How Fast Does Fire Spread? (House Fire, Wildfire)

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Fire seems like one of those inevitable risks in life and, in fact, no matter how careful you are and how many precautions you take – it’s possible for a fire to start by accident. But once it does start, how long do you have to deal with it before it gets out of control? And how long is it likely to be before the fire spreads over the whole structure you’re in?

A house fire can go from an incipient (just starting) fire to a fully involved in as little as 4-5 minutes. A forest fire or wildfire can spread as quickly as an acre per second!

That means if you intend to tackle a fire (and you can do it safely), you should do so very quickly before it gets out of hand. Let’s take a look at how a typical fire might behave. 

Your # 1 priority is keeping your family safe. As a firefighter, I recommend everyone has updated smoke detectors that don’t require battery changes, like these ones from Kidde, a fire extinguisher, like this one from Amerex, and a fire escape ladder if you have bedrooms above the first floor, I recommend this one from Hausse.

Also read: House Fire Temperature: How Hot Does It Get?

How Fast Does Fire Spread?

How fast does fire spread

There’s no such thing as a standard fire.

We can’t give you a single rule that helps you predict how long you have to tackle a fire.

What we can do is give you a general rule of thumb for a standard-ish fire.

Say a wastepaper basket catching fire near some curtains. 

We have to stress at this point: if you ever feel unsafe or unable to tackle a blaze in any way, leave the property and call the fire department. The fire service is trained to handle fires and it’s far better to be safe than sorry. Nobody will be mad at you for not trying harder to tackle a fire. 

Take a look at this video to see how fast a house fire can spread in certain conditions:

Also read: How Long Does It Take To Put Out a House Fire?

The Evolution Of A House Fire

So, let’s take a look at the evolution of the kind of fire that many of us might be unlucky enough to encounter in our lives – the house fire.

The progress of the fire in an industrial setting is also very, very similar to that of a house fire, but it might take a little bit longer due to the scale of a typical industrial building when compared to a house.

But then again, it might not, depending on what is being stored in the building. 

Also read: What Is The Temperature Of Fire? How Hot Does it Get?

House Fire: 0 to 30 Seconds

In our example fire, we’re going to imagine that the fire starts when a pan on the stove catches fire. This is not an arbitrary circumstance – nearly half of the house fires in the United States begin in this way. 

Oil in the pan overflows due to boiling, it runs down the side of the pan and onto the gas flame or electric ring below, and “whoosh!” it’s alight. 

This is one of the many good reasons, you should never, ever leave a pan with oil unattended. 

However, once our pan has caught fire, the flames start to spread across the stove, the oil is liquid it rolls as it burns. Any existing oil residue on the stove will catch fire too, any paper, cardboard, or dish towels nearby will easily catch from these flames and smolder then burst into flame themselves.

The fire is now producing smoke and vapor, and this contains a range of unpleasant and poisonous chemicals which are themselves very hot and rising and taking their heat with them in the air. 

This is also your chance to extinguish this fire. Don’t move the pan. Switch off the electricity or gas and then either cover the pan with a lid or fire blanket. Whatever you do, don’t throw water, you’ll just send burning oil flying over more of your kitchen. 

This will deprive your fire of oxygen and fuel and it will quickly go out. 

Also read: What Type Of Fire Can Be Put Out Safely With Water?

House Fire: 30 to 60 seconds

It’s all going to start going downhill from here.

As you fire gets hotter, the flames will burn higher and higher and come into contact with more flammable objects in the kitchen – surfaces, cupboards, curtains, hanging decorations. 

And as they burn, the smoke rises and starts to coat the ceiling. You should be long gone by now because this hot, filthy smoke will burn your airways and may contain incredibly toxic chemicals.

In some fires, as little as 2-3 breaths of toxic smoke can render someone unconscious, this is going to put you in incredible danger. 

Also read: What Is A (1, 2, 3, 4, 5) Alarm Fire? Firefighter Answers

House Fire: 1 to 2 Minutes

The temperature of the fire continues to rise.

