The listed height on mine was 12'6" which I thought to be the tallest point. It wasn't, the 12'6" was to the top edge of the roof. Vents etc were above that. To be sure I added a 12" tall AC. I'm very cautious and aware of overpass clearances. I figure if a semi trailer labelled 13'6" can go thru so can I. Watch the trucks...
The DOT rule on the interstates:
Minimum vertical clearance under overhead structures (including over the paved shoulders) of 16 feet (4.88 m) in rural areas and 14 feet (4.27 m) in urban areas, with allowance for extra layers of pavement.