Chimney Leaks: A Deerfield Customer Asks — Is It a Roof Leak or a Chimney Leak?

Last week, a homeowner near Deerfield’s Wilmot Road called us with a familiar problem. A brown stain had spread across her ceiling, right next to the fireplace. Her first thought was a roof leak. But was it really the roof? Or was her chimney the true culprit?

This mix-up happens all the time. Chimneys and roofs sit right next to each other. So water damage near one often gets blamed on the other. At Chimney Monkey, we inspect this exact issue for homeowners across Buffalo Grove, Deerfield, and the rest of the Northshore every week. Here’s how you can tell the difference — and what to do next.

Why Chimney Leaks and Roof Leaks Look So Similar

Both problems show up the same way. You’ll usually notice:

• Brown or yellow ceiling stains near the fireplace
• Damp drywall or peeling paint on walls beside the chimney
• A musty smell in the room after it rains
• Water dripping directly from the firebox or damper

Because the symptoms overlap, guessing isn’t a reliable strategy. Fortunately, the location of the damage usually points to the real source.

Signs That Point to a Chimney Leak

If the stain sits directly around the chimney chase, and not spread across the wider ceiling, your chimney is the likely source. Chimney leaks commonly come from one of four places.

• Cracked chimney crown. The crown is the concrete cap that seals the top of the chimney. Chicago winters cause it to crack and let water seep straight down into the flue.
• Damaged flashing. Flashing is the metal seal where the chimney meets the roofline. If it’s rusted, loose, or was installed poorly, water sneaks underneath it during every rainstorm.
• Missing or damaged chimney cap. Without a proper cap, rain falls directly into the open flue. This is one of the most common issues we find on older Deerfield and Highland Park homes.
• Deteriorated mortar joints. Brick and mortar are porous. Over time, they absorb water like a sponge, especially where winter freeze-thaw cycles have already caused small cracks.

Signs That Point to a Roof Leak Instead

Sometimes the chimney is innocent. A roof leak is more likely if you notice:

• Staining spread across a wider section of ceiling, not just near the chimney
• Water stains that appear near skylights, vents, or valleys elsewhere on the roof
• Missing or curling shingles visible from the ground
• Leaks that worsen specifically during heavy wind-driven rain, not steady rain

A roof leak often travels along rafters before it shows up on your ceiling. That means the wet spot inside your home isn’t always directly below the actual leak outside.

How Professionals Tell the Difference

At Chimney Monkey, we don’t guess. Our technicians perform a full exterior inspection of the chimney crown, cap, flashing, and mortar joints. We also check the attic space around the chimney chase for water trails, since these often reveal exactly where water is entering.

In many cases, a simple water test — applying water in stages from the roofline down to the chimney base — pinpoints the exact entry point within minutes.

What Deerfield Homeowners Should Do Next

If you notice water stains near your fireplace or chimney, don’t wait. Small chimney leaks turn into expensive problems fast. Left untreated, they can damage the damper, rust the firebox, and even crack interior walls.

Here’s what we recommend:

1. Take a photo of the stain and note when it appears (during rain, snowmelt, or wind).
2. Check your attic, if it’s accessible, for visible moisture near the chimney chase.
3. Schedule an inspection before your next rainstorm, not after.

How Much Does It Cost to Fix a Chimney Leak?

Costs vary depending on the cause. A new chimney cap is typically the most affordable fix. Flashing repair and crown resealing cost more, since they require careful sealing work to prevent future leaks. A full inspection from Chimney Monkey will give you an exact quote before any work begins.

Can I Wait Until Spring or Summer to Fix It?

We don’t recommend it. Water that enters through a cracked crown or damaged flashing freezes and expands during Chicago winters. That freeze-thaw cycle widens existing cracks every season, turning a small repair into a full rebuild. The sooner it’s addressed, the less it usually costs.

Serving Deerfield and the Northshore

Chimney Monkey brings expert care straight to your doorstep from our home base in Buffalo Grove. We proudly serve Lake and Cook Counties—including Deerfield, Highland Park, Northbrook, Lincolnshire, Wheeling, and all of our neighboring communities just a short drive away.

If you’re staring at a mystery stain near your fireplace, don’t leave it to guesswork. Contact Chimney Monkey today for a full chimney and flashing inspection, and get a clear answer on whether your leak is coming from the roof or the chimney.