My parents home has a metal roof and they are having trouble keeping up with snow sliding off, blocking the garage door. I want to install a snow fence to eliminate the problem, but can't find any info on installation. I'm not even sure of what this fence looks like as I had my wife stop by the building supply and get a price ($30 for a 20' length), so I'm assuming this is the one that runs horizontal, on the top of the little ridges, near the lower part of the roof. I was thinking of putting it up the roof, at the wall line and attaching it with screws thru the ridges into the deck. Am I missing anything?