Nashville Real Estate - While on a listing appointment on a home approximately 10 years old, I was asked by the homeowner if they should replace the roof. I asked them if it was leaking, no, but it was dirty.
So I went to the front of the home (south side), and didn't see anything out of the ordinary. The north side of the home did have some discoloration that they thought was dirt. It's Algae. It grows in humid areas on the north side of some roofs and siding. You can buy a liquid at Home Depot designed to remove the Algae, and make the roof look much better.
Some modern roof materials have an Algae preventive coating to prevent this from happening.
The bottom line is that instead of spending several thousand dollars replacing a roof, they can spend a few dollars and have the discoloration removed.
