Hello new to forum.
I'm looking to put a full bath room into our basement. My main drain is under ground and I have no existing fixures. I've located where the main runs though the basement and plan on cutting into the drain in two places. One to hook up the toilet and the other to hook up the bathtub and sink. First question is with the toilet hooked up alone do I need a vent? Second question is where do the vents need to be for the bathtub and sink? The sink would be first and tub second. Can I then take the vent and run it over the main vent stack and tap into it?

I know I'm getting to some major concrete busting and pipe splicing. The work I'm capable of doing its making sure I'm getting my pipes in the right spot I'm not.

I've attached an autocad drawing converted to jpg to help show what I'm talking about.

Thanks
James

Yellow indicates pipes with the long yellow one being the main waste drain under the floor.

Hey James,

First question is with the toilet hooked up alone do I need a vent?
In my area,no, but check local codes. Some areas mandate a vent on each fixture.

Second question is where do the vents need to be for the bathtub and sink? The sink would be first and tub second. Can I then take the vent and run it over the main vent stack and tap into it?

Let me lay it out for you. Toilet to connect to the main. Lavatory to connect to the toilet and a vent off the lav. The tub to connect to the lavatory drain and be wet vented by it.

You MAY NOT connect the lavatory vent to the stack vent, (which is not a vent stack when fixtures discharge into it) You must run the lav vent up through the roof or tie it back to a existing dry vent stack. However,
If codes permit you may install a Oatey AAV( Air Admittance Vent.) in place of a regular vent. Good luck on your project. Tom