Black mould in bathroom in Barcelona: 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 Barcelona
80–280 €
Silicone replacement and antimould primer.
Contexto local · Barcelona
Barcelona's climate has high humidity year-round.
Barcelona is the bulk of our work and demands judgement: Eixample is full of modernista buildings with 3 m+ ceilings, original gotelé render, electrics with no RCD and cast-iron stacks still in service — all of which stretch any refurb. Gràcia and Sant Antoni are dominated by 1930s–60s flats with hydraulic-tile floors we have to protect before touching walls. Ciutat Vella adds narrow building entrances and BCN ASIA façade rules, so we coordinate scaffolding and permits when needed. Sant Martí (22@) is another world: new-builds and offices converted to lofts that drag along under-sized electrical panels. The ZBE low-emission zone and AREA paid parking push us to load/unload early to keep costs down.
- Comarca: Barcelonès
- Población: 1.660.122 hab.
- Parque de vivienda predominante: piso-eixample
- Año medio de construcción: 1955
- Códigos postales: 08001, 08002, 08003, 08004, 08005, 08006, 08007, 08008, 08009, 08010, 08011, 08012, 08013, 08014, 08015, 08016, 08017, 08018, 08019, 08020, 08021, 08022, 08023, 08024, 08025, 08026, 08027, 08028, 08029, 08030, 08031, 08032, 08033, 08034, 08035, 08036, 08037, 08038, 08039, 08040, 08041, 08042
Capital catalana con un parque de viviendas dominado por pisos del Eixample, fincas modernistas y bloques de los 60–70 en distritos como Sant Andreu o Nou Barris.
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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Más sobre Damp, mould and paint
Sources and regulation
- CTE DB-HS 1 — Protección frente a la humedad — Código Técnico de la Edificación