A house fire refers to a fire that starts and spreads within a residential home. Understanding how long house fires typically last is critical for several reasons:
First, it provides crucial information for firefighters responding to the scene. Knowing the expected stages and duration of a house fire allows them to properly deploy resources and personnel to contain and extinguish the fire as efficiently as possible.
Second, it gives homeowners and residents an idea of how much time they have to safely evacuate the building when a fire breaks out. Most fire deaths actually occur from smoke inhalation, so escaping quickly before the smoke spreads is essential.
Finally, being aware of the duration and behavior of house fires helps guide prevention and preparedness measures. With this knowledge, steps can be taken to avoid fires or limit their spread and damage.
Stages of a House Fire
According to sources, there are typically 3 stages of a house fire: growth, fully developed, and decay. https://medium.com/@Campbel1/5-stages-of-a-house-fire-b3239ec3f9a8
The growth stage is the initial period where heat, oxygen, and fuel combine to ignite and rapidly accelerate the fire. Temperatures can reach over 1200°F during this period as the fire spreads and consumes nearby combustibles. The smoke and heat make conditions dangerous even though the actual flames may still be limited at this point.
The fully developed stage is when the fire has spread to multiple rooms and the entire structure is involved. This is typically when flames are at their peak intensity with temperatures exceeding 1400°F in a home’s interior. Flashover and backdraft explosions can occur as superheated gases accumulate. The fire will be emitting massive smoke and heat during this stage.
Finally, the decay stage is when the fire begins to die down as the fuel and oxygen are consumed. Temperatures start to decrease as the flames lose intensity, though the structure will remain extremely hot. Collapsing sections of walls and floors are a major risk during this stage. The fire is still not safe until completely extinguished.
Factors That Influence Fire Duration
Several key factors influence how long a house fire will last before it is extinguished or burns itself out:
Construction Materials – Homes built with non-combustible materials like brick, concrete, and steel will resist burning longer than homes built with wood, vinyl, or other flammable materials. Wood frame construction with combustible finishes allows fires to spread quickly from room to room.
Room Size – The size of the room where the fire starts is a major factor. Fires in smaller rooms will be more contained, while fires starting in larger open spaces can spread rapidly.
Ventilation – The amount of oxygen and airflow feeding the fire impacts duration. Well ventilated spaces allow fires to grow bigger and burn longer. Limited ventilation helps limit the fire’s size and spread.
Contents – The types of furnishings and belongings in the room influence fire growth. Flammable items like fabrics, papers, and plastics burn readily and accelerate fire spread.
According to research from UC Berkeley (https://www.quora.com/How-long-does-the-average-house-fire-last), fires burn faster and hotter than ever before due to synthetic furnishings found in many modern homes. These materials ignite more easily and burn extremely quickly.
Growth Stage
The growth stage, also called the incipient stage, is the first stage of a house fire. This initial phase lasts around 30 seconds to around 5 minutes (Abbotts Fire and Flood). During the growth stage, the fire starts small, such as from a cigarette, candle, or electrical spark. It quickly spreads across nearby combustible materials like furniture, carpet, drapes, or debris (Davie County).
As the fire grows, it produces smoke and dangerous gases like carbon monoxide. Temperatures rapidly increase, potentially reaching over 1,000°F. The heat dries out nearby materials, helping the fire spread exponentially across floors, walls, and ceilings (Abbotts). This intense heat can also cause flashover, where combustible gases ignite.
Fully Developed Stage
The fully developed stage, also known as the free burning stage, is the most intense part of a house fire. This is when the fire has spread to multiple rooms and the temperature peaks. According to [1], temperatures can reach over 1000°F during this stage. The extreme heat causes windows to break and flashover may occur, where the contents of the room burst into flames. Most of the structural damage happens during this stage as walls, floors, and the roof are compromised. The high temperatures also allow the fire to spread rapidly throughout the home. The fully developed stage lasts around 10-20 minutes in a typical home before transitioning to the decay stage.
[1] https://www.firetrace.com/fire-protection-blog/different-stages-of-a-fire
Decay Stage
Once the fire has reached the decay stage, the temperature starts to decrease as the fire runs low on oxygen and fuel.1 This stage begins when the fire has consumed most of the available combustible materials and oxygen in the room or building where it started.2 As the fire decays, the smoke turns from black to gray or white in color. The flames also become smaller and less intense.
