Staining is just one method of treatment and not a very good one. The objectives of maintaining a cedar roof are threefold: Clean the roof, Preserve the wood, and Prevent moss. No where can it found found that changing the color is a necessary goal. One of the main reasons roofs started getting stained was simply to hide another, less attractive color – green. Copper Napthanate was commonly and still is used as a roof preservative. Aside from it’s nasty smell and harshness on the enviroment, it is a good wood preservative. Unfortunately, it is green.
Since very few people want a green cedar roof, the habit was started of adding pigment (stain) to the solution to hide the green. While this is the lesser of two evils, is still had its shortcomings. Even when treatments that are clear became available, many contractors and homeowners became accustomed to see a “stained” roof and used it as a milestone of determining that the roof was treated. Of course, some unscrupulous roofing contractors then realized that they could cut down on the “good stuff” and as long as the roof had a nice tint of orange or putty brown (the two most common options available), homeowners would consider their roof maintained. Take a look at the attached photo of such a roof – what a disaster.