How to tell if worn chimney flashing is leaking
Worn or poorly sealed chimney flashing can hide leaks that eventually cause water to drip into lower levels during heavy rainfall. Because flashing often conceals vulnerable areas—like roof transitions or covered porch ceilings—it is difficult to spot active damage without checking for hidden moisture entry points.
What the numbers show
Counted from the threads quoted below. How we count
- This comes up 34.9× more often in r/Roofing than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1cleaning, removing moss, and resealing stone and mortarDid this help you?
- 2Applying roofing tar or caulking around the base of the chimneyDid this help you?
- 3Installing flashing along the baseDid this help you?
- 4Cutting out bad pieces, replacing them, caulking, and paintingDid this help you?
- 5Hosing the top of the chimney while inspecting underneath to check for leaksDid this help you?
- 6Inspecting under the deckDid this help you?
- 7Ripping up a small section of shingles adjacent to the chimney to check flashing and sheathingDid this help you?
- 8Hiring a roofing professionalDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Wanting to make this chimney look better. My gut tells me water is running behind the trim because they didn’t caulk.”source ↗
“Should I just replace trim? Or does this need to be a full gut and resheath?”source ↗
“Unsure what I’m getting myself into and wondering what someone who charge to fix.”source ↗
“However with heavy rainfall we are now getting rain water dripping into our basement along the chimney vent.”source ↗
“No flashing = leak. They just caulked the fuck out of it”source ↗
“How bad is this and how concerned should I be? I'm not sure how to go about this.”source ↗
“I recently found some water seeping down into our crawlspace from this fireplace chimney shoot-out off of our house.”source ↗
“was looking at this strip of flashing and it looks pretty worn.”source ↗
“am I missing any glaring red flags here?”source ↗
“I don’t any see signs of leaking but this goes down into covered porch ceiling so hard to tell. Any maintenance or touch ups I should be doing?”source ↗
Where this came up
People with this problem also raised
- 6Why does a chimney keep leaking after multiple repairs?
- 52How to tell if roof flashing is installed wrong
- 4How to tell if crusty residue on a basement pipe is a sewage leak
- 4What is this part of my roof called?
- 2Rotted roof decking and mold around chimney
- 2Roof or gutter contractors missed rotting fascia board