Toilet Installation - New Construction

Discussion in 'Toilet Forum discussions' started by techinstructor, Apr 3, 2011.

  1. techinstructor

    techinstructor New Member

    Messages:
    81
    Location:
    North Carolina
    We are doing our rough plumbing and need to install the toilet flange at the proper height to allow for the thickness of the floors. We are planning to use 3/4" hardwood floors, but we need some advice as to how to install the toilet flange so that it will not have to be removed later when the flooring is installed.

    Our thoughts were to install a square of 3/4" plywood that would be slightly larger than the flange diameter but smaller than the width of the toilet base. Then the hardwood flooring could be butted up against plywood. Consequently the plywood and the flange could remain in place when the finished floor is installed.

    Are there materials other than plywood that would work better in this application? We've thought about polypropylene - if we could find a 3/4" piece. Any suggestions?

    We are also concerned about moisture getting under the toilet, either from leaks (hopefully not) or from condensation caused by the cool water in the bowl. Years ago, my husband heard of a pad of some polymer that was installed under toilets to prevent any moisture from getting onto the floor. Does anyone know what this is and if it is still sold? Suggestions please?

    We thought about using some of our left over Bituthene (bituminous sheet membrane) for this purpose. We would cut the Bituthene into the shape of the toilet bowl base, cut out for the flange and stick this onto the floor after the finished floor is installed. Once the toilet bowl is installed it would be sealed along the outside. The Bituthene would make the floor about 1/16" higher under the rim than under the flange.

    How would this affect the wax seal?

    How much variation can there be in the floor height between the floor under the flange and the floor under the rim and still get a good seal from the wax ring?

    Thanks in advance.
  2. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    Do you have the flooring material yet?

    If so just cut a few small blocks to put under the flange to use as temporary spacers. Make sure you use a flange that has a stainless steel ring and not a flange that is all plastic or has a painted steel ring.
  3. Terry

    Terry Administrator Staff Member

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    Location:
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    Last edited: Apr 7, 2011
  4. Basement_Lurker

    Basement_Lurker One who lurks

    Messages:
    668
    Location:
    Victoria, BC
    You do know that installing wood in a bathroom is not a good idea right?

    Just stub up a 4" riser with cap, and scribe your flooring to it, and then install a flange once the floor and trim is done.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,804
    Location:
    New England
    Most of the flanges sold at the big box stores have a socket in them, so getting the height of the pipe right is important. You can buy flanges that slide over the pipe and the pipe will project through. If you buy one of those, leave the pipe long, cap it, then after the flooring is installed, cut off the cap, glue up the fitting and pipe, slide it on so it is now tight on the floor. After the glue sets, or as you do it, screw the flange down to the floor, and then cut the excess pipe off. Then, it will be perfect, regardless of how high the floor ends up.
  6. techinstructor

    techinstructor New Member

    Messages:
    81
    Location:
    North Carolina
    Thank you for your responses. I still have some questions about spacer. It is my understanding that the flange has to be glued to the drain line below the floor, so if you use spacers, how do you remove the flange later so as to remove the spacer and install the finished floor? Or do the spacers stay in place and you install the flooring around it?

    Redwood - No we don't have the flooring yet. Why do I need a stainless ring on the flange (I've bought three different ones, with the intention of returning two, but none have the stainless ring.)

    Basement Lurker - Yes, I know wood is not best for bathrooms, but I don't like vinyl and don't know how to lay tile. We plan to be very careful about getting water up from the floor.

    Yes, this makes sense, but the inspector said he would prefer to see the flange connected to the floor when he inspects the rough plumbing. Otherwise he'll have to make another trip. But then they are not very busy these days, so that might be the best option.

    jadnashua - We're also considering you're idea. Just have to find the fitting.
  7. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    Because painted steel rusts.
  8. techinstructor

    techinstructor New Member

    Messages:
    81
    Location:
    North Carolina
    Are the PVC ones prone to breaking? (That's what I have.)
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,804
    Location:
    New England
    Yes, an all plastic one can break out at the slot that holds the toilet anchor bolt ...the metal ones are much better. You want something with at least a little meat in it to hold the toilet to the flange.

    All inspectors are different, but what those wanted where I've done some remodeling (limited exposure mind you) was to view the placement of the items and the venting. The final stuff, where the actual finished fixtures were in place was often minor. I've gotten 'final' inspections when the things like the toilets weren't installed when he saw and measured where the pipe were.

    If they do either a pressure or water test, with the cap in place, it would actually work, where it couldn't if the toilet was already installed. They're looking for leaks, proper location and types of fittings, and how the stuff is run...the cosmetics aren't that important for the function, it's the 'guts' that count.
    Last edited: Apr 3, 2011
  10. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,236
    Location:
    Land of Cheese
    Most inspections will require a stack test or a pressure test. For a rough-in inspection, the stub for the water closet is normally capped off for the test. The flanges are not normally installed until after the floors are finished.
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,251
    Location:
    Cave Creek, Arizona
    I install my flanges after the floor is installed, and metal flanges only rust if you have a leak that is not fixed for a year or so.
  12. techinstructor

    techinstructor New Member

    Messages:
    81
    Location:
    North Carolina
    Well, we were originally planning on putting tile in the bathroom, but had changed our minds because of being burnt out on learning to do so many new things. But it seems that everyone I talk to and every online source I've checked says NO to hardwood or even laminate, and YES to tile. So..... we're back to our original plan. We're going to lay our tile BEFORE we put in the flange, which means that all the rough plumbing is on hold until we get that done. (In NC the inspector has to see the flange connected to the floor and the pipe during the rough inspection.) I think this is a wise decision, because then the floor will be at the right level and of a material that should last and withstand the moist environment. Thank you to all who gave advice here. :)
    Last edited: Apr 9, 2011
  13. jamiedolan

    jamiedolan New Member

    Messages:
    28
    Location:
    Wisconsin
    A note about your flooring:

    Tile for a bathroom isn't normally very many sqft, so it should not be too expensive to have professionally installed. I'd hire someone for the tile install since you don't have any experience. Tile done wrong (not level, poor spacing, etc) looks horrible and isn't really fixable without chiseling it out.

