Horizontal Vent - Two Building Inspectors, Two Answers

I recently had my rough plumbing inspections for a new bathroom in my addition.

The first inspector to come out didn't see any problem with my vent system (but had me move an unrelated trap, hence the visit from the second BI for the correction). When the second BI came he was very unhappy that the first inspector approved my use of a sanitary tee rolled 45 degrees off of a horizontal 2" drain for the vent. (In the previously approved section).

He said I need to use a wye or combo-t-wye rolled 45, not a san-T. Since he is not allowed to re-inspect he could not force me to correct it. Being the home owner and not wanting to install a defect into my new bathroom I asked what the consequences, and associated likelyhood, of using the wrong TEE are. He said there is a pretty small chance of the san-T clogging the vent.

I spoke to a friend who is a general contractor and he said it won't matter, but I want to get the forum's opinion & advice.

One other tid-bit of info: The horizontal runs (with 1/4"/ft slope) are all in the crawl space and I probably do not have the vertical clearance to put a wye or combo in.

Thanks in advance for your inputs.

I probably do not have the vertical clearance to put a wye or combo in.

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In a crawl space you don't have room?

But the question is, will it work?
I plumbed the first twenty years that way, and then they changed to wyes and combo's on their backs.
The main reasoning they changed, was that people would add plumbing to vents, and the santees on their backs were "not" the right fitting for that.
So they decided that anything below the overflow level would be run as waste fittings. That way the future was guaranteed to work.

Hi Terry,

Thanks for the info. Regarding the crawl space clearance - as my main line rises towards the bottom of the floor joists the clearance decreases. Since I have to roll the vent 45 up any vent line coming off of that that isn't parallel to the joists won't work.

But the main point is - it sounds like using the san-T won't cause a problem in my application as long as one day someone doesn't decide to use that vent as a new drain.

Thanks again.
Jonathan

I've often wondered why you have to roll the fittings 45 deg. If it's a vent, it's mostly air in there, plus the occasional rainwater that's found its way into the stack. In either case, rolling it to a 1/4" slope should be sufficient.

Below the flood rim of the fixtures it serves it may get loaded with the nasty glop if there is a clog hence the requirement for more than minimum pitch.

vent

The 45 degree rule is to minimize the possibility of waste backing up into the vent during a high flow condition, and then staying there without something to wash it out. Many requirements, such as the horizontal vent being a minimum 42" high, are geared to the possibility that it could be used for something else some day.