Chapter 8 now moves to the component between the appliance and the chimney or vent: the connector. A connector is more than pipe between two points - its location, size, material, length, slope, support, pass-through, and clearance affect draft, safety, and inspection readiness.
Plain-English Overview
IMC 803 addresses: when connectors are required; location and minimum sizing; branch connections and dampers; multiple-appliance connections; connector materials and thickness; supports and joint fastening; maximum horizontal length; chimney liner connections; wall pass-through systems; minimum pitch; and clearance to combustibles.
For plan review, the permit set should show the complete path from the appliance flue collar to the vertical chimney or vent. The reviewer should be able to verify appliance and fuel type, connector size and material, horizontal length and slope, supports and joints, chimney or vent connection, wall penetrations, combustible clearances, and manufacturer requirements.
IMC 803 Six-Part Series
Part 1 (803.1-803.4) Connector Fundamentals: when connectors are required, permitted locations, sizing, and branch connections. Part 2 (803.5-803.7) Dampers and Multiple Appliances: manual and automatic damper requirements and connection order where multiple appliances enter a common vent or chimney. Part 3 (803.8 / 803.9) Connector Construction: vent connector materials and required thicknesses for low-, medium-, and high-heat appliances.
Part 4 (803.10.1-803.10.3 / 803.10.5) Installation Geometry: supports, joints, horizontal length, liner connections, thimbles, and minimum upward pitch. Part 5 (803.10.4) Connector Pass-Through: prohibited penetrations, listed assemblies, and Systems A through D for combustible walls. Part 6 (803.10.6) Clearances to Combustibles: required connector clearances, appliance listing requirements, and reductions under IMC 308.
Why It Matters
Connector deficiencies can cause poor draft, combustion product leakage, excessive heat exposure, creosote buildup, carbon monoxide risk, and chimney fires. Common plan and field issues include: reduced connector size; excessive horizontal length; missing upward pitch; unsupported joints; improper wall pass-through; inadequate combustible clearance; connector extending into the flue; and incorrect material or thickness.
Field Tip
Trace the connector from the appliance collar to the chimney or vent. If its size, material, length, slope, support, connection, penetrations, and clearances are unclear, the installation is not fully reviewable.
Masterbuild QA Lens
Most 803 rework does not come from missing a single requirement - it comes from the connector path never being traced start to finish on the permit set. Before submittal, walk the connector the same way a field inspector will: collar to chimney, checking size, material, slope, support, and clearance at every point along the way.
Next: Daily Code Talk #149: IMC 803.1-803.4 Connector Fundamentals (1 of 6).