During the decay stage, structural integrity becomes compromised as materials lose strength due to being charred and weakened by the fire. Walls, floors, ceilings, and roofs can collapse since they are no longer able to support themselves under the weight of the structure.3 Collapsed areas allow more oxygen to reach the fire, which may cause occasional surges of intensified burning. However, the overall trajectory is a continued reduction in heat output and flame size.
A decaying fire transitions from open flaming to smoldering combustion. The fire scene becomes darkened again as smoke increases from smoldering materials. Slow pyrolysis continues as embers burn and charring advances in depth. The decay stage ends when there is no more smoke or heat signature detected.
Fire Duration by Room
Fires can spread and last for different amounts of time depending on the room they originate in. According to fire prevention experts, a typical house fire will burn a room for around 20 minutes before moving on to adjacent areas [1]. However, some rooms tend to facilitate faster and hotter burning fires.
Kitchen fires often become the most dangerous. With many flammable materials and potential ignition sources, kitchen blazes can spread quickly. The synthetic materials, plastics, and chemicals found in kitchens release toxic fumes and burn rapidly at high temperatures. According to FEMA, cooking is the leading cause of home fires [2]. A kitchen fire can engulf the room in just 2-3 minutes if not contained.
Bedrooms also facilitate fast spreading fires. Mattresses, bedding, curtains and upholstered furniture provide fuel. Synthetic fibers and foams in modern furniture enable rapid fire growth. The confined space and limited exits make bedroom fires particularly dangerous. Bedroom doors should be closed at night to slow fire spread.
Living rooms tend to burn slower than kitchens or bedrooms. With more open space and less flammable furnishings, living room fires may take longer to fully develop. However, modern furnishings and building materials still enable fires to spread quickly throughout the home if not suppressed.
Prevention and Suppression
There are several key ways to help prevent and suppress house fires. Having working smoke detectors is one of the most important prevention measures according to Ready.gov. Smoke detectors should be installed on every level of the home and inside and outside of sleeping areas. Batteries should be replaced every 6 months. Sprinkler systems are another suppression system that can automatically extinguish fires before they spread. According to Real Simple, sprinklers contain and may even extinguish a fire before the fire department arrives. Portable fire extinguishers can also be used to put out small fires. The type of fire extinguisher used depends on the type of fire. Having working prevention and suppression systems in place gives you extra time to escape in a house fire.
What to Do During a House Fire
According to Ready.gov, having an escape plan is crucial for surviving a house fire. Map out all possible exit routes from each room, and identify two ways to escape from every room, if possible. Practice and memorize your home fire escape plan until it becomes second nature for your household.
When a fire occurs, act right away before the smoke and flames can block your primary escape route. Alert everyone in the household and execute your escape plan. Crawl low under the smoke on your hands and knees, and keep your head 12-24 inches above the floor. Test doors before opening them by feeling the doorknob and door with the back of your hand. If either is hot, leave the door closed, stuff towels in the cracks, and use your secondary escape route.
Make sure windows are not nailed or painted shut. Know how to use the emergency release device of security bars on windows and doors. Finally, have an outside meeting place a safe distance from your home where everyone should gather once they’ve escaped.
Conclusion
In summary, the duration of a typical house fire depends on several factors like the type of materials in the home, the room where it originates, and how quickly it spreads. A house fire generally progresses through three main stages: growth, fully developed, and decay. During the growth stage in the first few minutes, the fire gets an initial foothold and spreads rapidly. In the fully developed stage that lasts around 10-20 minutes, the fire reaches its peak size and intensity. Finally, in the decay stage, the fire begins to lose power and burn itself out as available fuel is consumed. This can last 30 minutes or longer.
While the average house fire may last around 20-30 minutes total, fires that start in concealed spaces like walls or attics can burn much longer before being detected. Kitchen, living room, and bedroom fires tend to be the shortest since they are often discovered quickly. Preventing fires through safety practices like installing smoke alarms, avoiding overloaded electrical circuits, and extinguishing cigarettes properly can limit the duration and damage of house fires.
Knowing what to do if a fire starts, like evacuating immediately and calling emergency services, is also crucial. With vigilance and preparedness, the harm from house fires can be reduced.
