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How to deal with suspected bathroom mould

We ask a recommended damp proofing expert how to tackle suspected mould in your bathroom. Plus all important 'need to know' nuggets for preventing damp-related problems.

Member question: I have suspected mould in my bathroom. The bathroom is quite small and has no window. I have a working extractor fan, installed on an external wall. Do I need to break the wall and put insulation in?

Ventilation not insulation

From your description, it doesn't sound as though your problem with mould is related to whether the cavity wall tie is insulated or not. It's much more likely that the fan is not ventilating the area sufficiently following showers and baths. 

Make sure the fan is set to the longest overrun, so that it continues to operate after the bathroom lights are switched off. A lack of airflow through the room is the most likely cause, so keeping the door open as much as possible may also help. 

Preventing potential damp issues

  • When it comes to preventing damp-related problems, don't just put all your efforts into the property's interior. Maintaining the exterior, including pointing of chimneys and ridge tiles is also important. 
  • Clean out your gutters and downpipes at least once a year to help water drain away efficiently. 
  • Misting on the inside of Upvc windows can easily be fixed with a replacement pane of glass - no need to replace the whole window. 
  • Always seek local authority guidance and/or approval before you start any building work. 

Our expert: James Spencer 

Founded in 2004, James P Spencer Ltd offers building and ladscaping services for consumers in the Nottingham area. 

James kindly takes time out of his busy schedule to regularly assist Which? members with all manner of questions in the Which? Local forums.