Author Topic: Fire blankets can protect buildings from wildfires  (Read 1771 times)

rcjordan

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Fire blankets can protect buildings from wildfires
« on: October 15, 2019, 10:10:29 PM »
Great!  Now how are you going to deploy it? 

Fire blankets can protect buildings from wildfires
https://techxplore.com/news/2019-10-blankets-wildfires.html

ergophobe

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Re: Fire blankets can protect buildings from wildfires
« Reply #1 on: October 15, 2019, 11:10:50 PM »
They have been using these for quite a while to protect infrastructure that can't be defended directly. During the Rough Fire in Kings Canyon, they wrapped a bunch of buildings before they evacced. Same last year with out sewer plant and well head.

I looked into what it would entail to get one for the house. It's neither cheap nor light and there's the question of how you would actually deploy it quickly.

Plus, there's another issue. The worst case in a wildfire is not that your house burns down, it's that all your friends' and neighbors' houses, your water supply system, sewage treatment system, power and phone lines all burn down and your house DOES NOT.

That was actually our biggest worry last year - to lose everything *except* the house and be stuck with no insurance settlement and a house that has no water, power, sewer or phone. So in the end, I decided the better thing to do is to work to harden the general area and just take reasonable precautions on your own house.

Maybe if I had 50 acres, no neighbors and was off the grid anyway, I would go for a fire blanket.

rcjordan

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Re: Fire blankets can protect buildings from wildfires
« Reply #2 on: October 16, 2019, 01:02:56 AM »
>deploy

I don't think homeowners or homeowner groups could muster enough help on short notice to get buildings wrapped.  Govs & utility companies have workers & equipment (cherry pickers, cranes) --oh yeah, and money- to attempt it.

This is somewhat like hurricane prep, except even less lead time.  When it get to the point that everyone knows it is coming, there is NO help as they are scrambling around trying to take care of their own property.  I've been hardening my house over the decades, even retrofitting steel hurricane clips which weren't readily available when we built the house.  They're passive. Great!  Any active stuff I design has to be deployable by an old man --me.

Brad

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Re: Fire blankets can protect buildings from wildfires
« Reply #3 on: October 16, 2019, 11:39:36 AM »
Many years ago I saw a news item about a spray foam that would protect a Cal house from wildfires.  It worked like the blanket.  It was supposed to revolutionize home defense.  Never heard of it again.

rcjordan

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Re: Fire blankets can protect buildings from wildfires
« Reply #4 on: October 16, 2019, 12:31:42 PM »
Whew!

"Peak air temperatures exceeded 1330 C (2426 F)''

(PDF) Measurements of radiant emission power and temperature in crown fires
https://www.researchgate.net/publication/249535257_Measurements_of_radiant_emission_power_and_temperature_in_crown_fires

ergophobe

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Re: Fire blankets can protect buildings from wildfires
« Reply #5 on: October 16, 2019, 04:17:25 PM »
Many years ago I saw a news item about a spray foam that would protect a Cal house from wildfires.  It worked like the blanket.  It was supposed to revolutionize home defense.  Never heard of it again.

It still exists, but suffers from an even more acute version of the problem RC points to. Our clueless neighbors who are second-home owners, asked one of the full-timers during our evac to swing by the house and put the pails of said product on the driveway so the firefighters could apply it to their house. Meanwhile, they had not even done basic prep and had trees touching the house on three sides and backed up to a dense, overgrown forest. Their house would have been in the last 20% they would have tried to save. Like I say, utter cluelessness and cognitive dissonance.

>>deploy

Well, that's the thing... I was pondering a system where it would be on rolls/racks like carpet racks and you could pull a few ropes on your way out like drawing the curtains. Upon reflection, it seemed completely absurd.

But it does work super well for protecting a small handful of very important structures that can't be defended in other ways. Our well head, for example, is deep into the forest where it is way, way too dangerous to leave a crew, but it has a nice 100 feet of clearance. That's the perfect situation for the blanket. Firefighters, if they have enough lead time, can get there, wrap it, clear a bit of brush and get out in a couple of hours and then be safe as the fire sweeps by. We had some damage to the subsurface drip system, which does not go as deep and is not as robust as the leech lines, but can handle more and lets the leech field rest. But the buildings even in the hot zone were unscathed due to this wrap.

rcjordan

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Re: Fire blankets can protect buildings from wildfires
« Reply #6 on: October 16, 2019, 04:30:27 PM »
>nice 100 feet of clearance

What's the recommended clearance for residences around your neighborhood?  I read somewhere that 65 feet was the magic point where radiant heat drops substantially --but looking at 1330 C / 2426 F, even 100 ft seems far too close.

ergophobe

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Re: Fire blankets can protect buildings from wildfires
« Reply #7 on: October 16, 2019, 07:42:50 PM »
100 feet is required by CA law. That's thinned though. It is supposed to cleared of brush at least 30 feet out.

