Services · Austin, TX
Roof cleaning in Austin, without taking the roof off with it
Black streaking on an Austin roof is almost always algae. It comes off with a low-pressure soft wash and the right solution. Pressure takes it off too, along with the granules that protect the shingle, and that is how a roof loses years.
What the black streaks actually are
Gloeocapsa magma is a blue-green algae that feeds on the limestone filler in asphalt shingles. It spreads downward with rainwater, which is why the streaks run in vertical stripes and why the north-facing slope is usually worst — it holds moisture longest.
It is not dirt, and it is not the roof failing. A roof can streak badly and still have most of its service life left.
Why pressure is the wrong tool here
The granules embedded in a shingle surface are what make it a shingle. They carry the UV protection and are part of its fire rating. A pressure washer strips them, and once they are in the gutter they do not go back.
Soft washing works the other way round: a cleaning solution does the work and time does the rest, at roughly garden-hose pressure. The algae dies and weathers off over the following weeks rather than being blasted away in an afternoon.
What happens to the plants and the gutters
Runoff off a roof lands in a wider ring than a wall wash does, so beds along the whole drip line get soaked with plain water first and rinsed again at the end. Pre-wetting dilutes whatever reaches the foliage; point out anything newly planted or unusual before we start.
Runoff follows the roof into the gutters and downspouts, so we look at them before we leave and tell you if they need clearing. Clearing them is the separate gutter-cleaning job.
Roof cleaning in Austin: questions people ask
Will this damage my shingles?
Not at soft-wash pressure — that is the entire reason for using it. The damage case is the opposite one: a pressure washer on asphalt shingle strips granules and shortens the life of the roof.
How long until the roof looks clean?
Some of it lifts immediately and the rest keeps lightening over the following weeks as the dead algae weathers off. A roof that is still lightening a month later is behaving normally, not failing to clean.
How often does a roof in Austin need this?
It depends on shade far more than on time. A roof under heavy live oak canopy streaks again much sooner than one in open sun, so shade is the variable to watch rather than the calendar.