April, 2004
Inspection News and Views from the American Society of Home Inspectors

On the Level


Editor’s note: Last month, we reported ASHI Director Jim Rooney, Freestate Home Inspections, Annapolis, Md., writes a column for several suburban Washington, D.C., area newspapers. Although the combined circulation of the “On The Level” column is approximately 400,000, he focuses on the concerns of one reader at a time. 

According to surveys, only “Dilbert” rates higher than “On The Level” with readers of the newspapers in which his column appears, suggesting readers relate to both the questions he chooses and his style of answering them.

Whether your audience is made up of newspaper readers or home inspection customers, technical knowledge and straight talk is a winning combination. For Rooney, writing a column keeps his name in front of readers who may someday be looking for a home inspector who will tell them what they need to know in language they understand.

Whether inspecting a home for a client or writing for the newspaper, this ASHI Member knows how to speak to his audience. For anyone interested in what appeals to newspaper editors and readers, here’s one of Rooney’s columns. 


Q: Last year or the year before you wrote a column on the spots that were appearing on roofs in our area. I had large dark spots that looked like something had hit the roof shingles and dripped downward. These were large dark areas, not the green mossy areas that appear on roofs in shady areas. You provided me the information for a fellow who cleaned roofs and I had this done. In the year after the cleaning, the shingles lost a lot of the surface grit (this was discovered during gutter cleaning) and there was still a shadow of where the spots had been. So, I’ve just had the roof re-shingled this past month and want to know how to avoid this black spot problem in the future. Is there anything I can do?

A: Oops—I wish you’d contacted me before the new shingles were applied because I would have recommended that you specify a shingle type that contains magnesium and copper granules in the top-coating—the aggregate or grit, as you call it—that prevents the staining from taking place.

The fellow who cleaned your roof was an applicator who used products available to certain contractors from Roof Brite of Atlanta, and there are no longer any contractors who do it locally listed on Roof Brite’s Web site—the closest being in Northern Virginia. I found your fellow over in Bethesda three years ago doing research for the column you remember, but he’s no longer doing it.

What you had cleaned off was an algae organism, and this year, due to our record-breaking amount of rain over the spring and summer months— more than 150 percent of normal precipitation—such growths have become common around here. The phenomenon is much more prevalent further south, with black streaks and stains on almost every light-colored roof not treated against it. It occurs on darker colored roofs—it’s just that you can’t see it. You can spot the green variety, but the black streaks just blend in.

You’re not alone. I’ve received dozens of e-mails and letters from distressed homeowners who have never experienced this problem until recently, and just don’t like the looks of the streaking. To them, the roofs look dirty and unkempt, and they are looking for some method of relief from the affliction. Some think that the growths are damaging to the roofs, but unless you get deep, thick growths—usually moss— in valleys or on sloped roof surfaces that can impede the flow of rainwater and force water under shingles or behind flashings, the problem is cosmetic only.

Some people try to power-wash these stains away. Too much nozzle pressure and you’ve blown your roof off in the worst case or at the bare minimum, over-pressure will shorten the shingles’ life. That is what may have caused your older roof to lose so much aggregate after cleaning. Roof shingles are more delicate than people think.

As for future stain prevention, there are some alternate strategies.If you’ve got patience, you can buy metal strips that you place near the peak of your roof for the length of the house, and as the rain washes over the strips, the oxides of the metals travel down the roof, inhibiting algae growth. They can be obtained from the Chicago Metallic Co., South Austin Ave., Chicago, Ill., 60638 for about $3 per lineal foot. So, measure the length of your house and multiply by two for the amount you’ll need.

Call the supplier for a quote to include shipping and handling. They can be reached at 800-638-5192. I’ll bet these strips will take a couple of years to clean the roof if the staining has taken hold, but they will certainly work to prevent it if applied to a new roof.

Or, you can buy a special roof and deck cleaner from K&B Custom Building Products Inc., P.O. Box 1323, Albertville, Ala., 25950. Their phone number is 800-776-9830.

The common household deck and siding wash recipe that I always recommend, which consists of one cup liquid laundry bleach with one quarter cup of powdered automatic dishwashing detergent in a gallon of warm to hot water, will work but the fancy Web sites carry on about how one shouldn’t use bleach. However, when I sometimes get hold of a list of ingredients for their secret formulas, the scientific name for bleach is almost always present, so I tend to disregard those claims.