I think both, its very acute I can spot the moss using binoculars but notice the mold discoloration on my northern exposure. I want to nail it before I have to start stripping shingles. I think I am going to double whammy with Vinegar and sprayer, the light bleach, dish soap concoction and do a final zap with the zinc. All of the materials are $10.00 combined so I can afford to experiment a little.

Had a little house under a big swamp maple,light green mold,distinct from moss,not only the roof shingles but the crappy vinyl siding as well.

We use Tri sodium phosphate,{available in powder form in Home Despot and other venues}mixed with equal amouts of bleach.

TSP comes in crystal or powder form so you mix it to a very strong solution with water,add the bleach and pour it into the tank of a good pressure washer {or wide pattern sprayer}set down for say,60-80 psi.

Did the trick for me. Of course I had to rinse the residuum off with clean water several hours afterwards.

Bleach and water seem to kill it. I use special mold cleaners they sell at say West Marine to remove the stains, they seem to work well.


Why is their mold? Cut down the trees!

Northern exposure in Michigan and a wet and mild summer, I am going to do all of the above. The problem and is hardly noticeable at this point so aspraying I go.

I do believe that bleach is all I need but once again with the total cost of material to be less than $10.00 vs $8.00 screw it. I guess the Zinc has a residual effect as well from what I have read while bleach or vinegar evaporates and does not have the lasting quality.

Thats a cold wet state.

If you don't like the weather.......wait 5 minutes.

Sounds familer...

I love it around here. One day its 90 and hotter than hell, the next its 40 and raining like crazy.

Do you think quaternary solution would kill it? Most chemical supply places that service the food industry sell it.

not off the top of my head.

It is not a common problem around here.

Tom W