The Chimney Is Where Roofs Leak
Ask any experienced roofer where most roof leaks start and you will hear the same answer: flashing — and chimneys are flashing ground zero. A chimney is a big masonry box punching through your roof, and the joint between brick and roofing moves, expands, and weathers differently on each side. Water loves that joint. In Baltimore, where freeze-thaw cycles work every seam all winter, chimney flashing fails on a predictable schedule — and when it fails, water runs down the chimney chase into your attic, your walls, and your ceilings.
Here is the industry's dirty secret: flashing is also the most commonly shortcut part of a roof replacement. Reusing old flashing "to save you money" saves a few hundred dollars and plants a leak timed to appear in three to five years — conveniently after the workmanship warranty expires. We replace chimney flashing on every job. No exceptions, no upsell conversation. It is part of a roof.
What Proper Chimney Flashing Includes
Step flashing — individual L-shaped pieces woven into each shingle course up both sides of the chimney, so water is directed out onto the shingles at every level. Not a single bent piece of metal caulked to the brick. Not roofing cement. Woven step flashing, done to spec.
Counter-flashing — metal set into a reglet cut in the mortar joint, folded down over the step flashing. This is the detail that separates real flashing from caulk jobs: it is mechanically locked into the chimney, not glued to its face. When the old mortar eventually needs repointing, the counter-flashing stays put.
Cricket (saddle) — on chimneys wider than about 30 inches, a small peaked diverter on the uphill side that splits water around the chimney instead of letting it pond against the brick. Skipped constantly, missed constantly. We install them where the width calls for it.
Material that matches the roof's life — on standard replacements, heavy-gauge aluminum or galvanized steel; on slate and premium jobs, copper or lead-coated copper that lasts as long as the roof it serves.
Our Process: Step by Step
- Inspected with your roof. We check the chimney flashing closely: rust, gaps, failed sealant, water stains on the attic side of the chase, and the mortar condition itself.
- Masonry assessment. Flashing cannot fix a failing chimney. If the brick is spalling or the mortar is shot, we will tell you the chimney needs a mason first — and we will tell you honestly rather than flash over a crumbling chimney.
- Quoted as part of the roof. Chimney flashing is a line item in your written replacement quote — priced by chimney size and condition, no mystery.
- Old flashing out. During tear-off, every piece of old flashing comes off. We see too many "new roofs" with 25-year-old flashing still in place.
- New system installed. Step flashing woven with the new shingles, counter-flashing reglet-cut into the mortar, cricket where needed — all integrated as the roof goes on.
- Water-tested. Before we call it done, the chimney area gets water-tested — because finding a leak with a hose today beats finding it in your living room in March.
What It Costs in Baltimore
As part of a roof replacement, new chimney flashing typically adds $600 to $1,500 per chimney depending on size, condition, and material — standard flashing on the low end, copper or complex multi-flue chimneys higher. As a standalone repair (re-flashing a chimney on an otherwise sound roof), expect $1,000 to $2,500. A cricket adds a few hundred where needed.
Disclaimer: typical ranges for Baltimore-area homes, not quotes. Chimney condition varies enormously — your written quote after inspection is the real number.
When the Chimney Needs a Mason, Not a Roofer
We will be straight with you: if your chimney's brick is spalling (faces popping off), the mortar is deeply deteriorated, or the crown is cracked and failing, new flashing alone will not save it. Those are masonry problems, and flashing over them is money wasted. We will document what we see, explain what a mason needs to do, and coordinate sequencing — masonry first, then our flashing work. A roofer who flashes a crumbling chimney without mentioning the masonry is selling you a future leak.
The Sealant Trap
If a previous roofer or handyman "fixed" your chimney leak with roofing cement or caulk smeared over the joint, you have seen the sealant trap: it holds for a season or two, then cracks, and the leak returns worse. Sealant is not flashing. During replacement we remove all of it and install the real mechanical system. If someone proposes re-caulking your chimney flashing as the fix, get another opinion.
The Crown and Cap: The Top of the System
While we are at your chimney for flashing, we look at the top too — because the crown and cap are part of the same water-management story. The crown is the concrete or mortar slab covering the top of the chimney; when it cracks (and they all crack eventually), water pours directly into the masonry, accelerating the spalling and deterioration that eventually undermines the flashing below. The cap (or rain cover) keeps water and animals out of the flue. A deteriorated crown is a masonry repair — we will flag it and explain what a mason needs to do — but catching it during the roofing job means one coordinated project instead of two separate discoveries. The chimney is a system: flashing at the roofline, sound brick and mortar in the middle, intact crown and cap on top. We assess all of it and tell you plainly which parts need a roofer, which need a mason, and in what order.