Adding Shower drain in Basement

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by finesstan, Feb 9, 2006.

  1. finesstan

    finesstan New Member

    Messages:
    12
    Location:
    Texas
    I'm in the process of adding a shower drain in my basement. My house is fairly new only 2yrs old. I had rough ends for toilet and sink added in during initial contsruction but now I would like to have a shower also. Can anyone give me the best approach as to adding the drain. Can I tap into the existing cleanout stack that runs above the concrete slab or would I be better off breaking the concrete to connect shower drain up with cleanout plumbing below.

    Thanks! Derrick
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,133
    Location:
    New England
    Break the concrete up and run a new drain line. Depending on how the vents are located, you probably will have to also run a new vent line. A shower drain needs to be a 2" run until it can run into a larger pipe. Ideally, it is also centered in the shower floor area.
  3. prashster

    prashster New Member

    Messages:
    941
    I'm doing a whole bathroom in my basement. I'm not a pro, but I've done a lot of research, and here's my 2c:

    I believe the right way to do it is to trench through the concrete floor. You have to put a trap under the shower drain and have enough fall to your main stack, so if you don't trench, you'd have to raise the shower base.

    Here's how I'd do it:

    Call yr construction office and make sure your slab is about 4" thick with no rebar or mesh, etc in it.
    Cut the sides of the trench with an electric concrete saw and a diamond blade. Rent these from a tool rental co. Cutting first will give you nice neat lines and avoid overbreaking the floor. Some may counsel you to use a regular circ saw or masonry blades. But my experience is that this will save only a few bucks, and it makes the job much harder.
    Chip out the center of the trench with a 'demolition hammer'. Don't use a rotary hammer that doubles as a demo hammer. It takes too long. Use something that draws at least 11-15 amps. You can use a fullblown electric j-hammer (breaker hammer) but for a novice concrete demo-er, the demo hammer is a little less unwieldy.

    Don't try to save money by renting smaller equipment. It makes the job much more difficult than it's worth.
    Last edited: Feb 9, 2006
  4. finesstan

    finesstan New Member

    Messages:
    12
    Location:
    Texas
    Thanks for the adive. If I decide to take the easy route by raising the shower base how would I tap into the clean out stack. Would I add a (T) just above the grade to attach the drain for the shower? I know I would need a 2" trap beneath the shower drain so I'm assuming I would need to rasie the shower base at least 6" minimum?

    Or should I still stick with forming a trench thru the concrete?
  5. prashster

    prashster New Member

    Messages:
    941
    Personal opinion: raised will feel less sturdy and sacrifices head room.
    Take the extra time and do it the right way. If you don't have far to trench, you could easily cut the lines of the trench in the c-crete and then break up the meat with a sledge manually.

    Then tie in to the existing drain (you do mean 'drain' right? not 'cleanout'?) under ground. I assume you thought about venting, right? In the long run it's cleaner.

    IF you tie in above ground to the drain, I'd guess you have to come in on a downslope and the fitting alone would put you a few inches above ground already.
  6. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,358
    Location:
    Yakima WA
    Building a floor up to gain the height to slope a drain is never a good choice. Spend a little time now and have a job you can be proud of showing off instead of one you will always have to explain and make excuses for. As far as the trenching is concerned, if the trench will be entirely under the shower, you don't have to worry about the clean lines on the edges, they won't show or affect the finished floor anyway. If you do need the clean edges, then all you need to do is score the lines before you break the concrete. It's your call on what saw to use. Personally, I'd use my circular saw with a masonery blade and make several passes. If there is rebar or mesh in the concrete, you can cut that as you come to it with a small grinder. As far as the tool to use, I have my own 3 function hammer/drill, and that's what I use for all minor concrete work including chiseling and drilling for anchors. This was $100 very well spend even though it only gets occasional use. I suppose if I had to rent one, maybe I'd go a tad larger, but again it's your call. It is a dusty job, so close off the area as best you can. This is a job where all of the safety equipment is important. Wear a face mask, ear protection, and goggles. As previously noted, shower drains must be 2", trapped, vented and, like all drains, have a minimum 1/4" per foot slope. If you are going to use a one piece shower stall, set it in a mortar base. This will really firm up the base and it will last longer.
  7. finesstan

    finesstan New Member

    Messages:
    12
    Location:
    Texas
    Thanks again! OK, you talked me into breaking up the Concrete. Here is a picture I attached just the give a lay out of what I'm trying to do. On the picture you can see where I plan to trench into the existing Clean-out beneath the c-crete. As far as venting I assumed the Clean-Out line is already vented thru the house plus the venting on the sink rough-in is connecting up with the clean-out line below the C-crete. Please let me know if this is the best approach.

