We have a roof leak which seems to be "mystifying" our roofer. 6 months after our roof was reshingled and about 2 years after a total chimney rebuild, we are still dealing with a roof leak along where the chimney meets the roof of the house - leaking inside and running down wall above fireplace. When our roofer and a friend who is an inspector went up there to inspect 2 days ago, they found underside of shingles, and underlayment all dry. Underneath those layers, however, there was an area of plywood about 2 feet by 3 feet all wet and moldy. When that plywood was cut out, our inspector reached up under the step flashing and counterflashing in between that and the chimney. The brick chimney was soaking wet under there! Our roofer proceeeded then to replace the plywood and shingles and claim that the chimney is where the problem lies.The only wet area found was under the counterflashing and an area of plywood roof that rests against the chimney. Our mason is coming out in a few days to inspect and possibly redo our chimney crown even though we don't get any water inside the chimney or the fireplace and no significant cracks were seen in chimney. Our roofer denies that the leak could be due to their work since the shingles and underlayment were dry and he does not want to take off or reflash the chimney. He did caulk around the flashing to seal it. He inserted the counterflashing into a cut he made in the brick (not the mortar joint). The counterflashing is one continuous piece of copper running up ward on an angle following the angle of the chimney. I would be interested in opinions on whether this is a roof/flashing issue or a chimney problem. Thanks for reading! 
-
Generally this is the roofers fault - they did the last work. I think pictures would help. I also suggest you get some water up there and test it if you can. If you test one spot a day you should be able to narrow down how water is getting in.– DMooreCommented Dec 7, 2018 at 19:25
-
Thanks DMoore1. I just attached some photos which I hope are helpful. I am,trying tonunderstand how a chimney could cause this problem as our roofer said. The bricks were waterproofed and the cement atvthe top has a thick impermeable layer on top of the chimney crown. Also flues are have caps.– DebCommented Dec 7, 2018 at 21:16
-
P.S. The roofers peeled back and bent the flashing and then slid the membrane paper under the new shingle which theyaid on top. Now rhe shingkes dont lay flat and he just squirted some silicone caulk under and around it.– DebCommented Dec 7, 2018 at 21:19
2 Answers
Honestly I can't see this being the chimney. I know it looks nice and tight but this is exactly why I wouldn't suggest putting the chimney flashing under the shingles. You now have a seem that is guarded by caulk and not gravity or a harder material like the nice copper flashing.
So my guess is that the rain came down roof, hit chimney and then entered a hole in the caulking. Gravity tells it to go to that hole. Now if flashing is on the outside/over the shingles then the rain has go under the flashing and then over - which is against the laws of nature. In this scenario a small hole in caulking can go unnoticed for years.
-
He did not go cheap but it looks a bit short at the top I usually like the flashing at the top if flat like that to be closer to 2' I will usually ridge the flashing to push the water to the side. When the water hits the chimney it has to go sideways and can back up a bit and that's probably causing the problem.– Ed BealCommented Dec 7, 2018 at 23:22
-
Are you talking about using a cricket? Im not really sure what you mean.– DebCommented Dec 8, 2018 at 17:22
-
I can't see how this isn't a flashing issue. Correct? What should we tell the roofers to do? Thanks for your input!!– DebCommented Dec 8, 2018 at 17:58
Use chimney crown coat sealant and coat the top crown. Use duck tape around the chimney to make a clean line. Let dry. Then use chimney brick waterproofing spray or cream. It’s siloxane based. Use as described.
It looks like your mortar is taking in water. That water gets behind the chimney flashing and behind the ice and water shield. Cheap fix and your should waterproof the chimney brick and seal coat the crown anyways to prevent issues.
