Hi,

We are going to install a bathroom in our basement. There are drain lines for a toilet, sink and a kitchen sink(which we intend to build a kitchen also). We were told that the drain lines need to have a trap under the concrete. The home is 1.5 years old. We just purchased it recently. We called the original builder and ask if a trap was placed under the concrete and was told no. do we need to dig up this co9ncrete and place a trap under it ? I am also wondering about venting this system. Is it posible to just tap into a sink or such up on the next level to satisfy venting, or just run a vent to the outside of the basement at ceiling height ? Any help would be appreciated

Trap below the concrete is required for tub, shower, and floor drain. You do not list any of those in your description of intended work. Then, do not worry about traps. Sinks have exposed traps. These traps are inside cabinet under the sink. Toilet has its own trap built into the china bowl.

You can combine all vents into one 2" vent and connect to the existing 2" vent on the floor above. This connection should be at about 48" from the floor and higher.There is also so called remodeling vent (Air Admittance Vent) that - if allowed in your area by Code - you could install at each sink and behind traps. These vents eliminate running vent up the wall and through the roof.

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Originally Posted by Milo Dolezal

Trap below the concrete is required for tub, shower, and floor drain. You do not list any of those in your description of intended work. Then, do not worry about traps. Sinks have exposed traps. These traps are inside cabinet under the sink. Toilet has its own trap built into the china bowl.

You can combine all vents into one 2" vent and connect to the existing 2" vent on the floor above. This connection should be at about 48" from the floor and higher.There is also so called remodeling vent (Air Admittance Vent) that - if allowed in your area by Code - you could install at each sink and behind traps. These vents eliminate running vent up the wall and through the roof.

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Thanks for the comeback. Yes there is going to be a shower,vanity with sink, and the toilet.
I am now wondering if I have to dig up the concrete at all if I need only a trap for the shower.
I understand the sink has a trap under it so that is not a problem. My only problem looks like the shower. I have a large drain probably 4"{ or so coming up from the floor and also a drain 2" for the shower. Another drain also comes up from the floor that can be used for the kitchen sink and vanity sink. If this is right let me know. Also wondering what I have to do to vent all of this. Thinking possibly that I can raise the shower and place a trap on top of the concrete without digging it up. I take it that the vent would also tap into one or all of the drain pipes that are there now. Thanks for your response. Any help would be appreciated so I can get the whole picture of what I have to do.

Pour water down the two inch line. Take a flash light and see if water stands in drain. If so, there is a trap in place. If not the rough in was either not done for a shower, or it was done wrong. For tub, or shower rough in, you would usually box in the drain areas so you could dig up the dirt(gravel) and install trap. Milo nailed it on the venting. If access to upstairs vent is not available, then you can run a vent up in a corner of a closet, or somewhere it would out of sight, or easy to box around. Run it up into attic and tie in in attic, or take out through roof. Never have liked the idea of side venting(out through the side of house), but that is due to the area I work in. gets to cold here, vents freeze. Just follow your local code and you will be fine.

Can you snap a photo of the area of new bathroom? Give us detail or two, too...