I renovated my bathroom and got a new electric fan fitted. The builder connected it to the old vent pipe that goes up vertically through the roof. In the rain last week water has been coming into the pipe and down into the vent/bathroom. THere is a cap on top of the pipe but the builder said its not the correct one. Looking at my neighours houses they all have the same cap as I do. Is this a common problem? Do I need to get a different cap? Who would fit this? Would appreciate any help - hopes this makes sense.