While a professional roof cleaning removes dangerous mold and algae, does it add curb appeal?
Black streaks that form on the top of your roof can turn into a black mark for you home when it comes time to sell.
Spotting the undesirable marks before they spread and having your roof professionally cleaned can not only save your roof from damage, it can also add curb appeal to your home – and even improve your health.
The streaks are unpreventable and are actually caused from algae called Gloeocapsa magma that grows on the roof. But a thorough cleaning can take away those black streaks in less than a day and prevent you from having to spend thousands on a new roof.
“The moss is destroying your shingles and with that the infections on your shingles is deteriorating them and causing for early shingle replacement,” says Michael Spinczenski, owner of Indianapolis-based Indiana Roof and Exterior Cleaning. “Another reason to clean them would be a health issue. Some families feel that the mold on the roof itself should be removed because of a (potential) health issue.”
The mold has an appetite for limestone. So when manufacturers started mixing limestone with the asphalt shingle mix to add weight about 20 years ago, the streaking began. Manufacturers have begun moving away from limestone, says Grant Castell, with Bone Dry Roofing in Indianapolis, but thousands of homes are left with shingles with limestone — and black marks. If left untreated, experts say the streaks can lead to premature rotting of the shingles.
“Those stains can diminish the value of the house,” Casteel says. “It looks less appealing and it can raise your electricity bills because the attic is getting much hotter because of the black streaks. It can stop you from selling your house.”
Most black streaks on homes can be found on the northern slopes where it stays wet and darker, which is conducive to bacteria growing.
In regards to treatment, Casteel says his company uses a non-pressurized system to clean the roof by spraying a sodium hydrochloride; it usually takes about half the day for a company to perform the task. Castell says it is important to never power wash the roof of a home, as that can destroy the shingles.
Make sure the method a company uses is approved by the Asphalt Roofing Manufacturers Association. Also be sure the company protects grass, shrubs and flowers from runoff of the chemicals. Spinczenski says they usually perform two coats and added there is usually very little runoff because of a product they install on the roof before spraying which makes the chemicals stick to the roof.
The cleaning can cost between $350 and $1,500 depending on the size of the roof and its pitch and height, Casteel says. A new roof, meanwhile, can often cost more than $10,000.
“Roof cleaning is a lot more affordable that what people think,” Spinczenski says. “Generally speaking, I’m usually asked what is the cost of roof cleaning and I tell people it’s anywhere between three and five percent of overall replacement costs. So roof cleaning is a very affordable product and it’s something that enhances the beauty of your home, especially if you are going to resell your home.”
Even after the roof is cleaned, you’ll still need to maintain it. Casteel says, on average, the black streaks will need to be removed every three to five years.
Before hiring a company to clean, ask what method the technicians use. Check that the company carries liability and worker’s compensation insurance, so you’re protected in the event they cause unforeseen damage or someone gets injured on the job.
Cleaning your roof can be a dangerous project and you need the right chemicals, so it’s a project that’s better left to the professionals.
“The manufacturer’s warranty is very specific about not using a power sprayer, or you will void your warranty,” Casteel says. “Our solution, used properly, will be safe for plants, while cleaning your roof with a soft spray method. The wrong company that doesn’t know proper techniques and chemical additives will leave you with a damaged roof that now isn’t covered under warranty.”
Editor's note: This article was originally published in May of 2013.