Q & A – Is this leaking chimney caused by poor flashing?

When their friend’s roof began leaking around the chimney, this Massachusetts resident reached out to our roofing experts for answers. 

Chris from Martino, Massachusetts, sent in this question about his friend’s leaking chimney: 

I have a friend who had his roof shingled within the last couple of years. It is leaking around the chimney and he is asking my help. I can't see anything obvious. The only thing that seems unusual to me is the lead flashing on the chimney sits on top of the shingles not under them. Is the way it is done? Please help educate me. Thank you. 

Here is what roofing expert Greg Serevetas from USA General Contractors Corp. had to say in response to Chris’ question: 

It’s not as unusual as you think, but you are correct. The lead should be underneath the shingles in a step flashed install, from the bottom up, with each piece overlapping the lower piece. 

I can’t really tell from the one picture, if you had a couple more it might help. The problem can be multiple things.  

1. If there are nails holding the lead down, they could be leaking.  
2. If the caulking at top is not sealed to brick and lead properly, that could be leaking.  
3. The back of the chimney lead is also on top of the shingles, which will allow water underneath and will cause a leak.  

The recommended action is to remove the flashing and shingles around the chimney and do a rework with aluminum step and cap/cover metal (see above picture for an example). Notice how the metal at the low point of the chimney is the only exposed metal on the roof and there are no nails exposed. 

Hope this helps! 

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