Why Your Roof Is Leaking Around the Chimney

ByBenjamin Compas

The chimney is one of the most common “trouble spots” on any residential roof. While a well-built chimney adds character and warmth to your home, it also creates a massive structural “interruption” in your roofing system. Because the chimney is a vertical structure piercing through a sloped roof, it is constantly battling gravity and water runoff.

At Emerald Roofing Group, when a homeowner calls us about a leak, the chimney is often the first place we look. If you notice water stains on the ceiling near your fireplace or hear a faint dripping sound inside the wall behind your hearth, you are likely dealing with a chimney-specific roofing failure.

In this guide, we will explore the four primary reasons why chimneys leak and why a simple bucket of roofing cement is rarely the permanent fix.

1. Failed or Improperly Installed Flashing

Flashing is the thin metal (usually aluminum, copper, or galvanized steel) that bridges the gap between your shingles and the brick of your chimney.

On a standard chimney, there are actually two layers of metal working together:

  • Step Flashing: L-shaped pieces of metal that weave into the shingle layers.
  • Counter-Flashing: Metal that is tucked into the mortar joints of the brick and folds down over the step flashing.

The Problem: Over time, the sealant between the metal and the brick dries out and cracks. Furthermore, if a previous contractor used one solid piece of metal instead of individual “steps,” the house’s natural expansion and contraction will eventually tear the metal or pull it away from the brick, creating a direct path for water.

2. The Missing “Chimney Cricket”

If your chimney is wider than 30 inches, it acts like a dam on your roof. When heavy rain flows down your roof and hits the back of a wide chimney, the water pools and sits there.

The Solution: A “cricket” is a small, peaked structure built behind the chimney to divert water to either side. Many older homes were built without them. Without a cricket, water sits against the chimney’s back wall, eventually soaking through the shingles and underlayment. At Emerald Roofing Group, we often recommend installing a cricket during a roof replacement to prevent future leaks in these high-volume water areas.

3. Deteriorated Mortar Joints (Repointing Needed)

Sometimes, the leak isn’t the “roof’s” fault at all, it’s the masonry. Brick is porous, and the mortar joints holding those bricks together can crack due to “freeze-thaw” cycles.

When it rains, the brick and mortar absorb water. If the mortar is failing, the water can travel through the brickwork and emerge inside your house, appearing as a roof leak. If you see “efflorescence” (white, powdery salt stains) on your chimney bricks inside the attic, your masonry is likely the culprit.

4. Cracked Chimney Crowns and Caps

The “crown” is the concrete slab at the very top of your chimney. Its job is to shed water away from the bricks. Because the crown is exposed to the harshest sun and wind, it often develops cracks.

If the crown is cracked, water can seep down into the center of the chimney structure, eventually showing up on your ceiling or even damaging your fireplace liner. Similarly, a missing chimney cap (the metal “hat” over the flue) allows rain to fall directly down the hole and into your home.

The Danger of the “Quick Fix”

We often see homeowners (or inexperienced handymen) try to fix a chimney leak by slathering a thick layer of black roofing tar around the base.

Expert Warning: Roofing tar is a temporary patch, not a repair. As the tar bakes in the sun, it gets brittle and cracks. Even worse, it can trap moisture against the wood of your roof deck, leading to rot that you won’t see until it’s too late.

The only “true” fix for a flashing leak is to remove the old metal, inspect the wood underneath, and install new, custom-bent flashing with high-grade architectural sealant.

How Emerald Roofing Group Solves Chimney Leaks

A chimney leak requires a specialized approach that combines masonry knowledge with roofing expertise. Our process includes:

  • Water Testing: If the source isn’t obvious, we carefully simulate rain to find exactly where the water is entering.
  • Precision Flashing: We use high-quality metal and “kicked-out” flashing to ensure water is directed away from the house, not into it.
  • System Integrity: We check the surrounding shingles and underlayment to ensure the leak hasn’t caused hidden rot in the roof deck.

Protect Your Hearth and Home

A leaking chimney can lead to ruined drywall, mold in your attic, and even structural damage to your home’s framing. Don’t wait for the next big storm to address it.

Is your fireplace showing signs of water damage? Contact Emerald Roofing Group today for a comprehensive chimney and roof inspection. We’ll find the leak and fix it right the first time.