Chimney Liner Replacement Toronto 2026: Stainless Inserts, Cost & Code

# Chimney Liner Replacement Toronto 2026: Stainless Inserts, Cost & Code

Most Toronto homeowners learn what a chimney liner is the day their HVAC contractor says, "We can't pass inspection without a new liner." It's a $2,500–$5,500 line item that wasn't in the budget, comes up at the worst possible time, and has confusing terminology around it.

This post explains what a chimney liner is, when you need one, what it costs in Toronto in 2026, and how to know if a contractor is recommending the right specification — or just selling you the most expensive option.

For the broader chimney context, see our [Chimney Repair & Removal Toronto 2026 Complete Guide](/chimney-repair-removal-toronto-2026-complete-guide). If you upgraded your furnace and now have a venting issue, also read [Chimney Removal After Furnace Upgrade Toronto](/blog/chimney-removal-after-furnace-upgrade-toronto).

What a Liner Actually Is

A chimney liner is the inner channel inside the chimney that carries flue gases. The brick masonry around it is the structure; the liner is the working surface that handles heat, moisture, and combustion byproducts.

Three liner generations have been used in Toronto homes:

1. Unlined (Pre-1940)

Many original Toronto chimneys had no dedicated liner — flue gases ran straight up the brick chase. Code required a liner starting in the 1940s, but unlined chimneys still exist and are NOT compliant for any modern appliance.

2. Clay Tile Liners (1940s–1990s)

Stacked terracotta tiles, typically 8x8 or 8x12 inches. Standard for the second half of the 20th century. They crack from freeze-thaw, settling, and chimney fires. Cracks let combustion gases (including carbon monoxide) seep into the masonry and potentially into living spaces.

3. Stainless Steel Inserts (1990s–Present)

A continuous flexible or rigid stainless tube inserted from the top of the chimney down to the appliance. Modern standard. AmeriVent, Selkirk, and DuraVent are the brand leaders in 2026.

When You Need a New Liner

Five trigger scenarios in Toronto homes:

1. High-Efficiency Furnace Was Installed, but Water Heater Still Vents Up

This is the #1 reason Toronto homeowners need new liners in 2026. Old setup: 80% efficient furnace + 60-gallon natural-draft water heater both venting into the same masonry flue. New setup: 96% efficient furnace side-vents through the wall; water heater alone still uses the chimney.

Problem: that masonry flue is now grossly oversized for the water heater alone. Combustion gases cool too fast, condense into acidic moisture inside the chimney, and the flue runs too cold to draft properly. You get:

• Spillage of combustion gases (including CO) into the basement
• Accelerated mortar failure inside the flue
• Wet basement walls along the chimney chase

The fix is a right-sized stainless liner (typically 4" or 5" round) running from the water heater's draft hood to above the chimney top. Cost: $2,500–$3,800 for a water-heater-only insert.

2. Existing Clay Tile Liner Cracked or Damaged

A camera inspection ($200–$400) shows cracked tiles, mortar joints fallen out between tiles, or pieces missing. Once cracks exist, the liner is unsafe and needs replacement. New stainless insert: $3,500–$5,500.

3. Adding a Wood-Burning Insert to a Masonry Fireplace

Code (ULC S635 / S640) requires that a wood-burning insert vent through a connected liner all the way to the chimney top — not just into the open masonry flue above the firebox. Insulated stainless liner kit: $2,800–$4,500 depending on chimney height.

4. Conversion to Gas Fireplace from Wood

Direct-vent gas fireplaces don't use the chimney. But B-vent gas fireplaces do, and they need a properly sized stainless liner. $2,500–$3,800.

5. WETT Inspection or Insurance Failed You

WETT-certified inspectors will flag liners that are cracked, undersized, oversized, or missing. Insurance companies are increasingly requiring WETT inspection for any wood-burning system in homes built before 1980. Failure means: install a liner or stop using the appliance.

Cost Breakdown — Toronto, 2026

Add $300–$700 if scaffolding access is needed (very tall chimneys, steep roofs).

