I have water coming in through the ceiling when it rains heavily (like once a year or so). I have checked and can see no obvious holes, etc in the roof. My suspicion is that the downpipe is too small to carry the weight of water during heavy rain and that some is running over into the ceiling. Unfortunately it's a flat roof and so I can't get in and take a look to be certain. The roof area is approx 70 square meters, about two thirds on a very steep angle, the gutters are 165mm, but the downpipe, which is round, is only around 70mm in diameter.
I asked a plumber (here to do some unrelated work), he didn't think that was too small but I still have my suspicions.
Is this likely to be my problem, or should I be looking elsewhere.
Thanks in advance for your help on this!!!