Why do houses explode?

Factual Questions
1

The obvious answer to the subject line involves the ignition of flammable material, almost always an accumulation of natural gas or propane inside the home. But is there a common point of failure that is frequently pointed to as the root cause, i.e. the fire investigators write up their report and it says “yep, it was *** again”? Some potential examples:

  • Someone left a valve open on a gas stove
  • a gas pipeline somewhere in the home ruptured
  • the flex connector between the gas pipeline and the appliance ruptured
  • a flame detector failed in a “yes, there’s a flame” state, resulting in the gas valve on a furnace or water heater staying open when it shouldn’t have
    *a portable propane tank was stored inside the home or garage (by my math, a 20-lb propane tank is exactly the right size to turn a 20-foot-square garage into a 340-pound bomb)
2

NM, not enough sleep

3

Seems like a clear question to me: Are gas leaks (that cause an explosion) usually because of a ruptured pipeline, a malfunctioning appliance, or other?

4

Sometimes it is stupidity on the gas company’s part, and not a mechanical failure in the house.

5

There’s another reason: malicious, criminal intent.

This explosion, dramatic video below, is believed caused by the target of a warrant who barricaded himself in the house.

6

The most common root cause may be different for propane vs. natural gas. Propane is notoriously heavier than air, so will tend to settle into the lowest part of the house. If that house has a basement with little or no ventilation even a very small leak can cause propane to accumulate up to explosive levels given enough time. When I was a kid a house up the street exploded when propane accumulated in the basement. Mom flipped on the basement light switch and kaboom - the whole side of the house was blown off, mom was killed, and her kid was badly burned.

7

Someone I knew was in a caravan that had a propane leak. He woke in the morning and lit (well started to) a cigarette.

There was a Whoosh and he watched a flame spread all over the van and slowly (to him) burn down to the floor.

It was assumed that because there was very little air movement, there was no gas/air mixture to explode, so he saw the propane’s surface burning.

8

Sometimes it’s because someone didn’t call Dig Safe before starting up a backhoe.

9

Also sometimes they are being used to make meth.

10

Property Manager here. One of the homes we manage blew up recently (and took several more with it, also managed by us). It was caused by an elderly woman with dementia leaving the gas stove on. It was the second time she had done so.

Link.

11

Another one that is also natural gas, but way more convoluted than someone leaving the stove on.

A pipeline ran from an oil well near where the house was built. The oil well was not properly decommissioned which meant natural gas was still getting into the pipeline.

The pipeline was cut, probably when the homes were being constructed, which slowly saturated the soil with gas. This eventually caused an explosion killing two while they installed a hot water heater in the basement.

This did result in an $18.25 million fine against Anadarko Petroleum (or rather the companies that bought and merged with it).

12

That sounds like a front company run by
the hero’s archnemesis in a Simpson’s gag.