We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
20%? Where? Certainly not anywhere in the US. I've been a builder in Florida for almost 50 years and I can tell you that an impact resistant home is double and up the cost of a conventional,house. Hurricane resistance is mostly about getting the house out of the surge which means at least 15' up and piles another 25 or 30' down in the sand. Add in all the other impact requirements and you're looking at $1,000,000 plus for a basic house.
Once you're off the beach it's more affordable but certainly more than 20%.
We spent perhaps $200 per AC-sq.-ft. in 2006, but the figure was inflated by our very large wraparound porch, which increases costs substantially (perhaps 50% of the AC-space's cost/SF) without swelling the calculated air-conditioned area. We windstorm-engineered the house to 120 and then beefed it up with closed-cell foam. Metal roof, lots of bolts through columns, beefed-up foundation, the whole nine yards. It came through the eye of a Cat. 4 hurricane eye landfall with only the most superficial of damage. None of our small outbuildings blew down.
Now, it's true that we're a mile or so back from the bay, and the bay is behind a barrier island. There was no storm surge this far in, and therefore no debris wall. Building to withstand a debris wall is a special problem. Still, a nearby neighborhood's brand-new houses right on the waterfront stood up quite well. The new codes really work.
A guy from Guam who came to work for me down where Katrina hit in 2004, came back astounded after a drive about.
His one question is why are the houses build out of wood. Only the poor people in Guam build out of wood. Concrete and steel. Told me about on guy who had CONEX boxes bolted to a concrete pad built into a house.
And in Guam, they have real storms. He told me of one that sat over the island for days, after three days his storm shutters started to fail.
But idiot who want to build on the ocean should not be included in the insurance pool for those who build in more secure locations. Then the beach owners bitch when people who are subsidizing their homeowners insurance want to use the beach.
In the 60's I was stationed at Keesler AFB MS. Hurricanes were a yearly occurrence. While their a Hurricane came through and destroyed a lot of property. The eye of the storm passed over us in fact I took advantage of the eye calm to walk to the chow hall and eat lunch. The old WW II wooden barracks withstood the storm with zero damage. In fact they had withstood many storms even worse than this one for 25 years before I was their and many years afterwards. I can assure you that these buildings did not cost even 20% more than a similar building not built to withstand powerful hurricanes. It was a series of simple things and the expensive solutions are not a necessity to making a building hurricane proof.
I wasn't as clear as needed. I'm talking about beachfront houses being so expensive to build. Large, deep, concrete pilings, poured concrete walls, 170 mph doors and windows, mostly steel roofs, little to no soffit overhangs. Everything about them is high dollar.
Once you're inland and out of a flood zone things change. The problem is that in most coastal cities almost everyone lives in the flood zone which kicks the impact codes into place. My house is 10 miles inland but 3/4" mile from a river so we only have to build to 130 mph. It still runs the price way up.