Canada

It depends on the structure and foundation. Since those are unknown, the term near maximum damage is still the most logical. There are brick and concrete buildings that could stand 350 mph, there are those that you can push over by hand. They mostly determine damage by what happens to things that have tolerances that don't change much or don't vary.
With tornadoes EF5, maximum damage, is any tornado over 200 mph, with hurricanes it's anything with sustained winds over 156. A 300 mph tornado doesn't do more damage than a 200 mph one does.