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moondog111 04-18-2008 04:20 PM

Vent pipe where new window wants to be

I am remoldling my kitchen and want to put a 9' wide bay window where the kitchen sink is. The house is 2x4 framing with a brick veneer. A vent pipe for the sink is built into the kitchen exterior 2x4 wall, continues up through the second floor exterior wall and out the roof through the attic.

How do I use this existing pipe and detour around my window. I understand the concept of building a wet wall that carries my vent horizontally through the cripple studs under the window. But what do I do when I get to the jack stud that is supporting my new massive header? I have seen the metal brackets which allow you to cut a hole in a stud to pass a pipe through, but what about this case where the jack studs will be supporting a 9' header carrying another story?



Boston Plumber 04-18-2008 04:44 PM

Hi Rob:

Tell me is there a sink going back in this same location...? If not, then just run new vent with new sink hook up.

If sink going in same place, depending on local codes, just need to drill smallest holes possible, run pipe under new window, past/through jack studs, and then run pipe vertical into attic without returning over window to pick up old vent. Then in attic can attach the re-routed vent into the old vent.

I know it sounds like it should not be..but I have been doing this all my life and have never had any problem with drilling these studs as long as I kept hole as small as possible in relation to the pipe size.

In this case, may be appropriate to reduce the vent to 1.25" vent pipe (allowed by code).

I would also call the local building inspector just in case he has decided that this is not allowed in "his town/city"...;) It happens sometimes. Always easier to just call him and ask him.

One other idea is to run the vent through the cabinets and then up the outside wall into attic, and again connect vent in attic.

That is what I have for now..anything I missed..?


moondog111 04-18-2008 05:01 PM

Thanks Boston,

The new sink will be in slightly different location from old, but I was trying not to cut into the 2nd story wall with a new stack.

I take it that if I am above the "flood" level of the kitchen sink, I can run horizontally beneath my window sill, then through the jacks with potentially a 1-1/4" pipe, then up past my header, and then when I get into the ceiling, I can run horizontally back through the floor joists and reconnect to the old stack?


Cajun1 04-18-2008 07:22 PM

Is there any reason you can't put a Studor valve there?

Termite 04-18-2008 10:11 PM

Assuming you have 2x4 studs, there's no way to run that pipe through the trimmer and kingstud without "overdrilling" them. 40% of the stud's depth is the biggest hole you can drill, and you must maintain 5/8" spacing from the hole to the edges of the stud. The good news is that you can still do it....

Simpson Strong Tie and USP connectors both make a product commonly called stud shoes. There are light ones and heavy ones. With a 9' header sitting on those studs, you should use the heavy version. They come with SDS screws to attach them to the stud. The shoe fits over the stud like a saddle, and the heavier ones actually have a "flap" that folds up around the pipe. The lighter ones that are commony available at home depot and plumbing supply houses are not intended for studs that bear significant loads...Don't use them in this situation.

As for a Studor vent, there's no reason you couldn't use one. It wouldn't be the best way though. A piped vent is almost always a better way to go.

Ron The Plumber 04-19-2008 12:37 AM

Yep, we drill out below the sill plate, code says if your below the flood level rim, your vertical to horizontal 90 can be a med turn 90 but the horizontal to the vertical pipe needs top be a LT 90. Check and see if your state allows them, some do some don't.

moondog111 04-19-2008 06:47 PM

Thank you all,

I will get the Simpson heavy duty Strong Tie. If I run into problems tieing into the existing stack, it's nice to know Virginia is approved for the Studor Valve.

Thanks again,


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