The vent terminal shall pass through the roof at least 24″ above the roof IF this roof is used for weather protection ONLY if used for any purpose other then weather protection then the pipe shall be 7 feet ABOVE the roof.
The minimum size of the roof terminal according to GOOD plumbing practices is 4″ diameter
( prevents hoar frost)
No vent terminal shall be located below any door or operable window or adjacent building with in 10 feet horizontally Unless it is at least 3 feet above the top of such opening.
NO EXTENSIONS shall run through an exterior wall (WINDOW)
Check your local codes but remember codes only set up minimum guide lines.
Please feel free to send me an E mail and ILL explain WHY we professionals install the vents in this manner.
[Edited by John Aldrich on 29 April 2001]