How to Fit a Chimney Flue Liner: Step-by-Step Guide

Installing a chimney flue liner is an essential task for maintaining the safety and efficiency of a fireplace or wood burner. Over time, the already existing chimney flue can deteriorate due to the corrosive effects of combustion gases, leading to the potential for dangerous fumes to enter the living space. A new flue liner serves as a protective barrier, shielding the masonry from heat and corrosion while ensuring that exhaust gases are safely vented to the outside.

The process of fitting a chimney flue liner requires precision and adherence to safety standards. It typically involves threading a flexible liner down the chimney stack to the fireplace opening. Proper measurement of the chimney is crucial to selecting the correct liner size, and care must be taken to ensure that the liner is securely attached and sealed. Training and experience are highly beneficial when undertaking this task, as it involves working at heights and handling heavy materials.

Due to the technical and safety aspects of the job, professional installation is recommended. A certified technician will have the expertise to assess the condition of the chimney, recommend the appropriate type of liner, and confirm that the installation complies with relevant building regulations. This not only guarantees the workmanship but also ensures that the heating system operates efficiently and safely.

Flexible Flue Liner – Available in multiple sizes!

What is a Chimney Liner?

A chimney liner, also known as a flue liner, is a conduit made of metal, ceramic, or clay that lines the inside of a chimney’s flue. Its primary purpose is to protect the chimney walls from heat and corrosion, while also improving safety and efficiency.

Key Functions:

  • Protection: It shields the chimney walls from the corrosive by-products of combustion.

  • Efficiency: It assists in producing a correctly sized flue for optimal performance of heating appliances.

Types of Chimney Liners:

  1. Metal: Usually made of stainless steel or aluminium, used for gas, oil, and solid fuel fires.

  2. Ceramic: Commonly utilised for high-temperature applications.

  3. Cast-in-place: A cement-like product that provides a smooth, seamless lining.

Installation Considerations:

  • The liner must be correctly sized according to the heating appliance being used.

  • There are directional indications when fitting certain types, ensuring a proper installation.

  • Some liners are flexible, allowing for installation in chimneys with bends or offsets.

Compatibility: It is essential to ensure that the selected liner is compatible with the type of fuel and heating appliance in use, as per the manufacturer’s guidelines.

In summary, a chimney liner is an essential component of a functional and safe chimney, playing a crucial role in the maintenance and performance of a home’s heating system.

Why do you need to fit a chimney liner?

A chimney liner serves as a protective barrier within the chimney, ensuring that heat and combustible products are safely contained and directed out of the home. It’s essential to fit a chimney liner for several reasons:

  • Safety: The primary function of a liner is to protect the house from heat transfer and potential fire hazards. A well-fitted liner contains the combustion products and leads them safely to the exterior, minimising the risk of a chimney fire.

  • Efficiency: Liners help improve the efficiency of heating appliances by optimising the size and shape of the flue to ensure adequate draft and reduce excessive creosote buildup, which can result from condensation in an oversized flue.

  • Longevity: The chimney masonry is shielded from corrosive by-products of combustion, such as acidic moisture that can deteriorate brickwork over time

What tools do I need to fit flexible flue liners?

Installing a flexible flue liner requires specific tools to ensure the install job is done safely and effectively. Here’s a list of essential items one should have on hand before beginning the installation process:

  • Tape measure: To accurately measure the length of the flue.

  • Chimney brush: For cleaning the chimney before installation.

  • Rope and drawstring: These will be used to guide the flue liner down the chimney.

  • Nose cone: Attaches to the end of the liner to aid in pulling it through the chimney.

  • Gaffer tape: To secure the nose cone to the liner and seal any joins.

  • Protective gloves: Essential for protecting hands during installation.

  • Screwdriver set: For fittings that may need adjustments or securing.

Additionally, the following items are recommended to streamline the installation:

Roof LadderTo safely access the chimney from outside
Safety HarnessTo protect against falls when working at height
TorchFor visibility within the chimney shaft

It is imperative that one examines the condition of their work area and has safety protocols in place. Each flue liner may also come with manufacturer-specific instructions, which should always be followed to ensure compatibility and safety.

How to Fit a Flexible Flue Liner: A Step-by-Step Guide

Fitting the Flue Liner

Fitting a chimney flue liner is crucial for the safe operation of a fireplace or stove. This section provides a step-by-step approach, ensuring the liner is prepared and installed correctly.

Preparing the Flue Liner

The liner must be the correct diameter and length for the chimney. One should unfurl the liner and lay it out straight to remove any bends or kinks. If required, trim the liner using snips for the appropriate fit. It’s recommended to attach a drawstring to help guide the liner through the chimney.

Installation Process

Step 1: At the chimney top, attach the leading end of the liner to a pulling cone or similar tool.

Step 2: Connect a weight to the cone to facilitate the descent of the liner through the chimney. This ensures it doesn’t snag or fold during the process.

Step 3: Collaborate with a helper at the bottom of the chimney to feed the liner down. Communication between the parties is key, as one pushes gently from the top while the other guides and receives the liner at the bottom.

Step 4: Once in place, secure the flexible chimney liner at both ends following the manufacturer’s instructions. This often requires fitting a closure plate and top plate, to ensure stability and airtightness.

Step 5: Verify there are no obstructions or sharp bends in the liner and check it emerges sufficiently at both ends of the chimney.

Remember, fitting a chimney liner is a task that can improve the efficiency of a wood-burning stove and ensure the safety of a property by properly venting smoke. It should be done with care, using the correct tools and following safety standards.

Finishing Touches and Maintenance

Once the chimney flue liner is fitted, the finishing touches ensure it is secure and weatherproof, and a post-installation check confirms the system is safe and functional.

Securing and Weatherproofing

Securing the Flue Liner:

  • The top of the flue liner should be secured with a clamp and plate to prevent it from moving.

  • Ensure that the gap between the liner and the chimney pot is filled with a sand/cement mix, sloped at forty-five degrees for effective soot redirection.


  • A cowl or rain cap fitting is crucial for protecting against rain and preventing bird ingress. The cowl should be securely added to the top of the chimney stack.

Post-Installation Check

Visual Inspection:

  • Ensure the flue liner is free from damage and is correctly orientated, with any arrows facing upwards.

Smoke Test:

  • Conduct a smoke test to verify the correct draw of the chimney and absence of leaks, which also ensures the flue liner’s effective installation and operation.

Regular maintenance should include inspections and sweeping to keep the flue clear of obstructions and soot accumulation, maintaining optimal performance and safety.

Make sure to browse our store for more Chimney Flue Liners!

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