Here are some pix:
The first is the low headroom opener with the funny dual tracks. The upper track is just for the topmost panel. You can see how close the spring tensioner is to the ceiling, it's less than half an inch away. This made adjusting difficult since the holes in the tensioner are at 90 degree positions. Now if they put 5 holes in instead of four...
The next shot is the other end of the operation where the tracks end and the lift is mounted. Again, tight work. The length and placement of the small vertical pieces that support the items is another "more difficult" and time consuming instal. This is why 1 foot of clearance is suggested, and why the guy was able to squeeze it in about 9" giving me the extra 3" clearance for a total of about 8' 3".
Next shot is a normal track from my outbuilding on a 10 x 10 door. You can see the single track and all the space used by both the curve of the track and the spring tensioner.
Next, the 10' x 8.5' door had to use a fancy pants (and expensive) opener that works the tensioner spring. The rails are up at the same height as the 10 x 10 for inside clearance reasons and that meant that a normal door opener could not be used. The motor unit top is 3" higher than the pulley on the tensioner, so this does not solve the problem of a standard rail type opener for low ceiling garages. The unit also cost $$s because it needs a lock mechanism (the black brick below the red main unit) to lock the door. It also had a fancy push button device with time and temperature and a motion detector to turn on the light. I guess they figured that since it already cost too much, lets go nuts. The clock can also be used to program automatic open and close times. But they failed to put a capacitor backup for the clock. so if the power is off for a second no clock :confused2:! All that high end jack up the price and they blew it. Another problem with this timed open design is of course that it doesn't know about holidays. They threw in a cheap feature done wrong to jack up the price on an expensive unit. Idiots. Getting off the soap box now...
I do have remote controls for the tractor garage doors in the cab of my tractor. If you're booking passage on the Titanic, why go steerage

?
Last shot is from garage to mud room in the house showing that they are on the same level. The apron into the garage is 24' long and is the ramp for the house. All part of getting ready to get old some year (or on some days, in a few minutes :laughing

.
Hope these pix help...
Pete