Clean your roof!
Your roof is a host for bacteria, algae, moss and lichen. It can be unsightly and can even cause premature failure of your roof. There is a easy fix for that though. Here is a few pictures of a roof that was cleaned in Bolton Mass. This house had an addition put on. Its the part of the roof that you can see in the far left of the picture. You can see that where the two roofs come together there are some shingles that are a lighter color. That is because, well they just aren’t dirty because they are brand new. The dark discoloration that you are you looking at is Gloeocapsa magma which is a species of cyanobacteria (also known as bluegreen algae).
Now the after picture. Notice the dark shingles in the valley where the addition is. It looked light before because when you buy something of the same color at different times, the color lot may be different.
Please remember that pressure of any type should never be used on your roof. We are constantly being called with requests to “pressure wash my roof.” Pressure will damage your roof… you never want more than what will come out of a garden hose. When calling companies to compare service and price, ask LOTS of questions. The wrong process can be a VERY expensive mistake.