A vent terminal is 7 feet horizontally from an openable window. Under UPC 906.2, what is required?

The vent must terminate at least 3 feet above the window. Section 906.2 requires each vent to terminate at least 10 feet from, or at least 3 feet above, an openable window, door, opening, air intake, or vent shaft. At 7 feet horizontally, the 10-foot distance is not met, so the vent must terminate at least 3 feet above the window.

A vent stack passes through part of a roof deck used for parking. Under UPC 906.3, how must vents within 10 feet of the parking area terminate?

At least 7 feet above the roof and securely stayed. Section 906.3 prohibits flagpoling vents except where the roof is used for assembly purposes or parking. Vents within 10 feet of a part of the roof used for assembly or parking must extend at least 7 feet above the roof and be securely stayed.

In a location where frost closure is likely and the design temperature is below 0°F, a 1-1/2-inch vent reaches the roof. What does UPC 906.7 require?

Increase the terminal to at least 2 inches inside the building at least 1 foot below the roof in an insulated space, and extend it at least 10 inches above the roof. Section 906.7 requires vent terminals of at least 2 inches, but never smaller than the required vent, where frost or snow closure is likely at design temperatures below 0°F. The increase in diameter is made inside the building at least 1 foot below the roof in an insulated space, and the terminal extends at least 10 inches above the roof, or as the AHJ requires.

Vent Terminations: Roof Height, Clearances, | Free Guide 2026

Key Takeaways

Each vent terminates vertically at least 6 inches above the roof and at least 1 foot from any vertical surface (UPC 906.1).
A vent must terminate at least 10 feet from, or at least 3 feet above, any openable window, door, opening, air intake, or vent shaft (UPC 906.2).
A vent must terminate at least 3 feet in every direction from a lot line, alleys and streets excepted (UPC 906.2).
Vents within 10 feet of a roof area used for assembly or parking must extend at least 7 feet above that roof and be securely stayed (UPC 906.3).
Where frost closure is likely at design temperatures below 0°F, vent terminals are at least 2 inches, enlarged at least 1 foot below the roof, and extended at least 10 inches above the roof (UPC 906.7).

Why Termination Rules Matter

The vent terminal is where sewer gas leaves the building. Its location keeps that gas away from people and air intakes, and its size keeps it from freezing shut. A vent that closes with frost or snow cannot protect trap seals. Every vent through the roof must also extend undiminished in size (905.4) and be flashed watertight (906.5 and 312.8).

Roof Terminations (UPC 906.1 and 906.3)

906.1: Each vent pipe or stack extends through its flashing and terminates vertically at least 6 inches above the roof and at least 1 foot from a vertical surface.
906.3: Vents, whether separate or combined, extend full required size at least 6 inches above the roof or fire wall.
Flagpoling (a vent pipe standing high above the roof) is prohibited, except where the roof is used for assembly purposes or parking.
On such used roofs, vents within 10 feet of the used area extend at least 7 feet above the roof and are securely stayed.

Clearance to Openings and Lot Lines (UPC 906.2)

Condition	Required clearance
Openable window, door, opening, air intake, or vent shaft	At least 10 feet horizontally away, or at least 3 feet above it
Lot line	At least 3 feet in every direction; alleys and streets excepted

How to apply 906.2: Measure horizontally from the terminal to the opening. If that distance is less than 10 feet, the terminal must be at least 3 feet higher than the top of the opening.

Example: A vent terminal is 6 feet horizontally from a dormer window whose top is 2 feet above the roof surface at the vent. Because 6 feet is less than 10 feet, the vent must terminate at least 3 feet above the window top, which is 5 feet above the roof at that point. The 6-inch roof minimum is not enough here.

Outdoor Installations (UPC 906.4)

Vent pipes for outdoor installations extend at least 10 feet above the surrounding ground and are securely supported.

Flashing and Waterproofing

906.5: Joints at the roof around vent pipes are made watertight with approved flashings or flashing material.
312.8: Roof joints around pipes use lead, copper, galvanized iron, or other approved flashings. Counterflashing may not restrict the vent's required internal cross-sectional area.
906.6: Sheet lead used for flashings or vent terminals is at least 3 pounds per square foot. Safe pans use at least 4 pounds per square foot.

Frost or Snow Closure (UPC 906.7)

Where frost or snow closure is likely in locations with a minimum design temperature below 0°F:

Vent terminals are at least 2 inches in diameter, and never smaller than the required vent pipe.
The change in diameter (the increaser) is made inside the building, at least 1 foot below the roof, in an insulated space.
The terminal extends at least 10 inches above the roof, or as the AHJ requires.

The larger terminal holds warm, moist air longer and resists building up enough frost to close. Putting the increaser inside the insulated space keeps the transition warm. Whether a Washington location's design temperature falls below 0°F is a local design condition, and the AHJ may set how the rule is applied.

Other Vent Terminal Rules

1008.1: A building trap's relieving vent or fresh-air intake terminates above grade in a screened outlet outside the building. It need not be larger than half the diameter of the drain it connects to.
710.10: A sump vent may extend separately through the roof or combine with other vents. An air-operated ejector's vent may not combine with other vents.
803.3: A vent from indirect waste piping may not combine with a sewer-connected vent. It extends separately outdoors.
1017.1: Oil interceptor vapor vents are at least 2 inches and are independent of the sanitary vents.

Termination Checklist for Part 1 Questions

At least 6 inches above the roof, and 1 foot from any vertical surface?
At least 10 feet from openings, or at least 3 feet above them?
At least 3 feet from lot lines (streets and alleys excepted)?
Used roof (assembly or parking) within 10 feet? Then 7 feet high and stayed.
Cold location below 0°F design? Then a 2-inch minimum terminal, enlarged 1 foot below the roof inside insulation, extending 10 inches up.
Full size through the roof, and flashed watertight?

Washington Journeyman Plumber

9.1 Vent Terminations: Roof Height, Clearances, Used Roofs, Outdoor Vents, & Frost Closure (UPC 906)