I put an addition on my house 3 years ago. Yesterday water started leaking through the light in our new bathroom. We traced it to a leaking joint in a plumbing vent in the attic crawl space above the bathroom. There were two problems. First, the joint of the vent (pvc) had not been properly primed or sealed ( it just pulled apart). I primed and glued it which will hopefully fix that issue. The other problem and why there was enough water in the line to leak out is there is a horizontal run on the line that is pitched in the wrong direction- so any water coming in from rain cannot drain but rather just stays in the first joint coming in from the roof. Is the plumber responsible to fix this? How much would it cost to replace this ( do not want to do it myself)?. I would guess the line from where in entere from the roof to where it goes down into the bathroom wall is only around 6-8 feet. If I don’t do anything how big of an issue will this be if the joint is now properly sealed? Thanks.