Chimney Foundation: 6 WARNING Signs Homeowners Can’t Ignore

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Masonry chimneys are huge structures weighing up to 30,000 pounds. A chimney foundation is a thick slab of concrete that supports a chimney. But things start to go wrong when the foundation is not done correctly.

Your chimney foundation is important for the structural integrity of your chimney. Without a proper foundation or footing, your chimney will crack and eventually fall to the ground. Not only does this put your whole house at risk but also your loved ones.

That is why it is important to know the various signs of a damaged chimney foundation so that if it is compromised, you can take action before it’s too late.

What Is a Chimney Foundation?

Your chimney rests on a 12″ (minimum) slab of concrete or solid masonry, called a chimney foundation.

For most houses, the foundation for the house and its chimney are poured simultaneously. But sometimes, it is built separately, making the chimney foundation (chimney footing) vulnerable.

Add to that the immense weight of a brick chimney concentrated on a single spot, and you’ve got a recipe for disaster.

Signs Your Chimney Foundation Needs Repair

If you notice a slight tilt in your chimney or if there is a visible gap between your chimney and your house, that means that a foundation problem is lurking below.

There are other signs as well, but homeowners usually don’t worry about their chimneys unless the damage is obvious and hindering the normal operation of their chimneys. Sadly, that happens when significant damage has already taken place.

A chimney’s foundation supports the entire chimney. Any problem with the foundation could result in the chimney falling off. That’s why any damage to the foundation needs to be diagnosed before it is too late. Once diagnosed, it should be fixed immediately to prevent serious damage and safety risks.

Here are the most common signs of a chimney foundation problem that you need to look out for: 

Tilting Chimney

If you notice a slight lean at the top of your chimney, that means it is tilting. A chimney tilting away from your home means something’s wrong with your foundation. The lean look unpleasant and is dangerous for your house’s structural integrity and your loved ones’ safety.

Exterior and Interior Cracks

When a chimney pulls away from your home due to a damaged footing, it cracks various areas inside your home and chimney. So, you may have a foundation problem if you notice cracks on the:

  • Chimney masonry
  • walls near your chimney
  • ceiling
  • flooring e.g. broken tiles
  • fireplace walls, etc.

Chimney Foundation Leak

A damaged foundation causes the chimney to separate from your home, leaving a gap between your home and the chimney. This gap exposes the chimney to environmental elements and water damage. You’ll notice chimney leaks and mold growth where the gap is located.

Caulking in the Gap

Some homeowners add caulking or some other material to fill the gap created by a leaning chimney. However, this is a temporary fix to a much larger problem.

If you are looking for a new home, beware of caulking between your house and the chimney. This would mean that you’re buying a house with a chimney foundation problem.

If that’s the case, you can either look for another home or try to negotiate a fair price. The new rice should compensate for the extra cost of fixing the chimney foundation and the resulting damage.

Roof Damage

A leaning chimney can also result in roof damage. So, look out for damaged shingles or broken gutters near your chimney. In certain cases, parts of your roof may start to fall off.

Smoke Problem

A damaged foundation causes a tilt in your chimney. This can damage various parts inside your chimney, including the chimney liner. When you ignite a fire in a chimney with a damaged chimney liner (flue), the outside air pushes the smoke back inside, causing chimney smoke problems that can cause various respiratory issues.


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Most Common Causes of Chimney Foundation Damage

A chimney foundation can be damaged due to various reasons. Once a chimney expert knows what caused the damage, he can provide a viable solution. Here are some of the most common causes of chimney foundation damage:

Poor Soil Conditions

If your chimney foundation is laid on expansive soil, the ground below your chimney foundation shifts. This causes your chimney to lean away from your house. A similar scenario occurs with loose soil. Soil erosion is another factor that plays a detrimental role.

Poor Drainage

Poor drainage, such as leaking pipes, can create moisture build-up below the chimney. The water collected as a result puts immense pressure on your chimney foundation. If left unchecked, the water pressure creates tiny cracks in the foundation that expand as time passes.

