IMC 803.10.4 is where connector routing becomes a fire-safety issue. A chimney connector cannot simply pass through any wall, floor, or ceiling on its way to a masonry chimney.
Plain-English Highlights
Chimney connectors cannot pass through floors, ceilings, or fire-resistance-rated wall assemblies. For domestic-type appliances, connectors also cannot pass through combustible walls or partitions unless an approved method is used. Three compliance paths are available: a connector listed for wall pass-through and installed per manufacturer instructions; a listed wall pass-through device; or a connector not larger than 10 inches installed using Table 803.10.4.
Table 803.10.4 provides four systems - System A with 12-inch clearance, System B with 9-inch clearance, System C with 6-inch clearance, and System D with 2-inch clearance - each with specific requirements for liners, insulation, supports, airspace, connector construction, and attachment; the clearance dimension alone does not establish compliance.
Additional requirements include noncombustible penetration seals, listed clearances and thicknesses treated as minimums, concealed metal exposed to flue gases resisting corrosion and temperatures up to 1,800 degrees F, and, except for System B, the connector extending to the inner face of the flue liner.
Permit Proof Chain
Wall, floor, or ceiling assembly identified at every connector pass-through, including fire-resistance rating and combustibility -> compliance path selected (listed wall pass-through device, listed connector per manufacturer instructions, or Table 803.10.4 for connectors 10 in. or smaller) -> specific System A through D selected and its clearance, liner, insulation, and support requirements matched -> noncombustible penetration seal confirmed -> connector-to-flue-liner connection confirmed at the inner face except where System B applies.
Where To Show It
M-001: connector pass-through criteria. M-101: connector routing and wall locations. M-501: listed pass-through or Table 803.10.4 detail. A / LS sheets: wall construction, ratings, and combustible materials.
Do
Identify wall construction and rating before selecting the pass-through method. - Use a listed system or a specific Table 803.10.4 system (A, B, C, or D). - Show the required clearances, liner, insulation, and noncombustible sealing for the selected system. - Coordinate the pass-through detail with the architectural and life-safety drawings.
Do Not
Pass a chimney connector through a floor or ceiling. - Penetrate a fire-resistance-rated wall assembly with an unlisted connector. - Treat the Table 803.10.4 clearance dimension as the only requirement. - Improvise a combustible-wall penetration in the field without a documented listed system.
Masterbuild QA Lens
Improper pass-through details can expose combustible framing to high temperatures or compromise rated construction - the result can be ignition, concealed fire spread, flue gas leakage, and failed inspections. This detail requires mechanical, architectural, and life-safety coordination, not a mechanical-only sign-off.
Drawing / Submittal Check
When a connector reaches a wall, review the assembly, not just the pipe. Confirm wall type, fire-resistance rating, selected pass-through system, and required clearance are all shown together before approving the penetration.
Common Review Risk
A connector detail cites a Table 803.10.4 clearance dimension without identifying which System (A through D) is being used - the clearance number alone does not establish which liner, insulation, and support requirements actually apply, so the detail cannot be verified as complete.
When To Escalate
Escalate any pass-through through a floor or ceiling assembly (not permitted), any fire-resistance-rated wall penetration without a listed assembly, any Table 803.10.4 application that does not name the specific System, and any concealed metal detail that does not address corrosion resistance and the 1,800 degree F exposure requirement.
Field Tip
When a connector reaches a wall, review the assembly, not just the pipe. Confirm wall type, rating, pass-through system, and required clearance before approving the penetration.