Basement tile shower (drain) install - converting existing floor drain

Discussion in 'Shower & Bathtub Forum & Blog' started by nbarr7, Mar 13, 2014.

  1. nbarr7

    nbarr7 New Member

    Messages:
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    Location:
    minnesota
    Redirected here from the johnbridge forums...

    Ok, I've found a lot of helpful information that is similar to my situation, but nothing that seems to quite match exactly, and rather than piece conflicting things together, I thought I would simply state my circumstances to see if I can get a more complete recommendation. Here goes...

    We recently bought our first house (built in 1972) and we're completely ripping out and redoing a bathroom in the basement that was done almost entirely wrong. The toilet and vanity function perfectly fine (both run into the main stack witch happens to run through the corner of this bathroom). The shower is the area I have questions about.

    First some basic info. The basement floor is poured concrete. There is a 6" cast iron floor drain with a clean out plug in this bathroom already (we live in rural Minnesota so we have a septic system, incidentally). I'm considering ways I can adapt this area into a tiled shower (previous owners were basically using this drain as it is for a rudimentary "shower" and I'm interested in redoing it more correctly.)

    I'm planning on using the vapor barrier/cbu method for the walls, and was considering some variation of the deck mud/membrane treatment for the floor, as there is already considerable 'pre slope' in the concrete as it is. I guess my question revolves around the best actual drain solution since I realize there is some demolition involved and I want to make sure I know what I'm getting into before I start busting up the floor. So...

    My main question I suppose revolves around the 'venting' issue... I've read about people breaking up concrete, removing the cast iron drain/trap then using a shielded clamp/coupling to attach their shower drain piping to the cast iron pipe. What might be the recommendation in terms of venting in this situation? The floor drain is only about 5' from the main stack, but the clean out plug is on the opposite side of the drain, which I assume means the plumbing underneath runs that direction (i.e. away from the stack, but towards the septic system itself, I suppose, and actually towards the other floor drain in the basement about 10 feet away which is close to the washer and dryer).

    I'm trying to absorb a lot of new information here, so my apologies if these questions appear... uneducated...
  2. cacher_chick

    cacher_chick Test, Don't Guess!

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    Disregard that there is a floor drain, except to aknowledge that you will likely have to remove it and at least some of it's drain line. You will need to determine where the drain line is, before you can determine how the connection will be made. There will need to be a new vent rising vertically from the new shower drain line, between the shower trap and it's connection to any existing drain line, and this vent will need to go through the roof or tie into an existing vent above all of the existing fixture drains which are connected to it.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
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    The floor drain may not have a trap, and adapting a shower drain to it because of the size means, it really does need to come out.

    Ideally, your shower drain will go in the middle of your new shower, and you should plan to move it there. The shower drain line needs to be 2" to mate up with most any shower drain, but it can go into a bigger pipe without issues. The problem you may have is how deep the line runs - you must have enough depth to install the trap, then get 1/4" per foot slope to where you can connect it to the existing drain line. On a 2" line, you must run the vent line within 5' of the trap (if I remember properly), and the drain line cannot turn down before you get the vent line turning up.

    As mentioned, the vent needs to go up, and it could be all alone to the roof, but if you revent it into an existing one, the code says it must be at least 42" above the floor of the drains above, OR 6" above the height of the flood rim, whichever is higher. That means, you could revent it in the attic, but you don't have to go that far, if it's easier.

    Sounds like you're planning a conventional, liner-type shower. Those work fine if you follow all of the rules. I prefer one with a surface membrane, but they tend to cost a bit more in materials, but because everything beneath that surface membrane stays dry, the whole shower dries out quicker. Not a big deal to many, but it is an issue for some.
  4. nbarr7

    nbarr7 New Member

    Messages:
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    Location:
    minnesota
    Thank you both for your replies - the floor drain does have a trap, and I believe it's already vented, though I've always been working under the assumption the drain needs to come out, yes. You're referring to a vent 6" higher than the flood rim of the highest fixture in the house, yes?

