Drain / Vent Layout Question

philwgreenJuly 25, 2013

In the process of building a garage addition that has living space above. There is a single bathroom on the second story with a lav, toilet and shower. The bathoom is 12' long with the toilet and shower on opposite ends. The main stack will pass up through the wall next to the shower.

Just getting ready to start my rough in and wanted to run my dmv diagram past everyone here. My main questions are:

1. First off, does this diagram look correct or am I way off?
2. There is a utility sink on the first floor, I know I can't vent it using the bathroom lav drain but can it connect to the lav vent in the attic? And can that vent tie back into the main stack or does it need its own roof penetration? In my drawing I have it going up through the roof.
3. My toilet is roughly 12' from the main stack so I've added a vent. Would a 2" vent be sufficient for the toilet?

Any help/feedback is appreciated.

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You can possibly install a wet/dry vent. Depending on where you live code might allow a Air Admittance Valve. This would eliminate cutting holes in the roof and give you more options.

Good Luck

Here is a link that might be useful: Toilet ventilation system

    Bookmark   July 27, 2013 at 7:01PM
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The toilet vent must rise vertically from the drain line (it appears to start horizontally in the drawing)
I believe you may tie the lav vent line into the main stack vent 6" or more above the flood line of any other fixture on that vent, providing you do not exceed the permissible fixture units on that vent (which yours does not)
A 2" vent for the water closet is adequate (and is the minimum allowable)

    Bookmark   July 30, 2013 at 10:58AM
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