Green algae or mildew on siding — Amsterdam, Noord-Holland
Green or black streaks on vinyl, wood, or fiber-cement siding are usually algae (Gloeocapsa magma) or mildew colonies fed by moisture and shade. Left alone they trap moisture against the surface, accelerating rot in wood and degrading paint. A professional pressure washing ($200–$500 for an average home exterior) removes these growths in 2–3 hours using a soft-wash technique — low pressure (under 1,500 PSI) with a sodium hypochlorite or oxygen bleach solution that kills spores without damaging siding. Standard high-pressure washing can force water behind siding laps on vinyl and splinter softwood grain, so soft-wash is the industry standard for building exteriors.
Who to call
For this problem in Amsterdam, call a: Schoonmaker
Vind een Schoonmaker in AmsterdamSymptoms to look for
- Green, black, or dark streaks on siding that don't wash off with a garden hose
- Siding feels slimy or slippery to the touch in shaded areas
- Discoloration worsens on north-facing walls or under trees
- Musty outdoor smell near the house foundation
Spoeddienst in Amsterdam
Spoeddiensten in Amsterdam reageren doorgaans binnen 30–60 minuten, al verlengen de autoluwe binnenstad en parkeerdruk de aanrijtijd. Spoedtarieven liggen rond €80–€180 voorrijden plus €70–€130/uur incl. btw — het hoogste van Nederland.