IMC 802.3 and 802.4 reinforce a core venting principle: the vent and appliance manufacturer's installation instructions are part of the design basis, not a substitute for one.
Plain-English Highlights
Section 802.3 requires vent systems to be sized, installed, and terminated in accordance with both the vent manufacturer's installation instructions and the appliance manufacturer's installation instructions. For plan review, verify vent size, vent type and material, maximum allowable offsets, horizontal and vertical routing, required slope, joint and fitting requirements, support spacing, clearance to combustibles, penetration details, and termination location and configuration.
Both manufacturers matter: the appliance manufacturer establishes the acceptable venting method for the equipment, and the vent manufacturer establishes how the listed vent system must be assembled, supported, routed, and terminated. Where the requirements differ, the design needs to resolve the conflict rather than leave it to field interpretation.
Section 802.4 requires Type L vents to terminate with a listed and labeled cap installed in accordance with the vent manufacturer's instructions - the termination cap is part of the listed vent system and should be compatible with the vent type, diameter, and installation condition.
Permit Proof Chain
Appliance and vent manufacturer instructions obtained -> vent size, material, and type confirmed against both instruction sets -> offsets, routing, slope, joints, and support spacing documented -> clearance to combustibles and penetration details coordinated -> termination location selected and matched to a listed, labeled cap for the vent diameter and type -> conflicts between appliance and vent manufacturer requirements resolved in the design before submittal.
Where To Show It
M-001: vent installation and manufacturer coordination notes. M-101: appliance location and complete vent routing. M-501: joints, offsets, supports, penetrations, clearances, and termination cap. M-601: appliance schedule with vent type and size. Roof plan: vent termination location and surrounding conditions. Specifications: listed vent system and manufacturer requirements.
**Do** - Coordinate the appliance and vent manufacturer's instructions before finalizing the vent detail. - Show vent size, route, support, and termination together on the same detail. - Specify a listed and labeled Type L termination cap matched to the vent diameter and type. - Resolve any conflict between the two manufacturers' requirements in the drawings, not in the field.
**Do Not** - Use an install-per-manufacturer note as the only venting design information on the drawings. - Select the vent size without checking the appliance manufacturer's requirements. - Leave offsets, supports, or termination configuration to field selection. - Specify a generic or unlisted cap at the vent termination.
Masterbuild QA Lens
Treat the termination cap as a listed component with its own compatibility requirement, not as a finishing touch added after the vent route is set. Confirm the cap's listing matches the vent type and diameter before the roof or wall detail is accepted.
Drawing / Submittal Check
Compare the vent manufacturer's installation instructions and the appliance manufacturer's installation instructions side by side. Confirm offsets, slope, support spacing, and clearances shown on the drawings fall within both sets of limits, and confirm the specified termination cap is listed for the exact vent type and diameter installed.
Common Review Risk
A vent detail follows the vent manufacturer's generic support and offset limits but does not check them against the appliance manufacturer's more restrictive venting instructions, or vice versa. Separately, a roof plan shows a vent termination with no cap specified, leaving a listed-system component undocumented.
When To Escalate
Escalate any conflict between the appliance and vent manufacturer's installation instructions, offsets or routing that exceed either manufacturer's stated limits, missing or unlisted termination caps, and any vent installation where support spacing is not documented against the manufacturer's requirements.
Field Tip
A manufacturer note does not replace a coordinated design. The drawings should still show the vent size, route, support, clearances, and listed termination cap needed to verify compliance.