Some neighbors reported that their roof sagged anyway. Fire resistance is fantastic. Appears similar to Hardishake, but not as strong. Very good fire resistance. Rejected only because it didn't go with our house style.
Minor disadvantage is that special edging is required to keep out birds, squirrels, etc.
Lighter than Cal-Shake. Permatek tiles are all the same size, looking rather like many of the concrete tiles. Strength is superior to Cal-Shake, but not as good as Hardishake. Fire resistance is good, but not as good as Maxi-Tile. After 15 minutes with the propane torch, the heated spot crumbled when whacked with a rod.