You better make sure   your insurance will cover you   since you're gonna be higher than two steps on a step ladder.  Besides, when obtaining the permit to do such work.... as you put it 'That High' you'll need to show   proof of probably at least 2 or 3 million worth of liability insurance  .  If you go up there and don't hurt yourself, can you imagine the damage you could do if a drill or hammer falls, let alone if you step back to admire your own work ??