heat and combustion. Would not a house beneath such a tarp simply combust from the heat? In my childhood seeing many houses burn in malibu fires, it struck me as inevitable once a huge fireball gets that close to a building.

If you really want to fireproof, build with concrete block, use ceramic roof slates and fireproof window sashes with rolldown metal shutters like in germany. Cut down all nearby trees and brush with a chainsaw, and install a sprinkler system under the eaves to wet the house's sides during intensive heat exposure.

If you've ever stood near a burning house, the heat generated is soooooo hot, it can make a car explode 30 feet away... the idea is a good one, but there is no replacement for fire-resistant construction.

In reply to the combustion question (good point)... I wonder if the house simply could not be quickly sealed up Windows / Doors / vents and a sort of protective insulating temporary foam be injected between the Tarp and the house ? I imagine there must be something existing which could be added as a extra protective layer between the intense heat and the house ???I wish I knew more about the Physics of combustion to comment. I am only a "What If / Why Not" sort of guy.

I also wish you knew more about physics. Covering a house will not prevent combustion, no matter the material you utilize. Heat (energy) must be transfered somewhere and a tarp of any known material will not absorb and sink enough heat to be of any use. There were a few houses that utilized stored gels and large underground water resiviors with automatic deployment systems to prevent the loss of one or more structures, the costs associated with these systems were reprted to be about 40% of the cost of the original property/structures. Consider also, these systems did not prevent smoke damage and did, in fact, inflict quite a bit of water damage. Either way, burn, smoke or water, the insurance company will pay.

I think you're on the right track though. It's probably well-nigh impossible to save any house in close proximity to the kind of energy released in these wildfire firestorms. But that's only true if the fire in all its intensity gets that close. I think the solution is for semi-rural/suburban at-risk homes to have a kind of layered common defense consisting of interconnected pipe and sprinkler systems that begin to knock down and slow the fire before it gets too close to the structures. Pools could be required for each house and used as resevoirs. Generators and the necessary pumps would likewise be required, all interlinked into a common sprinkler/fire-defense system that would extend hundreds of feet into the brush/woods. Such provisions of course would be expensive but probably not all that prohibitively compared to the incredibly high home values existing in most of these fire-prone areas anyway. Being able to light off such a system to completely drench a large buffer zone in the advance of a fire would do much to take the destructive power out of it...

In considering it, would not a large bottle of liquid nitrogen vented in to a tent around a house lower the temperature. Perhaps a ceramic fibre/metal tent fabric with mirror coating could reflect back the hot fire heat. You'd need "stand-off" brackets to keep the tarp 3 feet or so about the house that the liquid nitrogen cool inside the tent. It would probably take about 2000 gallons. Lets figure the tent costs 10K, and the standoff metal arrangement 10K. Then water vapour-fireproof gas and liquid nitrogen to fill the tent. It would keep a positive pressure blowing out the tent. Such a system would be a huge pressurized tank in the back of the garage, and a bunch of metal pipe bits that sit in the garage and when used, they bold on to pre-bolted fixtures. The tent would probably take an hour to put up. and 10 minutest to fill with fireproof positive pressure (to end smoke damage).

I think the idea really has merit... and it does fit with physics if the right gasses are used.. just that would have to have a fairly deep supply to keep it going during say 24 hours of exposure, as a neighboring house could burn to embers over that time during the greatest danger. How much is Halon? CO2?

A great idea! The insurance companies should be all over this approach to avoiding loss.

The concept is very sound. A reflective fabric would be like the shelters firefighter already use.

Solutions

I have recently been thinking about this and my alternative to it is coming up through the very center of your house, to the roof, possibly beside the fire place if center of house, is a 6 inch water main coming up to about the same height as your chimney. In the event of a fire, no matter if your neighbors house or a raging wildfire, turn this system on and leave your house basically drenched in water for however long the threat is present. Please no one mention that the cost of water would be a lot. It would, but if you are protecting a home say in excess of 50,000.00 in value, it would be worth it, easy to turn on and off. I think that would be the way I would do it. Maybe the insurance company will bear the cost of the water if it were truly that much money on your water bill. I don't think that would be an issue in light of the situation.

I believe it would help with the burning ember problem, but not with a full flash-over from the house next door.

While I agree that once a house is near a hot raging fire it is nearly impossible to save, the idea of a flame resistant tarp, whether for the whole house or just for the woodpile, is worth consideration. One problem of the California wildfires was the movement of sparks to new high-fuel areas by wind. I think the tarps would primarily eliminate the odd chance of your house having a spark nestled in your shingles or woodpile - a real homeowner fear. People would spend the money on the house tarp. HOWEVER, deployment of such a tarp requires on demand action, and many of the Tahoe homes were vacation homes, with absentee owners. If you can figure out a way to make it rain, we'd be in better shape.

The show "Smash Lab" tried this very concept. Their system had some bugs that prevented it from working as planned, but it did show promise. It looked like it might be workable, though they would need to solve a few design issues.

The tarp would be made of the material "Nomex", which is used in the suits of firemen. But I would personally take the low tech solution. Of preventative measures. Make the house out of fireproof materials like adobe and plaster. And since heat rises have half of the house under ground like a basement, and then all that is needed is radiated heat protection. But also don't have tall trees right by the house or another house built only 10 feet away from yours.