For the Dutch owner of a ten year old house located within the northern coastal zone of Barcelona, which suffers from serious problems with humidity and condensation, we have realised an exhaustive survey on the origins of the problems and presented a series of solutions to resolve them. These kind of problems, that eventually might even cause health consequences, are mostly due to a bad execution of the building. When approached with professional knowledge, normally we find the way to get back to a healthy interior climate in the house!