Roof Cleaning in Chesterfield Township

The dark streaks running down a Chesterfield roof are a colony, not dirt. The organism is an airborne algae that settles on asphalt shingles and eats the limestone filler mixed into them, and it holds moisture against the mat while it does. It needs three things: spores in the air, a surface it can feed on, and hours of damp. The bay supplies the third in quantity. Morning fog and heavy dew sit on a roof deck long after an inland roof has dried, so a north slope here streaks years before the same shingle on an inland street.

Moss is the second problem, and it belongs to the shaded side of the township. Under the older, taller trees on the shore plats and the streets south of 23 Mile Rd, a north slope can stay wet most of the day, and moss takes hold in the keyways between shingles. Unlike algae it has structure: it lifts the shingle edge, holds water underneath, and pulls granules off when it is scraped or blown. Lichen goes further and bonds to the granule surface itself. All three come off the same way, with chemistry that kills them and weather that rinses them, never with a wand.

The treatment is a soft wash sized for a roof. A measured solution goes on with enough reach to cover a slope from a ladder or the ground, it dwells until the growth is dead, and the rain that follows carries the residue off over the next few weeks, so the roof keeps lightening after we leave. Nobody walks the slope more than the job requires, and the granules stay where the manufacturer put them. A treatment starts at $450 and holds three to five years, the short end of that range on the bay side; the streak explainer shows what the colony looks like up close.

What a Wand Costs You on a Roof

A pressure washer on asphalt shingles blasts the granules off, and those granules are the shingle's sunscreen and its fire rating. Strip them and the mat underneath ages fast, curls, and stops shedding water at the laps. The damage does not show the day it happens. It shows two summers later, as a slope that has aged a decade. Scraping or blowing moss off does the same thing slowly and leaves the rhizoids in the keyway to regrow. The last mistake is waiting: algae that has fed on a slope for years leaves a faint shadow after treatment, because the filler it ate is gone.

Timing It Right

Spring through fall, on a calm day with no rain due for a few hours so the solution has time to work. April to June is the heaviest stretch, when a winter of growth is showing and owners want it gone before listing photos or a graduation party. Moss on the shore plats treats fastest in spring while it is actively growing. Roofs in Lottivue, Point Lakeview and Sebille Manor run on the same rotation, every three to five years.