Chimney Liners
Canadian Chimney Liners

---

Chimney Lining and Relining Systems

​Chimney lining systems are responsible to vent an appliances flue gasses to the exterior of your home.  In a chimney, the liner is the inner flue component and can be fabricated from metal or clay, and have specific classifications and standards that define a liners certification, design, and suitable usage.

---

Acceptable Liners in Canada

To determine what liner is suitable  \ compliant, chimney liners must meet one of the following standards:

• CSA A324 Clay Flue Liners 
• ULC S635, Standard Lining Systems for Existing Masonry or Factory Built Chimneys and Vents.  There are 3 classes within this standard that outline suitable uses for each ULC-S635
• ULC S639M, Standard for Steel Liner Assemblies for Solid-Fuel Burning Masonry Fireplaces
  
• ULC S640, Standard Lining Systems for New Masonry Chimney

---

Chimney Liners Suitable for Installation in an Existing Masonry Chimney in Canada

Use of a Replacement Chimney Liner 

Liners meeting ULC-S635 are intended to correct problems with an existing masonry chimney and factory built chimneys.

Examples of When a Replacement Chimney Liner is Installed

Chimney relining installation may be needed to:

• Repair a chimney with cracked or broken clay liners
• Reduce the liner size to match the appliance output
• Meet the requirements for fireplace insert installation
• Reduce heat loss from the flue gasses
• Line an unlined chimney.

ULC-S635 - ​Standard for Lining Systems for Existing Masonry or Factory-Built Chimneys and Vents

This Standard covers lining systems for existing masonry chimneys, which may or may not incorporate a liner of fire-clay tile, or factory-built chimneys and vents.

Classes of ULC-S635 Chimney Liners

          Class 1

             For the venting of gas-fired appliances where the temperature of the flue-gas products is 135°C or above, but does not exceed 245°C;

          Class 2

             For the venting of oil and gas-fired appliances where the temperature of the flue-gas products does not normally exceed 300°C; and

          Class 3

             For the venting of oil-, gas- and solid fuel-fired appliances where the temperature of the flue-gas products does not normally exceed 650°C.

Replacement Liner Types

There are four relining options available:

• ​Replacement clay or other masonry material liners
• Rigid stainless steel
• Flexible stainless steel
• Poured in place refractory liners.

---

Chimney Liners Suitable for New Construction or Liners for New Appliance Installation

The following standards are applicable to new chimneys and components

• ULC-S604, Standard for type A chimneys - oil appliances
  
• ULC-S610, Standard for factory built fireplaces and their chimneys
  
• ULC-S629, Standard for factory built chimneys - 650 degree celsius chimney
• ULC-S639, Standard for steel liner assemblies for masonry fireplaces
• ULC-S640, Standard for liners in new masonry chimneys
• ULC-S640, Standard for stove pipe connectors

Steel Liners

Metal liners must be installed in accordance with the installation instructions in that standard. 

CAN/ULC-S639M - Standard for Steel Liner Assemblies for Solid-Fuel Burning Masonry Fireplaces

Requirements for prefabricated steel liners that incorporate a smoke chamber, damper, and other associated masonry fireplace components.  The ULC S639 steel liners are intended as an alternative chimney lining during construction.  ​The standard requires these liner to be installed in accordance with the applicable building codes and manufacturers installation requirements.  

ULC-S639M is Not Suitable for Installation

​These liners are not suitable for factory built fireplaces, inserts or space heaters.

Steel Liners - Building Code

9.22.2.3. Steel Liners

(1) Steel liners for fireplaces shall conform to CAN/ULC-S639M, “Standard for Steel Liner Assemblies for Solid-Fuel Burning Masonry Fireplaces”, and shall be installed in accordance with the installation instructions in that Standard.

---

Relining a Masonry Fireplace

Source:  WETT - Chapter 4 - Chimneys and Venting - 3. Chimney Types -  3.6 Chimney Lining and Relining Systems

When considering relining a masonry fireplace \ chimney (site built), one must appease the local AHJ (Authority Having Jurisdiction), Building Code and any applicable Installation Codes.  When installing factory built components they all must be tested and listed under the appropriate listing standards.  If the products have not been tested and listed for use, a report by a Mechanical Engineer, stamped (P.Eng) with all the product specs, drawings along with the applicable codes may be accepted by your AHJ.  As this is on an individual basis, many factors may dictate what you may require or if approval will be granted at all.   

To reline with a stainless steel liner, consideration of the size of the masonry fireplace opening must be installed.  A liner diameter that fulfills the requirements outlined in 9.21.5.2. of the Building Code and appease other requirements as outlined in 9.21. & 9.22 (Exterior clearances etc).  Most liner manufacturers have a limited size, so if the opening is large, fabrication of a custom liner is may be needed.

There are some large, "commercial" liner options available, but a custom bottom plate will still likely require fabrication. Alternatively, a mechanical ventilation system may be used with a smaller diameter of liner (P.Eng or listing certification required). 

The liner will need to be connected to a bottom plate (mesh), and either create a transition (site built) or utilize a fabricated transition box (factory built) from the throat to the liner.  The SS liner will require spacing - brackets for the required air gap \ clearances or utilize compliant insulation or an insulated liner.  Top mount, rain cap etc are to be installed similar to installing a liner for an insert.

Masonry Flue Size Requirements

Table 9.21.2.5.A. Diameter of Round Flues for
Fireplace Chimneys Forming Part of Sentence 9.21.2.5.(1)

​