[TowerTalk] Distance from an airport and tower height

[Cqtestk4xs at aol.com]

Way back a long time ago I knew where to look this  up.
 
I am presently kicking the tires on a few places back in FL.   One looks 
interesting, but is a little over 2 miles from a PRIVATE  airport.
 
I think the rule of thumb for tower height allowed from a  
commercial/public airport is 1 foot for every 100 feet, and the height allowed  from a 
private airport is 1 foot for every 50 feet.  Am I right, or has  this changed?  
Where can I find info on this?
 
Thanks!
 
Bill KH7XS