Toilet Flange Too Low? Double Wax Ring or Extender Spacer Kit?

AllThumbsDIY - Toilet Flange Too Low

Low toilet flange is a common problem when installing a new (or in my case thicker mortar base). Unless your toilet is properly mated and sealed to the waste pipe, you may face problems related to sewer gas odor (it’s very unhealthy and unpleasant) and/or fluid leaks.

The purpose of this article is to review current products that may solve this problem.


Last year I decided to gut and remodel my small bathroom. Because the sub flooring around the waste pipe was in very good shape, I left it in place.

allthumbsdiy-images-toilet-flange-extender-b010-toilet-flange-old-vs-new-flBeing a newbie DIYer, I realized I made a mistake AFTER tiling my new floor. You see, because my bathroom was so small, I decided not to use a shower pan which meant I poured thicker mortar bed than I normally would have to pitch water to the shower drain.

To make the long story short, my thicker mortar bed, mesh backer, liner, thinset and new floor tiles all added up to raising the overall height of the floor by approximately 1.25”. That meant my toilet flange was now 1.25” BELOW my new floor. Yikes!

allthumbsdiy-images-toilet-flange-extender-b020-fluidmaster-jumbo-wax-ring-with-cone-flAfter researching around a bit, I noticed lot of people in my situation used double (stacked) toilet wax rings to compensate for the height disparity so I took one plumber’s advice and bought two wax rings: a regular “thin” wax ring along with FluidMaster’s jumbo wax ring extender kit (which included extra thick wax ring with a built-in polyethylene flange, similar to Oatey 90203 Jumbo Johni-Ring with Plastic Horn and Extra Long Bolts).

This solution seemed to have accomplished the job except that a year later, I am now starting to smell a faint sewer gas odor on and off. Obviously breathing in sewer gas is very very unhealthy, especially when all windows are closed during the hot summer or freezing cold days, I decided to research little bit more in depth about implementing a permanent fix.


allthumbsdiy-images-toilet-flange-anatomy-copper-to-brass-flange-v4-flOf course, the obvious solution was to gut the floor, remove the lead and oakum, de-solder the flange, add a coupling and extra pipe and add a new flange to match the higher.

But that solution was unappetizing not only because of the time and expense involved, but that would have forced me to disturb the mortar bed along with a PVC bed liner that was pitched to the shower drain. So I decided to explore some NON-DESTRUCTIVE options:

  • Option #1: STACKED WAX Rings – Simply use the same double stacked toilet wax ring setup again.
  • Option #2: Extender Kit – Extender is nothing more than a “funnel” that provides solid conduit path from the bowl horn to the toilet flange. Some are standalone (Zurn Flo-Bowl Jr) and some are part of a kit (Set-Rite).
  • Option #3: Spacer Kit – Spacer kits come with hard PVC rings with various thickness. Some comes with built in gaskets, others either come with separate gaskets or none at all (in that instance you need to use mastic of some sort like a caulking or plumbers putty). These rings are designed to be stacked in whatever combination to match the new floor surface level. Some kits also come with a toilet flange extender (see option #2).
  • Option #4: Sani Seal – This is a fairly new product on the market. Sani Seal is a thick, doughnut shaped made of polyurethane foam ring with a built in cone mold on the bottom that is designed to replace the stacked wax rings. According to the manufacturer, Sani Seal can also be stacked.
All of these products require that your old toilet flange be in a good physical condition to ensure positive seal. If you find that the flange has rust rot, cracks, or other physical defects, or any rots on the subflooring, you need to address those issue first.)



allthumbsdiy-images-toilet-flange-extender-b024-stacked-wax-ring-weak-points-flThis is probably the most common path taken by DIYers. It’s a simple configuration of one regular wax ring stacked on top by another “extra thick” wax ring with a built-in flange. The entire setup can be purchased under $10 and can be installed with relative ease (although it was a nerve wrecking process for me because you won’t know if the proper seal was made until you flush the toilet).