The cracks allow more water to penetrate the foundation and weaken its structure. Once weakened, the foundation becomes incapable of bearing a huge load of a brick chimney. If the drainage problem is not fixed and the foundation is not repaired, your chimney could start to crumble.

Improper Installation or Repair

Sometimes contractors do not follow proper installation methods, resulting in future chimney damage.

For example, you need to compact the soil before pouring the concrete. Contractors do this by using Padfoot and tamping foot rollers or pneumatic rollers. Sometimes even the soil is replaced with one that is more stable.

When contractors don’t treat the soil and make it compact, the chimney footing starts to crack, and the chimney begins to crumble within a few years.

Undersized Footing 

A small foundation or one that does not follow the state standards is likely to cause issues.

That is why it is essential to design and construct a chimney foundation according to your set standards and dimensions. Standard practice is constructing a foundation at least 6 in. extended on all sides. 

Low-Grade Raw Materials

Your chimney foundation is what gives it stability and holds it in place. Since it is responsible for holding such a huge and heavy structure, it is important to construct it properly and use only top-grade materials.

Some contractors use low-grade materials to cut costs. This reduces the strength and the life of the footing.

Sulfur Damage

If your chimney has a tilt at the top, it is probably suffering from damage caused by sulfuric acid.

Appliances that run on oil discharge water vapors mixed with oil. This oil-infused water condenses into sulfuric acid. Since sulfuric acid is corrosive, it damages the top of your chimney.

A chimney flue liner is the only solution to sulfur damage.

Wear & Tear

Sometimes the lean in your chimney is not caused by a single factor but by multiple issues. The aging of a chimney and natural wear and tear can take a significant toll on your chimney and result in a tilt.

However, the degradation of your chimney and its parts can be delayed. Through regular cleaning, maintenance, and inspection by a professional chimney sweep, you can increase the lifespan of your chimney.


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Natural Foundation Settling

Like everything else, a chimney foundation is constructed with proper design and top-grade materials. Eventually, there comes a time when your chimney foundation begins to shift and sink, causing your chimney to lean.

Chimney Foundation Repair Cost

If your chimney is leaning because of a damaged foundation, expect to pay around $1,500 – $4,000. The actual price may vary based on various factors including:

  • The extent of damage
  • Type of repair
  • Chimney design and dimensions
  • Locality
  • Whether additional repairs are needed

Usually, helical piers are installed to support the damaged chimney foundation. Two helical piers are installed on each side and one at the back. The average cost of a single helical pier is around $1,000 – $2,000.

Slabjacking is another method to fix a damaged chimney footing that costs around $1500 to $2000.

The Takeaway

A chimney foundation supports the immense weight of a chimney. If the foundation is compromised, the chimney begins to lean and crumble. This is a dangerous and safety risk for you and your loved ones.

That is why it is important to keep an eye out for signs of a chimney foundation problem, such as:

  • Leaning chimney
  • Cracked masonry
  • Smoke problem
  • Damaged chimney roof
  • Caulking in the gap between your chimney and house

If you notice any of these signs, call a chimney expert to inspect your chimney, diagnose the cause of the chimney foundation damage, and provide the best possible solution.


Do chimney foundation problems affect appraisal?

Chimney foundation problems have a negative impact on appraisal. A house with a damaged chimney and cracked foundation will sell at a price much lower than the market value.

Does fixing your chimney foundation increase home value?

A damaged chimney foundation will lower the price of your house which is why if you have a damaged chimney footing, get it fixed before you set your house on sale. This improves the market value of your house.

Is chimney foundation repair tax deductible?

A chimney foundation repair is not tax deductible. That is because home repairs and fixes are not tax deductible. However, if you upgrade a part of your rental property, you can claim a tax deduction.

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Thomas Green

Thomas has worked in the Chimney & Fireplace field for over 12 years. He is an expert in his trade and loves to help People with their needs. Thomas Write helpful articles so that homeowners can make the most informed decisions about their fireplace and chimney.