I have a original 30 yr. old clay tile roof. There are no leaks or broken tiles that I know of. The whole roof has become a light green color (ugly) due to algae, I believe. My house is a 2100 sf, single story with a simple roof shape (an inverted V going from front to back) I was once on the roof to take a look at my TV antenna and noticed that light rubbing of the tiles exposed the nice red color. Whats the best way to get these tiles cleaned without introducing problems? Would it have to be scrubbed, sprayed? Any help would be appreciated.

Hello, I have posted a similar question before but I am totaly stumped. I had a new roof put on last spring. I added plenty of soffit vents and one large roof vent. I also added insulation giving me an R 35 value. I went in the attic yesterday morning after the temp dropped to about 19 F. My roof sheating in my attic had frost on it and all the nail heads were frosted over. In my previuos post it was recommended that I close the Gable end vent because they were likely short circuting the soffit and the ridge. I did do that but obviously I am still having a problem. My attic is sealed to what I think is tight and I have no idea how that much hot air would be getting in to cause this problem. The soffit vents seem to be un-restristed. Is there anything I can do to correct this or is this just an engineering flaw in the house? BTW my house humidity is only at around 36%-38%. Please help I am totaly baffled. Thank You, Tom