But in reviewing the double stacked wax ring configuration in detail, I started to wonder if there were some inherent design flaws or weaknesses that attributed to my (sewer gas) situation. After some thinking, I came up with three possible flaws:

(A) Horizontal racking force on the toilet flange bolts – With approximately 1.5″ space between the flange and the bottom of the toilet, flange bolts are not supported horizontally. It would only take a slight bump on the toilet to throw these bolts sideways, possibly damaging the wax ring, creating gaps or even possibly cracking the toilet ceramic.
(B) Bonding failure between the toilet wax rings – with the toilet being slightly wobbly due to uneven tile floor, it is conceivable that the vertical pressure applied on these wax rings are not even, possibly causing gaps in certain spots between wax rings.
(c) Top wax ring seal failure – I’d imagine you want a solid “squishing” effect on the top (toilet bowl horn) and the bottom (toilet flange). However, in the case of a stacked wax rings, top wax ring is forced down on another wax ring that is softer than a toilet flange surface. Since there is no solid bottom surface to squeeze the top ring, that could potentially prevent the top ring from being seated tightly against the bowl horn.
(d) Head or Hydrostatic pressure failure – Increased fluid pressure due to clogs (or even using a plunger) can potentially burst weak spots in between “seams”.

Due to these reasons, I decided AGAINST implementing the double or stacked wax ring setup.


Toilet flange extenders are constructed with either soft or hard PVC, providing solid pathway from the bowl horn to the toilet flange on the floor. I believe products in this category are designed to replace the use of wax rings only, although Fernco advertises that it can handle toilet flanges that are up to 3/4″ lower than the floor surface.
Most are designed to fit INSIDE the toilet drain pipe which will provide a good, solid, positive seal but there are potential issues to be aware:

  • You need to know the exact size of the drain pipe in order to purchase the right part. That meant taking the toilet apart for few days.
  • It’s my understanding that if you have a 4″ drain pipe, small reduction to inner diameter is acceptable. But if you have a 3″ drain pipe, you would want to minimize any reduction to the inner diameter as that would reduce the flow rate. I found out that the bowl horn’s inner diameter is anywhere between 2.0″ to 2.5″. So as long as the product does not reduce the maximum size of a bowl horn, clog won’t be an issue.
  • Some older toilet designs from 1960s or earlier may have a protruding bowl horn which might create some clearance issues.



allthumbsdiy-images-toilet-flange-extender-d030-review-ferncoManufacturer URL: Fernco Inc.
Origin: Made in USA
Product: Wax Free Toilet Seal, Part # FTs-3, FTS-4, FTS-4CF
Installation Instructions: Click here and here
Price: FTS-3, FTS-4 , and FTS-4CF
Fernco has been around for a long time and I know most plumbers I have used in the past (yes, I hire plumbers for jobs that are beyond my DIY skills) all recommend Fernco. Fernco is synonymous with rubber products like ProFlex shielded coupling, etc.

Fernco’s wax-free toilet seal product is comprised of flexible PVC that uses adhesives and barbed fitting (in lieu of gaskets) to create positive bowl horn and waste pipe seals. These positive seal connections are designed to seal out any fluid or gas leaks in addition to handling head-pressure (when a clog occurs).

However, there may be some potential issues:

  • Concern #1 – Fernco’s installation instruction stresses that the bowl horn surface needs to be absolutely clean of oil or wax residue that might prevent the adhesive from sticking properly. But what about toilet surface imperfections like pits, bumps, or irregular bull horn shape?
  • Concern #2 – The adhesive surface ring is approximately .29″ wide. What is the life expectancy of this adhesive under repeated exposure to liquid? I am not exactly sure how the gasket is made but maybe it is something like Loctite Elastomeric Adhesives and Sealants with Flextec™ Technology?
  • Concern #3 – Barbed mating reduces the inner diameter of the waste pipe. Does that increase the likelihood of a clog?
  • Concern #4 – Fernco’s advertising states that “… Toilet can be removed and reinstalled with the same Fernco Wax Free Toilet Seal still attached…”. Maybe that’s true but unseating a toilet places a lot of pulling stress on that narrow adhesive surface due to the barbed connection. If it were me, I would opt to install a new one and not risk getting a leak
  • Lastly, some users have complained that in contrast to Fernco’s advertising, this product does not fit well with certain cast iron waste pipes (click here for complaints). According to Fernco’s customer rep, FTS-4 works with cast iron pipes with inner diameter between 3.96″ to 4.02″ but some customers reported that their cast iron waste pipes measured 3.75″ I.D. In addition, unlike PVC or copper waste pipes, cast iron pipes tend to cling on to aggregates in its pipe, which might also contribute to poor-fitting.

    Fluid Master

    allthumbsdiy-images-toilet-flange-extender-d050-fluidmasterManufacturer URL: FluidMaster
    Origin: Assembled in Mexico
    Product: Wax-free Bowl Kit 3″ or 4″, 3″ only or 4″ only.
    Installation Instructions: Click here (very basic – they need to have the detail instructions online!)
    Price: 7500P8, 7503, 7504

    You’ve probably seen Fluidmaster’s plumbing products that come in red and green boxes and are ubiquitous in any plumbing sections at large home improvement stores.

    Unlike Fernco, Fluidmaster utilizes a “special rubber”. Based on how it felt and looked, I believe the gasket is made from “red rubber” or styrene butadiene rubber. Red rubber is considered to be a low cost flange gasket material that is non-oil resistant compound and resists flow under compression. It is supposed to offer moderate to good performance against low pressure with good aging characteristics and abrasion resistance. On the flange side, it uses what looks like an closed-cell foam based O-ring to create a positive seal.

    Here some potential issues that I thought of that may apply to your situation:

    • Concern #1 – Fluidmaster extender is made of hard PVC. That means there is no “give” when compressed down by the toilet. If the toilet flange is too high or there simple is not enough clearance between the extender and toilet flange, one or both components might break
    • Concern #1 – Although Fluidmaster 7500P is an universal model that can fit either the 3″ or 4″ waste pipe, using this model on a 4″ waste pipe may reduce the flow rate.
    • In addition, one user have complained that his older 1950’s toilet design (with protruding horn) prevented him from using this product so you may want to pay attention to when your toilet was made (if you were going to re-use it).


      allthumbsdiy-images-toilet-flange-extender-d010-review-extender-set-rite-flManufacturer URL: Set-Rite
      Product: Single Extender Only, Part # SREX2003Y
      Origin: Made in USA
      Price: $5.99

      Set-rite is a relative new comer based out of New Jersey. Although you can purchase this extender by itself, it is really meant to be used along with Set-Rite’s spacer rings. So instead of repeating myself, read the review on Set-Rite’s extension kit in the Extension Review section.


      allthumbsdiy-images-toilet-flange-extender-c020-review-zurn-flo-bowl-jr-flManufacturer URL: Zurn Industries LLC
      Product: Flo-Bowl Jr, Part # CF2991
      Origin: Made in USA
      Price: $8 (found only at local plumbing stores)

      Zurn manufactures products for use in commercial, municipal, and industrial markets. As far as I can tell, this particular Zurn part is found at plumbing supply stores. Information found on this product is non-existent but based on the picture, it follows the same design principle as the Fluidmaster’s wax-free seal products.

      Based on lack of information and reviews, I would suggest you look at alternative products.


      If your floor surface is more than half an inch above the closet flange (in my case 1.25″), you must extend the flange so it’s flush with the new floor surface.

      A closet flange extender or spacer ring(s) with flexible gaskets can do that job.

      Oatey 1/2 inch Toilet Flange Spacer

      allthumbsdiy-articles-plumbing-toilet-flange-extender-oatey-spacer-ring-flI have seen this product being recommended by professional plumbers in various forums. One distinguishing feature being promoted by the manufacturer is that its space rings are made of solid polyurethane (not hollow) and thus can be stacked with confidence.

