IMC 802.5 and 802.6 establish two different height checks: how high the vent terminates above the roof, and how much vertical vent height exists above the appliance. Passing one does not mean the other is satisfied.
Plain-English Highlights
Section 802.5 requires Type L vent terminations to be at least 2 feet above the highest point where the vent penetrates the roof, and at least 2 feet higher than any portion of the building within 10 feet - both conditions must be satisfied, measured from the actual surrounding building geometry rather than a generic roof detail. For plan review, verify nearby roof ridges, parapets, higher roof levels, penthouse walls, dormers and projections, and adjacent building portions within 10 feet.
Section 802.6 requires vents to provide at least 5 feet of vertical height above the highest connected appliance flue collar, supporting the draft needed to convey combustion products outdoors. Exceptions apply to direct-vent appliances, outdoor-listed appliances with integral venting, and pellet vents, each installed per the appliance and vent manufacturer's instructions - the exception shifts the design criteria to the applicable listing and manufacturer instructions, it does not eliminate the venting basis.
Permit Proof Chain
Appliance flue collar elevation identified -> vertical vent height measured to the highest connected collar -> 5-foot minimum confirmed or applicable listed exception documented -> roof penetration point located -> 2-foot roof clearance and 2-foot/10-foot building clearance checked against actual surrounding geometry -> termination height and location shown in both plan and section.
Where To Show It
M-001: termination height and manufacturer criteria. M-101: appliance location and vent route. M-501: roof penetration and termination details. M-601: appliance schedule with flue collar elevation and vent type.
**Do** - Verify both Type L roof-clearance conditions against the actual surrounding building geometry, not a generic detail. - Show the 5-foot minimum vertical height measured from the highest connected flue collar. - Identify the specific listing basis when a Section 802.6 exception applies. - Check the vent in section as well as in plan.
**Do Not** - Apply the 2-foot / 10-foot rule without checking nearby roof ridges, parapets, and adjacent building portions. - Measure the 5-foot height from the floor or the appliance base instead of the flue collar. - Assume a listed appliance eliminates all termination requirements without checking its specific listing. - Leave final termination height to field adjustment.
Masterbuild QA Lens
Check both height rules independently and record both results. A vent can clear the roof by 2 feet and still fall short of the 5-foot minimum vertical rise, or the reverse - meeting one does not imply the other.
Drawing / Submittal Check
Compare the roof plan against the appliance schedule's flue collar elevation. Confirm the section view shows the vertical rise from the collar to the termination, and confirm the roof plan shows every building portion, ridge, and parapet within 10 feet of the termination.
Common Review Risk
A vent termination is shown clearing the roof deck by 2 feet in a typical detail, but the actual roof has a parapet or higher adjacent section within 10 feet that was not checked against the drawing. Separately, the 5-foot minimum is measured from the appliance base rather than the flue collar, understating the vertical rise actually achieved.
When To Escalate
Escalate any termination near a parapet, higher roof level, penthouse wall, dormer, or adjacent building portion within 10 feet, any vertical rise close to the 5-foot minimum without a clear collar-to-termination measurement, any Section 802.6 exception claimed without the specific appliance or vent listing cited, and pellet vent terminations without their manufacturer-based height criteria documented.
Field Tip
Check the vent in section, not only in plan. One view should confirm the vertical rise from the appliance collar, and another should confirm the termination height relative to the roof and nearby building surfaces.