    At this point I haven't been researching the Kerdi-type system much, mostly because of the cost, quite honestly, though I can understand the benefits...
  5. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Do you know the size of the drain line hooked up to this 6" drain you mention?

    In Vancouver a 3" P-Trap and 3" drain line does need to be vented. I have in my mud room a 3" Ptrap that runs into my main waste stack and directly above it I bushed down from 3" to 2" and installed a Kerdi Drain over top. I plan to install an nice Linear drain over that one day when I finally get around to tiling that room.

    You could convert the old 6" drain (you have) to any clamping drain and do the same - Noble Company has a nice selection to choose from. Then you need to install your liner (assuming you have proper pre-slope) and flood test.
  6. nbarr7

    nbarr7 New Member

    Messages:
    7
    Location:
    minnesota
    I don't know the size of the drain line, unfortunately - it is original to this house (built in 1972 - in rural Minnesota. Standard 70's split) and appears to run directly towards the septic under the concrete floor (the main stack is further 'upstream' if you will). The 6" I refer to is merely the size of the drain opening at the floor (the cast iron 'bowl' as it were). There is a cast iron (I assume) 'vent' pipe that comes up through the floor in this same room which lines up directly beneath the abs vent pipe that runs through the roof (someone somewhere back through the years cut the abs pipe off at the ceiling! I'm assuming this should be re-attached...) My 'pre-slope' definitely exceeds the 1/4 per foot ratio, but it's almost too severe to provide comfort while standing, so I'd like to even it out a bit and then add a liner. And yes, the drain is close to centered, but not quite, so it may be nice to move it over.
  7. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
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    Location:
    North Vancouver, BC
    No need to change the pre-slope. Leave it steep.

    Change the drain.

    Install the liner.

    Do a flood test.

    Then add your mud bed - at this step you can adjust the slope so it's less severe.

    If your budget opens up consider using a linear shower drain. The ones from ACO are my favourite! ;)
  8. nbarr7

    nbarr7 New Member

    Messages:
    7
    Location:
    minnesota
    I could leave the pre slope as long as the clamping drain extends high enough to accommodate the less severe slope of the new mud pan...
  9. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,406
    Location:
    North Vancouver, BC
    Once you install the new clamping drain it will have an adjustable strainer. You will want a good 1.5" - 2" of mortar bed over top of this.

    So if you have for example a slope of 1/2" per foot now and switch to a 1/4" per foot later you will do this change in the mortar thickness.

    You might have 2" of mortar around the drain and 1.5" of mortar at the edges of your shower. This of course on top of the new liner.

    Do not go lower than 1.5" - 2".

    If you go to the Noble Company Online Store you can order your liner, your drain and also order a tube of Noble Sealant 150 and two outside dam corners. They will ship it all to your house for only $5.00

    Email Nelson for more help: Nelson Wilner nwilner@noblecompany.com He will put you in touch with the right sales girl and right tech support person
    Last edited: Mar 14, 2014
  10. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
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    Location:
    North Vancouver, BC
    Thanks for the Private Message NBarr. If I answer your question via a private message then now one else will benefit from the answer.

    You may not need to bust out the old P Trap if you can crack the portion of cast pipe above it cleanly.

    Any chance you own a 1" demo hammer?
    Last edited: Mar 15, 2014
  11. nbarr7

    nbarr7 New Member

    Messages:
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    Location:
    minnesota
    I don't own a demo hammer, but a local hardware store rents things of that nature. I'm sure it's possible to get one.

    Is there any way the p trap wouldn't run the same direction as the clean out plug?

    In other words, I have what I assume to be a cast iron version of this:
    Floor-Drain-with-Cleanout-Plug.jpg
    Last edited: Mar 15, 2014
  12. cacher_chick

    cacher_chick Test, Don't Guess!

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    Location:
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    That was my assumption, and the reason why I stated that you will need to remove it. You might be able to tie into that drain line IF the floor drain was vented as per the current plumbing code. There were things done 50 years ago that do not meet today's standards.

