Once you get above 120mph, it becomes very difficult to build 2x4 homes because of the sheer magnitude of the forces involved- on a typical home in 120mph winds, you're looking at about 500lbs of uplift force on every joist-wall connection point to keep the roof from being torn off, which has to be transferred through the wall into the foundation to keep the entire house from taking off like an airplane. And laterally, there's 15-20 pounds per ever square foot of force exerted on exterior walls, doors and windows. It's counterintuitive, but the worst pressure is not on the windward side of the structure, but the leeward side where there is a negative pressure created- the differential pressure is enough to tear sheathing right off a wall.
One problem in particular is garages- that little stub wall framers love to build flanking garage doors to keep the garage as small as possible offers next to no strength when that wall is in shear. A storm with 120mph winds will exert leverage forces on that wall section can exceed 2 tons of force trying to pull out on the anchor bolts and rack it out of true and just push it right over, collapsing the 2nd floor right on top of the 1st.
Wood 2x4 construction is cheap in the US which is why it's so prevalant- cheaper than masonry or steel frame- except for Florida. In florida, you can still build multistory wood homes, but the building codes are so restrictive and techniques so expensive that single-family masonry homes might just as well be required. (Helps with termites, too!) If you get out to places like Guam where they build to exceed 150mph supertyphoons, the buildings are often solid concrete with concrete roofs and start to actually look like bunkers! The lesson here isn't that masonry is necessarily any better, but that US is smarter than the rest of the world and farms trees!
