I have a room that is on the back of my house at the same level as my walkout basement. I currently have only a French drain in the center of the room. I would like to put in a laundry sink and a proper floor drain in that room. The room has a concrete floor and the main 4" drain line from the house runs 2 feet below this room out to city sewer. The room is about 20 feet from the main stack in the house. If the sink and floor drain are each tied directly to the main line below the floor will they need vent lines? If so how would it be arranged?

Hi Macdee...

In my area you would be required to install a vent on both the sink and the floor drain...

In other areas of the country, the floor drain may not need to be vented, but for sure the sink will need to have a vent.

A ventless sink will gurgle and sputter and the p-trap can get siphoned out when a major fixture such as your toilet flushes water past the sink. This would allow sewer gasses into the home which is definitely a health hazard!

Anyway, check local codes in your area to determine if floor drain needs a vent... can always call the local plumbing inspector and ask him.

Let me know if you have more questions here...

MARK

Perfect advice from massplumber


If a vent is required for your floor drain, then it must be a separate vent that ties in at least six inches above the highest fixture flood rim. You can tie it into the sink vent(above flood rim) and take it either out through the roof , or tie it into a vent above all fixtures in the house. If you have more questions, I will try to help

I'm in MA so I assume both are required. But how would they be arranged. Would a single drain line run under the slab past the floor drain and out of the slab to the sink and vented to the roof be the way to go?

You may also be required to install Primer on your floor drain. Check with your local Plumbing Code.

Hiya neighbor!

In MA, the easiest way to do this will be to run 2" pipe for floor drain and then take a 2" vent off the drain line about 2 feet behind the trap and run that over to the sink. You will then stub out for sink (1.5") and then run the 2" vent up and out the roof.

The way I just described the piping arrangement is referred to as wet venting a fixture. Here, the sink drain acts as vent for the floor drain as well as a vent for itself. In Mass you need to roll the wye fitting for the vent ABOVE centerline of the horizontal drain pipe for floor drain. This is all legal in MA and will be easiest way to go!

The vent must penetrate the roof between 18" and 24" above the roof because we get so much snow.

Also, note that you need to use a LONG SWEEP elbow as you come out of the floor to pick up the sink and should attach a DANDY CLEANOUT just after you come out of the floor. This cleanout can face in toward cabinet as long as you provide opening in wall for it, or you can face cleanout away from sink as long as it is readily accessible.

Rarely, some inspectors will make you install a trap-primer as Milo has suggested you may need... this is city/town dependent and will be up to the plumbing inspector if you are pulling a permit (which you can't do.. plumber would have to do this for you in MA). If not pulling permit then you need to be sure to keep the trap wetted (filled with water) at least once a month or sewer gasses could escape into house and that is very unhealthy condition for you and family/friends!

Let me know if need more info. Here...

MARK