You could replace all the roofing with new shingles dark enough to disguise the staining or with shingles laced with copper granules which are lethal to algae.
How to clean algae off roof shingles.
While an occasional cleaning might not harm your roof repeated use of harsh chemicals or the erosive effects of pressure washing can damage or shorten the life of asphalt shingles.
Simple cover your plants just as painters do.
But once the algicide wears off your roof hosts an all you can eat buffet for the neighborhood algae spores.
Using shingles that have been treated with algicide keeps the growth at bay for about 10 years thus the 10 year algae warranty.
To learn how to prevent moss and algae from getting on your shingles keep reading.
The less expensive solution is to spray wash the roof with a 50 percent mix of water and bleach to get rid of the algae.
So it pays to clean your shingles as soon as you spot algae growth.
Both algae and moss can be easily removed from asphalt shingles with a 50 50 solution of chlorine bleach and water.
The most effective method of cleaning algae and moss from a roof is w ith a 50 50 mix of laundry strength liquid chlorine bleach and w ater.
After 15 to 20 minutes rinse the solution off with a sprayer that has enough force to dislodge algae and moss without damaging the shingles.
For deep stains let the roof dry then reapply the cleaning solution and rinse it off again after no more than 30 minutes.
There are several products on the market specifically designed to remove algae stains from roofs such as wet forget outdoor.
Heavy moss growth can actually form dams that can cause water to back up under the shingles and damage the roof deck.
It s best to clean moss off a roof as soon as you notice it s growing there.