Short answer: those dark streaks are usually a type of algae, not dirt. In Florida it is commonly a cyanobacterium called Gloeocapsa magma. It spreads in humidity and shade, and rain does not wash it off.

Why they show up

Streaks usually start on the north and west slopes, where the roof stays damp longest. Wind and rain carry spores across the roof, so the streaks spread downhill. Tree cover and nearby lakes make it worse.

Is it harmful?

It is mostly a looks and roof-life issue. Algae holds moisture against the roof, and heavy buildup can make shingles age faster. It can also make a home look older and less cared for.

Why pressure washing is the wrong fix

High pressure can strip granules off asphalt shingles and force water under them. That can shorten the life of the roof. Soft washing uses low pressure and a cleaning solution that kills the algae, which is the safer approach.

How a roof soft wash works

Plants and grass are pre-soaked and protected.
A cleaning solution is applied at low pressure and left to work.
The roof is rinsed gently.
Streaks fade as the treated algae rinses away, and some continue to fade over the following weeks.

What it costs

Every roof is different (size, pitch and condition), so we quote roofs free after we see them. Call or text (407) 534-0047 or tap Get an Estimate.

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What Are the Black Streaks on Your Florida Roof?

Those streaks are algae, not dirt. Here is the safe fix. Free estimate: (407) 534-0047.

What Are the Black Streaks on Your Florida Roof?

Protect Your Roof Today

Schedule a professional cleaning with Elite Pressure Washing Pros to restore your roof's appearance and durability.