Q. I have a light-colored roof that is only 9 years old, and over the past year I've developed dark streaks throughout the roof. I've been told that it is mildew. I have no high trees nearby, and no one else in the neighborhood has such a condition. What causes it, and how can it be cleaned up? -- George Borguno, Moriches

A. The streaking in this case stems from a moisture issue, says Jerry Burdi, owner of DJ's Home Improvements in Franklin Square.

Burdi offers an explanation. But first a quick note regarding roof shingles: Shingles in the past were primarily made of asphalt. Today, materials often used in shingles contain fillers, including limestone.

That said, when a roof has moisture, mold or algae will grow. Limestone is an organic matter, which mold and algae feed on. So, essentially, the limestone in the shingle feeds the beast, allowing it to grow and grow.

The good news: This process does not compromise the integrity of the roof, Burdi says. And there are ways to combat the unsightly problem. First, clean the roof. If you don't hire a professional, you can use either bleach or purchase certain chemicals.

A word of caution to DIYer, though. You'll need a ladder, so be careful. Burdi warns, "If (you are) not familiar with the way roofs are constructed, you may create problems by allowing water to penetrate or cause extra wear of the roof by just being up there walking around."

Finish by applying zinc strips to the top edge of the roof. Zinc prohibits the growth of mold and algae. When it rains, the minerals in the zinc leach out of the metal and wash down the entire roof - a process that kills future growth.

Burdi suggests two brands: Z-Stop and Shingleshield - both less than $2 per linear foot.

Finding a real estate expert in senior condos


Q. I read, with interest, your recent answer about senior condos. I was unaware that there were real estate specialists in the area of adult communities. Do you have a list of these real estate agencies? -- Maureen Cunningham, Oakdale

A. First, a word about Seniors Real Estate Specialist (SRES). Agents interested in obtaining this national designation to work with adults 50-plus take a course and sit for an exam. "It's for those who want to spend extra time working with seniors," says Bonnie Doran, associate broker of the Manhasset office of Daniel Gale Sotheby's International Realty.

"Some folks have been in their homes 30 or 40 years. They need to develop a plan," Doran said, noting this is where the specialists come in.

Agents with this designation are well versed and have plenty of resources to help folks through the process of selling, buying or both. So to answer the question, many agencies have an SRES on staff. You can locate one by visiting the Seniors Real Estate Specialist website at seniorsrealestate.com (the right side of the home page has a box labeled "Locate an SRES designee"). If you don't have Internet access, shop for a specialist by calling around to local real estate agencies.

Also, if you work with an SRES to sell your house on Long Island but are moving out of state, your agent can help you locate a specialist in another area, Doran said.

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