The extreme heat beings to radiate from the stove to other parts of the kitchen that it’s not directly in contact with. This can start to heat furniture, cookbooks, etc. 

And the smoke is just getting thicker and more toxic as you go. Carbon monoxide, in particular, starts to skyrocket in volumes during this minute. 

And sometime during this minute, the smoke completely fills our kitchen and even though the doors are closed, the smoke starts to vent from the kitchen into other parts of the house, and then it rises up towards the floors above. 

Also read: How Do Firefighters Check for Carbon Monoxide (CO)?

House Fire: 2 to 3 Minutes

Nearly everything that can burn in your kitchen is now on fire. The contents of the cupboards too.

Cereals, flour, crackers, etc. are all ablaze, and as each thing starts to burn it contributes even more heat to the blaze. 

It’s not hot enough in the kitchen for the temperature to kill human beings. The smoke is choking, acrid, toxic and if you were to breathe it, it could kill you too, it would certainly knock you out. 

And the fire Is still spreading… either by direct flame contact or by making things so hot that they auto-ignite! Yes, if things get hot enough, they burst into flame without any need for a flame in the first place. 

Furnishings, ceiling material, floorboards, etc. are all vulnerable to this. 

Also read: Is Smoke Flammable? You May Be Surprised…

House Fire: 3 to 3.5 Minutes

Once the temperature hits 1100 degrees Fahrenheit, you’re going to get a “flashover”. 

That is the entire room bursts into flames simultaneously, all the oxygen is lost in a minute, the windows shatter, and a fireball shoots out of any window or doorway. 

Now, the rest of the house starts to burn too and is quickly filled with toxic smoke. 

Also read: Black Smoke: What Does It Mean And What Causes It?

House Fire: 3.5 to 4 Minutes

The rooms nearby start to burn fully. Sofas, furniture, books, etc. all catch fire as do your carpets, rugs, and curtains. 

They add even more heat to the blaze and in the kitchen.

The flame is now pouring through the ceiling into the floors above. 

House Fire: 4 to 5 Minutes

Anyone trapped on the second floor at this point may not be able to escape the blaze. You can see the flames from the house from a distance. 

More flashovers occur in other rooms, each one increasing the severity of the fire, parts of the framework may start to buckle (in some houses this can take up to 6 minutes but don’t stake your life on this) and even the roof can collapse. 

Also read: Is Flammability A Chemical Or Physical Property? 

What Do Firefighters Do With A House/Property Fire?

The first objective of firefighters at a house fire is to save many lives if possible (human lives first, possibly pets as well) and if anyone is trapped inside they will strategize to try and save them.

Assuming there is no one inside or this phase is complete, they will then seek to extinguish the fire by cooling and smothering it in water. It can take up to 3,000 gallons to extinguish a house fire! Sometimes much more.

They may also cut holes in the roof to allow smoke and poisonous chemicals to escape. 

Also read: Why Do Firefighters Cut Holes In Roofs?

How Fast Does Wildfire Spread?

If you thought house fires were scary, wildfires can spread at rates of up to an acre a second!

They can reach speeds of up to 20 kilometers an hour! 

This video lets you see just how fast a wildfire can spread with high winds:

Why Does Wildfire Spread So Quickly?

Wildfires tend to spread quickly based on multiple factors.

The 3 main factors are:

  • Fuel (size, layout, dryness, type) What types of trees, grasses, logs, etc.
  • Weather (wind, temperature, humidity, rain) Wind and humidity have the largest affect on wildfires.
  • Topography (terrain, grades) Fire burns much faster uphill.

There are entire teams of people that are constantly monitoring all these things, especially weather, on a wildfire. This allows them to try and predict what the fire will do, so they can safely direct firefighters the manage and extinguish the fire as efficiently and with as little loss as possible.

This video goes into more about how wildfires can spread:

Sources: 1 2 3 4 5 6 7 8 9 10 

What Do Wildland Firefighters Do In The Off-Season?

Is It Safe To Sleep In A House After A Small Fire?

Do You Get Charged When the Fire Department Comes?

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