It's interesting, when you think about it, just how many unsung heroes exist in our homes. Our properties are full of features and contraptions that quietly keep us safe, warm, and secure, without even realising they are there.

Chimney liners are a great example of this. Hidden out of view, rarely do we give any thought to how important chimney liners are as they quietly and diligently make sure our homes are free from the byproducts of combustion, toxic gases, and excessive heat.

If that’s not enough reason to appreciate their importance, chimney liners also protect our chimneys from unwanted damage caused by relentless heat, moisture, and corrosives. They are an important but invisible feature of our homes.


  • Identify Issues early: Be vigilant for signs like excessive smoke and creosote buildup, indicating potential chimney liner problems.
  • Regular Maintenance: Schedule annual inspections and cleanings to ensure chimney liner integrity and efficient operation.
  • Material Quality: Choose HETAS-approved, double-skinned stainless steel liners for durability and safety.
  • Proper Sizing: Select the correct liner size to match your chimney dimensions for optimal airflow and productivity.

Commonly Overlooked

However, to maintain the safety of your home, it's important to keep your chimney liner in good working condition. While it is certainly not something you need to worry about, it is one aspect of property maintenance and upkeep that you should keep an eye on from time to time. Do so, and your home will simply function better.

Through this guide, we shall look at how to do just that, as we consider the common issues with chimney liners and their obvious warning signs.

These warning signs are only obvious if you know what to look for, however, and by the end of this quick guide, you shall. We will also look into the reasons behind potential problems before offering practical and helpful solutions.

In no particular order, let's take a look.

  1. Corrosion Issues in Chimney Liners

Corrosion in chimney liners is commonly born out of constant exposure to corrosive flue gases produced during combustion. These aggressive gases interact with the construction materials of a weaker chimney liner, causing gradual wear and possible property damage.

This corrosion varies in severity, type, and impact on the chimney walls in the form of the following:

Galvanic Corrosion

This particular form of corrosion transpires if your chimney liner consists of different metals. In galvanic corrosion, when two dissimilar metals are in contact (in the presence of an electrolyte, such as moisture), a natural electrochemical reaction takes place. This reaction eventually leads to the slow deterioration of the more reactive metal.

Acidic Corrosion

Common in many households, acidic corrosion stems mostly from acidic flue gases like sulphur dioxide and nitrogen oxides, which, when mixed with moisture, produce acidic compounds that wear down some liner materials - especially poor quality liners - causing them to thin and pit. Good quality chimney flue liners will last longer at a surprisingly reasonable cost.

Crevice Corrosion

Occurring in the smaller confined spaces of a chimney liner, crevice corrosion is a result of moisture accumulation in these areas. Over time, the persistent moisture leads to material thinning, pitting, and general deterioration, particularly in confined spaces.

Strategies for Preventing and Repairing Corrosion

To effectively prevent and address corrosion in your chimney liner, consider these tips:

  • Choose corrosion-resistant materials, such as stainless steel chimney flue liners.
  • Maintain proper chimney ventilation to reduce the buildup of corrosive gases.
  • Schedule regular chimney inspections to identify early signs of corrosion.
  • Act quickly to repair any issues to avoid further deterioration - overlooking minor corrosion can result in extensive, expensive repairs later.
  • Address any moisture issues to prevent its accumulation and the inevitable corrosion that follows.

  1. Issues with Cracks and Wear in Chimney Liners

While chimney liners do an important job of ensuring safety and productivity, they are susceptible to cracks and general wear. As a home owner, you need to know why these issues develop to stand a chance of preventing them. Let’s take a look at the most common causes:

Impact of High Heat on Chimney Liners

Chimney liners are obviously built to handle high temperatures, although exposure to temperatures above 1000C can create thermal stress, leading to cracks. This is more common in larger, intense fireplaces that are consistently fueled by large heaps of wood or other combustibles.

Effects of Moisture on Chimney Liners

When excess moisture penetrates the chimney liner, it can (and probably will) cause erosion, repeated freeze-thaw cycles, and a general worsening in the quality of the chimney liner materials.

Damage from Corrosive Flue Gases

Flue gases can speed up the wear of chimney liners, especially those that are made from older masonry. These gases will eventually interact with the chimney liner materials, making them even more liable to cracking and weakening.

How Cracks and Gaps Affect Chimney Liners

The presence of cracks and gaps in chimney liners will eventually lead to various problems, including:

  • Increased risk of chimney fires as heat and embers reach nearby flammable materials.
  • Poor ventilation, resulting in dangerous gases (like carbon monoxide) building up indoors.
  • Structural damage due to water infiltration, destabilising the chimney’s strength over time.
  • Poor productivity caused by disrupted airflow.

Strategies for Spotting and Fixing Cracks and Gaps

To detect and mend cracks and gaps in chimney liners, you might want to consider these strategies:

  • Regular Checks: Have a professional team conduct thorough inspections using specialised tools. In cases of significant damage, relining the chimney might be recommended.
  • Flashlight Inspection: Regularly use a flashlight to examine your chimney for any noticeable cracks or openings.
  • Attentive Listening: Be aware of unusual sounds - like debris falling into the firebox - which could indicate structural issues.
  • Productivity Monitoring: Increased indoor smoke or decreased heating productivity can be a sign of cracks affecting proper ventilation.
  1. Creosote Accumulation in Chimney Liners

Being such an extremely sticky tar-like substance, creosote is liable to stubbornly accumulate on the inner surfaces of chimneys due to incomplete combustion. If and when that happens, a very real risk of fire is posed and can actually cause real harm to both your flue liner and chimney's overall structure.

Again, many homeowners possibly do not fully understand the risks associated with creosote or the methods available for repairing chimney liners, as they are out of sight. However, repairs are absolutely vitalfor both the productivity and general safety of your chimney and home.

