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We all know to ventilate all structures when needed.  But have we ever thought of ventilating the crawl space? 

It was about 2 years ago and we responded to a house fire just down the street from our station 2.  Upon arrival found heavy fire on the Alpha (A) Delta (D) side of the house.  While performing fire attack and search, there was a sudden explosion within the structure.  All firefighters made an emergency evacuation, and all were accounted for.  So what happened?  Well from what we can gather after investigation and talking to other experts in the fire service, we found that we had a smoke explosion in the crawl space of the structure.

So my discussion is

  1. How will your department avoid this?
  2. What can we as a fire service make sure that all spaces and compartments are ventilated properly?


Pics:  These are pics from the fire scene.  Pay attention to the smoke conditions and the smoke stain on the vent holes.  The last pic is after the smoke explosion.  Look at the damage to the house.



Todd Jennings

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You can have a room full of extremly explosive gases and let the room intact for minutes, hourse, days or month: nothing will happened. Explosion is not a "magical effect". To explode, gases need to be blended, to touch something hot, and so on.

So the main question is not "how to avoid that". The main question is "What (or who) ignite the gases?"

Read here ( the article about vent induced flashover. You will see that in many cases, the accident came when FF trigg it. This is not a "natural effect", a "magical" one in front of which we just have to cry.

For answering your question, we need more detail. On picture 1, what has been done? Ventilation? Breaking of windows? Use of nozzle? And in this case what kind of nozzle, flow rate, pattern, continuous or no continuous flowing?

Same for picture 2. What have you done exactly to go from state of picture 1 (heavy dark smoke and no flames) to state of picture 2 (pyrolysis smoke on the left, flames at the center and from the roof)? And what is the laps of time between picture 1 and 2?


Pierre-Louis /

We know what happened.  The crawl space was exposed to the fire by the incorrect use of a hose stream.  This is what caused the smoke explosion.

In this case, as the house is not yours, you are not able to know were are the crawl spaces. So saying "you must ventilate the crawl space" is not the right answer as in order to do that, you need to know where they are, it will takes time toi find and ventilate, this will need guys and so on. And this will use time "on the scene" so, at the moment you have less.

The conclusion? Spend time before going to a fire, in order to correct what the conclusion show you: your guys don't know how to use a nozzle.






I have to disagree. You can ventilated the crawl space. They have vent openings on all sides of the house. You can simply knock them out to help ventilate. This will only take a few min. I will agree with the hose open but we have corrected that.

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