Liner size by appliance outlet & standard clay-tile sizes
Typical published planning values — NOT a certified spec or professional advice. The 1/10–1/12 flue rule, the 3-2-10 height rule, creosote stages, NFPA 211 inspection levels, clearances and cost bands vary by chimney and appliance; confirm your exact dimensions and follow the manufacturer’s instructions and local code. Creosote, chimney fire, carbon monoxide, structural and code judgement are a CSIA-certified sweep / licensed mason / NFPA 211 / local-code matter — have a certified professional inspect; never a step-by-step procedure or medical advice here.
This companion gives the LABELED recommended liner diameter by appliance outlet (match the outlet — a modern wood stove is usually 6") and the standard clay flue-tile nominal sizes with their approximate inside area, so you can convert an opening or an outlet into a real, buyable size. Measure your own outlet and confirm the manufacturer’s instructions. It backs the flue-liner-size calculator and the wood-stove flue-size calculator.
Recommended liner by appliance outlet
| Appliance / outlet | Typical outlet (in) | Outlet area (in²) | Recommended liner (in) |
|---|---|---|---|
| Modern wood stove / insert | 6 | ~28.3 | 6 (insulated) |
| Larger wood stove / high output | 8 | ~50.3 | 8 (insulated) |
| Wood-fireplace flue (by opening) | per rule / listing | — | per opening / manufacturer |
| Gas appliance (Cat. I) | per rule / listing | — | per opening / manufacturer |
Standard clay flue-tile nominal sizes
| Nominal clay tile | Approx. inside area (in²) | Round-equivalent d (in) | Suits opening up to ~ (in²) |
|---|---|---|---|
| 8x8 | ~28–33 | ~6 | ~330 |
| 8x12 | ~55–68 | ~9 | ~615 |
| 12x12 | ~87–99 | ~11 | ~930 |
| 12x16 | ~120–135 | ~13 | ~1,275 |
| 16x16 | ~140–160 | ~14 | ~1,500 |
LABELED planning snapshot — match a liner to the appliance outlet (never smaller), confirm the manufacturer’s instructions, and round a required area UP to the next standard tile or liner. Snapshot: 2026-07-14.