The solution is simple: choose a good-quality chimney flue liner to negate the chances of creosote becoming a serious safety concern. The right quality chimney liner not only offers much-needed (and commonly overlooked) extra protection but also improves the overall chimney performance.

Excessive buildup of creosote can impact the flue's diameter, obstructing airflow and potentially causing smoke to enter indoor spaces while also hastening the wear of chimney liners, possibly leading to expensive and unnecessary repairs or replacements.

Strategies for Mitigating Creosote Buildup

Apart from the previous suggestion of insisting on a good quality chimney liner, you might also consider these strategies to prevent and eliminate creosote accumulation.

  • Use Seasoned Wood: Burning wood with low moisture content (below 20%), which has been seasoned for 6 to 12 months, results in cleaner combustion and less creosote formation.
  • Schedule Annual Chimney Inspections: Annual inspections of your chimney, preferably before heating seasons begin, should result in early detection and resolution of creosote buildup and related issues.

  • Regular Chimney Cleaning: Hiring chimney professionals for annual cleanings is something you should get into the habit of scheduling. Their expertise not only helps in removing creosote effectively but also in assessing any damage to the flue liner.
  • Employ Effective Burning Methods: If you run higher temperatures when burning your fuel, you will greatly reduce the chances of creosote buildup. Complete combustion is the trick here, and fewer ‘low burn-out’ fires, (a consistently raging fire, in other words).
  • Proper Airflow: A fully open damper is required to provide enough oxygen, supporting better burning and reducing the risk of creosote formation over time.
  1. Addressing Chimney Liner Blockages

Blockages in your chimney liner, which naturally hinder the fluid movement of smoke, gases, and air, can seriously affect the performance of your fireplace or heating system, creating safety hazards by blocking the release of combustion byproducts.

Again, knowing the causes helps mitigate the issues - three of which are the following main contenders for blockages:

  1. Accumulation of Soot and Debris: Over time, substances like soot, creosote, and debris from fires may gather inside the chimney liner, leading to a narrower flue and restricted airflow.
  2. Wear or Breakage of Liner Components: Damaged or worn parts within the liner can block the flow of smoke and gases.
  3. Nesting Animals or Birds: Animals such as birds (or even rodents) might build nests inside the chimney liner, obstructing the flue and increasing the risk of fires and health issues.

How Obstructions Impact Chimney Liners

Blockages in chimney liners can affect your chimney's flow, functionality, and productivity in several ways:

Weak Draft

Obstructions lead to limited airflow in the chimney, resulting in a weak draft. This is a condition that hampers the ignition and maintenance of fires, leading to inefficient burning.

Reverse Flow of Smoke

A blocked chimney can cause smoke and gases to re-enter your living space, creating discomfort and exposing inhabitants to truly hazardous particles - or even life-threatening, in the extreme.

Risks from Carbon Monoxide

When chimney liners are badly obstructed, dangerous carbon monoxide can quickly accumulate indoors, potentially causing serious health issues like headaches, dizziness, and even fatal incidents.

Fire Risks

Blockages in the chimney that catch fire can quickly escalate into major house fires, endangering your property and loved ones. You might be surprised just how quickly they can grow from a blockage.

Strategies for Identifying and Clearing Obstructions

To detect and clear blockages in your chimney, take the following four approaches into consideration:

  1. Pay attention to unusual sounds that could indicate loose debris.
  2. Regularly inspect the chimney cap and screen.
  3. Observe your fireplace's performance for any signs of blockage.
  4. Arrange for professional chimney inspections to assess and address any issues thoroughly.

Identifying Chimney Liner Issues

Most of us enjoy the warmth of a cosy fireplace or wood-burning stove in the cold winter months. However, being fully aware of potential chimney liner problems is important for your family's safety - it helps to know the signs of a chimney liner with problems.

The most striking, obvious indicator of chimney flue liner issues is a general decrease in fire output, which is usually accompanied by excessive smoke around the home. This probably means that the chimney liner isn't properly drawing smoke out of the house, suggesting it may be in poor condition in some way.

Another obvious sign of chimney liner trouble, as mentioned earlier, is the quick build-up of creosote. A properly functioning chimney liner efficiently releases smoke and gases, reducing creosote formation. By the same token, if you notice an accelerated accumulation, this could point to a chimney liner malfunction.

Additionally, water leakage around the chimney area often hints at a breach in the liner, which not only affects the liner’s reliability but can also lead to more far-reaching structural concerns.

Cold drafts in your home may also indicate chimney liner damage. Visible cracks or pieces of chimney liner material in the fireplace or hearth area are clear signs of deterioration, often caused by exposure to high temperatures and corrosive byproducts from combustion.

Protect Your Home with

Keeping an eye on the health of your chimney liner will lead to a safe, productive fireplace or stove. Regular inspections and timely maintenance will keep your home warm, secure, and free of major issues.

Arguably the biggest factor in maintaining a healthy chimney is the quality of the chimney flue liner you are using. The last decade or two has seen a rise in poor-quality chimney liners, resulting in frequent problems.

Reliable Chimney Flue Liner Solutions

Avoid that same fate by insisting on a quality chimney flue liner, and in that regard, has got your chimney and flue needs covered. Specialising in flexible flue liners, we provide quality options for various fuel types, from 5" and 6" liners to chimney cowls, all designed for optimal performance.

Our double-skinned stainless steel liners are available in 316 and 904 grades for a wide range of heating appliances. They are HETAS-approved, durable against high temperatures and come with lifetime warranties for solid reliability and peace of mind.

View our flue liner products for more information. Questions? Contact Flue-Pipes directly. Our team of experts are always ready and eager to assist!