Why Roofs Leak at the Chimney
Chimney leaks usually start at failed flashing. Learn how step and counter flashing work, the warning signs, and how The Great House fixes them.
ROOFING
12/2/20263 min read
ASK MASON · ROOF
Why Roofs Leak at the Chimney: Step and Counter Flashing
Mason shows how chimney flashing works, the warning signs, and how we fix it.
Roofs rarely leak in the middle. They leak where they meet something, like a chimney.
Watch Mason’s video, then read how chimney flashing works, the warning signs, and how we fix it.
IN THIS GUIDE
01
What Mason Checks
How Chimney Flashing Works
THE JOINT
Where roof meets chimney, water can get in.
STEP FLASHING
One piece with each row of shingles.
COUNTER FLASHING
Covers it from above, set into the chimney.
Where the roof meets a chimney or a wall, there’s a joint that water can get into.
Step flashing goes in piece by piece, one with each row of shingles. Counter flashing covers it from above, so water always runs over the top.
Flashing can come loose, rust through, or be replaced with just a bead of caulk.
Mason’s diagram: step flashing and counter flashing at a chimney
Caulk is not flashing. It cracks in a few years.
02
Warning Signs
Signs Your Chimney Flashing Is Failing
STAINS
Stains on ceilings or walls near the chimney.
RUSTY METAL
Rusted or lifted flashing.
CRACKED CAULK
Caulk that’s cracked and peeling.
Water runs behind the flashing and soaks the roof wood and the framing around the chimney.
It shows up as stains on the ceiling or the wall inside.
Check this today
With binoculars, look where the roof meets the chimney. You should see metal flashing in steps, not just a thick line of caulk.
03
How We Fix It
A Flashing Repair Now, or Rotted Framing Later
We remove the shingles and old flashing around the chimney. We install new step flashing with each row, add new counter flashing into the chimney, and seal it properly, with no caulk shortcuts.
Caught early vs. caught late
Caught early, it’s a flashing repair. Caught late, it’s rotted framing and interior repairs.
In Northern Virginia
The DC area averages about 42 inches of rain a year (NWS, 1991–2020), so a weak chimney joint gets tested often. Many Northern Virginia homes are 40 to 60 years old. In Arlington, about 45% of homes were built before 1970 (U.S. Census, 2019–2023). We fixed this on our Jansen Dr renovation in Springfield.
Planning a bigger project?
Getting a new roof? We replace chimney flashing properly instead of caulking over the old metal. See prices and real projects on our roofing page.
The fix: new step flashing with each shingle row
ASK MASON · ROOF
Want to know another problem?
SPOTTED ONE OF THESE SIGNS?
We’ll check it before it turns into a big repair
Free in-home visit from a Class A licensed team. We check the problem, your roof and your attic, then give you a clear written plan.
ABOUT THE AUTHOR
The Great House team
Written by the team at The Great House LLC, a Class A licensed builder and remodeler in McLean, VA (License #2705197237). We have renovated 30+ Northern Virginia homes since 2022.
PLANNING A PROJECT?
Our roofing service
See prices, real photos and how we work: our roofing page. Real projects: our project gallery.
Serving McLean, Vienna, Great Falls, Fairfax, all of Northern Virginia.