Sizing — The Specification That Matters Most

A liner that's too big runs cold and condenses moisture. A liner that's too small chokes the appliance and risks spillage. Sizing is determined by:

• BTU input of the appliance (off the appliance nameplate)
• Effective height of the chimney (top of appliance to chimney top)
• Number of appliances connected to the same flue
• Outdoor design temperature for the location

For Toronto, ASHRAE design temp is around -22 °C, which affects draft calculations. A reputable installer runs the math from the appliance manual or NFPA 31 / ULC S635 sizing tables. If a contractor doesn't ask the BTU rating of your appliance, they're guessing.

Quick reference (NOT a substitute for proper calculation):

• 35,000–60,000 BTU water heater alone → 4" round liner
• 75,000–100,000 BTU furnace + water heater → 5" or 6" round
• 100,000+ BTU furnace alone → 6" round
• Wood-burning fireplace insert → match the appliance flue collar (typically 6" or 8")

Material & Brand Specifications

Stainless Steel Grades

• 316Ti / 316L — wood-burning, multi-fuel, severe-condensing applications. Premium grade.
• 304 — gas appliances only. Cost-effective and code-compliant for gas.

If a contractor offers you a single price for "stainless liner," ask which grade. A 304 liner sold for a wood-burning system is non-compliant.

Insulation

For wood-burning applications and for liners running through unheated chase space, rock-wool insulation wrap is required by code to maintain flue temperature and prevent condensation. Adds $400–$800 to the install.

Brands

• AmeriVent (Eccotemp / Selkirk family) — common spec, readily available
• Selkirk Sentinel — premium, often used for wood-burning
• DuraVent DuraLiner — flex liner, easy install in offset chimneys
• Olympia Forever Flex — pro-installer favourite for retrofit

We don't recommend off-brand or imported flex liners — wall thickness and seam quality matter for safety and longevity.

Installation — What Should Happen

A proper liner install:

• 1. Camera inspection first — confirm the chimney is sound enough to host a liner (cracks, offsets, blockages)
• 2. Cleanout if existing creosote or debris
• 3. Drop the liner from the top — flexible liner pulls down through the chimney
• 4. Insulation wrap for wood-burning or condensing applications
• 5. Connect at the appliance — proper draft-hood connector, sealed
• 6. Top plate at the chimney top, weather-sealed
• 7. Cap installed on top plate
• 8. Pressure or smoke test to verify draft and seal
• 9. TSSA or municipal permit where applicable for gas appliance reconnection

Time on site: half day to full day depending on complexity.

TSSA & Permits

In Ontario, gas appliance work requires a TSSA-licensed gas technician. Liner installation that involves disconnecting/reconnecting a gas appliance must be done by or supervised by a licensed gas tech. RenoHouse coordinates with TSSA-licensed HVAC partners for the gas-side work; we manage the masonry-side coordination, scaffolding, and overall project.

For wood-burning systems, WETT certification is the relevant credential — typically held by chimney sweeps and fireplace specialists. We refer to WETT-certified installers for wood-burning liner work.

How RenoHouse Coordinates Liner Work

• Camera inspection scheduled with our partner inspector
• Sizing review with HVAC partner (if gas) or WETT-certified specialist (if wood)
• Stainless liner sourced from preferred suppliers (AmeriVent, Selkirk, DuraVent)
• Installation by TSSA gas tech (gas) or WETT installer (wood)
• We handle the masonry-side coordination — staging, top-plate seal, chimney-top weatherproofing
• Single point of contact, single warranty

Bundle Opportunities

Liner replacement often pairs well with:

• Cap installation (you're on the roof anyway): see [Chimney Cap Installation Toronto](/blog/chimney-cap-installation-toronto)
• Crown repair (the top of the chimney is open during liner install)
• Repointing (if mortar is failing — bundle the staging): see [Chimney Repointing Cost Toronto](/blog/chimney-repointing-cost-toronto)

A "top-end" package — liner + crown + cap + 4 feet of repointing — typically runs $5,000–$8,000 all-in and resets the chimney for another 25–30 years.

Book your liner consultation through our [Chimney Repair & Removal services page](/services/exterior/chimney-repair-removal). We'll diagnose, size, and quote — and pull in the right licensed partner for your specific appliance.