What are those ugly stains on my roof?
By David M. Haught CHI
The most common question asked while performing home inspections in this area is “How is the Roof? It looks old” As you drive around the Tri-State and look at roofs on homes you will notice a black stain that looks like soot stains. This stain is most prominent on 3 tab light color shingles.
Most homes in our area have their primary heating energy source of natural gas, or electric. And in our immediate area there are few heavy industries to create soot, therefore the source of the black stains are “natural” and come from the growth of a fungus. All this roof fungus needs to grow is a water source, a food source and air. All are present on our home’s roofs.
The fungus will shorten the normal life of your roof, but cleaning will usually damage the roof surface, shorting the normal life of the roof more than just leaving it alone.
When the roof reaches the end of it’s useful life, or the stains are just so unsightly that you decide to replace the roof, make sure your new roof shingles are algae/fungus resistant. By selecting these shingles you should greatly reduce the chance of unsightly stains on your new roof for years.
These new algae/fungus resistant shingles have small granules of copper that keep the fungus from growing. Many years ago hospitals used copper door handles to rooms to help stop the spread of germs. Scientists knew that bacteria, and funguses would not grow on the copper and this reduced the spread of infections.
Many of my home inspection clients will tell you I advised them to install a small copper strip on both sides of the roof ridge to help reduce the chance of fungus growth, if a non-resistant roof is already installed. Our rain has a higher than usual acid content. When it falls on the copper it slowly has a chemical reaction, eroding some copper in solution, that will run down over the shingles helping reduce the growth of fungus.
While on the roof, don’t forget those often neglected gutters and downspouts. Clean out the leaves, and make sure the slope to the downspouts is adequate to drain the gutters. And make sure the downspouts are clear and open to carrying water away from the foundation.
