8 Ways on How to Repair a Leaking Chimney

July 7, 2024
Avatar for Shakil AhmedShakil Ahmed
8 Ways on How to Repair a Leaking Chimney

Picture this: It’s raining outside, and you see water dripping down from your fireplace. A leaky chimney can let in water that can damage your roof and walls. 

Dealing with this trouble can be annoying, but knowing how to repair a leaking chimney can save you a lot of trouble. The good news is that you can fix this with a little know-how.

Simply put, to repair a leaking chimney, —

  • find where water enters, 
  • seal cracks, 
  • and replace damaged parts like flashing or caps. 

Let’s go through how water gets into your chimney, signs that show you have a leak and easy ways to fix it for good.

How Does Water Get In There Anyway?

Chimneys are like tunnels that carry smoke out of your house. But if they’re not looked after, they can let water in, too. Here’s how:

Cracks and Gaps

As chimneys get older, the mortar between the bricks can wear away. This creates holes where water can sneak in.

Faulty Flashing

Around the bottom of the chimney, where it meets the roof, there’s usually metal called flashing. If this metal gets damaged or isn’t put in right, water can get through.

Chimney Crown Issues

At the very top of the chimney, there’s something called a crown. If it gets cracks or isn’t sealed well, water can seep through.

Damaged Chimney Cap

Imagine a lid on top of the chimney that stops rain from going straight in. If this lid is broken or missing, water can easily get into your chimney.


Inside the chimney, the walls can get wet from moisture. Over time, this moisture can build up and cause leaks if it’s not managed properly.

How to Identify Leaking Issues

How to Identify Leaking Issues

Here’s what to look out for:

  • Water Stains: If you see dark streaks or brown spots on your chimney walls or ceiling, it means water is getting in.
  • Crumbling Mortar: When the stuff holding the bricks together (called mortar) starts to crumble or look powdery, it’s a weak spot where water can easily come in.
  • Musty Odors: A damp chimney can grow mold and mildew, which can make your chimney smell musty.
  • Peeling Paint: If the paint around your chimney starts to peel or bubble, it’s probably because of water damage.

Sometimes, you only notice leaks when it’s raining hard or after snow melts. So, it’s really important to fix leaks quickly to stop more damage to your house and chimney.

Ways on How to Repair a Leaking Chimney

Now that you know the enemy, here’s how to repair a leaking chimney stack:

Safety First!

Chimney repairs can be risky. If you’re not comfortable working on a roof, call a professional chimney sweep or roofer.

Inspect Thoroughly

Look closely at your chimney for cracks, holes, or broken metal around the bottom (flashing). If you can’t see well, use binoculars to check the top part (crown) and the lid (cap) from the ground.

Repair Cracks and Holes

If you find small cracks, use a special putty to fill them. For bigger holes, it’s best to get help from a professional who knows about fixing bricks.

Replace Flashing

If the metal around your chimney bottom is broken, here’s how to find and repair a leak in the chimney flashing:

  • Spot the Leak: Look for water stains inside or outside near the chimney base.
  • Inspect the Flashing: Check for loose or damaged metal around the chimney and roof joint.
  • Get New Metal: Replace the broken metal with new pieces that fit snugly against the chimney and roof.
  • Use Cement and Nails: Secure the new metal with special cement and nails to keep it in place.
  • Reseal the Shingles: Make sure the shingles on your roof are sealed tightly around the metal to stop water from getting in.

Remember, stay safe! If it seems tricky, it’s okay to ask a professional for help.

Seal the Chimney Top

To seal the top of your chimney, you can use tape around the edges for neat lines. For paste sealant, use a caulking gun or trowel to fill cracks and smooth them out. 

For liquid sealant, brush it on, covering everything and adding extra layers if needed. Make sure the whole top is sealed well.

Take off the tape before the sealant dries, clean any extra sealant off the bricks, and let it dry completely.

Check out our insightful blog to learn how to repair a chimney crown.

Install or Replace the Chimney Lid

Install or Replace the Chimney Lid

If your chimney’s lid is missing or broken, put on a new one. This stops rain from going straight into the chimney.

To pick the right chimney cap, measure the top opening to get the correct size. It should cover the opening but still let air flow (usually 1-3 inches of space between the top of the flue and the cap). When working on the roof, use a strong ladder, wear safety gear, and have someone with you. 

Follow the instructions to attach the cap using bands or screws. For extra protection, apply a high-temperature sealant around the base of the cap where it meets the chimney.

Check Inside Walls

To fix wet walls inside your chimney, first check for water stains, peeling paint, or crumbling mortar. These show moisture problems. You can improve airflow by getting a professional to clean the chimney and check the liner for damage. 

The liner might need fixing or replacing to help airflow and stop moisture. Make sure the room is well-ventilated by opening a window a little when using the fireplace, and don’t burn wet wood. 

Because fixing wet chimney walls can be tricky, it’s best to ask a professional for help.

Get a Professional Check

Once a year, think about asking a chimney expert to look at your chimney. They can find new problems early and help keep your chimney working well.

Interested in learning how often to clean your chimney? Visit our helpful blog to learn more.

Leak Prevention is Super Important!

Leak Prevention is Super Important!

The best way to stop leaks is to prevent them! Here’s how:

  • Regular Inspections: Have a professional check your chimney every year, especially before it gets cold and rainy.
  • Trim Trees: Cut back branches hanging over your chimney. They can trap leaves and debris, which can cause leaks.
  • Use waterproof sealants: Put waterproof products on the outside of your chimney to keep moisture out.
  • Monitor interior conditions: Check inside walls for any signs of moisture or mold.
  • Keep Gutters Clean: Clogged gutters and downspouts can make water spill over and gather around your chimney. This can cause leaks and water damage. Clean your gutters often to stop this from happening.
  • Watch Humidity: Keep an eye on humidity levels inside your home and use a dehumidifier if needed to keep them in check.
  • Do Regular Maintenance: Clean and maintain your chimney regularly to prevent leaks and keep it working well.

Want to learn why your chimney is pulling away from your house? Check out our blog to find out why.

How Much Does It Cost to Repair a Leaking Chimney?

Fixing a leaking chimney usually costs between $150 and $350 for fixing water leaks and chimney tops. Prices can change depending on how bad it is and where it’s happening. 

Using extra waterproofing treatments might make it cost more. Sometimes, leaks might actually start from the roof, which can change how much it costs to fix.

Why You Need Professional Chimney Leak Repair

Chimney leaks can cause big problems like water damage and mold. They can even harm the chimney itself, causing cracks and other issues that make it less safe. 

Here’s why getting professional help is important:

  • Pros know how to find where the leak is coming from and how to fix it.
  • Fixing chimneys can be risky without the right training. Pros have the tools and know-how to do repairs safely.
  • They use special equipment to make sure repairs are done well. This helps prevent more damage and future leaks.
  • They follow safety rules to keep accidents from happening.
  • When pros do the job, it often comes with a guarantee. If there’s a problem later, they’ll fix it without extra cost.

Wrapping Up

Hopefully, you now have at least a pretty good idea of how to repair a leaking chimney. By following these tips, you can keep your chimney leak-free and protect your home from water damage. But remember, if the job seems too daunting, don’t hesitate to call a professional for help!

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