3" drain through structural wall.

[Pardner]

I recently purchased a house that was being used as an office. Previous owner removed the
bath tub, but assured me there was one there at one time. I am trying to do the majority of
the work myself; not my first bathroom, but far from a professional.

My first project was to remove the drywall under the bathroom and inspect the existing
plumbing and to my horror, the floor joists in the second floor run perpendicular to the floor
joists in the first floor (opposite of what I expected).

So, the bathroom is on the second floor, it is a 60"x74" with a toilet and a sink:
https://drive.google.com/file/d/0B3Vhk3HHFW2oWU1VbjBod0JWakk/view?usp=sharing

I would like to shift the sink and the toilet to make room for the tub:
https://drive.google.com/file/d/0B3Vhk3HHFW2ob1h6dHpzWWdXQUU/view?usp=sharing

Under the bathroom, there is a structural wall and 2" x 8" floor joist running North/
South. The toilet drain runs along one of the floor joists, then snakes behind one of the
split joists: https://drive.google.com/file/d/0B3Vhk3HHFW2oWkdfUWY0UmU4TGs/view?usp=sharing

So now if I shift the toilet over 32" to make room for the tub... I have nowhere to run the drain!
https://drive.google.com/file/d/0B3Vhk3HHFW2oQUV0WGtOZXltZEE/view?usp=sharing

I am guessing it's not possible to run a 3" drain through a double top-plate structural wall, but I
wanted to present that idea. I was planning on putting in another floor joist in the 25" gap, run
the toilet drain down through the structural wall (through the double top plate), nailing a stud
strap on either side of the top plate where the drain cuts through the top plate, add stud
directly under the new floor joist

Now, I have not started cutting/hacking anything. Only the drywall in the 1st floor ceiling is down.
I was hoping to get some opinions on how/where to run the toilet drain. Please don't answer
"call a professional contractor/plumber/engineer". I wanted to get some opinions and educate
myself before I talk to the pros.

Thank you very much for reading my post... more thanks for input!

 

[cda]

Welcome

I am far from qualified

Give it a few days, for replies

 

[Robert]

Hi Pardner, not sure which code you are using but here in CA the toilet requires 1'-3" clear from its centerline to a wall or tub.

 

[steveray]

Plates are way more forgiving than joists....You would just have to use a structural strap to repair....They make a combo strap/ nailplate piece that works well....
Simpson PSPN516Z (16 gauge ZMAX) at top plates

 

[north star]

~ ~ & ~ ~

Pardner,

Also, ...Welcome to The Building Codes Forum !

A 3" pvc pipe has an outside diameter of 3.5", so essentially
you will be cutting the exterior wall, double top plates almost
completely thru.

You are allowed to do this, but as **steveray** mentioned,
you must use an approved type of nailing strap such as the
Simpson-Strongtie PSPN516Z strap at the top and bottom plates.
See Page 5 in this Link: https://www.madison-heights.org/DocumentCenter/Home/View/186

I too would add a 2" x 4" on both sides of the cut plates.


~ ~ & ~ ~

 

[SCBO1]

There's also an offset toilet flange available if you fur-out the wall that might be useful. just saying

 

[Francis Vineyard]

 

[classicT]

Plates are way more forgiving than joists....You would just have to use a structural strap to repair....They make a combo strap/ nailplate piece that works well....
Simpson PSPN516Z (16 gauge ZMAX) at top plates

Just at Steveray said, use a Simpson PSPN516Z strap at both top and bottom plates and add a stud either side of the stack.

But as Robert identified, you must meet the separation requirements for the toilet - 15" from CL each way.

 

[Francis Vineyard]

IRC Interpretation No. 15-03; https://www2.iccsafe.org/cs/committeeArea/pdf_file/RE_00_15_03.pdf