Why new homes burn faster
New homes and their modern construction materials and features actually make fires more dangerous
As the housing market continues to recover and more new homes are built, many homebuyers will assume modern construction materials offer themselves and their families greater safety. That’s because the homebuilding and real estate industries typically promote today’s homes as being built better and safer than homes of the past.
Yet, research conducted over the past decade reveals that when fires occur in new homes, their modern construction materials and features actually make fires more dangerous than in older homes. New homes burn hotter and faster than ever, presenting unique and challenging fire hazards both to residents and responding firefighters.
Installing fire sprinklers in new homes is the best defense against these dangers. Fire sprinklers put water on a fire while it is still small, so it does not have the opportunity to spread or reach flashover — the point where everything in the room ignites in flames. There is no equivalent to the safety that is provided by home fire sprinklers.
Homebuyers may not realize they can ask their builders to have fire sprinklers installed when they build new homes. And many homebuilders do not yet recognize that offering fire sprinklers makes their product more appealing to homebuyers. But today’s consumers are better educated and safety is a priority, especially for families. In fact, a 2014 national Harris Poll showed that 74% of homeowners said they would be more likely to buy a home protected by fire sprinklers.
So what makes today’s new homes so much more dangerous in a fire? The answers lie in research and studies that have been conducted by Underwriters Laboratories and the National Institute of Standards & Technology, specifically the UL report “Analysis of Changing Residential Fire Dynamics and Its Implications on Firefighter Operational Timeframes,” published by UL’s Stephen Kerber.
On average, homes built today are much larger than homes built several decades ago. Popular open construction design and higher ceilings add to the volume of a home and create a lack of compartmentation. Without barriers such as walls and ceilings, heat, flames and smoke can readily spread from room to room and between multiple levels of a home, the report notes. With a greater volume of air available, fires are able to grow larger and more quickly, making them deadly to residents and much more difficult to extinguish when fire crews arrive.
The quick response and cooling action of home fire sprinklers counteracts the dangers found in modern-home fires, giving residents a safer passage of escape and responding firefighters a safer fireground.
Over the last several decades, the materials used to construct homes have evolved. In the past, new homes were commonly built with solid, old-growth, dimensional lumber. Homebuilders today favor engineered lightweight construction materials, and wood trusses and engineered I-joists. These are strong and economical materials, which reduce build times and save money. They also are more environmentally sustainable and structurally stable under normal circumstances.
However, when exposed to fire, UL and NIST have proven that these engineered lightweight materials, combined with modern open layouts, create more dangerous conditions faster and fail sooner compared to older dimensional lumber systems.
Lightweight construction materials are not solid wood. They are typically a composition of wood-chip particles and glue and, as a result, they do not hold up to the extreme heat from a fire. A 2008 study by UL simulated fires on two unprotected floor systems — modern lightweight, engineered I-joists compared with legacy dimensional lumber. Two weighted mannequins were placed on each of the floor systems to simulate responding firefighters. When exposed to a fire, the engineered I-joist floor collapsed in only six minutes, while the dimensional lumber floor collapsed in 18 minutes and 35 seconds.
Beyond the structural components of homes, other modern construction materials also fail sooner. Additional tests have shown that today’s gypsum board contains a fire for far less time than plaster and lath. Modern windows break and allow air to fuel a fire much sooner than legacy windows did. The thicker, solid doors that were more common in older homes better contain a fire than the thinner, often hollow-core doors found in new construction today.
As the popularity of green building continues to grow, airtight construction and energy-conserving building materials such as double-glazed (vinyl) windows, synthetic insulation materials and foam sheathing also can make for faster-spreading fires, note UL studies.
Greater, more toxic fuel loads
Many homes today are filled with combustible furnishings and contents that can lead to quicker flashover in a fire and billowing, poisonous smoke. Most modern furnishings are no longer comprised of natural fibers such as cotton or wool, solid woods or other natural materials. Rather, they are often made with engineered wood and polyurethane foam, and covered with synthetic materials, such as plastics. Much of today’s carpeting is synthetic and numerous consumer electronics are present in homes.
When these products are combined with the challenges of engineered construction materials and popular open floor plans, the fire dangers are greatly increased.
To compare fire behaviors in new and older homes, UL conducted a study of rooms constructed and furnished as modern vs. legacy. The rooms had similar products and furnishings, except those in the modern rooms came from retail stores, while those in the legacy rooms came from secondhand stores, which meant they were made from different materials. Each fire was started to simulate a candle falling on a couch.
Flashover occurred in as few as three minutes and 20 seconds in the modern rooms, while the legacy rooms transitioned to flashover at approximately 29 minutes or more. This study showed the heat clearly grew hotter and faster and the smoke was much more toxic in modern rooms than in the legacy rooms.
The age of consumer electronics also has added more dangerous materials to the fuel load of all home fires. Just a few decades ago, only a handful of electronic devices were present in an average home. Today, most homes have consumer electronics numbering in the dozens. Many of these products contain lead and other harmful materials. In a fire, their presence contributes to thick, toxic smoke.
Fire sprinkler solution
In the United States, more than eight out of 10 fire deaths occur in homes. As the UL and NIST research shows, new construction homes are more dangerous when fires occur. Despite the tremendous protection fire sprinklers provide, most new homes today do not have fire sprinklers installed.
With greater understanding of the fire dangers associated with modern construction materials, national model codes now require fire sprinklers to be installed in new homes. California and Maryland have adopted these fire sprinkler requirements statewide and Minnesota requires fire sprinklers in new homes 4,500 sq. ft. and larger. Other states also are considering requirements in response to large-loss fires in unprotected buildings. Home fire sprinklers remain an emerging trend across most of the country as they are increasingly adopted as local requirements in jurisdictions nationwide.
The national nonprofit educational organization Home Fire Sprinkler Coalition offers free information on fire sprinklers for consumers, homebuilders, real estate and insurance agents, water purveyors, elected officials, building officials, firefighters and others in the construction industry. HFSC helps the public understand the risks in today’s home fires and the life- and property-saving benefits provided by home fire sprinklers.
The HFSC video, “Protecting Your Community with Home Fire Sprinklers,” includes interviews with experts from UL and NIST. The video can be viewed at www.homefiresprinkler.org/building-officials-video.
Author bio: Erik Hoffer is a writer for Frankfort, Ill.-based Peg Paul & Associates. He writes most often about structural fire safety and fire sprinkler advocacy and education.