How do fires work?
 

I lived in Southern California for over 40 years. My house, and most houses there are stucco over wood frame with Class A roofing shingles made of fiberglass/asphalt or clay.

Stucco is not a flammable material. It is composed of Portland cement and sand, neither of which are flammable. Class A roofing shingles are fire-resistant and can withstand exposure to direct flames without catching fire, according to numerous online sources. You’ll find inside most of these upscale houses lots of tiling, stainless steel, mirrors, glass, and other non-flammable materials.

So how do embers get to the wood frame leading to the burning down of the entire house? And how do the fires spread so quickly from house to house (one report says “length of a football field in 90 seconds”). Yes, wind is an accelerant, but fire needs flammable fuel.

I don’t disbelieve the pictures I’m seeing, just trying to understand how this happens.

Just a guess but wood trim, plastic soffits, and general attic ventilation would all contribute.

The fire rating of the shingles are no match for the temperatures of a wind-driven wildfire.

A wildfire can get to temperatures reaching close to 1500°F. Glass can liquefy at 1400°. Class A shingles are designed to withstand temperatures under 700°.

Unless you live in a brick house with a brick foundation and a brick roof, with no windows at all, your house is likely to burn in a wildfire. And if you do live in that brick house, it will become the oven that consumes you.

I thought I saw the winds were 80-100 mph so we are talking about a hurricane type of blow torch coming down the street. The fire department is taking a beating but I am not sure how you can easily direct water from a fire hose with that kind of wind speed? Apparently it’s disastrous enough the insurance companies are pulling out (prior to theses fires) similar to Florida.

I fought wildland fires in the west for 20 years. There is very little that won’t burn given enough heat. With the winds they get in SoCal this time of year, if there’s any way for the fire to find a way in it will. It doesn’t even need to have flames hit. Just the amount of conductive and radiated heat will get things burning.

& there's your answer. It explains a football field length in 90 seconds.

Embers flying though the air at 100 mph start the vegetation on fire around your house. Don't forget humidity is 8 percent.

I saw an article that referenced why the Getty mansion (and museum) in Malibu survived. It is not the same as the Getty Museum in the Sepulveda Pass area.

It survived because staff had maintained a rigorous schedule of trimming back vegetation, staff turned on all irrigation to wet/cool the surrounding vegetation, and they turned off / closed vents and A/C systems that suck in and spread hot air and embers.

Not saying it was fool proof, but centrally seemed to have worked wonders in this instance.

Mechanisms of Fire Spread
 

Mechanisms of Fire Spread

"When a fire starts, it can spread in four ways: conduction, convection, radiation, and direct flame contact. Understanding these mechanisms of fire spread is essential for enhancing fire safety and protection.
Conduction

Conduction is the transfer of heat through a material or between materials that are in contact. Materials such as metal, wood, and other solids conduct heat well. When a fire is in contact with a material, it can transfer heat to the material. The heat then spreads through the material, causing it to ignite and spread the fire further.
Convection

Convection is the transfer of heat through a fluid, such as gas or liquid. When a fire heats up the air around it, the hot air rises and cooler air rushes in to replace it. This creates a convection current that can spread the fire to other areas.
Radiation

Radiation is the transfer of heat through electromagnetic waves. When a fire burns, it emits heat in the form of radiation. This heat can travel through the air and ignite other materials that are not in direct contact with the fire.
Direct Flame Contact

Direct flame contact occurs when a fire comes into direct contact with a material and ignites it. Materials such as paper, wood, and other solids are highly flammable and can easily catch fire when exposed to flames.

Fire spread can also occur through heat transfer. Heat can ignite nearby materials, even if they are not in direct contact with the fire. Materials that are highly flammable, such as gas and liquid, can quickly spread a fire.

By understanding the mechanisms of fire spread, you can take steps to prevent fires from starting and spreading. Ensure that materials that are highly flammable are stored safely and away from potential ignition sources. Install fire alarms and sprinkler systems to detect and extinguish fires before they can spread."

Just read this article this afternoon that addresses this very question.

California Fires: Why Some Houses Burn and Others Are Untouched in L.A.

Interesting article. However, I’m still trying to imagine how the house ignites if windows and doors are closed. Let’s say one of those embers gets into a vent as the article suggests. If an ember were to get in a plumbing vent jutting up from the roof, for example, it would drop down through a copper pipe and likely be doused by the water in the p-trap. Plus, inside the pipe, there is no wind to stoke the ember.

Some of the houses in the photos have nothing left but ashes. Did the refrigerator melt?? Stainless steel has a melting point of 2500 deg. F. Clay bricks will crumble to ash at 2000 deg. F, yet many houses saw only the brick chimneys survive. It takes time to melt metal even at very high temps. So what is fueling the fire to make it hot enough long enough to melt metal and crumble the stucco walls?

First of all, you're not looking at nothing but ash. You're looking at ash covering whatever is under it. Probably those refrigerators you're wondering about, in various degrees of disrepair since any wooden flooring under the refrigerator, and the electric cords, and the door handles, and the feet, and the plastic inside of it, would have all burned and melted long before it was completely ensconced in ash.

