We had a number of issues with a cowboy builder which are having to get fixed as time goes by. one we have recently noticed is on our soffits which are leaking out of the top end of the pipe as though it is overflowing. we have noticed that the piping has some form of black substance that appears to have been put into it that seems to limit the amount of water that can enter. the leaking only occurs when it is raining heavily or consistently over a period of time. we were wondering if this black substance is needed or if removing this would help with the overflowing water.
apologies that i cannnot describe this any better but i really do not have much clue on diy at all hence coming to here. attached are two images from a video made to show the issue
