Ran across this situation today on a Warranty Inspection.
The picture show a plumbing vent in the attic. The vent runs horizontal for 20 - -25 feet across the attic to the vertical pipe that goes through the roof. Appeared to be plumbed to 4 incoming pipes.
First question: is this horizontal run allowed.
Second Question: The horizontal pipe appears to go downhill after the ‘tee’ fitting. So that in my opinion it would/could form a trap if rain water entered the vent from outside. I think you can see this in the first picture. This would be in need of repair, correct?
Third Question: If this setup caused the vent pipe to fill with water and form a trap, would that cause the attached fixture drains to drain slowly? The homeowner had showed me the last sink on the line and complained that it often seems to have a slow drain and backs up at the beginning of the inspection. It did not do it when I was there. It seems that intermittant blockage from rain water could explain this type of intermittant problem. Reasonable?
Any input or advice would be appreciated. Thanks in advance.