    I'd either hire someone to do the tile or look at a product like Konecto Prestige which is tough, highly water resistant and DIY friendly.

    Jamie
  14. techinstructor

    techinstructor New Member

    Messages:
    81
    Location:
    North Carolina
    Ok, we are still planning to tile the bathroom floor, but we want to waterproof it. We are using Ditra underlayment and to waterproof it correctly, we have to put a strip of Kerdi-band along the intersection of the floor and the wall. Therefore, we have to have the walls installed prior to installing the tile floor.

    So, I'm back to my original problem with needing to install the closet flange PRIOR to installing the finished floor. We decided to use spacers, as suggested above. My question concerns the variation in height between the closet flange and the finished floor. I can only estimate the finished floor height. There will be thinset (using a 1/4" by 3/16" v notched trowel), Ditra (1/8"), more thinset (using a 1/4" x 3/8" sq notched trowel) and then tile (6 mm or slightly less than 1/4") I've tried to estimate the finished height and figure it will be between 9/16" and 3/4".

    It is my understanding that the closet flange can be higher than the finished floor but NOT lower. My question is how much higher can it by and still be ensured of getting a good seal with the wax ring. If I use 3/4" spacers, then I'm running a risk of the flange being too low (should the thinset turn out to be thicker than my estimate). If I use 1" spacer, I'm assured of being higher than the finished floor height, but will that create a problem if my finished floor turns out to be only 9/16" high?

    Simply put, how much variation can there be between the height of the flange and the height of the finished floor?

    Thanks in advance.
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,804
    Location:
    New England
    The flange is designed to lap over the finished floor and sit on it, anchored through it to the subflooring. Some toilets don't have all that much gap under them, so a too high flange is much more of a problem than one a little low. When it's low, you can use a thicker wax ring, but if it's too high, the toilet may not sit flat on the floor and rock on the flange. So, you're a little better off estimating low than high. If it ends up too low, they also sell extension rings that get attached to the top to raise it up, but you often can get by with just a normal or jumbo wax ring unless it's really low.
  16. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,251
    Location:
    Cave Creek, Arizona
    One minor point. Condensation ONLY occurs when moist air contacts a cool surface. The air UNDER the toilet will NOT be "moist" unless you have some construction defect that allows "fresh air" to flow around under the toilet.
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,804
    Location:
    New England
    Also, all of the new gravity flush low-flow toilets do not empty the tank when you flush them. So, unless the thing was recently flushed, the water that's there is close to room temperature, mixing with the incoming water, and it often doesn't get cold enough to cause condensation. Your results may differ, especially if you have a deep well where the water is really cold (but it often sits in the bladder tank, and warms up before it gets to the toilet).
  18. techinstructor

    techinstructor New Member

    Messages:
    81
    Location:
    North Carolina
    I'm still confused about this issue. I've heard from a plumber and read from other sources that the flange should not be lower than the finished floor because then the toilet edge would prevent the horn from being able to seal properly. This makes logical sense to me given the design. However, jadnashua, you make a valid point about the issue of rocking. I also wandered just how much you can compress the wax seal and still have adequate coverage. Therefore I'm still trying to figure out what the parameters are. I've read in tile books that the flange can be from 1/4" - 3/8" higher than the finished floor. But I'd like to hear more from the experts in the field.

    I'm thinking of measuring my toilet (a Toto Drake) to see just how much space there is between the horn and the edge of the toilet, but I still need to have some idea of how much compression the wax seal can withstand.
  19. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,804
    Location:
    New England
    Measure the thickness of the flange. As I said, it is designed to sit on TOP of the finished floor, so the thickness of that part is where it should be by design. They aren't all the same thickness, though, and range from maybe 1/4" to 3/8" or so. Any standard toilet should fit on one, if the flange is installed properly (tight on TOP of the finished floor). But, there are probably millions of toilets out there where people have remodeled, added tile, and not raised the flange to where it should be. You then have several options: a thicker wax ring, stacking two together, adding a flange extension, using something like the Fluidmaster waxless seal. But, the best thing is to wake up the inspector and enable it to be installed after the finished flooring is in so it's where it's supposed to be. The all plastic and cast iron flanges tend to be thicker than a stamped metal ringed one. If you go that route, use one with SS rather than painted steel.
  20. techinstructor

    techinstructor New Member

    Messages:
    81
    Location:
    North Carolina
    We checked the bottom of the toilet and found that the horn and the toilet rim are flush with each other. It seems to me that there isn't a lot of leeway for the flange being too high or too low. DH agreed with jadnashua about estimating on the "low" side. We're going to make up a mock tiled board using all the materials, thinset, ditra, etc to try to get an accurate estimate of just how thick the floor will be. I think that will help as well.
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