I live in a 3 unit condo in a 160 Year old Brick building. I have had an intermittent leak in my (1st floor) bathroom ceiling that I know could be coming from anywhere. We've checked the appliances and what pipes we can see upstairs. Other sources might include leaking from the brick where mortar is insufficient, Vents for B.R vent or oven vent, cracked (PVC) pipe.... This has been going on for a year and I am about to cut a patch out of my ceiling to try to see where it is dripping. (intermittent nature, if that is the case, makes this a crap shoot.) What kind of contractor or person is right to do the spy work? Already tried a plumber.

I'll leave the condo related issues out of this...

Help?