I use a roof mounted Butternut HF-9V. My roof is metal, because I live in a Mobile Home!
I mounted the antenna on a 16' 4x4 post at roof level and about 4-6" away from the roof. I grounded the antenna to the roof with a ground strap and a sheet metal screw.
I have been very pleased with the performance. I never wanted a vertical, but it is the only choice that I have in this neighborhood. Now that I have tried it, I can't beleive how well it works. Even on 75 meters.
73,
Brian