I got an e-mail from KI4HEX, Tom about my roof that I am using a stand-by antenna primarily for winter time when I have a problem on my regular antenna.
I show my response to him below.
Re: Roof antenna
construction: My roof is constructed with many aluminum sheets, 1ft x 1ft, interlocked, covering whole roof. The picture is shown in my webpage.
Connecting : I use coax cable, RG-58, connecting the center copper cable to the roof with a brass screw fastened to the roof and needs water-proof. The outer stranded copper wire is grounded with a piece wire extended from the wire at the roof level down to the ground level to the grounding rod. I use a grounding rod, 3ft long, from Radio Shack. My area is next to the Lake Huron and the ground is wet and effective grounding. (You may use a ladder line also, instead of the coax cable.)
Character: It is a great stand-by or emergency antenna. I used this as my usual antenna for one winter before I put up a loop wire antenna. I still use this antenna for a fun of it and winter stand-by antenna. I have had DX to Africa and Europe and I use it for QRP too. It tends to pick up noise. It takes all HF band (including 160m) with a tuner and without tuner it takes 6m, 2m, and 440 because I do not have a tuner for those.
It can be used when it is rain and snow up to 6 inches on the roof but exceeding 6 inches I noticed less signal going out.
Side effect: corrosion may be taken place but not significant. I have been using this roof as an antenna for about 5 years and the roof is about ten years old. I guess the interlocking portion may generate some kind of corrosion because I noticed the tuning on 160m band gives me a bit slow process but there is no problem for tuning for the rest of HF bands.
Heating up at feed line connecting point is never noticed. In fact I never thought about it so at this stage I guess nothing is happening.
No one (no neighbor) knows that I am using my roof as an antenna, perhaps only a few hams in the world exist that the roof is used an antenna. The roof can be used as some kind of counterpoise but this is not my case.