Leak at the Stack?
 

I had my roof replaced 6 years ago. The roofer installed the flashing device pictured here. I now believe there is a leak at the stack. (During some bad storms a stain develops on my bathroom wall above the toilet right where the stack pipe runs.) My sense is this IPS flashing device is not for cast iron stacks and the rubber collar may well have been compromised by being forced over that existing old ring of cement. My inclination is to attempt to seal around the rubber collar with roofing cement. Would that be just making more of a mess? Or might there be a problem elsewhere around the flashing? The roofer won't respond to my calls. Thanks for your advice.

http://i201.photobucket.com/albums/a...oof2011002.jpg
http://i201.photobucket.com/albums/a...oof2011004.jpg
http://i201.photobucket.com/albums/a...oof2011012.jpg
http://i201.photobucket.com/albums/a...oof2011005.jpg

Time for a new flashing boot. Carefully remove the shingles around the area with a shingle pry bar and you can use them again. Remove the plumbing boot and clean off all that old caulking so the pipe is smooth. Install a new flashing boot, reinstall the shingles and hand seal down the shingles along the old seal strip. Not a dificult repair IF you are comfortable on the roof. Also, while you have the shingles off, sand down the pipe to get the loose stuff off and hit it with a coat of paint to slow down the rusting.

And, welcome to House Repair Talk!

Another idea is you could also just change the pipe comming out of the roof. Cut it with a hacksaw or sawzall in the attic . To reconnect just use a hubless connector ( fernco is one)and put in a new piece of PVC ( plastic pipe) of the same size out the boot.

Thanks so much for your help!

As bad as that pipe is I also feel it's still going to leak if it's not replaced.