# Signs Your Chimney Liner Is Damaged or Cracked > Flue tile shards in the firebox, draft problems, and CO concerns can signal liner damage. The warning signs and how a scan confirms. URL: https://westhartfordchimneyrepair.com/guide/signs-your-chimney-liner-is-damaged/ Last-Modified: 2026-07-01 concern guide # Signs Your Chimney Liner Is Damaged or Cracked Flue tile shards in the firebox, draft problems, and CO concerns can signal liner damage. The warning signs and how a video scan confirms. ![Broken clay flue tile shards in the bottom of a fireplace firebox](/images/featured/broken-clay-flue-tile-shards-in-bottom-of-fireplac.webp) Your chimney’s flue liner is the layer that keeps combustion gases inside the chimney and away from your home’s structure. When it’s damaged — cracked clay tiles, corroded metal liner, gaps at the joints — heat and carbon monoxide can escape into wall spaces and framing, and chimney relining [/chimney-relining/ →](/chimney-relining/) is the fix. Here’s how to spot a compromised liner. ## Sign 1: Flue Tile Shards in the Firebox The most obvious sign. If you find pieces of terracotta or clay tile in the bottom of the firebox, they came from a cracked flue tile above. This is a stop-using-the-fireplace-until-inspected situation. ## Sign 2: Draft Problems That Don’t Improve After Cleaning Smoke back-up that a chimney sweep doesn’t fix often traces to liner damage — cracks that disrupt the smooth interior flow, gaps that leak draft pressure, or partially collapsed sections that restrict airflow. ![Technician viewing a cracked flue liner on a video-scan monitor](/images/misc/technician-viewing-cracked-flue-liner-on-video-sca.webp) ## Sign 3: Carbon Monoxide Alarm Activity Especially when the alarm goes off during furnace or fireplace operation and there’s no other obvious cause. Cracked liners are a leading pathway for CO to escape the chimney into the home. See our CO safety guide [/guide/chimney-carbon-monoxide-safety/ →](/guide/chimney-carbon-monoxide-safety/) for what to do. ## Sign 4: Water Stains on Adjacent Walls A cracked liner lets rainwater that enters through the top penetrate through the chimney walls into your interior. Water stains on walls next to the chimney chase, especially after storms, can indicate liner damage combined with a cap or crown problem. ## Sign 5: Signs of a Prior Chimney Fire Chimney fires often damage liners without homeowners realizing. Signs from a past fire: - Puffy, honeycomb-textured creosote - Warped or discolored damper - Cracked or missing pieces of flue tile - Discolored exterior brick above the roof - Bulging or separated masonry Any of these means a Level 2 inspection immediately, and probably relining. ## Sign 6: Aging Metal Liner Corrosion If your chimney has an existing metal liner and it’s more than 20–30 years old (or was installed on an oil appliance without proper corrosion resistance), the liner may be corroded through in places invisible from the firebox. ![Level 2 video scan revealing a damaged clay tile with missing mortar joints](/images/misc/level-2-chimney-video-scan-revealing-damaged-clay-.webp) ## How Damage Gets Confirmed Every one of these signs requires a **Level 2 video inspection** to confirm. See our inspection levels guide [/guide/chimney-inspection-levels-explained/ →](/guide/chimney-inspection-levels-explained/) for details, or book directly. The video scan drops a camera down the flue and shows you exactly what’s happening — cracks, gaps, corrosion, missing mortar. We record it and share it with you. ## What Happens Next If the scan confirms damage, we recommend one of two options based on the extent: - ** HeatShield cerfractory sealant [/guide/stainless-steel-liners-vs-heatshield/ →](/guide/stainless-steel-liners-vs-heatshield/) ** for mostly-sound clay tile with cracks or joint problems - **Stainless steel sleeve** relining for structurally failed liners Both restore safety and drafting. See our chimney relining service [/chimney-relining/ →](/chimney-relining/) for details. ## Book an Inspection Any suspected liner damage means schedule an inspection this week — before the next fire. Contact us [/contact/ →](/contact/) or read more about our inspection service [/chimney-inspections/ →](/chimney-inspections/) . Related Service ## Chimney Relining & HeatShield Stainless steel liner installation and HeatShield cerfractory repair to restore structural integrity and safe drafting in cracked or deteriorated flues. Learn About Chimney Relining [/chimney-relining/ →](/chimney-relining/) ## Common Questions ### How do I know if my chimney liner is cracked? + Tile shards in the firebox, poor draft, smoke issues, and CO alarm activity are common signs. A Level 2 video scan confirms. ### Is a damaged liner dangerous? + Yes. It can let heat and carbon monoxide reach the home and adjacent framing. It needs to be relined before continued use. ### How is liner damage confirmed? + An interior video scan shows cracks, gaps, and corrosion the eye can't see from the firebox or the top of the chimney. ## Related Guides ### Do Gas and Oil Appliances Need a Chimney Liner? decision stage [Do Gas and Oil Appliances Need a Chimney Liner? →](/guide/do-gas-and-oil-appliances-need-a-liner/) ### Stainless Steel Liners vs HeatShield Relining Explained definition [Stainless Steel Liners vs HeatShield Relining Explained →](/guide/stainless-steel-liners-vs-heatshield/) ## Ready to Take the Next Step? Book a sweep, schedule an inspection, or ask us a chimney question. We reply within one business day. Schedule Now [/contact/ →](/contact/) Call (860) 305-5234 [tel:+18603055234 →](tel:+18603055234)