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2nd floor bathroom

yojimbo2 | Posted in Construction Techniques on April 20, 2008 03:55am

Currently reviewing plans on a remodel project.  It calls for a bathroom on the 2nd floor.  It will be located at the back of the house, farthest point from the street.  The walls are 2×4, and the floor joists on the 2nd floor will be 2×10.  This is my first project with a 2nd floor bathroom, I just don’t see how to plumb in the drain lines with these framing limitations.

I was thinking of increasing the wall framing to 2×6, that way I would have enough wood left to run the 3″ drain line.  Does a 2×10 give you enough space for your toilet and shower p-traps?  If not will a 2×12 suffice?

I see 2×4 construction all the time with 3″ drain lines blowing through bottom and top plates.  That always made me wonder about the integrity of the wall.

I would love to know this info before I consult with the sub.

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  1. MSA1 | Apr 20, 2008 04:44am | #1

    Way not enough info. Do the joists at least run the right way or do you have to cross 5 of them to run the tub drain?

    As long as your running PVC you should be able to get a stack in a 2x4 wall.

    As far as wall integrity you are supposed to run an 18ga steel plate on at least one side of a top plate that is cut for things like plumbing & HVAC. I dont remember if that applies to non bearing walls though.

  2. Jim_Allen | Apr 20, 2008 06:55pm | #2

    Have any of those houses with the walls "compromised" fell down? If so, I would avoid it.

    Bob's next test date: 12/10/07

    1. yojimbo2 | Apr 22, 2008 04:50am | #3

      good point.  Know what the minimum joist is for the toilet p-trap?

      1. Jim_Allen | Apr 22, 2008 05:18am | #4

        I've known a lot of houses having 2x8 floor systems but 2x10 is more typical. Bob's next test date: 12/10/07

        1. yojimbo2 | Apr 22, 2008 06:01pm | #5

          thanks for your replys, much appreciated.

      2. Shacko | Apr 22, 2008 08:58pm | #6

        Toilets do not have p-traps, they are built into the toilet,[S-TRAP].

        1. yojimbo2 | Apr 23, 2008 06:34am | #7

          you are right, I totally forgot about that.

          1. Billy | Apr 25, 2008 08:18am | #8

            You were thinking of a pee-trap, right?  ;-)

            And the s-trap... we won't go there...

            Billy

            Edited 4/25/2008 1:19 am ET by Billy

      3. Piffin | Apr 30, 2008 06:25pm | #18

        If you mean space elevation, I have fit them into a 2x6 space over concrete or a timberframe exposed 

         

        Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

  3. fingersandtoes | Apr 26, 2008 03:37am | #9

    You can get the trap for a tub or shower into a 2"x8" joist space quite easily.

    A 3"abs pipe fits into a 3 1/2" stud space, but its couplings don't. So if you have any connections in the wall, you've got difficulties.

    Cutting out a section of the top and bottom plates effectively leaves you with two shorter walls. If you block them appropriately, they are fine. The metal strapping is to protect against mechanical damage like drywall screws or nails. (I assume you are talking about interior walls, since the drains can't be lead through exterior ones.)

    1. yojimbo2 | Apr 26, 2008 04:50am | #10

      I was not aware that you could not run drain lines down an exterior wall.  Makes sense though, and I was referring to exterior walls.

      1. MMitrano | Apr 26, 2008 06:47am | #11

        We added a second story with 2 baths to what had been a cape,  and I did the plumbing.  Thoughts to consider:

        - You may fit the el below the toilet into a certain joist debth, but you have to allow for the pitch of the horizontal line within the floor to where it hits the stack, AND the curve of the sanitary tee where the horizontal run connects to the stack.  My stack was in the center of the house and I the toilets were about 12' away against the outside walls.  I used 4" PVC (no clogs in this house) and I needed 2 x 10 joints to make it work.

        - This also allows more space to pack fiberglass insulation around the drain pipe and in the bay, so that every flush is not clearly audible in the room below if that is a concern.  (We have one bathroom above the LR and the other above the DR.)

        - If you can, plan the fixture layout to that the toilet waste line remains in one joist bay from the fixture to the stack.  Then you won't be drilling huge holes in your beautiful new joists.

      2. fingersandtoes | Apr 30, 2008 12:41am | #12

        "I was not aware that you could not run drain lines down an exterior wall"

        I don't know where my head was. The restriction only applies to water supply pipes, not drains. Sorry. You should probably check your local plumbing code.

        1. yojimbo2 | Apr 30, 2008 01:49am | #13

          I have seen water supply lines in exterior walls.  Is this restriction because of nailing from the siding and the possibility that you could pierce a line with an 8d nail from a gun?

          1. Nathar | Apr 30, 2008 02:30am | #14

            I would assume it's because of the threat of freezing pipes.

          2. plumbbill | Apr 30, 2008 04:55am | #15

            It's a freeze protection code---- & different locals have different codes.

            Plenty of plumbing in 2x10 floor joist.

            If you have any specific questions feel free to ask, but a floor plan with joist direction would be helpfull.

            “The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.” —Albert Einstein

          3. fingersandtoes | Apr 30, 2008 07:21am | #16

            As Nathar says it's the freezing pipes. They used to let you put them in 2"x6" walls with rigid on the exterior side, but now not even that passes. That means lots more rough-ins for sinks and toilets are in the floors. Makes for a messy holes in  the vanity as the drain is usually on the back wall.

    2. Nathar | Apr 30, 2008 05:50pm | #17

      Looking over an attic renovation plan right now, that includes putting in a bathroom. The architect drew the finished space of the bathroom to be 5' 10" wide, with a 5' tub, and some extra "space" for plumbing at the end of the bathtub. The "wet wall" for the tub is an interior wall, but it is directly adjacent to the exterior wall (the side of the bathtub is the exterior wall).

      My question is, do we need that extra space for the plumbing? We could easily make the bathroom 6' wide, and then have room for a 6' tub. The only issue then is that all the plumbing has to fit in the 2X4 wall space. Is this an issue? This is essentially new contruction.

      1. fingersandtoes | Apr 30, 2008 08:01pm | #19

        I find this all the time on plans. A 2"x6" wall behind the toilet, or as you say just some space "for plumbing". It reflects the designers rather sketchy knowledge as to how a bathroom is actually plumbed.

        Above the floor level, none of the pipes exceed 2". The toilet has no plumbing in the wall behind it at all, and if you can't get everything needed for tub, vanity and shower into a 2"x4" wall something has gone wrong.

        The only instance where additional space is needed is if there is something in the floor below the wall, such as a flush beam or duct, that precludes you running plumbing there. Don't see why a 6 ft tub wouldn't work.

         

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