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Living Smart: Roof Cleaning

by Angie Hicks, Founder of Angie’s List

You may have the most attractive landscaping, beautiful windows and charming mailbox, but black streaks running down your roof can ruin your home’s curb appeal.

What causes those dark marks, and what can be done to eradicate them?

Roof experts who are highly rated by members of Angie’s List say the source is an algae called Gloeocapsa magma. And depending on the age and condition of your roof, cleaning may be the most cost-effective solution, since it’s about 5 to 10 percent of the price of a roof replacement, which can be as much as $10,000.

Algae-caused marking isn’t preventable but can be removed, though not always permanently. The algae survive through photosynthesis and by feeding on limestone filler used in asphalt shingles.

Black marks became a problem about 20 years ago, when manufacturers began adding limestone granules to add weight to material used to coat shingles.

Roof experts tell our researchers that though other components are being added to shingles to hinder algae growth, they still get calls to deal with black marks on relatively new roofs. They say that while shingle manufacturers offer products treated with copper or zinc to inhibit algae growth, their effect wears down over time.

The Value of Curb Appeal

Creating curb appeal is a wise investment that often requires brains and brawn, but not necessarily a big budget, says Jeffrey Fick, winner of the National Association of the Remodeling Industry's 2014 Contractor of the Year award for residential exteriors.

He goes on to say, "It doesn't matter if your home's worth is $50,000 or $500,000, how it looks from the street certainly affects the property's value:'

How much more would you pay for the house on the right?


The only difference between the two pictures is the one on the right is after the homeowner had their house, walkways and roof cleaned.

In a recent article titled "12 Upkeep Ideas to Add Curb Appeal" Alexandra Bandon from This Old House Online listed the following as the top seven:

1. Clean your windows

2. Fix up your front door

3. Get rid of rotten wood

4. Repair/Clean your roof

5. Polish up paths and patios

6. Spruce up your exteriors

7. Renew porches and decks

One small step is too many - try a Gentle Touch instead!

Can hiring a roof cleaning company impact the warranty on your tile roof? Absolutely.

As a homeowner, it's critical you understand the most important warranty you've got on your home - your roof.

Most reputable builders offer a 20-year to lifetime warranty on their tile products, protecting you from leak-related damage due to manufacturing defects. Among other things, these warranties do not typically cover damage to the tiles resulting from traffic on the roof.

In a recent review of the most prevalent builders in the Southwest Florida region, their roofing contractors/suppliers (Eagle Roofing, Hanson, and Boral Roofing) provided clear guidance for proper protection of their roofs.

In a letter to new owners, they present virtually the same clear direction:

"To assure maximum benefits from your tile roof, minimize walking on the roof to avoid damaging tiles.'

Only one company in Southwest Florida has a proven technology and process to provide a superior cleaning without anyone stepping foot on your roof. Allied Roof Cleaning uses low pressure cleaning and does NOT walk on the surface of your roof. Most pressure washers use systems that generate 3,500 psi. They typically walk on the roof keeping the tip inches from the surface of the tile.