Black mould in bathroom in L'Hospitalet de Llobregat: 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 L'Hospitalet de Llobregat
80–280 €
Silicone replacement and antimould primer.
Contexto local · L'Hospitalet de Llobregat
L'Hospitalet de Llobregat's climate has high humidity year-round.
L'Hospitalet de Llobregat is Spain's second densest city and it shapes everything. In Collblanc-La Torrassa we work in 1960s–70s blocks whose narrow light wells force us to carry full plasterboard sheets down the stairs, not the lift. Santa Eulàlia and La Florida have buildings whose communal stacks block up every few years — when we repair a bathroom we have to warn the leak may not be theirs. Bellvitge is dominated by 12-storey blocks still running 1970s gas pipework, so we coordinate water shut-offs with the building manager. Street parking is scarce, so we unload before 9 a.m.
- Comarca: Barcelonès
- Población: 269.382 hab.
- Parque de vivienda predominante: piso-moderno
- Año medio de construcción: 1968
- Códigos postales: 08901, 08902, 08903, 08904, 08905, 08906, 08907, 08908
Segunda ciudad de Catalunya, con alta densidad de bloques de los 60 y 70 en Bellvitge, La Florida y Collblanc.
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.
¿Prefieres que vayamos nosotros?
Diagnóstico y presupuesto en L'Hospitalet de Llobregat normalmente el mismo día.
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Sources and regulation
- CTE DB-HS 1 — Protección frente a la humedad — Código Técnico de la Edificación