Black mould in bathroom in Castelldefels: causes, cleaning and lasting fix
Resumen rápido
Bathroom mould is usually condensation, not a leak.
¿Qué está pasando?
Shower steam pushes humidity above 80%.
Causas más probables
Poor ventilation after showering
altaSmall fan or blocked duct.
Failing silicone seals
altaAfter 3-5 years it loses its biocide.
Thermal bridge on outer wall
mediaBuildings without insulation have cold corners.
Pasos de diagnóstico
- 1
Clean with diluted bleach
Spray, wait, scrub.
⚠ Parada de seguridad: Never mix bleach with ammonia. - 2
Replace blackened silicone
Cut out and apply sanitary silicone.
- 3
Improve post-shower ventilation
Run the fan 15-20 min after.
Cuándo llamar a un profesional
Call if it returns in 2-3 weeks or exceeds 1 m².
Coste orientativo en Castelldefels
80–280 €
Silicone replacement and antimould primer.
Contexto local · Castelldefels
Castelldefels's climate has high humidity year-round.
Castelldefels mixes a seafront strip of villas and holiday flats with a dense town centre below the castle. Salt air is our worst enemy: in under five years it corrodes untreated aluminium blinds, lock cylinders and ironwork, so we always quote marine-grade parts. Second homes drive a lot of between-season work: deep cleans, AC and blind check-ups after winter, and discreet repairs during holiday lets. Up in Bellamar and Montemar we service villas with pools and heat pumps. The N-340 and C-32 jam early, so we keep first slots for nearby clients.
- Comarca: Baix Llobregat
- Población: 67.999 hab.
- Parque de vivienda predominante: unifamiliar
- Año medio de construcción: 1987
- Códigos postales: 08860
Predominio de chalets y unifamiliares en Bellamar y Montemar, con bloques modernos en Centre y Vista Alegre.
Preguntas frecuentes
Is bathroom mould a health risk?
For asthmatics and young children, yes.
Does bleach kill mould completely?
Surface only — if it penetrated it returns.
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Diagnóstico y presupuesto en Castelldefels normalmente el mismo día.
Pedir presupuesto gratisProblemas relacionados en Castelldefels
Más sobre Damp, mould and paint
Sources and regulation
- CTE DB-HS 1 — Protección frente a la humedad — Código Técnico de la Edificación