Stopping fire requires knowledge of physics and house building; use of teamwork and communication | News


by Gordon Wolf

The exterior of the home at 421 North 15th Street in Denison paints a misleading picture of the severity of the fire that occurred inside on Monday afternoon.

Outside, a passerby can see a few broken windows for ventilation, a still stretched fire hose, and minor exterior smoke damage.

The exterior appears calm compared to the story the interior tells about the physics of fire, the balloon construction of the house, and the coordination, discipline, teamwork, and communication needed to extinguish the fire and save property.

The physics of fire is that it creates pockets of high pressure, and the fire seeks to move to areas of lower pressure, Denison Fire Chief Cory Snowgren explained.

Balloon-frame house construction describes a style of construction used from about the 1890s until 1940 in which the exterior walls were framed by long vertical two-by-fours that extended from the sill of the foundation to the roof. . This construction creates wall cavities inside the house that can act as chimneys, allowing fire to spread quickly from the basement to the roof.

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Snowgren said many homes in the older part of Denison have balloon frame construction.

“There is no firebreak between the floors,” he explained. “One way to put it is that the second floor is basically hanging from these vertical posts.”

While fire acts in predictable ways, advancing horizontally and vertically toward areas of lower pressure, the unknown variable is how the construction and contents of a house will affect this path.

Snowgren said that’s what firefighters from multiple departments were dealing with Monday afternoon.

Fire Chief and Firefighter Colby Ellis was in one of the department’s fast attack units on Highway 30 just off 7th Street, heading toward a field fire on the Earling Highway. They were following another Denison unit consisting of two firefighters. When the call came from the communications center that a fire was behind the house at 421 North 15th Street, Snowgren turned his vehicle around.

When he arrived on the scene, he could see a neighbor pointing to the south end of the house where there is a porch. What was not present was a single plume of smoke indicating a fire in the back yard. What Snowgren saw, instead, was a smoky haze that enveloped the neighborhood, indicating a house fire.

“Smoke was coming out of all the watches in every corner on every side,” Snowgren said. “Communication Center (communications) has been contacted and told to move to structure fire, which means different fire units are being dispatched.”

Engines and labor from the Vail, Kiron, Manila, and Charter Oak fire departments responded, along with Denison’s engines and tower truck. And when the field fire near Dow City was put out, these firefighters and fast attack units responded to the house fire in Denison.

By the time services were notified, the fire had been burning for perhaps an hour. No one had been home for about an hour; the fire was started by a neighbour.

This means firefighters were using their first 10 minutes on the scene to catch up.

Snowgren explained that the first 10 minutes at the scene of a fire are critical and will determine the progress of the next two hours.

“Regardless of the type of fire, the answer is the same. Connect the hose, fill it with water and start spraying water,” he said.

It’s a drill that’s practiced over and over again until firefighters can perform that initial attack automatically, without having to stop and think about what they’re supposed to do.

The cause of the fire was a wire connecting the outside of the house to an electrical panel in the basement; it was the weak link, Snowgren said.

Looking from outside into the basement, he could see that firefighters were working in a balloon frame house.

Two firefighters entered the kitchen of the house through a south door onto the porch, but were told to stop at the door and spray water. The reason for this was that the fire in the basement was an unknown factor at the time. The precaution paid off as it was later discovered that three two-by-eight ceiling joists supporting the kitchen floor had been totally burned and other ceiling joists were on fire. The missing (burnt) ceiling joists were between six and eight feet on the south side of the kitchen door.

Walking on the kitchen floor above the scorching and missing floor joists would have been tragic for the firefighters, who would likely have fallen through the floor to become tangled in hanging wires and injured themselves falling on heating ducts and on beams that had been placed at some point. in the basement to help support the kitchen floor.

Snowgren said no matter what type of house fire, even if it appears the fire is confined to one room, check the basement first. It only takes 10 seconds and can save injury or death.

The basement fire was attacked for several minutes with water through the hole that had burned through the siding next to the electrical panel. This helped put out part of the fire, allowing a crew from the Vail Fire Department to enter the basement through a ground-level door on the north side of the house.

Snowgren said the fire traveled horizontally from west to east along the basement ceiling joists to a doorway that separated the kitchen from a living room. At that time, the fire came up in one of the cavities created by an interior wall.

A third team of firefighters, from Manila and Kiron, was on the porch roof on the east side of the house. When it was determined it was safe to ventilate the house, an east bedroom window was smashed. Snowgren said he used a thermal camera on the open window and found the heat escaping from the house at the time was 1,000 degrees.

The adjoining rooms on the second floor seemed untouched by the fire.

“I had to determine if the fire was following the stairs to the second floor or if it was following a cavity between the first and second floors,” Snowgren said.

The latter was the case as a closet in the second floor bedroom turned out to be the path of the fire.

With the fire in the basement, kitchen and second floor, Snowgren said firefighters at the kitchen entrance were literally surrounded by fire, but it was a fire that could not be seen or stopped. at first.

“One of the problems was that we couldn’t get into the house until we stopped the fire in the basement from advancing any further, and to do that we had to have a line working in the basement. ground. The first line was in the kitchen and the second line hit the hole where the fire started for just a few minutes and then repositioned,” Snowgren said.

“We literally had fire on all three levels of the house, as well as in the walls, floors and ceilings. It was the worst case scenario. »

Snowgren said if the fire had been known to be in one room, it could have been vented right away.

“But with this one, we couldn’t. We knew where the fire was coming from. We knew where it was. What we didn’t know was how far he got into the empty spaces of the house,” Snowgren said.

He described knowing when to use ventilation in a house with balloon frame construction as being similar to playing chess on a three-dimensional board. If you move a piece, the pieces on the other two boards move automatically.

“When you move part of the house, it creates an area of ​​less pressure. Somewhere in this house, the fire, smoke and heat – products of combustion – begin to change direction towards the area of ​​low pressure,” he explained. “In a balloon frame house, I don’t ventilate it until I have a good idea of ​​the progress of the fire and the position of the firefighters in relation to it.”

Firefighters were able to stop the fire from progressing to the attic and they were able to save a number of property.

“A lot of property has been saved, but it’s absolutely a tragedy, especially during the holidays. I don’t think the house will be rebuilt, but a lot has been saved,” Snowgren said.

Snowgren said the house had working smoke detectors and there wasn’t much more to do in terms of detection.

He added that firestops can be installed in balloon frame homes. However, the most likely time that would be done is when the interior of the house is already due for renovation.

If the landlord removes the plaster and battens and replaces them with drywall, a piece of lumber the size of the floor joists can be used to fill the gaps between floors, Snowgren said.

When it comes to rebuilding the house, Snowgren said the best way to sum up balloon frame construction is for a fire to burn directly on the structural support members.

As a learning tool, firefighters review each occurrence in an After Action Review. Snowgren said he explains what the response was and why certain tactics and strategies were used. Firefighters are encouraged to express what could have been done better.

He added that what he does not want is to simply say that the fire has died down and no one has been injured. On the surface, that’s important, but Snowgren stressed that a fire would go out and no one would be hurt if no one responded.

“It’s not an assessment,” he explained. “We look at what went well, what could have been done better, and what went wrong for whatever reason.”


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