Plumbing vent Routing Question

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.

Olympia Dr - October 26, 2006 021 (Custom).jpg

Olympia Dr - October 26, 2006 022 (Custom).jpg

Olympia Dr - October 26, 2006 023 (Custom).jpg

Horz run is allowed. It should slope to the drain at 1/4" per foot (just as a drainline is required to slope).

After that, nothing else really matters. It needs correction and could potentially cause drainage issues with the drain lines it serves.

I wouldn’t speculate as to rain water or anything else for that matter. Just recommend appropriate repairs.

Thanks for confirming for me, Jeff.

I was speculating more for my information than to include specific speculation in the report.

Back up…is this a vent pipe or a drain pipe?


Here’s the specific reference and commentary. . .

Last picture shows what appears to be an air conditioning duct. It does not appear to be installed properly. Maximum sag should be nor more than 1/2 foot per meter. That sag looks greater than that.

That is not a sag it is travelling down to the ceiling vent. Though sagging is not that uncommon around here with the soddy way the flex duct is installed.