    Attached Files:

  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    drains

    1. Not all cleanouts can be used for a drain connection.
    2. No cleanouts are vented.
    3. You have to rethink what you plan to do.
  9. finesstan

    finesstan New Member

    Messages:
    12
    Location:
    Texas
    Sorry, I'm a first timer. I didn't word my plan correctly. I plan to tie into the waste line drain beneath the concrete slab not the clean out. I'm assuming the waste line drain is vented along with the sink rough-in that is connecting beneath the slab also. On the picture there is a pipe which is coming from my first floor and going into the concrete. The (T) that comes off of it I'm hoping is for the sink.
  10. prashster

    prashster New Member

    Messages:
    941
    From one first-timer to another

    I appreciate what yr doing; I'm doing it myself too. Kudos to ambition. That being said, you need to get some good books on plumbing code before you go any further.

    To me, venting was the most difficult thing to grasp. I would originally have thought what you think, but I've been given advice from experts (namely, HJ and Gary) and have read everywhere that every single fixture needs to be individually vented. If you don't do this, there are many reasons why the shower trap may fail to work properly. In your proposed configuration, I'd speculate that the toilet draining past the shower branch could pull water out of the trap, or that if the shower is far enough from the drain, draining water from the shower could siphon out its trap.

    I assume you'll build a wall between the shower and the drain, so that'd be a convenient place to put the shower vent. That vent line can join the sink or toilet or main vent line along the ceiling of the basement. You don't have to run a separate, dedicated vent out the roof - just a separate branch to the fixture.

    Also, I defer to Gary's experience with a hammer drill, but for what it's worth, I used an SDSMax rotary hammer which is a quite a bit more powerful than a hammer drill, and it still took reasonable effort to drill and chip out a sump hole. I drilled 1/2" holes on the perimeter of the hole and chipped out the center. I will say, though that it made for a neat job, and was virtually dust free. I think, though, in the end it's worth the extra $ and clean up to saw and chip with a larger hammer. The less stress you can put on your back, the better (IMHO).

    BTW, where's the toilet vent? Am I missing something?

    PS: I'm jealous your main drain exits the house below the slab! I have to use a pump.
    Last edited: Mar 1, 2006
  11. finesstan

    finesstan New Member

    Messages:
    12
    Location:
    Texas
    Thanks again for advice. As far as the toilet vent I don't know where that is. What you see in the picture is pretty much the rough-ins for 1/2 bath (sink and toilet. I don't know if the plumber left of the toilet vent by mistake during the initial contruction. Or there's a possibilty it could connect up with sink vent beneath the slab. I'm sure the plumber could have not forgotten to add toilet vent on????
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    vent

    There are too many possibilities as to how the piping could be arranged under the floor to try to tell you how to do it, until you actually open the floor and see where, and which way, the drains run. That vertical pipe next to your new shower location could be the drain from the upstairs, in which case your drain would need a new vent connection, or it could be the vent for the basement toilet. Not likely, but if it is, then your location to connect the shower drain would have to be reconsidered.
  13. prashster

    prashster New Member

    Messages:
    941
    If your house is new - like mine - the township construction office should have the plumbing diagrams. At the very least, they'll have the name of the plumber who installed it. Before you do a lot of exploratory destruction, I'd check there for a possibly easy answer.
Similar Threads: Adding Shower
Forum Title Date
Plumbing Forum, Professional & DIY Advice Adding shower to bathroom.... Jan 8, 2014
Plumbing Forum, Professional & DIY Advice Shower panel conversion connections adding a shut off valve. Sep 29, 2013
Plumbing Forum, Professional & DIY Advice Adding Fixed Showerhead to Kingston Brass Tub/Shower Faucet Mar 12, 2013
Plumbing Forum, Professional & DIY Advice adding shower to 1/2 bath - questions around drains Jan 29, 2012
Plumbing Forum, Professional & DIY Advice Adding shower to powder room? Dec 30, 2009

Share This Page