    This is the last part of a shower build that you would want to realize you did wrong later.
  13. nbarr7

    nbarr7 New Member

    Messages:
    7
    Location:
    minnesota
    House is circa 1972. 42 years old already, I guess...
    Last edited: Mar 15, 2014
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,139
    Location:
    New England
    FWIW, even with a permit, sometimes the inspections are not that comprehensive. Keep in mind that the codes are constantly being updated as experiences and situations and materials science advance. The codes are designed to handle many of the 'what-if' situations that people run into...what MIGHT work in one situation may not work in all, and the codes have learned how to adjust to account for those changes.

    For example, old toilets drained quite slowly, so the fittings they used didn't really matter much. Today, using maybe 25% of the water, to get them to flush, they must move the water much faster, and those fittings used back then that worked, no longer do in things like back-to-back toilet installations. Yet another (true in the USA), shower drains must be 2" (or larger), where they used to be 1.5" (and still can be in Canada). Another, used to be able to plumb a washing machine standpipe with 1.5" pipe - the tub style washing machines drained water fairly slowly. Update to today, when a front-loading WM might spin at MUCH higher speeds, and it can throw the water out faster, which can also cause more sudsing along the way, and you need a bigger pipe to work.

    All this to say, you won't know how it is plumbed until you start to tear things out. Procedures call for the changes to meet today's codes. The inspector has the last word, and he might allow deviations, or he may not. On a 2" pipe, you need your vent to come off within (I think) 5' to work properly. So, depending on which way the line runs, and whether it is vented or not already, you may need to deal with the vent separately.
  15. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Location:
    North Vancouver, BC
    I think that's a safe assumption.

    When we dig up a drain embedded in concrete we drill holes down through the concrete so we can bust out the floor easier. With a demo hammer and a 5/8" drill bit this work is done quickly. I do not want to hit the drain pipe so we drill a few holes away from where we think the drain line is (opposite side - left side if we where looking at your picture above) then slowly chip away at the concrete.


    You need to cut the old cast iron pipe. Small chain breaks are great but a few cast iron saws-all bits can do the job. Then its a no-hub connector and new drain and your back off and running.
  16. nbarr7

    nbarr7 New Member

    Messages:
    7
    Location:
    minnesota
    Ok, so just as an update as to where we went with this (for better or for worse). We used a reciprocating hammer drill with a masonry bit to drill holes spaced approximately an inch or so apart on every side of the cast iron drain (except the side with the clean out plug - to avoid hitting the pipe) Then using a masonry chisel my great-grandfather made about 60 years ago and a sledgehammer, we busted out an oval of concrete maybe 16" by 12". This was enough to reveal the entirety of the drain and trap (and its connection). In this case, the floor drain used 2" pipe, which ran into a rubber bushing/doughnut that fit into a housing on the 3" cast iron line. (The 3" line itself met the main drain line only about 5-6 inches back from this point). So we were able to pry the drain out of the existing rubber bushing, purchase a new identical bushing (from a plumbing specialty store NOT one of the big chain stores), and then run a standard 2" clamping pvc shower drain and trap into this new bushing. No cutting cast iron required. Backfill with wet sand, and fill the hole with cement.

    The center of the drain itself is maybe only about 10" from the main line, and it connects to the main line only about 5' away from the main stack/vent. I know it was recommended to vent this drain individually, but in this case there wasn't really room between the drain and the main line.

    I don't know that this information will be helpful to anyone, but I wanted to report what we found when we busted up the floor. And of course thank everyone for their advice/expertise.
    Last edited: Mar 29, 2014
  17. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,406
    Location:
    North Vancouver, BC
    Thanks for the feed back.

    One other thing you can do is check the flow rate of your new drain line. We like to hook up the shower's new water lines and dump them full blast into the new system. To do this you can make a simple sump or use some scrap 2" or 1.5" ABS or PVC pipe.

    Run the water down your new drain. Can it handle the max flow rate? If so it must certainly handle the lesser flow once the fixtures go in with their pressure balancing gizmos and water restrictors.
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