What is a Chimney Liner?
Chimney liners serve as the direct venting path from your fireplace or appliance to the top of the chimney. Additionally, together with the brick or wood chimney structure, they provide an incremental layer of protection between venting flue gases and your residence.
There are three main types of chimney liners:
- Clay tile liners (sometimes called “terra cotta”) are fired clay liners, usually around two feet in length, that are stacked one of top of another and sealed with heat-resistant mortar. These are typically found in classic brick chimneys.
- Cast-in-place liners are liners made from materials similar to concrete that are pumped into the chimney to create a tunnel from the bottom to top. These are generally replacement liners found in historic chimneys where additional structural strength is required.
- Metal liners are liners made from stainless steel or aluminum. Their primary application is replacing damaged or missing clay tile liners and are the most popular repair / upgrade option used today.
Liner defects, no matter how small the gap or crack, can begin a process that will further erode the chimney structure’s integrity and can pose a threat to your family’s safety via carbon monoxide leakage.
More critically, combustible creosote or soot can also escape through these gaps and build up outside the chimney flue liner, which results in a significant fire hazard.
If the creosote were to catch fire in this area, serious damage can occur, because the fire will no longer be contained within the flue but rather spread outside the flue – immediately adjacent to the main building structure.
Do I need a Chimney Liner?
There are three reasons you may need a chimney liner:
- Because your chimney has no clay tile chimney liner (older chimneys were often not lined when built)
- The clay tile chimney liner is damaged due to shifting, fire damage, or age- or use-related damage;
- A new appliance (furnace, stove, or water heater) is being installed and vented via a masonry chimney.
For readers in the Washington, DC metropolitan region: Current WSSC regulations require that gas or oil-fueled furnaces and water heaters be connected to a metal liner in order to meet code. Additional information can be found here.
To evaluate the condition of your chimney liner, our certified chimney sweep will conduct a Level 2 inspection, including a video scan to view the interior of your flues, to determine whether a new liner is needed.
If the existing liner is damaged, it will no longer able to contain smoke ingredients such as soot, creosote, and carbon monoxide. Simply put, it cannot adequately protect the chimney or your house.
Ask A Sweep Tip: Note that gas-fired furnaces, boilers and hot water heaters produce large quantities of water vapor during the normal combustion process. In addition to this heavy moisture load, oil and gas furnaces produce acidic exhaust that literally eats away the flue lining.
A furnace liner that is offset (i.e. showing gaps at flue seams) creates conditions for a fire, as escaped heat can reach combustible structures and harmful gases can migrate into the home.
Additionally, a liner that has gaps or cracks can allow exhaust moisture into the surrounding chimney structure, eventually deteriorating the masonry from the inside out.
Chimney Liner Installation Instructions
Relining efforts are generally straightforward:
- Priddy’s reliner team begins by placing drop cloths in the work area (usually covering three feet around the fireplace or appliance) to protect your floors and furnishings. Any fragile and decorative items on the mantle or hanging above the fireplace are removed to prevent them from falling during the breakout process. Our reliners will also remove the fireplace doors, grate, and damper plate at this stage.
- The masonry chimney will then be cleaned to remove tar glaze and creosote, as well as checked for loose or missing bricks, mortar or other materials that could inhibit the correct installation of the chimney lining system.
- In the case of masonry chimneys that vent wood-burning fireplaces, the defective clay liner will be removed prior to the installation of the stainless steel liner. This process is known simply as “breakout”. Our certified reliner will use a high-power drill with special rods to shatter and dismantle the defective clay liner. During this process, your firebox opening is covered with plywood and cardboard to prevent debris from coming into the living area.
- The replacement stainless steel liner is then lowered from the top of the chimney. A typical installation will require a reliner on the roof and another at the bottom of the chimney with a rope helping to pull and guide the liner through the flue area.
- For wood-burning fireplaces, once the liner is in place, our reliner team will hand-seal the smoke chamber with high-heat cement to insulate and smooth out the walls, a process known as “parging”. This helps promote efficient drafting and reduces future creosote build-up in the smoke chamber.
- An insulation mix is then poured around the liner.
- For hearth stoves and appliances (gas furnaces, oil burners or water heaters), the installation requires connecting a stainless steel “t-connector” to the liner in accordance with NFPA standards and the manufacturer’s installation requirements.
- Finally, to complete the installation, Priddy’s chimney reliners install a top-mounted damper system or termination cap to ensure that your fireplace and appliance flue is protected against rain and animal intrusion.
How Much Does it Cost to Install a Chimney Liner?
A stainless steel liner for a gas furnace typically ranges from $1,800 to $2,500, while fireplace liner installations cost anywhere from $2,700 to $4,000.
The cost largely depends on difficulty (roof type and slope, if there are curves in the flue), liner dimensions (length and diameter), number of appliances, as well as connector types needed.
Maintaining your chimney liner
It is important that the chimney lining system be checked and cleaned annually. This is for the safety of the homeowner and often necessary to meet the warranty requirements for stainless steel liners. In the case of solid fuel-burning appliances, more frequent maintenance may be required, depending on use.
The entire system, from the connection at the appliance to the top of the liner, must be completely inspected and cleaned.