I saw a chart once that showed survival rate for different roof types. Basically, at 15' every house is screwed. At 60 feet, the survival is very high for tile or metal roofs and still attrocious for shake roofs... which are illegal... but still common

ergophobe

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Re: Fire blankets can protect buildings from wildfires
« Reply #8 on: October 16, 2019, 07:44:24 PM »
The probability that a house of a given roof type and with brush clearance will be burned can be estimated from records compiled by the Los Angeles City Fire Department for the 1961 Bel Air Fire, in southern California. These records cover a sampling of 1,850 homes. For the probabilities shown it is assumed that houses are exposed to the rate of wildfire destruction observed in the Bel Air Fire. Values have been interpolated to match the brush clearance categories of insurance industry (Howard and others 1973):

 
  Brush                  Roof type
clearance     Approved by        Unapproved by
(ft):      insurance industry  insurance industry

  0 to  30      0.243                0.495
 30 to  60       .054                 .286
 60 to 100       .016                 .144
100+             .007                 .148
The most cost-effective means of protecting homes from destruction by fire in or near the wildlands is a combination of approved fire-resistive roofing and clearance of 100 feet or more from the native brush for each home

https://www.fs.fed.us/psw/publications/documents/gtr-050/struct.html

rcjordan

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Re: Fire blankets can protect buildings from wildfires
« Reply #9 on: October 16, 2019, 08:01:02 PM »
I forgot that CA does tile roofs (almost non-existent in NC).  What type do you have?

ergophobe

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Re: Fire blankets can protect buildings from wildfires
« Reply #10 on: October 16, 2019, 09:35:58 PM »
Fiberglass composite... not great, but not terrible

rcjordan

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Re: Fire blankets can protect buildings from wildfires
« Reply #11 on: October 17, 2019, 02:40:26 PM »
As you mentioned, EG...

In fire-prone California, many residents can't afford wildfire insurance
http://theconversation.com/in-fire-prone-california-many-residents-cant-afford-wildfire-insurance-119451

ergophobe

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Re: Fire blankets can protect buildings from wildfires
« Reply #12 on: October 19, 2019, 04:01:14 AM »
I just listened to a Fresh Air interview with Gilbert Gaul, author of The Geography of Risk: Epic Storms, Rising Seas, and the Cost of America's Coasts
https://www.amazon.com/Geography-Risk-Storms-Rising-Americas/dp/0374160805

He said that in 2012, they revamped the system, realizing that it was absurd that the government was footing the bill for wealthy people to rebuild in flood plains because of the national flood insurance system. But as the premiums rose, people freaked out, mayors complained their towns would be depopulated and so forth. So it's still a complete mess that distorts the risk and who pays.

I feel like we're getting there with wildfires. I'm afraid that pretty soon, people will start pushing for subsidized fire insurance (even though I would benefit, I am against this on principle) and it seems like there are few constraints on rebuilding after wildfires.

The hurricane/flood plain problem is off the hook because of the subsidies in place since 1965, but if we are not careful, the wildfire problem could get just as bad if similar subsidies distort the market.

But anyway, all I really wanted to say was that it's sort of an answer to your question elsewhere about whether insurance rates could make people move. Apparently, if you charge the true cost of flood insurance at rates that accurately reflect the risk, people start moving away in droves.

Brad

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Re: Fire blankets can protect buildings from wildfires
« Reply #13 on: October 19, 2019, 10:31:43 AM »
It's a matter of time before the Fed flood insurance gets reformed.  It might take a generation tho.

rcjordan

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Re: Fire blankets can protect buildings from wildfires
« Reply #14 on: October 19, 2019, 12:55:42 PM »
Fed flood insurance has a substantial cap -$500k structure / $50k contents, residential OR commercial. So it (or CA fire insurance) isn't enough to adequately cover the cost of replacement.  Since it isn't indexed to inflation, it's being reformed as construction prices increase.

Lots of qualifying parameters are mandated and many now-expensive items are not covered (heat pump outdoor units, piers, bulkheads, lanscaping). If a similar program were to be developed for CA fires, it would likely mandate the setbacks and clearings, roof types, etc. If the adjuster found that you are were in violation (brush near house, new addition with shake roof) you wouldn't be able to collect.