Cedar shakes have always stood the test of time. Wood shakes are made out of Cedar wood, there are four types of Cedar shakes, Jumbo shakes, heavy shakes, medium shakes, and would shingle.
There are two kinds of the cut of the wood, a premium cut and a regular cut. The premium cut is straighter, lays down better, and has wider shakes. The regular grade is rougher, and has more knots, and has smaller shakes. In California, Cedar shakes have to be fired rated. There is a class C fire rating and a class B fire rating. The difference between these two ratings is basically how long it takes them to burn.
There are problems with Cedar shakes; the fire treatment is a product that causes nails to rust out. You have to use stainless steel nails to install a fire treated shake. Fire treated shakes our dryer and do not hold the color or shape, they tend to dry out earlier and curl and break. In days of old Cedar shakes were called heavy shakes because they were soaked in water from the logs coming down the river. The bundles of shakes were very heavy to pick up, you would install a shake roof and the color of the Cedar shake, because of the water would last 8 to 12 months. I still enjoy shake roofs and think they are the best roof, if you can install them without being fire treated. To many laws have taken the best roof out of California.