Roof washing clears black streaks, moss and lichen from asphalt shingles by letting a mild solution do the work, with a gentle rinse instead of a pressure blast. Rob, a Woodstock contractor working solo and without subcontractors, washes roofs in Union, IL, where windbreak trees keep some slopes damp. Roof washing starts from $250. Pictures of the roof sent to (815) 451-0106 bring a quote with no charge.
Drive any road around Union and you will see roofs with dark stripes running down one side and clean shingles on the other. That pattern is not random. The streaks are Gloeocapsa magna, an algae that feeds on moisture and limestone filler in shingles, and it settles first wherever the roof stays damp.
A roof wash is not a cure-all and not every roof should get one. Below is how Rob decides, what he does when a roof is a good candidate, and the signs that point to a roofer instead. The goal is a roof that lasts, not one that merely looks fresh for a season.
Why one side of a Union roof goes dark
North-facing slopes get the least direct sun. Add a windbreak row of pines or a stand of old maples nearby and the shingles stay damp long after rain. Algae spreads fastest in those conditions, and the dark side of the roof also absorbs more summer heat, which can age shingles sooner.
On open lots, the south slope usually dries quickly and looks fine. If your roof is streaked evenly on every side, something else may be going on, such as a high humidity pocket near a pond or trees on all sides. Pictures from the ground help Rob see the pattern.
How Rob washes shingles without damaging them
Strong jets scour the mineral granules off asphalt shingles, which is why roofing manufacturers generally advise against them. Rob sprays on a cleaning solution with little force, waits while it kills the growth, then rinses from the ridge downward so water never gets shoved beneath the shingle edges.
He protects plants and shrubs below, keeps runoff away from the well head and septic field, and watches the gutters during the rinse. The guide on roof washing safety covers the method in more detail.
Signs the roof is past washing
Cleaning cannot restore shingles that are already failing. Curling edges, bald patches where granules have worn off, exposed fiberglass mat, and soft, spongy decking all point to replacement or repair. If granules fill your gutters in handfuls, a wash may speed up the loss rather than help.
If he sees any of that, he will say so. In a village with a lot of older roofs, he would rather send you to a roofer than take your money for a wash that shortens the life of what remains.
- Curled or cupped shingle edges
- Granules collecting in gutters or at downspouts
- Visible fiberglass mat through worn spots
- Moss thick enough to lift shingle tabs
- Sagging or soft areas on the roofline
Moss, lichen and the trees overhead
Moss is another matter. It holds water against the shingle, lifts the tabs and can work under them. Tree limbs overhanging the roof keep it shaded and drop acorns, needles and twigs that feed the growth.
Rob can wash moss off, but he will also tell you which branches are worth trimming. A roof wash without light and airflow tends to be a temporary fix. A tree service handles anything near power lines or large limbs.
Timing a roof wash around the Illinois calendar
Roof work fits between late May and September, when it is warm enough for the solution to act and the surface dries fast. Early spring can be fine on a mild day, but frost and wet shingles slow everything down. Winter is off the table.
Do not schedule a roof wash while gutters are packed. Clearing them first, either with Rob's gutter cleaning or on your own, keeps rinse water flowing instead of overflowing. After the wash, black streaks may fade over a few weeks as dead growth washes off with rain.
Roof Washing through the year in Union
Spring
Inspect shingles after winter. Look for lifted tabs or ice damage before booking, since repair comes before cleaning.
Summer
Best season for roof washing. Dry weather and warm temperatures help the solution work, and growth is easiest to see now.
Early fall
Another solid window. Clean before leaves and needles fall so the roof stays clear heading into winter.
Winter
Not a washing season. Watch eaves for ice dams and send photos if you notice streaking, so Rob can plan a spring visit.
Getting a quote
A good roof wash is almost invisible work: no scraping, no walking hard on the shingles, no drama, and a roof that simply looks like itself again after a few rains. If you are not sure whether yours qualifies, text a few pictures to Rob at (815) 451-0106. His reply will sort it into one of three piles: wash, roofer, or trim a tree first.