I've just had an offer accepted on a property which has a downstairs toilet installed by the current owner within the last year or so. A corner of the dining room has been stolen to create the space and it has no window or external wall. There is no fan or other ventilation so far I could tell. The owner admitted that he hadn't obtained building regulations approval. Does anyone know what the implications of this are? I will flag it with the surveyor when he goes around but it would be helpful to know in advance if this is going to be an issue. Thanks.