There is no more effective way to maintain or improve the attractiveness of your home then by keeping the exterior in great shape, this includes your roof. Over time many roofs in the St. Louis & St Charles MO area start to accumulate black patches and streaks that make them look as if they are dirty. This leads many homeowners to consider replacing their roof. But replacing a roof is an expensive proposition, before you spend thousands of dollars you need to answer one important question.