Under unamended 2021 IPC Section 903.5, an open drainage vent terminal is not directly beneath a door, openable window or air intake. What clearance rule applies relative to such an opening on this or an adjacent building?
- AAt least 4 feet horizontally, unless at least 2 feet above the opening’s top
- BAt least 25 feet horizontally, with no height alternative
- CAt least 10 feet horizontally, unless at least 1 foot above the opening’s top
- At least 10 feet horizontally, unless at least 3 feet above the opening’s top
Where to look it up
https://www.ncosfm.gov/b-1-2024-ncpc/open
Why D is correct
Section 903.5 prohibits a terminal directly beneath the specified openings. Otherwise, it requires 10 feet of horizontal separation unless the terminal is at least 3 feet above the opening’s top. The height alternative does not cancel other applicable termination requirements. The 3-foot figure is the 2021 model value; do not confuse the NC comparison’s proposed 2-foot replacement with a general statement about earlier model editions. See PDF p.125. Reference: unamended 2021 IPC base text reproduced in the official OSFM comparison, https://www.ncosfm.gov/b-1-2024-ncpc/open