I have the "low clearance" (also sometimes called "low lift") doors in the garage attached to the house. The low lift kit has a separate little track at the top for the top roller on the top panel. Officially, it needs 12" of clearance. I had a 9' ceiling and wanted 8.5' doors. Architect talked to salesman who said no problem. The blind leading the blind.
Installer gets there, laughs, tells me about the 12" clearance. He did a great job of squishing everything up tight. I had put blocking on floor trusses which helped him squish stuff in there. So I had the 8.5' doors, but got only 8' 3" clearance. Not what I wanted, but the best that could be done in a bad situation. These were Clopay doors. Good installer, silly sales people (Hmm. is that a redundant statment :laughing

. I have a garage door opener on it. This was in 2007.
"normal" doors officially need 18" of clearance. These are the ones with a single track. They are slightly cheaper than the low lift doors. I have these in my outbuilding garage. I can take a picture of the track if someone wants to see what I'm talking about.
The garage attached to the house is at 1st floor level, and the 1st floor had 9' ceilings. A lot of the time, the garage is at grade and the house is up by 2 feet or more on a foundation giving 10' of clearance in the garage even if you have 8' 1st floor heights.
Pete