Green algae or mildew on siding — Valencia, Valencian Community
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 Valencia, call a: Schoonmaker
Vind een Schoonmaker in ValenciaSymptoms 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 Valencia
Emergency services in Valencia respond within 30–90 minutes in the city core (faster in l'Eixample and Ruzafa, slower in outlying districts). Callout rates run €50–€130 plus €35–€65/hour including IVA. Post-DANA (November 2024) contractor availability in the southern metro area (Horta Sud) remains constrained due to ongoing flood remediation work — expect longer waits and higher rates for any flood-zone adjacent property.