Second, as I said in my previous response, shingle roofs CANNOT withstand the temperatures of wildfires, which can get up to almost 1500°F. California was experiencing hurricane-force winds of up to 100MPH, so basically it was a neighborhood-sized flying blowtorch, as someone else referenced upthread.

Doors aren't made of metal. Glass melts, air pressure shatters glass, and the flames just waltz right into the houses, burning them to a crisp. Garage doors are not made of stucco, and many stucco homes have wood frames. When you surround a home with 1400 degrees of fire, it will burn.

I also lived in California (Montecito Santa Barbara area) and our house was burned down with 230 others back in 1977 due to Santa Ana winds. 1977 Sycamore Fire - Santa Barbara Bucket Brigade
Back then we had cedar shingle roofs, Beauty brick, wood siding. We lived in a canyon and while packing up the van, fire jumped over the hill, over half a mile were the fire was burning and now it was directly on the other side of the road from us. Winds were almost 100mph. We left down the road and parked about a mile away. We had the same issue with no water pressure. We saw a fire truck try to hook up to a hydrant near us and got nothing so they kept going. My neighbor stayed with his house so I tried to walk back to the house in the dry creek along the road but the embers were flying all around me so I went back to the car.
According to my neighbor, the houses with storage sheds started burning and embers were landing on the cedar shingles and that’s all it took. My neighbor with little water pressure put as many sheets and bed covers in the bathtub to get them soaked and laid them on his roof and this saved his house. He was lucky.

We were in another 20,000 acre fire some 15 years later and had to be evacuated. This time, we all had asphalt shingles but with high winds, burning tree branches falling on the houses, and cedar wood siding, it didn’t take much to start the houses on fire.
Fires create an inferno and embers fly blocks if not miles from the existing fire to start new fires.

With enough heat anything will burn

Thank you for asking these questions; I’ve learned a lot.

I also lived in Southern California in a fire area. I had to evacuate twice do to fire. Our house had concrete tiles as do most houses in fire zones but still wood facia.

There are several ways the houses still burn. One is with 60-80 mph winds the temperature is so hot anything flammable will burst into flame including asphalt shingles which are made from petroleum (asphalt) and wood covered in stucco. Another way is the embers get sucked into the attic and the house burns down from the inside.

These fires are so bad because of the wind the fire is much hotter and spreads so quickly. No amount of water is going to stop the fire it just needs to run out of fuel or the wind to stop.

I was in a fire in Southern California and a 80 million dollar mansion on the top of the hill was the only house left standing. The reason was the owner sprayed his house with fire retardant which most people couldn’t afford. His house was the pink house standing out for a while on the top of the hill till he could get it painted.

California houses
 

Many of those older houses were torn down and replaced.
Not same materials

Cardinals Send Planes to Help Evacuate Rams Players, Families and Pets

@rsmurano's post says alot about the history of the Santa Ana winds and CA wildfires. . been happening for along time, we are sure that there wasn't all climate change . . . but I wouldn't be surprised about some arson attempts from foreign actors

California Fires
 

When I lived in L.A. our homes were surrounded by ice plants. I have spoken to a few Californians who have never heard of ice plants.

go to the nearest fire station and get the lowdown on this. They will tell you the real story

How could you not believe the pictures/film coverage of the fires? Do you think it is a conspiracy? Really! I can't take your post seriously.

On December 30, 2021, a wildfire driven by heavy winds near Boulder, Colorado burned to the ground over a thousand suburban homes in two neighborhoods. I’d been visiting my dad in Denver, and no spotted the plume of smoke as my plane took off that morning. One of my nieces is a firefighter and fought that fire.

I spent five years of my childhood in Northern California, in the mountains above St. Helena and its vineyards. Our first home had varnished redwood siding and redwood shakes on the roof. Most homes were stucco (fireproof concrete), but with shake roofs. Surrounding us was miles of big evergreen trees and dry grass.

My in-laws live in Loma Linda, California, a couple hours east of Pacific Palisades. They live high on a hill, with a gorgeous view, and there are miles of hills behind the house a couple hundred miles away. No trees. Just oily dry brush, tumbleweeds, dry grass.

It’s certainly possible to design homes less likely to burn. However, a home that can withstand, say a dry grass fire when the wind is low, buffered by bare dirt or well-watered grass, on a day when the wind isn’t high, still can’t usually survive 80 mph winds and the heat from a fast-moving fire racing through dry forests. Things like burning pine cones and pine needles and burning brush fragments soar as if in hurricane and can start new fires hundreds of years in advance.

Lots of these Southern California homes have roofs made of clay tiles. Those are half an inch thick and essentially fireproof. Drop a basket of burning pine cones on the roof and they will burn themselves out. Lost house walls are stucco, and that is also mostly fireproof. Glass doesn’t easily melt or burn, either. Studies show that the weak spot is the soffits, often called the eaves, the area under where the roof juts out from the walls. These are usually made from either half-inch painted plywood or thin vinyl. Both burn easily. Also, building codes usually require attic ventilation. Vents in the soffits let air be sucked up into the attic, thanks to vents at the top of the roof. When homes in these situations catch fire, the fire tends to start in the soffits let air area because they are more flammable than stucco or roof tiles. It doesn’t take long when the air is 400°. The flames are sucked into the attic and start burning themselves wood roof trusses and the plywood sheathing. Seconds later, the entire roof is ablaze. That’s the end of the house.

