How to Repair a Chimney: A Detailed Guide

July 1, 2024
Avatar for Shakil AhmedShakil Ahmed
How to Repair a Chimney A Detailed Guide

Imagine it’s a cold evening, and you’re looking forward to sitting by a warm, crackling fire. But when you light your fireplace, smoke fills your living room instead of going outside. How to repair a chimney becomes an important question then. A good chimney is necessary for safely enjoying your fireplace.

To put it simply, to repair a chimney, clean it first, then fix any cracks or broken parts with new mortar or sealant. As for the metal chimneys, remove rust and secure loose flashing.

Here’s What You’ll Learn

  • Know about the signs that show your chimney needs repair, 
  • common problems with different types of chimneys, 
  • easy steps to fix them, 
  • and tips to keep your chimney in good condition.

Uh-Oh, My Chimney Needs Help? Signs You Shouldn’t Ignore

It’s important to check your chimney regularly for signs of damage. Here are some signs that your chimney might need repair:

  • Missing Mortar: Mortar is the stuff that holds your chimney bricks together. If it’s crumbling or missing in big chunks, you need to fix it.
  • Cracks in the Chimney: Look for cracks in the bricks or mortar.
  • Damaged Chimney Crown: The top part of the chimney, called the crown, can crack and let water in.
  • Rust: If you have a metal pipe inside your chimney (called a flue liner), rust can weaken it and make it dangerous. Plus, rust on the damper or firebox indicates moisture problems. 
  • Water Stains: Water stains inside or outside your house near the chimney are a big warning. It means water is getting in somewhere, and you need to stop it.
  • Efflorescence: This is a white stain on the bricks, which shows there’s too much moisture.
  • Deteriorating Mortar Joints: The mortar between the bricks can wear away.
  • Spalling Bricks: Bricks that are flaking or crumbling.
  • Chimney Leaks: Water leaks inside your house around the chimney.
  • Smoke Problems: Smoke is not venting properly and coming back into the house.
  • Animal Guests: Birds, squirrels, or raccoons might move into your chimney. This is not good!
  • Loose or Missing Flashing: Flashing is the metal that seals the roof where it meets the chimney. If it’s loose, missing, or rusty, water can get in and cause damage.
  • Lopsided Chimney Cap: The cap on your chimney keeps rain, animals, and debris out. If it’s tilted or broken, it can’t do its job properly.

Want to learn, “How often should a chimney be cleaned?” Visit our informative blog to learn.

How to Repair a Chimney

How to Repair a Chimney

There are two main types of chimneys: masonry chimneys (made of bricks or stones) and metal chimneys. Each type has its own common problems and repair methods.

Masonry Chimneys

Below are some common problems you can face.

  • Cracked Bricks or Mortar.
  • Damaged Chimney Crown.
  • Spalling Bricks.

How to Repair:

Cracked Bricks or Mortar:

  • Use a hammer and chisel to remove the cracked or broken mortar.
  • Mix new mortar and fill in the gaps.
  • If a brick is broken, take it out and put in a new one using fresh mortar.

Damaged Chimney Crown:

  • Clean the crown and apply a special high-heat sealant to small cracks.
  • For bigger cracks, remove the damaged part and apply new concrete to make a new crown.

Spalling Bricks:

  • Take out the bricks that are flaking or crumbling.
  • Put in new bricks and secure them with mortar.

Metal Chimneys

Below are some common problems you can face.

  • Rust issues.
  • Loose flashing.
  • Chimney cap issue.

How to Repair:


  • Use a wire brush to clean off the rust.
  • Apply rust-resistant paint or sealant to protect the metal.
  • If you find rust on the flue liner, this can be a serious issue. It’s best to call a professional chimney sweep to inspect and recommend repairs or replacements.

Loose Flashing:

  • Use roofing cement to secure the flashing back in place.
  • Apply a sealant around the edges to stop water from leaking in.

Chimney Cap Issue:

To repair a chimney cap, clean it thoroughly and apply sealant to small cracks. For larger damage, replace the cap.

Do you know why your chimney is pulling away from your house? Check out our blog to learn.

In General, What are the Steps to Fix up a Chimney?

What are the Steps to Fix up a Chimney?

