h20ski,
The height can change if you ordered it with the 16" wheels or the Equa flex option. I beleive the highest it can be is 12'4". I hope that helps.
I have 2 maxi vent covers installed and i figure my 31 RETS is just under 13' measured as close as I can with a tape measure to the side. I just figure I will need at least 13' to clear. HTH.
It's sitting in the driveway now. I guess i'll go measure it today. It looks like I'll be replacing the 12 foot barn door with a 14 foot door over the 3 day weekend.