On Mar 7, 4:45*pm, Dottie wrote:
I live in FL where algae growing on the roof is a big problem. *When I
had a tile roof I had it sprayed every year with some kind of
mildewcide....a man comes around and does several houses in the
neighborhood. *Last June I got a new GAF ultra Timberline shingle roof
that is supposed to be pre-treated with some kind of chemical to keep
algae from growing. *So, when the man came around I said I wouldn't be
needing the treatment anymore. *He said the stuff that was used to pre-
treat roofs didn't really help and I should go ahead and let him treat
mine. *I didn't .. because I was afraid it might affect the warranty.
I called the contractor who said I didn't need anything else and I e-
mailed GAF while waiting to hear from contractor. *Haven't heard back
from them.

Thing is, there are several houses around me who have newish roofs -
older than mine but not a lot older - and they are beginning to show
dark spots in places. *Now I am wondering if I should call the guy
back and have him treat my roof before I get spots ... Anybody know
whether the GAF anti-fungal properties really work or not? *Thanks.

Get in touch with a good roofer and ask him to install a copper strip
across the peak of the roof on both sides of the roof and when it
rains the copper will react and stop mildew, it works, good luck henry
penta, i seen this on the, this old house progran.