Cedar shingles will turn grey, although ones which get no direct sun will take longer to do so.

New cedar left in the sun will turn in a year or so, while others may take several years.

A roof CAN be your "friend"...rather than "that thing you hate".

Thank you for the answer I was looking for! Believe it or not, I've asked this question of GC's who looked at me like I had two heads! I wasn't sure if they needed to be treated to turn gray! Again, thanks for your info!

I like the red cedar look. My 40 year old cedar barn shakes have the red look but the gray on the lower edges. I want to power wash them to restore the red cedar look. Does this make sense?

I think you can bleach new cedar to give instant greying