Chimney repairs range from straightforward maintenance (cleaning, cap replacement, minor tuckpointing) to significant structural work (relining, crown rebuilding, full chimney reconstruction). The key is ensuring the repair being recommended is actually warranted by what the inspection found — and that the materials and methods used are appropriate for your specific chimney and appliance.

“The most important thing I tell homeowners before they agree to a reline is: make sure you understand exactly why relining is necessary. Was a crack found in the liner? Multiple cracks? Complete liner deterioration? A liner that’s the wrong size for the appliance? Those are all legitimate reasons. ‘Your chimney is old’ or ‘we recommend it for chimneys like yours’ is not a reason. Relining is expensive and it’s the right answer in specific situations — not every situation.”

— Bridget Oyelaran, WETT-certified chimney inspector and fireplace technician with 16 years of experience in residential chimney inspection, cleaning, and repair in the local area

Questions About Relining

A small campfire flickering within a rustic brick enclosure outdoors.

Why specifically is relining recommended for my chimney?

Before agreeing to any relining, ask for the specific documented reason. Legitimate reasons for relining include:

Liner deterioration: Cracked, spalling, or missing clay tile sections documented in the camera inspection footage. This allows combustion gases — including carbon monoxide — to escape the flue into the wall cavity or living space.

No existing liner: Many older chimneys (pre-1960) were built without a liner. Installing one significantly improves safety.

Wrong liner size for the current appliance: A liner must be appropriately sized for the appliance connected to it. When a high-efficiency gas appliance replaces an older oil furnace, the smaller flue gas volume may condense in an oversized liner, causing rapid liner deterioration.

Damage from a chimney fire: A chimney fire can crack or shatter clay tile liners. After a confirmed chimney fire, relining is typically required.

What is NOT a legitimate reason for relining: “Your chimney is 30 years old” or “we recommend relining for chimneys like yours” without documented findings from a camera inspection.

What liner material are you recommending, and why?

A man in a yellow shirt tends to the burning fire in a cozy indoor fireplace.

Stainless steel flexible liner (most common):
Appropriate for most residential applications. Inserted from the top and connected to the appliance at the bottom.

Key specifications:
– Alloy: 316L stainless steel for wood-burning and gas appliances. 904L stainless for oil appliance venting (higher acid resistance required).
– Diameter: Must be correctly sized for the appliance. An undersized liner restricts draft; an oversized liner can cause condensation problems with gas appliances.
– Gauge: Thicker gauge (lighter gauge number) is more durable. Ask what gauge is being installed.

Cast-in-place liner:
A poured castable material fills the existing flue, creating a seamless, jointless liner within the old chimney walls. More expensive than flexible liner but very durable and can structurally reinforce a deteriorated chimney. Appropriate when the existing chimney structure has significant mortar deterioration.

Clay tile replacement:
Replacing individual damaged clay tile sections. Appropriate when damage is isolated and the rest of the liner is sound. A camera inspection is essential to confirm that the replacement section is adequate.

What a good answer looks like: A specific liner type recommended with a rationale tied to the inspection findings, the appliance type, and the chimney dimensions.

What accessories are included?

A complete relining includes more than just the liner:

  • Top plate: Seals the liner to the chimney at the top and provides a base for the chimney cap
  • Chimney cap: Prevents rain and animal intrusion. Should be stainless steel
  • Connector at the appliance: Properly sealing the liner to the appliance connection
  • Insulation: For wood stove applications, insulation around the liner in the flue improves draft performance and is often required

Ask specifically what’s included in the relining scope.

Questions About Masonry Repairs

For tuckpointing: what mortar type is being used?

Tuckpointing (repointing) removes deteriorated mortar and replaces it with fresh mortar. The mortar type matters:

Type S mortar: A strong, moderately flexible mortar. Appropriate for below-grade and exposed applications.

Type N mortar: Medium-strength, more flexible. Good for above-grade chimney work.

Refractory mortar: Required for joints inside the firebox and smoke chamber — areas directly exposed to high heat.

What NOT to use: Standard pre-mixed construction mortar from a hardware store. It’s not rated for the thermal cycling a chimney experiences and will deteriorate rapidly.

Ask specifically what mortar specification is being used for each location (exterior joints, firebox, smoke chamber).

For chimney crown repair or replacement: patch or replace?

The chimney crown is the concrete cap at the very top of the chimney that seals the masonry and directs water away. It’s distinct from the chimney cap (the metal cap over the flue opening).

Patching: Appropriate for minor cracks. Crown sealants (like CrownCoat) can be applied to hairline cracks to prevent water infiltration.

Replacement: Required when the crown is significantly cracked, crumbling, or shaped incorrectly (inadequate slope or overhang). A properly constructed crown has a slight slope to shed water and overhangs the chimney masonry by at least 2 inches.

Ask specifically whether patching or full replacement is being recommended and why.

For masonry repair: is there an underlying moisture problem?

Masonry chimney deterioration is often driven by moisture — rain penetrating through a failed crown or cap, water infiltrating through cracked mortar joints and then freezing and expanding (spalling brick). Ask whether the source of moisture that caused the deterioration has been identified and addressed. Repointing a chimney without addressing the moisture source will result in rapid re-deterioration.

Questions About Waterproofing

Is chimney waterproofing being recommended, and is it appropriate?

Some chimney contractors recommend applying a masonry waterproofing sealer to the exterior of the chimney. This can be appropriate — breathable (vapor-permeable) waterproofing products allow moisture vapor to escape from the masonry while blocking liquid water infiltration.

Ask specifically what product is being used and whether it’s vapor-permeable (critical — a non-permeable sealer can trap moisture inside the masonry and accelerate deterioration). Reputable products include ChimneySaver and similar breathable masonry sealers.

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