Here’s a step-by-step guide to get your chimney back in top shape:

Step 1: Safety First!

  • Clear the Area: Move anything near the chimney that could catch fire.
  • Protect Yourself: Wear gloves, safety glasses, and a dust mask.

Step 2: Check for Problems

  • Inspect Carefully: Look at the top of the chimney and the bricks for cracks or water marks.
  • Tap Gently: Use a hammer to tap the bricks gently. A hollow sound means loose mortar.

Step 3: Get Your Tools

You’ll need:

  • Cloth to catch debris
  • Brush for cleaning
  • Hammer and chisel
  • Trowel for mortar
  • Bucket
  • Heat-resistant sealant
  • Mortar mix

Step 4: Prepare Your Work Area

  • Cover the Floor: Put down a cloth to catch any mess.
  • Block the Chimney: Use a wet rag or paper to stop debris from falling inside.

Step 5: Fix Cracks (if any)

  • Clean Cracks: Use the brush to clear loose bits.
  • Make Cracks Bigger: If needed, use the hammer and chisel.
  • Fill with Sealant: Apply sealant to fill cracks, following the manufacturer’s instructions.

Step 6: Fill Mortar (if needed)

  • Remove Old Mortar: Use the hammer and chisel to clear away old, loose bits.
  • Clean the joints: Brush away any dust or debris from the empty joints.
  • Mix New Mortar: Follow package instructions to mix mortar in the bucket.
  • Fill Gaps: Use the trowel to press mortar into gaps between bricks.
  • Smooth It: Use the trowel to make it neat.

Step 7: Clean Up

  • Let It Dry: Wait for everything to dry completely.
  • Remove Coverings: Take away the cloth and chimney block.
  • Throw Away Trash: Bag up leftover stuff and throw it away.

Step 8: Call for Help

If there’s lots of damage or rust on the inside, it’s better to get a chimney expert to help. They know how to fix big problems safely.

Check out our insightful blog to learn how to fix a chimney flashing leak.

How Much Does It Cost to Repair a Chimney?

How Much Does It Cost to Repair a Chimney?

Chimney repairs usually cost about $700, but the price can change depending on the type of repair, your chimney’s materials, and age. Rebuilding a chimney can cost between $8,000 and $10,000.

There are four types of chimneys: brick, stucco, metal, and prefabricated. Fixing a brick chimney costs between $300 and $1,500 while fixing a prefab chimney costs between $250 and $1,200.

Learn why your chimney is leaking and how to repair a leaking chimney.

How to Keep Chimneys in Good Condition

Keeping your chimney in good shape is important. Here are some easy tips:

Get it Swept Yearly

Hire a professional chimney sweep once a year to remove soot and debris that can cause fires.

Cover it Up

When you’re not using your fireplace, use a chimney cap to keep out rain, snow, and animals.

Burn the Right Stuff

Only burn dry, seasoned firewood. Wet or trash wood creates more creosote (a sticky black substance), which can cause chimney fires.

Check this blog to learn how to remove creosote from the chimney.

Clean the Chimney

Have a professional clean your chimney once a year to remove soot and creosote.

Install a Chimney Cap

This helps keep out rain, snow, and animals. 

Check out our informative blog to learn how to stop rain noise on the chimney cap.


Apply a waterproof sealant to the outside of your chimney to protect it from moisture.

Check Flashing

Make sure the metal flashing around the base of the chimney is secure and in good condition.

Repair Quickly

Fix any small problems as soon as you notice them to prevent bigger, more expensive issues.

Want to learn how to get rid of bees in the chimney? Check out our informative blog to learn.

Contact Air Duct Now for the Premium-level Chimney Repair & Cleaning Service

Reach out to Air Duct Now for the best chimney repair and cleaning in Los Angeles. We inspect, repair, and clean chimneys to keep your home safe and warm. 

Our skilled team makes sure your chimney is clean and works well. We offer low prices, quick service, and a satisfaction guarantee. 

Call us today to book your inspection!

Wrapping Up

Hopefully, you’ve got a pretty good idea of how to repair a chimney. Watch for warning signs and follow these easy tips to keep your chimney in great shape for years. If you don’t feel comfortable fixing it yourself, call a professional chimney sweep. They are experts and will make sure your chimney is safe and in good condition.

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