Chimney Relining in Northwest Indiana
The liner is the part of the chimney that actually contains the fire’s exhaust. When it cracks, the brick around it is only decoration.
By Mark Jason, owner of NWI Chimney Sweep · 34 years working on NWI chimneys
Four situations that call for a new liner
A chimney needs a new liner when the existing flue is cracked, missing, or the wrong size for the appliance venting into it. Homeowners usually notice it as tile shards in the firebox, a smoky stove, white staining on the brick or rust on top of the water heater.
- Cracked or missing clay tile. Found on a camera scan, often after a chimney fire. Heat and gas now reach the brick shell directly.
- An insert or wood stove going into an open fireplace. A stove outlet is six or eight inches across; a fireplace flue may be twelve by twelve. Dumping stove exhaust into that much space cools it, kills the draft and plates the flue with creosote.
- A furnace upgrade that left the water heater alone. When the old furnace is replaced by a high-efficiency unit vented through the wall in plastic pipe, the small water heater is left venting into a flue sized for both. Its exhaust condenses before it reaches the top.
- No liner at all. Some chimneys built before the 1940s are bare brick inside. Many of the mill-era houses in the north county were built this way.
Matching the alloy to the fuel
The liner alloy is chosen by fuel: 304 or 316Ti stainless for wood, 316Ti for oil and coal, AL29-4C for condensing gas. The wrong grade corrodes through from the inside in a few years, so the first question is always what will be burning below it.
| What vents into it | Liner material | Why |
|---|---|---|
| Wood stove, insert or open fireplace | 304 or 316Ti stainless, insulated | Handles high flue temperatures; insulation keeps gases hot and protects nearby framing |
| Oil or coal appliance | 316Ti stainless | Titanium-stabilized alloy resists the sulfur acids these fuels produce |
| Standard-efficiency gas furnace or water heater | 316Ti stainless or aluminum liner listed for gas | Lower temperatures, but wet, mildly acidic exhaust |
| Condensing gas appliance | AL29-4C stainless or the plastic venting the maker specifies | Exhaust is cool and constantly wet; ordinary stainless pits |
Sizing is the whole job
Liner diameter follows the appliance, not the old flue. A wood stove liner matches the stove collar. A gas appliance liner comes from the venting tables using its BTU input, the liner height and the connector length. Oversizing by “one size to be safe” is the mistake that causes condensation and backdrafting.
How a liner goes in
A stainless chimney liner is installed from the roof down in six steps, and a straight flue is normally completed in one day.
Scan and measure
The flue is swept and run with a camera to find offsets, protruding mortar and the tightest tile. Height is measured from thimble or firebox to crown.
Prepare the flue
Mortar snots are knocked back. If the liner plus insulation will not pass, the old clay tiles are broken out with a rotary tile breaker and removed from the bottom.
Insulate and lower
For solid fuel the liner is wrapped in foil-faced ceramic blanket and mesh, then fed down from the roof on a pulling cone while a second person guides it below.
Connect the bottom
A stove gets an appliance connector at the collar; a furnace or water heater gets a tee with a removable cap for cleaning; an open fireplace needs a sealed transition at the smoke chamber.
Seal the top
A top plate is bedded in sealant on the crown, the liner is clamped off, and a rain cap finishes it.
Test the draft
The appliance is fired, draft is checked at the connector, and for gas the draft hood is tested for spillage with all exhaust fans in the house running.
What the listing means, and what relining leaves out
UL 1777 is the test standard for chimney liner systems, and a liner only carries that listing when it is installed the way it was tested. For wood-burning use in most systems that means with the specified insulation. Skip the wrap and the liner is no longer a listed assembly, whatever is printed on the box. We install to the manufacturer’s instructions and to NFPA 211, and you keep the paperwork for the product that went into your chimney.
A liner does not repair the outside of the chimney. Loose brick, a broken crown or leaking flashing still need masonry repair, ideally before the liner goes in so the new top plate sits on something solid. It also does not make a factory-built metal chimney serviceable again; those are replaced with matching listed pipe, not relined.
What affects the cost of relining
Chimney relining cost is set mainly by liner length and diameter, the alloy required, insulation, and whether clay tile must be removed first. A two-story flue takes roughly twice the material of a single-story ranch chimney, and eight-inch liner costs more per foot than six-inch. Offsets slow the pull, and breaking out tile can add most of a day. That is why a liner is quoted after the flue has been measured and scanned, never over the phone. The published starting price for a stainless liner is on the chimney liner pricing page.
Relining tends to be needed where older housing meets new appliances, and we serve homes in Merrillville, Portage and South Haven.
Chimney liner questions
How long does a stainless liner installation take?
A straight flue with no tile removal is normally finished in a day. Breaking out clay tile, working around an offset or relining two flues in one stack can push it into a second day. Either way the appliance stays off until the stainless liner is connected and draft-tested.
Does a chimney liner have to be insulated?
For wood, in nearly every case: it is part of the UL 1777 listing for most systems and it keeps flue gases hot enough to draft. For gas appliances insulation is often optional, but it helps on tall exterior chimneys that run cold.
Can a chimney with a bend in it be relined?
Yes. Flexible corrugated liner follows offsets that rigid pipe cannot. The limit is cross-section, not the bend; if the tightest point is too small, tiles are removed to make room. A camera scan before the job shows where the chimney bends and how tight it gets.
Why did my chimney start causing problems after a new furnace was installed?
The new furnace probably vents through a side wall, leaving only the water heater on the old flue. That flue is now far too big, the exhaust cools and condenses, and you see white staining, damp brick or rust on the heater top. A properly sized liner corrects it.
Is rigid or flexible liner better?
Rigid has smooth walls and suits a dead-straight flue. Flexible suits anything with an offset and is what most masonry chimneys receive. Smooth-wall flexible liner exists for cases where draft is marginal. Whichever is used, the chimney liner must be continuous from the appliance to the cap.
Does a stainless liner still need sweeping?
Yes, every year for wood. Stainless builds creosote like any other surface, just more slowly when it is insulated and correctly sized. It is brushed with poly heads because steel wire scratches the alloy. Gas appliance liners are checked yearly for corrosion instead.
Can cracked clay tiles be repaired instead of relined?
Individual damaged tiles near the top can sometimes be replaced, and resurfacing coatings exist for certain joint defects. When cracks run through several tiles, or an appliance is changing, a full stainless liner is the repair we carry out. A camera scan shows which case applies.
What is the difference between 304 and 316Ti stainless?
Both handle wood. 316Ti adds molybdenum and titanium, which resist the acids in coal, oil and gas exhaust, so it is the multi-fuel choice. 304 is fine where only dry cordwood will ever be burned. If the appliance might change later, 316Ti keeps the chimney liner usable.
Told you need a liner? Call for a second look.
A person answers the phone from 7am to 9pm, every day of the week.
Call (219) 203-9797