Diagnosing chimney leaks

Spring brings a lot of things: Warmer weather, sunny skies, thunderstorms and flowers. It also can bring on some home maintenance problems, including chimney leaks.

If water is making its way into your chimney, there are some signs that could tip you off. Water pooling in your firebox is a certain sign that water is making its way into your chimney, as are rusting dampers, fire grates or fireplace doors. On the interior of your home, a leaking chimney could mean pealing or discolored wallpaper, stained ceilings or sagging ceilings or wallboard. On the exterior of your chimney, white staining on the masonry indicates that water is seeping in.

If you see signs of leaking chimney in your fireplace, in your home or on the exterior of your chimney, you’ll need to call a chimney professional. Unchecked water leaks can cause major and expensive problems with your chimney or your home’s structure. You’ll need a professional to identify the source of the leak and recommend a course of repairs.

When examining your chimney for the source of a water leak, there are several common culprits your chimney sweep will inspect.

Diagnosing chimney leaks - Indianapolis IN - Your Chimney SweepChimney cap

Your chimney cap is your chimney’s primary defense against leaks. The chimney cap covers the opening at the top of your chimney to prevent water from running down the interior walls of your flue. If that cap is missing, damaged or dislodged, water can run unchecked into your chimney and fireplace, causing water damage to the flue and firebox.

Chimney crown or chase cover

On a masonry chimney, the chimney crown is the concrete portion that surrounds the chimney opening. It slants away from the flue to direct water outward, and it should overhang the exterior edges of the chimney to help protect the chimney from rainwater. On a prefabricated chimney, a metal chase cover serves the same purpose. Both the chimney crown and the chase cover can develop cracks over time that can allow water to leak into the chimney.


At the base of the chimney, where the chimney meets your roof, the chimney is surrounded by metal flashing. The flashing seals the gap between the chimney and the roof, preventing water from damaging your roof or the interior wooden supports of your roofline. Improperly installed flashing or corroded flashing can cause major water leaks around your chimney that can cause major damage to your home’s structure.

Bricks and mortar are incredibly porous, and they readily absorb moisture. That can cause cracks in the chimney and weaken the chimney structure over time, and weakness in the chimney’s masonry can cause more moisture to get into the interior of the chimney and cause more extensive damage.

If you’ve noticed signs of a water leak around your chimney, call Your Chimney Sweep to schedule an appointment today! We’ll help diagnose your chimney leak and help you find the best way to repair it, before the leak causes more damage to your chimney or your home.

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