What Happens During a House Fire
- By Jeremy Thompson
- 03 Mar, 2014
The temperatures drop and the amount of home fires increase. Home fires occur more during the winter than any other season. Approximately 905 people die each year in winter home fires, according to the U.S. Fire Administration. The administration also reports that $2,091,000,000 in property loss occurs during winter home fires. About 67% of winter […]
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The folks at This Old House
(TOH) offer a great explanation of what happens in a typical kitchen fire. Since cooking fires are the cause behind about half of all fires, they use a stovetop fire to describe what happens from beginning to end.
Ignition:The fire ignites. In the TOH example the fire occurs when a pot or pan boils over, causing oil to spill directly onto the stovetop flame or burner. It only takes a few hundredths of a second for fatty substances to ignite.
First 30 Seconds:It only takes a few seconds after a flame-up for the fire to spread. Flames will travel across the stove. The oily residue on cooking utensils can ignite, and any other combustible materials around the stove, including paper towels or dish towels, will begin to burn. This is a critical point to extinguish the fires. Remember never move the pot/pan, or use water to attempt to extinguish the flames. Instead cover the pot/pan with a lid.
30 Seconds to 1 Minute:The fire spreads igniting more objects including wooden cabinets, wallpaper and curtains. A dense plume of hot, smoky air develops, which can burn your breathing passages. The fire generates poisonous gases like carbon monoxide and hydrogen cyanide, and it only takes a few breaths of it to cause someone to pass out.
1 to 2 Minutes:The flames intensify, spreading heat to other parts of the kitchen. Cyanide and carbon monoxide levels increase. In an enclosed fire room, the typical level of these gases is 3,400 parts-per-million, which cuts survival time to less than one minute. The poisonous smoke begins to travel, and once it reaches a vent or the top of a doorway it can begin to travel through halls and up stairwells.
2 to 3 Minutes:The fire continues to burn cabinets, countertops and shelves and anything within them including dry goods, containers and cardboard boxes. This generates more heat, making the upper level of gases rise up to 400 degrees F, which is hot enough to kill someone. The smoke may now include other toxic components from the items being burned including arsenic (a wood preservative), lead (from paint) and other toxins such as ammonia and hydrogen chloride. The fire is now hot enough to spread not only by direct flame contact but also by auto-ignition. Objects spontaneously begin to burn without even touching the flames.
3.5 Minutes:The heat reaches as high as 1100 degrees F and flashover occurs. Everything in the room can burst into flames. Oxygen is sucked out of the room. Windows shatter and balls of fires shoot out of them. Upper level rooms fill with thick, hot smoke, and because of the high flashover temperatures, all of the rooms throughout the house are at risk.
3.5-4 Minutes:Flames begin pouring through the doorway into neighboring rooms setting carpet and furniture on fire. In the kitchen the fire penetrates the walls and ceiling, sending flames to the second floor.
4-5 minutes:Flames can be seen from outside the home as they travel through doors and broken windows. At this point, it’s much more difficult to rescue anyone on the second floor. Rooms neighboring the kitchen flashover. The materials used in construction impact the damage. Synthetics including polystyrene and PVC auto-ignite at temperatures between 850 and 1075 degrees. Steel plates used in roof trusses start to buckle at 1000 degrees F. The roof may begin to collapse as the blaze burns uncontrollably.
Firefighters Arrive:Firefighters take immediate aggressive action if flames are visible from the outside when they arrive. They’ll use as much as 3,000 gallons of water to extinguish the flames. They may also use dry chemicals to extinguish flames, and they may break open windows or cut open the roof to vent off smoke and gases.
After the Fire:Extensive property damage is incurred. Even if flames did not touch a room, the high heat softens glass and melts plastics. Most appliances are ruined as their interior parts are likely melted. The burned or melted plastics and other synthetic materials will off-gas toxins. There are unseen weaknesses in the structure. It is unsafe for anyone to be in the home.
Returning Home:You’ll need permission from the Fire Marshall to enter the home. Smoke damage is severe and permeates everything, leaving an odor that is difficult to remove. Water damage can cause mold to grow rapidly. It will likely take weeks or months to sufficiently cleanup and repair the home to a state that makes it safe and comfortable enough to live in again.