A valuable characteristic of any Key West home is that it be constructed of Dade County Pine. There is no "new" Dade County Pine because almost all the trees were cut down years ago. Dade County Pine is native to South Florida and is an aged wood of superior strength and therefore very desirable.
Dade County Pine is found in almost every old house in Key West. Those houses may be over 150 years old or more. Key West still has a some homes built in the early 1800s and many built soon after the Civil War. The Dade County Pine used to construct those homes was "old" when it was used, and by the passage of time that wood has become extremely hardened and resistant to termites.
If you think about how the big houses were constructed years ago they were made of Dade County Pine on the outside walls, the inside portion of the outside walls, the interior walls (both sides), the ceilings, and the floors. That is a lot of wood, and the houses are very strong because of it.