I am installing a freestanding tub on my main floor master bathroom. There wasn't any kind of tub in this bathroom previously - it only had a shower. I cut a few holes in the ceiling in the basement to do the plumbing work. My question is about the drain for the new tub. The tub will be positioned roughly in between the sink and the shower. Through the ceiling holes I can see where the drain pipe from the sink runs through the joists and where the shower drain connects to it then continues on it's way. For the new tub drain I'm installing, can I simply cut and "T" into the drain pipe in between the sink and where the shower drain connects to the pipe?

 

1st I would cut one nice big rectangle in the ceiling instead of many small holes. It will make patching the sheetrock much easier and allow you better visibility and access for your work. Cut on the center of the joist so there is half a joist to rest the new sheetrock on.

No, you can not use a "T". You should use a wye and a 1/8 bend like the line going to your shower.

The big issue is venting. Where is your plumbing vent(s)? You need to have a vent within 5 pipe feet of the tub's trap assuming that is 2" drain line.

 

Thanks for the first two suggestions. These holes were just my first exploratory holes and I planned on consolidating them. And I mistyped when I said "T". I was planning on the 1/8. But thanks because even still, your suggestions clarified a couple things for me.

The venting is what I'm mainly wondering about. This is a 2" drain line and I don't know where the vents are. I was hoping to not cut out more drywall to find them or put a new vent in. But whatever must be done, I will do. Please see this new image I just attached that shows the lengths pipes and how close this new tub will be.

 

Your drain plan looks reasonable.

For venting, is there an attic above this bathroom? Usually, the vent is from the sink, but with the spacing, it's definitely pushing the distances having only one vent. Where is the toilet in this bath?

 

Finding an existing vent won't help. Even if there is a vent at the sink and shower they are both two far away from the new tub's location. You'll need to install another vent.

Is there an interior wall nearby? You could cut out the sheetrock in one joist bay. Drill through the top and bottom plates and get a vent line up into the attic. Then you can tie it into your other vents so you don't have another hole in the roof. I would not run a vent in an exterior wall because you'd have to remove a slot of insulation to make room for the pipe.

 

Thanks to both of you. Here's a new image that shows where the toilet is, but more importantly where the shower wall is. It's right above where I'm working. The shower wall goes all the way to the ceiling. Does this look like a good plan for the vent?

 

Yes, it looks like a vent there would be well within the distance requirement.

 

Thank you, I really appreciate the help!

 

Agreed!
But as mentioned before - you'll connect to your new vent with a combo wye, not a tee. (but you probably already knew that!)

Good luck!