How would you plumb this basement bath?

**pghsebring** · 04-30-2011, 09:16 PM

I'm going to put in rough plumbing for a bathroom in the basement while i have the floor torn up. I drew up a diagram, i wonder how exactly you'd plumb this...the whole width of the bath is maybe 10' max. Its going to go in the corner of the basement...so here it is...this is the view from directly above, looking down at the basement floor...

I want a showerstall on the left, sink in the middle, toilet on the right...

Right now, there are no walls. I am going to put 6" stud walls up so pipes can be run through them with ease. Because we are pluming our upstairs bathroom which is directly over this one, we need to tie in the 3" drain stack from above too - it can come down the wall at the top of the picture, preferably near the current drain. Vents must go up the wall at the top of the picture. The current "trench" i have busted out of the concrete floor is indicated in the diagram - it is 25" wide. The lav drain spot should actually be in the wall i imagine...1.5" lav drain, 2" shower, 3" or 4" toilet...

The current drain runs at about a 60/120 degree angle to the wall...it is 4" clay...i wanted to use a donut in it, reduce it to 3" pvc for the whole bathroom...but am open to other ideas...

So, how would you connect the dots?

I could probably enlarge the trench if needed...

**cacher_chick** · 05-01-2011, 06:09 AM

You had better use some thought if you start cutting that much concrete slab away from the outer wall, as the slab is the only thing holding the bottom of the wall on the footing. When the ground gets saturated with water outside, that wall can get pushed inward off the footing and collapse. There are a lot of depending factors, but it does happen and it is a very bad thing.

As for the plumbing, I would run a main line from the toilet to the clay pipe and then run branch drains for the lav and shower at 90 degree angles into the new main line, attaching with combos. The lav drain and vent stack will come up inside the wall. The shower vent will come up inside the wall of the shower alcove.

The new main will need to attach to the clay with a wye also. I have never worked with clay, nor do I ever hope to, so I cannot help you there.

**jimbo** · 05-01-2011, 06:16 AM

The fly in the ointment is the vent. How do you plan to get a vent up to the roof!

**pghsebring** · 05-01-2011, 10:27 AM

Originally Posted by jimbo

The fly in the ointment is the vent. How do you plan to get a vent up to the roof!

Actually the room right above this area is also demolished right now, so i can easily run a vent up that "top" wall (in the picture), up the wall in the room above (nothing at all in that wall aside from one window to avoid) and up into the attic.

My main question is, how do i vent the shower and the toilet? I'm used to a shower ptrap then drain arm going into a sanitee and the top of the sanitee going up a wall...i don't see how that's possible here...

I understand what cacher is saying, and i think the lav drain will wet vent the toilet...but i'm not sure how to vent the shower...

...that, and getting both the stack from first floor bathroom, and the new main line into the clay line...

**cacher_chick** · 05-01-2011, 03:08 PM

The shower vent comes off the trap arm with a wye and 45 up into the wall of the shower alcove.

**pghsebring** · 05-01-2011, 03:29 PM

My problem is that the main line actually will run under the shower...so its kind of hard to jam all that in there...if the ptrap heads towards the top wall, it would cross through the new main line...if it heads towards the left wall it would cross the clay line...this would all be easier if the old clay main line wasn't running under the new shower area...

...i guess i'll have to buy a bunch of parts, nail down some absolute locations for the fixtures/drains, and have at it...i'll post a diagram when i figure out what i think'll work and you guys can review it...

I can wet vent the toilet with a 2" line for the lav, right?

hj · 05-02-2011, 08:21 AM

quote; I can wet vent the toilet with a 2" line for the lav, right?

Maybe. It depends on how you do the whole piping installation. You are trying a very ambitious project for a first time DIY task. Some plumbers would even have a problem doing it the easiest way.

**pghsebring** · 05-02-2011, 09:26 AM

Well, i already replumbed the kitchen, half bath, laundry room, and was working on the other full bath, all based on advice from here, when this problem popped up....i didn't mean for the elbow to break under the basement floor, but i figure i shouldn't let this opportunity go to waste...i had to rent a concrete saw one way or the other...so i might as well get my money out of it...

...i'll lock down exactly where the shower alcove is, where the walls will be, etc...go buy some parts from a box store, see what fits and doesn't...

**pghsebring** · 05-02-2011, 09:50 AM

If i can get this to work, is it acceptable?

**Terry** · 05-02-2011, 10:15 AM

The shower is not vented and will siphon.

**jimbo** · 05-02-2011, 01:25 PM

The shower is not vented, and since it turns apparently 180º the would want a cleanout

**pghsebring** · 05-02-2011, 03:17 PM

This damn main drain line running right under where the shower is supposed to go is making my life hell...any suggestions?

**cacher_chick** · 05-02-2011, 06:31 PM

Run the lav drain and vent as a vertical stack in the wall. If you are not going to vent the w.c. separately, the wye in the main for the lavatory needs to be the first thing down from the w.c., within 8 feet by my local code (yours may vary)

Run the shower trap arm parallel to the new main line towards the water closet. Use a long sweep to turn it towards the new main and bring the vent up out of the floor into the shower alcove wall using a wye/45 combo. Then continue the drain to another combo into the new main.

If you need to, you can jog the main line over with a 1/16 or 1/8 bend to get a little more room for the shower.

Think about different sized showers and how the dimensions will effect where the trap needs to be. The further you push your shower out, the more room you have to get your vent and drain to line up.

You will have to figure out where to run the vents in the overhead, as it will depend on the direction of the floor joists.

**pghsebring** · 05-02-2011, 07:16 PM

Originally Posted by cacher_chick

Run the lav drain and vent as a vertical stack in the wall. If you are not going to vent the w.c. separately, the wye in the main for the lavatory needs to be the first thing down from the w.c., within 8 feet by my local code (yours may vary)

Run the shower trap arm parallel to the new main line towards the water closet. Use a long sweep to turn it towards the new main and bring the vent up out of the floor into the shower alcove wall using a wye/45 combo. Then continue the drain to another combo into the new main.

If you need to, you can jog the main line over with a 1/16 or 1/8 bend to get a little more room for the shower.

Think about different sized showers and how the dimensions will effect where the trap needs to be. The further you push your shower out, the more room you have to get your vent and drain to line up.

You will have to figure out where to run the vents in the overhead, as it will depend on the direction of the floor joists.

So more like this?

**cacher_chick** · 05-02-2011, 07:24 PM

Yes... and the shower vent only need be 1.5"

Instead of 2 45's at the WC, think simpler.
Run the line from the WC at a 45 degree angle to meet a single 45 bend.