With our aftermarket covers on the fantastic fans, we top out at 12'8" but to be safe, I always call it 13'
BTW, AllStays has a GREAT RV app (Camp & RV) for the iPhone/Pad (Android as well I think) that lists all sorts of neat info INCLUDING routes that have low bridges - and you can filter out how low can you go
Finally, on the way back from Goshen, right after passing under a 14' underpass we spied a oncoming RV with the antenna still in the "upright and fully locked position"
No manner of light flashing and pointing got their attention
Observation 1: A raised TV antenna increases clearance substantially
Observation 2: Watching a RV go under a 14' underpass under "full sail" is the classic defination of Schadenfreude
Observation 3: A $300 Winegard HD antenna when violently seperated from a RV roof leaves a lot of road debris (thankfully no one was following closely)