Mike58
New Member
I am an owner builder and it is time to plumb the drains (actually, it has been time to do that for longer than I want to admit).
The idea is for the main drain (3") to run horizontally under the floor joists and through the foundation out to the septic tank. This means that for the shower, I have to run a vent horizontally under the floor to get to a wall to run up through the roof. My understanding is you are not supposed to run a vent horizontally until it gets up to about 4" above the flood level of the fixture it is venting. However, that seems like a good trick for a shower with a drain that is in the crawlspace of a ground floor.
The attached picture shows the layout and has my questions. I don't think distances are an issue, as no runs are more than about 3 feet. The main drain (3") has a cleanout at the far end, so the cleanout question is really just about whether the horizontal vent should have its own cleanout (which I would rather avoid, unless ...). The 2" verticle vent in the exterior wall will go up through the roof. Thanks for any help you can give me on this.
The idea is for the main drain (3") to run horizontally under the floor joists and through the foundation out to the septic tank. This means that for the shower, I have to run a vent horizontally under the floor to get to a wall to run up through the roof. My understanding is you are not supposed to run a vent horizontally until it gets up to about 4" above the flood level of the fixture it is venting. However, that seems like a good trick for a shower with a drain that is in the crawlspace of a ground floor.
The attached picture shows the layout and has my questions. I don't think distances are an issue, as no runs are more than about 3 feet. The main drain (3") has a cleanout at the far end, so the cleanout question is really just about whether the horizontal vent should have its own cleanout (which I would rather avoid, unless ...). The 2" verticle vent in the exterior wall will go up through the roof. Thanks for any help you can give me on this.