Normally, places like New York State and New Jersey get rain and humidity and dew in the summer and don’t easily burn. Last summer, you may recall, there were big fires there due to unusually dry conditions.

In the winter in The Villages, we get very little rain. Grasses and trees dry out. We are surrounded by many miles of fields and forest. Not far away is the Ocala National Forest, 673 square miles of brush and short pines inhabited by thousands of people in old house trailers, many of them drug addicts. If we have a drought here some summer that lasts several months, could we have a fire that burns out of control and burns thousands of homes? Yes. Could it reach The Villages? Yes.

Consider. My home is framed with wood, covered with vinyl siding that melts and burns, the soffits are vinyl. Thousands of homes here are similar. Faced with a fire similar to the Pacific Palisades fire, The Villages could burn, too. Even homes with concrete walls have vinyl soffits vented to let air (and flames) into the attic. Class A shingles won’t do anything to stop a fire that has already entered the attic and is burning from the inside out.

I don’t live in terror of this happening here, but it certainly could. Some homeless person neglects a little campfire in a hidden spot a mile from here, and because of extreme drought, the glade catches fire, and then the surrounding trees and scrub. If it reaches The Villages as a big wildfire, yes, The Villages could burn, house after house. The fire department can put out two or three house fires at once, but not a hundred. We have lots of ponds that can be used for extra water, but with a fire like that, the closest ones would be quickly drained. Yes, it could happen here.

As I said, "I don’t disbelieve the pictures I’m seeing, just trying to understand how this happens."

It just boggles my mind that temperatures can get so high to cause roofs to burn, glass to melt, and concrete to crumble, but the trees are left intact (see previously posted photo)

Those trees are not intact. They haven't fallen yet but they are severely damaged and many likely will not recover.

In the movies you cut down a tree, light a match, and have a campfire. In real life you learn that green, wet wood does not burn. The dry shingles, dry framing, dry furniture all burned as well as the dry back on the trees. The wet interior of a live tree does not burn well at all. The leaves on the tree were also wet but that much heat for even a short time dried and burned them just as it scorched and damaged the wet interior of the tree.

Try googling forest fires, grass fires, or wild fires to learn more about how this type of fire works.

Santa Ana
 

I also lived in California - LOOOOONG ago when they had a responsible government and government "services," for which we paid. Yes, stucco is a cement product, BUT: if you hold a blow torch against an outside wall for a minute or two and the heat/fire will reach the inside. Then, as the wind continues at 80 to 100 mph, the effect will be similar to that in a blast furnace.

How SAD, what has happened to the (once) golden state!

Maybe it's me but, there are places that are known for potential problems, yet people flock there.
Now I'm not saying they shouldn't, what I'm suggesting is the homes they build even if does not conform what we expect a home to look like should be designed to deal with the environment. You live in the Midwest where hurricanes are common build a home with the majority of the home is below ground and what is above maybe 3D printed. You live in a flood zone build a home that is high enough to withstand any flooding. You live in a fire zone build something that is totally fire resistant. We all want the house with the white picket fence, but nature is not going to change for us, so we are going to have to change if we want to survive

Saw one video of a car, rather what’s left of it, melted metal on the ground… now that’s hot.

I can’t take your post seriously as you clearly did not read or understand what he said.

He said he was NOT disbelieving. He was trying to understand how this could be so destructive.

I also lived in So Cal. There are ways that embers can get into a house. They are not totally fireproof. Most of the previous fires were in more isolated areas. These fires are not and you cannot do much against 100 mph winds. The houses in Altadena are most likely not stucco as they were built years ago. I remember being scared during the Oak Park fire in 2003. I left my home in the middle of the night. I feel for all these people. I know at least one person who lost their home.

But people refuse to believe in climate change.

Think about it even the fridge and washer & dryer along with the water heater will melt in that heat.

Why are you even questioning this? Do you think this was made up?

Ice plant used to be all over, but like ivy, people rid their yards of it because it was messy looking, anything dropped in it was lost forever, and snakes/mice loved living in it. Much of it was replaced with Marathon sod. I think some ice plant "writing" I did in the 80's is still on the curb at the beach where everyone waited for their moms to pick them up at the end of a long summer day, and the "writing" was all over the wall at my school. I'm sure others have "written" with ice plant.

To some, curiosity killed the cat. To me, lack of curiosity keeps you in the dark. I'm always trying to understand the world in which I live and how things work, especially when perceived events are counterintuitive. Questions are the foundation of knowledge. If you're NOT 'questioning this', perhaps your time would be better spent on other forum topics.

But let's not just blame a homeless person for being careless. How about those that toss their cigarettes without a thought? Possibly, this happened in LA. I remember telling a landscaper not to smoke while he was working as everything was dry. Some people just don't think.

Then why don't you go see for yourself Mr. Doubting Thomas?

Read Post #9

Noticed on News Broadcasts that homes had shurbs and trees close to the homes.