flames began to burn their helmets. And sadly, an Alexander Avenue fire took the lives of three adults. Over the weekend, a fire in a Charleswood home left a family of five homeless and a firefighter with injuries.

Modern-day fire departments are staffed under international standards that take into account the new dangers firefighters face today.

With these standards, it is not unusual to see an initial complement of 16 firefighters fighting a common house fire, with an additional 10 firefighters because of the dangers related to the newer building construction standards. These 26 firefighters then need relief, owing to the heavy physical labour involved in fighting today’s fires. Fighting house fires is also made more dangerous and complicated because of Winnipeg’s extreme heat and cold environment. These staffing standards are set with an eye toward the safety of firefighters and the public.

While Winnipeg has historically experienced more than its fair share of tragic fires, a closer examination reveals some of the significant causes. Two of the biggest contributing factors in fires today are the type of construction and the contents found in the home. Fires are becoming more dangerous with the increased use of plastics, both in home construction and modern-day household products.

Also, construction of newer homes incorporates design features such as open floor plans with higher ceilings, for example. This leads to the use of manufactured wood I-beams or TJI floor and ceiling joists. While providing superior strength and straightness, these mechanically produced joists quickly fail under fire conditions. Attics are now commonly constructed with lightweight wooden truss systems with metal fasteners and hangers. Again, compared to older housing stock made with dimensional lumber, these newer features of today’s homes burn hotter and much more quickly.

A number of tests were conducted by Underwriters Laboratories (UL) and the National Research Council of Canada (NRC) involving old-versus-new construction components. The results of these tests were alarming. The failure time when subjected to fire was more than 18 minutes for old construction; the tests saw the failure of the new construction in about six minutes.

Another factor contributing to rapid fire spread in modern construction is the use of manufactured beams made with laminated wood. OSB board, plywood and similar products employ the use of mechanically pressed wood saturated in glues and resins (or as we call it in the fire profession, “jet fuel”). These man-made products burn incredibly quickly and produce a horrendous amount of toxic smoke and gases.

The contents (or fire load) found in all of today’s homes has also changed dramatically over the years. Where once we saw furnishings made with natural materials and solid wood, we now see the overwhelming use of plastic, vinyl and man-made fibres. These predominately oil-based products are easily lit on fire and provide the fuel that produces hotter temperatures and more poisonous gases.

Another UL study compared the burning of a “legacy room” (an older, more traditionally furnished area) with a modern room containing all of today’s commonly found plastics. The legacy room released energy from fire more slowly than the room with the synthetic furnishings. The time to flashover, when all contents of the room reach ignition temperature and burn violently, is much faster in the modern room. Occupants now have much less time to escape a fire than they had in the past.

These findings are extremely important to today’s fire service. Modern fires are burning hotter and more quickly. The homes involved begin to collapse much sooner than in previous decades.

Today’s building codes are written to provide a minimum time for residents to escape from fire. Unfortunately, little thought has been put into firefighter safety when writing the building code. The result is fires spread quickly and tragically, and buildings collapse at, or shortly after, our arrival.

Hopefully, residents have maintained their smoke alarms, because that may be the early warning they need in order to make a quick exit.

Alex Forrest is a captain in the Winnipeg Fire Department and president of United Fire Fighters of Winnipeg. Russ Morrow is the platoon safety officer with the Winnipeg Fire Department.