Those black streaks on your roof are not dirt. They are algae — specifically a type called Gloeocapsa Magma that feeds on the limestone filler in asphalt shingles. Once it gets established, it spreads. Left alone it shortens the life of your roof and can void some manufacturer warranties. It also just looks bad.
Pressure washing a roof is the wrong approach. High pressure cracks granules off shingles, voids warranties, and can force water under flashing. We use a soft-wash process — low pressure, longer-dwell cleaning solution — that kills the algae and removes the streaks without damaging the shingles. The results last longer too because you are actually killing the organism instead of just blasting the surface.
What we treat
- Asphalt shingle roofs
- Metal roofs (adjusted solution)
- Tile roofs
- Low-slope membrane sections
What to expect
The streaks lift during the cleaning. On some heavily stained roofs, a small amount of discoloration may remain right after but continue to fade over the next few weeks as rain hits it. We will tell you what to expect on your specific roof before we start.
We work from the ground or from the roof edge — we do not walk on shingles any more than necessary. Gutters get rinsed as part of the job.
Common questions
Will this hurt my shingles?
No, when done correctly. The whole point of soft-wash is to clean without the pressure that damages shingles. We use the same process recommended by the ARMA (Asphalt Roofing Manufacturers Association).
How long does it last?
Typically two to four years before the algae starts coming back, depending on how much shade the roof gets and how close you are to the water. Heavy shade and moisture speed it up.
Is it worth it versus just replacing the roof?
If the shingles are otherwise in good shape, yes. Cleaning extends the life of the roof and costs a fraction of replacement. If the roof is already worn out, we will tell you that honestly too.
