Some folks are concerned about sealing the fasteners as they penetrate the roof. I have not had any trouble with mine. I simply use a good quality roofing product such as Henry #209 asphalt/rubber/mastic compound. I also install backing blocks on the attic side of the roof deck to ensure the lag bolts have some substantial wood to hold in.
However, gable brackets are stable and reliable. I've used them with success.
Which ever you choose, be sure you verify the proposed antenna location is able to produce reliable reception before you drill holes in your roof or siding.
Post #20 in this thread,
http://forum.tvfool.com/showthread.php?t=901 is my generic summary re. grounding.
Connect the antenna system ground to the same grounding system that serves your electrical service. Preferably, at the electrical service ground rod(s).
If I add a ground rod, I use not less than #6 AWG copper to connect the new ground to the existing electrical service ground. This ensures a low resistance throughout my grounding system, which will hold voltage differences to a low level. I want the grounded parts of the antenna system to always be at the same voltage level that any other grounded device is. I may add to the existing grounding system, but I never build isolated grounding systems.
I would not rely on a lone ground rod as the sole means of grounding the antenna system. The resistance of a lone ground rod is often quite high. The last two I installed measured greater than 1000 ohms which is not a surprise given the sand and gravel they were driven into. That means that during a fault event that produces 1 amp of fault current through my rod into earth, more than 1000 volts difference will exist between the rod and the average surrounding earth. This is why I choose to run a heavy gauge wire from the added ground rod and the existing grounding system that serves my electrical service.
