Chimney Liner Options, Compared
The liner is the part of the chimney that actually contains the fire, the smooth, sealed passage that carries heat and gases out while keeping them away from the surrounding brick and your home’s framing. Three materials dominate, and they suit very different situations. Here is how clay tile, stainless steel, and cast-in-place compare.
Clay tile
Clay flue tile is the traditional liner, and it is what sits inside most older Channahon chimneys. It is inexpensive, handles high heat well, and lasts a long time when it stays dry and undisturbed. Its weaknesses are specific: clay cracks under the thermal shock of a chimney fire, and it absorbs and transmits moisture at the mortar joints. Once tiles crack, they cannot be patched in place, so the practical fix is a new liner inside the old one. New clay remains a reasonable choice in new masonry construction, less so as a repair.
Stainless steel
Stainless steel is the modern workhorse and what we install most often as a relining. It comes rigid or flexible, drops into an existing chimney without rebuilding it, and when insulated it drafts beautifully and resists the corrosion that wood, gas, and oil exhaust throw at it. A quality stainless liner should list to UL 1777, the safety standard for chimney lining systems, and typically carries a long warranty when it is correctly sized and installed. For the great majority of relining jobs, this is the honest recommendation.
Cast-in-place
A cast-in-place liner pours a cement-like mixture around an inflated form inside the existing flue, leaving a smooth, seamless, insulated passage that also reinforces the surrounding masonry. It is the premium option: it can actually add structural strength to a marginal chimney and it handles all fuels. It costs more and the work is more involved, so we reserve it for chimneys where the masonry needs the extra support or where an irregular flue shape defeats a steel liner.
Compared at a glance
| Material | Best for | Notes |
| Clay tile | New masonry construction | Low cost, high heat tolerance; cracks under a chimney fire and cannot be patched in place |
| Stainless steel | Most relining jobs, all fuels | Drops into an existing chimney; should list to UL 1777; insulate for best draft |
| Cast-in-place | Weak masonry needing reinforcement | Seamless and insulated; adds strength; higher cost and labor |
Sizing is not optional
A liner has to match the appliance it serves. Too big, and gases cool and slow, dumping creosote and drafting poorly; too small, and the appliance cannot vent at all. The correct diameter depends on the stove, fireplace, or furnace at the bottom, which is why we size a liner to the appliance, not to whatever happened to fit before. A wrong-sized liner can perform worse than the cracked tile it replaced, so this is the step we never shortcut.
When to reline
Reline when a camera shows cracked or missing tiles, when you are connecting a new or different appliance that needs a different flue size, when glazed creosote will not come off the walls, or when a chimney fire has already damaged the flue. If you are not sure what is inside your chimney, an inspection with a camera answers it in one visit, and we will show you the footage. Pricing for lining systems is on the pricing page.
Frequently asked questions
What is a chimney liner?
It is the sealed inner passage of the chimney that carries heat and combustion gases out of the house while protecting the surrounding masonry and framing from that heat and from corrosive byproducts.
What is UL 1777?
UL 1777 is the safety standard for chimney lining systems. A quality stainless liner should be listed to it, which is one of the things we check when specifying a relining.
Which liner is best for my home?
For most relining jobs, an insulated stainless steel liner is the best balance of durability, draft, and cost. Cast-in-place is better where the masonry needs reinforcement, and new clay tile mainly suits new construction.
Can cracked clay tile be repaired?
Not in place. Once clay tiles crack, the practical and safe fix is to install a new liner, usually stainless steel, inside the existing flue rather than trying to patch the tiles.
Why does liner size matter so much?
A liner must match the appliance. Oversized, it lets gases cool and dump creosote and drafts poorly. Undersized, the appliance cannot vent. A wrong-sized liner can perform worse than the damaged one it replaced.
When should I reline my chimney?
Reline when a camera shows cracked or missing tiles, when you connect a new appliance that needs a different flue size, when glazed creosote will not come off, or when a chimney fire has damaged the flue.
How long does a stainless liner last?
A quality stainless liner that is correctly sized and installed typically lasts decades and usually carries a long warranty.
By Zack Matthews, owner of Apex Chimney Service, Channahon IL — 29 years in the trade.