Leaking Around the Chimney? Flashing Problems Explained

I’m Devin Orsi, owner of Peak Precision Contracting in Canonsburg. We’re a collective of tradespeople covering renovations—interior and exterior—plus roofing, siding, gutters, storm and insurance work, water mitigation, and mold remediation. Roof leak detection is my specialty.

If you’re dealing with a chimney flashing leak in Mt. Lebanon or elsewhere in the South Hills, the stain on the ceiling or the damp spot in the attic often starts at the metal and sealant where the chimney meets the roof—not inside the flue. Here’s how I think about chimney leak repair, what fails first, and what to do before freeze-thaw makes a small opening worse. Estimates are free.

Why chimneys leak even when the roof looks fine

A chimney is a vertical wall punching through a sloped roof. Water that hits the uphill side has to be redirected around the stack. That job belongs to step flashing, a cricket or saddle on wider chimneys when the design calls for one, counterflashing into the masonry, and sound joints—not a thick bead of caulk alone.

In Mt. Lebanon, Upper St. Clair, and nearby South Hills neighborhoods, many homes have older masonry chimneys with original or patched flashing. Fall rains and the first hard freezes of the season are when small gaps show up: daytime wet, nighttime freeze, then another round of wind-driven rain.

Flashing problems vs. masonry problems

Not every wet spot near a chimney is the same repair:

• Failed step flashing or base flashing. Metal pieces along the shingle course can pull, rust, or get covered incorrectly during a past reroof. Water runs under the shingles and into the deck.
• Counterflashing pulled out of the mortar. If the upper metal isn’t seated in a reglet or properly sealed into the brick, water slips behind the flashing.
• Missing or undersized cricket. On the high side of a wide chimney, water can pond against the masonry instead of splitting around it.
• Open mortar joints or cracked crown. Masonry issues can let water into the chimney structure itself. That’s a different path than a roof-to-chimney flashing leak, and it needs an honest assessment before anyone “just seals” the roof.
• Bad surface sealant repairs. Caulk over bad flashing is a temporary bandage. It hardens, cracks, and hides the real entry until the next storm.

My job on a chimney leak repair call is to separate roof flashing failure from masonry or liner issues so we fix the right assembly—not paint over a stain and hope.

What I check on a Mt. Lebanon or South Hills chimney leak

Peak Precision is a general contractor first. Roof leak detection is where I spend a lot of my own time on site:

1. Map the interior stain or attic dampness to the chimney location on the roof plan
2. Inspect the attic (when accessible) for staining on the deck, wet insulation, or daylight at the chimney chase
3. Look at the exterior: step flashing, counterflashing, shingle integration, cricket, and chimney base
4. Note masonry condition at the joints near the roof line without confusing every brick crack for the leak source
5. Confirm the entry before we scope repair—flashing rework, localized shingle work, or a larger roof section if the surrounding field is also failed

If water has already soaked drywall or insulation, we can move from leak finding into drying and repairs under one team. See our notes on roof repair in Canonsburg for how localized repairs fit a broader roofing scope. For active water in living space, water mitigation and, when needed, mold remediation are part of what our collective handles—not a separate scavenger hunt for three contractors.

Fall is the right time to stop a chimney flashing leak

Autumn in the South Hills brings more wind-driven rain and overnight temperatures that flirt with freezing. A gap that only dripped in a summer shower can ice, widen, and stain a ceiling by November. Catching a chimney flashing leak now—before heavy freeze-thaw and snowmelt—usually means a cleaner repair window and less interior damage.

Stay off a wet roof. From the ground or a safe attic access, photograph the chimney base if you can see it, note when the drip happens (only in rain vs. anytime), and call for a free estimate rather than buying another tube of caulk as a permanent fix.

What a proper flashing repair usually involves

Every roof is different, so this isn’t a one-size checklist you should DIY from a blog. In general, a durable chimney flashing repair means integrating metal correctly with the shingle courses, counterflashing into masonry the right way, and replacing damaged underlayment or decking if water has been running for a while. We’re Owens Corning Platinum Preferred when a roof system repair or replacement calls for that path.

If the rest of the roof is near the end of its life, we’ll say so on the estimate instead of selling an endless string of patches. If a small flashing repair is enough, we’ll say that too.

Call (412) 498-4299 or reach us through our homepage and contact page. We’re at 938 South Central Ave, Canonsburg, PA, and we serve Mt. Lebanon and the South Hills regularly.

Chimney flashing leak FAQ

Is a wet spot near the chimney always a flashing leak?

Often, but not always. Condensation, a plumbing issue, or masonry water entry can look similar. Tracing the path matters before anyone tears off shingles.

Can I just caulk the chimney base?

Surface caulk is not a substitute for correct flashing. It may slow a drip briefly and then fail—especially through a western PA winter.

Do you only fix roofs, or the interior damage too?

We’re a collective of tradespeople. We can address the roof entry and coordinate interior repairs, water mitigation, and mold remediation when the job needs it.

Is the estimate free?

Yes. Estimates are free. Call (412) 498-4299.

Do you serve Mt. Lebanon and the South Hills?

Yes. Peak Precision Contracting works throughout the South Hills from our Canonsburg shop, including Mt. Lebanon and nearby communities.

If you’re seeing a chimney flashing leak—or any roof leak you can’t pin down—call Peak Precision Contracting at (412) 498-4299. We’ll find the source and we won’t leave your doorstep until you’re satisfied.