US tornado damage

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Regardless, in my experience, if these events were an issue the insurance underwriters would be the first to drive such mitigative requirements like they do for structures in hurricane or flooding prone areas.

See Chock Pullers link above - tornadoes clearly are a bigger issue than many realise.

Performance Against Debris and Wind Loads

To simulate the wind speeds up to 250 MPH present in tornadoes, the Wind Engineering Research Center at Texas Tech University was the first to design an air cannon that could shoot 2x4s and other objects to duplicate flying debris conditions during high winds and tornadoes. Debris flying at over 100 MPH passed right through a standard wood framed wall leaving inhabitants at risk, while an ICF wall with 2 1/2” of Expanded Polystyrene (EPS) foam on each side of the concrete, was not damaged2.
The strength of a tornado in the United States is estimated using the Enhanced Fujita Scale (EF Scale). The scale has six categories from zero (EF-0) to five (EF-5) representing increasing degrees of damage.
An ICF wall can offer a wind resistance of 250 MPH which is equal to an EF-5 tornado. The strength is based on the wall’s composition of steel reinforcement and concrete. In addition, ICF walls are resistant to the water-damage often associated with tornadoes, hurricanes and other storms.
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https://alleguard.com/insights/torna...ncrete%20core.

[wrench1]

Originally Posted by [email protected]

See Chock Pullers link above - tornadoes clearly are a bigger issue than many realise.

How so? Ask anybody who lives in a tornado or hurricane prone region and they fully know the risks and protentional results with some having a more intimate knowledge than others. I think the question is, given ICF construction methods have been around for 60+ years, and since you imply it is the panacea for this type of damage and cost, why do you suppose ICF methods are not mandated in these areas by public building codes, but more importantly, by insurance underwriters?

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It's like safety - you get as much safety as you are prepared to pay for (Baltimore bridge again) - if you aren't prepared to wear the cost of protecting your assets then don't be surprised when something bad happens which, with hindsight, you realise you could have prevented.

Building codes are there to protect people but they are easily watered down by pressure from builders who want volume not quality. Why else do you still have so many wood frame houses in high fire risk or high tornado risk areas?

As for the underwriters, they know the probabilities and make more money out of charging people for unlikely outcomes - if you had a super safe building that would provide ultimate protection, how would they be able to justify hiking your premiums every year?

[wrench1]

Originally Posted by [email protected]

As for the underwriters, they know the probabilities and make more money out of charging people for unlikely outcomes - if you had a super safe building that would provide ultimate protection, how would they be able to justify hiking your premiums every year?

Easy because they do that now. You could build the safest, most storm proof structure and the insurance is under no obligation to reduce your rate. So why spend extra money on a super structure that you'll never recoup and still pay the same insurance premiums to cover that structure? Matter of fact they would probably up your rate since the cost to repair or replace that super structure cost a lot more. But thats provided the insurance would even write you a policy. If everyone started to built brick-sheet houses they would assume there was a known reason and probably leave the area like they've done in a number of hurricane prone states.

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Obviously you know best

[MechEngr]

I expect that insurance underwriters dislike uncertainty the most. If they don't have sufficient statistical data about something they are likely to charge more. For a large enough structure and large enough policy I expect they would hire structural and environmental engineers to reduce that uncertainty, but for a residential home? They will charge more because it cost more.

On the converse, in a place where they have seen certain structures do well they may change their minds when the accommodation is obvious. For example, the use of roof-ties in hurricane prone areas have been known for decades; also reinforced garage doors. They may drop insurance entirely if those are not in place.

The key is the amount of certainty based on experience.

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Originally Posted by wrench1

Easy because they do that now. You could build the safest, most storm proof structure and the insurance is under no obligation to reduce your rate. So why spend extra money on a super structure that you'll never recoup and still pay the same insurance premiums to cover that structure? Matter of fact they would probably up your rate since the cost to repair or replace that super structure cost a lot more. But thats provided the insurance would even write you a policy. If everyone started to built brick-sheet houses they would assume there was a known reason and probably leave the area like they've done in a number of hurricane prone states.

Easy - if you are unfortunate enough to get hit by whatever tornado/hurricane etc and your property survives intact when all around is debris - yours still being intact and surviving is something of a win and you don't have to jump through the insurers hoops when making a claim as they try to find any possible loophole to avoid paying out. Witness the brick built houses still standing after the LA fires when everyone else lost everything.

[wrench1]

Originally Posted by MechEngr

I expect that insurance underwriters dislike uncertainty the most. If they don't have sufficient statistical data about something they are likely to charge more.

I don't know. Even when they have the data it appears they still use some sort of voodoo calculation to determine cost or even coverage. For example, when I built my current house which is located 20 miles from the central Gulf coast, I had plans drawn that followed the requirements of the Dade County, FL Hurricane codes, which are considered the premier hurricane building codes in the industry, simply because my state didn't require any special codes. I took those plans to three of the A-rated insurance companies in my area for review and quotes. Two of those companies stated they could not write a policy since I was below a line on the map regardless of what additional codes I followed.

The third gave me a quote but offered no discount for the additional preventative measures I was taking in its construction. So since I was going to pay the same cost for replacement insurance, I had my builder cull out the overkill building items since I wasn't in a high velocity wind zone and kept the common sense items like you mentioned. Its been 17 years and I'm still money ahead than if I had built 100% Dade County compliant and thats even after a 300%+ increase in my premiums. I think if insurers were more proactive with preventing damage than just making a buck, more people like myself would take the initiative to invest in better mitigative options to reduce damages.