This thread is a good summary on grounding.
http://forum.tvfool.com/showthread.php?t=901
Your reception environment is quite favorable.
Realize that if you are not above the peak in the roof, the antenna will be partially obstructed by the building. Same thing applies to an attic installation. Same for surrounding trees and buildings. Might work, might not - depends on the nature of the obstruction and where the stations are broadcasting from. I'd try it out, but be prepared to put the antenna in a more favorable location on the roof. There are professional installers available if you are reluctant to install on the roof.