My neighbour has a single story extension which has a decked area on to and is accessed from a door on the first floor. She recently had repairs to the decking area and since then my outbuilding which houses my freezer has wet walls every time it rains heavy. She is a unpleasant individual and in the six months that she has owned the property has caused a number of problems to both myself and her adjoining neighbour.
I think that when she had the work done the DIY guy has damaged the flashing underneath the decking. What can I do? I have lived here for three years and the wall in my outbuilding has always been dry up until the last mth or so.