If you’ve noticed water stains near your fireplace, a musty smell coming from the chimney, or even rust on your firebox—your chimney could be leaking. And you’re not alone. Chimney leaks are one of the most common problems we deal with here at Mid-Valley Chimney Repair & Sweep, especially in the Cincinnati and Dayton areas where rain, snow, and seasonal temperature swings take a toll.

Let’s break down what causes chimney leaks, what signs to watch out for, and how we go about fixing them to protect your home for the long haul.

Why Is My Chimney Leaking?

Most chimneys aren’t leaking because of a single issue. In many cases, it’s a combination of small problems that build up over time. Here are a few of the usual suspects:

1. No Chimney Cap (or a Broken One)

Think of a chimney cap like a little roof for your chimney. It keeps out rain, snow, animals, and leaves. Without it, water can drop straight into the flue and down into your home. A missing or poorly installed cap is one of the first things we check during an inspection.

2. Cracked Chimney Crown

The crown is the cement layer at the top of your chimney. It’s supposed to push water away from the bricks. But if it’s cracked or poorly built, water gets in and starts seeping down—especially dangerous during freeze-thaw cycles common in Ohio winters.

3. Damaged Flashing

This is the metal seal where your chimney meets the roof. If it’s rusted, bent, or pulling away from the bricks, water sneaks in at the base. Many people mistake flashing leaks for roof leaks!

4. Porous Masonry

Bricks and mortar are like sponges—they absorb water. Over time, this can cause internal damage, cracks, and stains. Older chimneys that haven’t been waterproofed are especially vulnerable.

5. Rusted or Warped Chase Cover

If you have a prefab chimney with a metal chimney chase, the cover on top needs to be watertight. Once it starts rusting, even a small hole can let in gallons of rainwater over time.

Telltale Signs Your Chimney Might Be Leaking

Sometimes it’s obvious—other times it’s subtle. Here are a few red flags to look out for:

• Damp spots on the ceiling or walls near your fireplace
• Musty or moldy smells when it rains
• Dripping sounds from inside the chimney
• Water in the firebox
• Rust on fireplace components
• Crumbling mortar or stained brick on the outside

If anything on that list sounds familiar, it’s worth getting a professional to take a look.

How We Fix Chimney Leaks (The Right Way)

When homeowners call us about a chimney leak, we don’t just slap on a sealant and call it good. We take the time to find the source of the leak, assess any damage, and put together a plan that fixes the problem long-term—not just for this season, but for years to come.

Here’s what that looks like in practice:

Step 1: Full Inspection

We’ll check every potential leak point—starting at the top with the cap and crown, down through the flashing, bricks, and mortar. We’ll even check your attic if needed. This helps us find the actual entry point of water (not just where it’s showing up).

Step 2: Chimney Cap Replacement

If you don’t have a cap or yours is broken, we’ll install a custom-fit cap that keeps out moisture, animals, and debris. We use rust-resistant materials that are built to handle Midwest weather.

Step 3: Crown Repair or Rebuild

If the crown has cracks, we can patch them with a special sealant. In more serious cases, we’ll rebuild the entire crown using quality materials and the correct slope to push water away from your chimney.

Step 4: Flashing Repair or Replacement

If your flashing is the issue, we’ll remove the old metal and install new flashing, sealing it tightly to both the chimney and the roof with high-performance materials that resist rust and movement.

Step 5: Waterproofing the Masonry

We apply a breathable waterproofing agent to your chimney’s exterior. This keeps moisture out while still letting the bricks “breathe,” so you don’t end up trapping water inside.

Step 6: Chase Cover Installation

For prefab systems, we’ll replace any rusted or warped chase covers with custom-fabricated ones that fit perfectly and redirect water the way they should.

Why Acting Fast Matters

Chimney leaks don’t just go away on their own—and even a small drip can lead to bigger problems like mold, rotting wood, or structural damage if left unchecked. The sooner you take care of it, the easier (and cheaper) the fix.

At Mid-Valley Chimney Repair & Sweep, we treat every home like it’s our own. Whether you’re dealing with an active leak or just want peace of mind before the rainy season hits, we’re here to help.

Give us a call at 513-727-0994 or request a free estimate online. We’ll inspect your chimney, explain exactly what’s going on, and give you a clear plan to fix it—no fluff, no runaround.