Roof Soft Washing in Northern Kentucky

What Causes Black Streaks and Moss on Your Roof?

Those black streaks are almost always colonies of Gloeocapsa magma, a blue-green algae (technically a cyanobacterium). Spores travel through the air, land on your roof, and take hold where shingles stay damp longest. They feed on the limestone filler used in many asphalt shingles.

As the colony grows, it builds a dark protective coating against the sun. That coating is the black or dark-gray stain you see. Rainwater carries the growth down the roof, which creates the familiar streaked pattern.

North- and northeast-facing slopes, shaded valleys, and roofs under dense trees are hit hardest because they stay wet longer. Heat, humidity, and leaf debris all speed things up, and older shingles tend to streak faster.

Algae staining is mostly cosmetic. Moss is a bigger concern: it grows in the same shady spots, soaks up water like a sponge, and holds that moisture against your shingles.

Why Soft Washing Beats Pressure Washing for Shingles

Pressure washers commonly run at thousands of pounds per square inch. That force can strip the protective granules that shield asphalt from sun and weather, and it can drive water under the shingle tabs.

Shingle makers warn against it. GAF says not to power wash shingles because it may dislodge granules and lead to premature shingle failure. CertainTeed says not to use a power washer on an asphalt shingle roof. The Asphalt Roofing Manufacturers Association (ARMA) says high-pressure washing is likely to damage asphalt roofing.

Soft washing uses low pressure, closer to a garden hose than a pressure washer. The solution is a diluted sodium hypochlorite (bleach) blend with surfactants, the same basic chemistry GAF and ARMA describe for cleaning algae. The solution kills the algae, moss, and mildew. A gentle rinse carries away the dead growth with no scrubbing or blasting.

Our Roof Soft Washing Process

1. Inspection and plant protection. We check your roof's condition, pitch, and access. Then we water your plants and shrubs, cover them with plastic, and lay tarps over the beds below.
2. Low-pressure application. Our technician applies a properly diluted, roof-safe solution by hand with a backpack sprayer. Surfactants help it cling to the growth instead of running straight off.
3. Dwell time. The solution sits long enough to kill the algae and moss, typically 10 to 20 minutes, adjusted for temperature, shade, and how heavy the growth is.
4. Gentle rinse. We rinse the shingles with a low-pressure hose to remove dead growth and leftover cleaner.
5. Flush and final check. We flush your gutters and downspouts, give your landscaping a final rinse, remove the covers, and check the roof and property before we leave.

A typical home takes a few hours. Your roof can keep looking better over the next several days as rain washes off the remaining dead algae.

Roof Soft Washing Before and After in Northern Kentucky

These photos are from a real Fortress soft wash job in Union, Kentucky: heavy black streaking before, and clean, even shingles after.