Originally Posted by
imported_John Smith
Apparently if individual home owners want to have an individual elevation survey performed on their property,
They should already have one. It's called an Elevation Certificate, and it is issued by the surveyor.
Every time a home is sold, it is surveyed, the house (hopefully) never moves, the same elevation numbers should apply from Day 1 through today (unless there is a volcano or sink hole under the house raising or lowering the house).
What does change the flood plain maps, though, is updating do to construction. What used to be water runoff / discharge areas have now been filled in and are new subdivisions, so ... where does all that water go? Nowhere slowly ... which now causes flooding in areas where flooding never was a problem.
That's just one of the reasons for flood plain map changes.