Ok, what kind of lift will be needed for this work? Is this space wide open where a sissor lift will work? Are there areas where there will be obtructions such as racks or machines or anything where a sissor lift wouldn't work and maybe a boom type lift would be needed?
If a boom/bucket lift is needed there will be more up and down trips ( not as much room for extra materials).
The labor for a high ceiling is more because you will have to rent a lift if you don't own one and even if you do there are cost associated with ownership ( plus transporting it to and from job site).
If there are other people on the job site you may need to rope off the area where you are working or use a ground man just to keep people out of the area (safety).