We put an addition on a couple of years ago. Because the addition was more than 1/4 of our total square footage, city code (or county, I'm not sure which) made us bring the entire house up to Miami/Dade code.
New roof, all new windows, doors, electric panel, etc. It doubled the cost of our addition, but I'm glad when hurricane season rolls around. We have hurricane straps and roof straps that we didn't have before, and the windows and doors have a much high wind rating than our old ones. (of course the plywood is ready and waiting, so the window wind rating really doesn't come into play during a hurricane.)
Even our Wally Watt has a wind rating of 130 mph, LOL.
During Andrew, our plywood lasted for about an hour before it was ripped off the house.
The windows held...although they popped out of the concrete a bit, they did not shatter