/ Field knowledge · IMC 805
A line labeled “chimney” is not a listed system.
Factory-built chimneys are listed assemblies from appliance connection to termination. Diameter is the last decision, not the first.
Educational 2024 IMC 805 from Daily Code Talk. Confirm adopted edition, listing, and manufacturer instructions.
- 805.1–805.3. Listed and labeled. Match appliance and fuel. UL 103 Type HT where required for dwelling-unit solid-fuel. UL 127 for factory-built fireplaces. Do not mix incompatible components.
- 805.4 / 805.5. Offsets: maximum 30° from vertical, maximum four elbows. Structural members that support the chimney must be designed for the added load.
- 805.6. Flue-gas temperature over 1,000°F at the chimney entrance → UL 959. Entrance temperature, not just input or pipe size.
- 805.7. Decorative shrouds only if listed for that system.
- 805.8. Insulation shield; code-built path uses minimum No. 26 gage steel; attic shield at least 2 in above insulation; secured against displacement.
Source: 805 recap · metal: IMC 806 / NFPA 211 · shrouds: 805.7 · offsets: 805.4–805.5 · tool: chimney pathfinder.
If the set only says “chimney”
Send the appliance listing, the routing, and whether this is factory-built or metal. Masterbuild will say whether 805 or 806 is even on the path.
Send Project Background+1 (786) 398-6940 · osmany.portal@masterbuildconsulting.com
Masterbuild provides engineering services under a written scope. Nothing on this page is project-specific engineering advice, a code interpretation for your project, or a representation about permit approval.