I have some bulbs in the lobby at work that are probably about 12ft,maybe more. I do them with an 8footer. I hate moving the monster ladder. Lol If it really is a 12ft finished ceiling you may be to close to set it up
We had a 5 ft ladder I used for most everything in a office/ house environment. I would rather stand on the top of it, not allowed, then haul out the combo ladder.....8ft a frame extension combo...