A local church sadly burned down last night, and it made me think again about house fires. Obviously I know that houses can and do burn. But I've started camp fires, and we all know that can be somewhat of a challenge if you don't have good tinder, etc.

Of course a house is going to have very dry wood, but it's also mostly covered with sheetrock. When I look around my house, I think I could light the curtains on fire and they'd burn all the way up, but I doubt it would be enough to light the wall or the ceiling. If I burned my mattress, or my couch, how would that get anything else going? If I had a grease fire on the stove, it's surrounded by stainless, stone counters, backsplash, etc.

I apologize for the somewhat stupid question, but it's a little hard for me to imagine.

Stand in the room and look at all the fuel. Then realize how much has plastic or other petroleum/carbon based content. Paint is often latex/vinyl. All the burning items create gasses that contain a good deal of liberated fuel (incomplete burning and now aerosolized).

And the fact that the heat will be "contained" and increase the speed of burning, and that is a good portion of the riddle as to the how and why of a house fire being so rapid and hot.

Contrast that to the smaller, open fire and the ability for it to shed the heat, as well as the density of the wood creating a slower burning fuel until it is heated sufficiently to allow faste consumption of the fuel.

As sigmonkey said above, look at everything as fuel. Modern furnishings put off a TON of heat when they burn. The video below gives a good representation of how a room can go from ignition to flashover quickly.

There was a house fire in my neighborhood and it started from a single candle that caught the curtains on fire and quickly escalated.

The fireman said not to underestimate candle because once they catch something on fire the typical house fire doubled every four minutes which is devastating real quick.

So many plastics and synthetic materials that are used in making everything, burn much hotter and faster than wood.

How? Very easily.

Fire needs three elements: fuel, heat, and oxygen. Except for magnesium fires as it doesn't need oxygen or it creates its own oxygen.

It's just like how you start a camp fire. You don't put a match stick to a big log, you start with shavings, kindling, small sticks, then bigger branches, then the log.

There's also such a thing as spontaneous combustion in that oily rags stuck in some dark place builds up heat enough to start its own fire.

Church fires are not fun, I've fought a few. Even managed to lead an attack line crew right into a baptismal in the middle of the sanctuary (nope, couldn't see due to smoke. Yes, it was a surprise. No I didn't expect a 'hot tub' in the middle of a church floor). Churches have a lot of nooks and crannys fire chan hide in and run around for hours.

Back to your original question. Its the contents of the structure that burns first in most cases. As the fire begins to build it grows exponentially. As the radiant heat spreads items in proximity start to off-gas. A large portion of the contents of a modern home has synthetic or plastic materials that off-gas flammable substances. All of that is building. In the video bryan posted you can see it happening from the carpet at 03:14.

As heat builds more off-gas products ignite causing those materials to burn. This is inefficient combustion so its putting even more flammable gasses and particles in the room.

At 03:20 in that video it reaches flashover. This is the temperature where everything in the room ignites above a certain thermal level. Furniture, drapes, lamps, audio-video equipment, paint, trim, YOU, smoke, gasses, etc. That is not a place you want to be, even with full PPE and a charged hose line. Flash overs are near the top of the list of conditions that kill firefighters. I survived 3 and no it is not fun. The video lists time to flash over as 03:40, but that is total room involvement. Trust me, at 03:20 that is NOT a place you want to be.

Circling back to your question. You could build a cinder block room lined with fire brick and covered with drywall. That would be fairly fire resistant. As soon as you paint, trim, carpet, add furniture, etc., you are adding fire load.

^^^^ I'd say buy a lotto ticket but in your case it's a waste as you my friend/brother have used up your luck. Hray

Thanks for the answers. I think the “flashover” is what I was missing.