      Because these spacers are sold individually, you will need to purchase the hardware separately:

    Oatey Closet Flange Spacer Kit

    allthumbsdiy-images-toilet-flange-extender-c010-reviews-quik-fix-extension-kit-flManufacturer URL: Oatey
    Product: Closet Flange Spacer Kit, Part # 43645
    Origin: TBD
    Price: Oatey 43645 Closet Flange Spacer Kit, 1/2-Inch

    Oatey parts are widely available at various online and offline stores. Oatey is another trusted plumbing parts manufacturer that has been around for a long time.

    Oatey’s spacer rings are also constructed of solid polyurethane like Quik-Fix spacer rings, except that it does not come with built-in gaskets. Unlike Q-F’s foam gaskets, Oatey utilizes O-ring gaskets with 2 channel rings to block out liquid and gas.

    If the kit is not available, you can piece meal 2 parts together as seen above (BTW, two different gaskets seen are the same, one is just flipped over).


    allthumbsdiy-images-toilet-flange-extender-kits-e020-review-set-rite-flManufacturer URL: Set-Rite
    Product: Full Extender Kit, Spacer Kit
    Origin: Made in USA
    Price: Full Extender Kit $24.99, Spacer Kit $13.95

    I like this Full Extender Kit contains almost everything I need to solve my toilet flange problem. The kit included:

    • Four Spacer Rings – 1/8″, 1/4″, 1/2″ & 3/4″
    • One Set-Rite Gasket
    • One Set-Rite Extender
    • Six 3-1/2″ Stainless Steel Screws

    To complete the repair, you would also need to purchase a standard wax ring (without the plastic cone/funnel) as well as “Johnny” bolts or T-Bolts in proper length.

    Installation process is simple: install the gasket on top of the toilet flange on the floor, add spacer rings to match the new floor surface level, add the extender, add a standard wax ring the set the toilet on top. I like the product but I see some potential issues:

    • Set-Rite spacer rings are hollow.
    • Rings also serve as bay flanges by having joints that can be snapped in half.
    • One foam gasket (3/16″ thick) mounted on the flange serves to prevent both the liquid and sewer gas leaks

    Although the ring is hollow, I don’t think that is a big deal since it has a sectional ribbing support so I doubt it will have a structural failure (I am guessing the toilet will break before the rings are crushed).

    The part I do not like is that it has weakened joints to snap the ring in half (to convert it into bay flanges). I would like to see Set-Rite make two different types of rings for difference purposes.

    The other part I do not like is that a 3/16″ thick foam ring sits on top of the toilet flange to seal out any liquid or gas. I think the thickness should be increased to provide seal to uneven surface but I would much prefer to see something like Fernco’s barbed pipe end or Fluidmaster’s foam ring that gets inserted into the waste pipe.


    With so many good products on the market, it’s easier than ever to properly raise a toilet flange that is too low.

    Just make sure to take your time to assess your own situation before making any purchases.

    In my next post, I will show you how I corrected my low toilet flange.


    PS. If you found this article to be useful, why not sign up for my newsletter? Just look for a signup form on the upper right hand side of your screen. Thanks!



  1. Tom McGaughan says

    I read your article on Toilet Flange Too Low? and I believe you have some of the facts wrong on a number of the products you reviewed. Specifically, the Set-Rite Extender Kit is the only product you featured that is Code Approved out of all of them. As far as I am concerned the other kits are pretty much worthless. Some of the ‘plastic rings’ shown involve the use of silicone between rings. Which if you have ever seen silicone exposed to moisture it becomes literally ‘peelable’ just like caulking will. The push type flange repair kits with ribbed will only work on a ‘perfect’ flange and not one with uneven surfaces like a lead bend or cast iron flange. I spoke with the owner Alan Hughes about 6 months ago and had asked him some of the same questions you had…namely the spacer construction which I found out were tested to 500 lb rigidity and the gasket was designed to be flexible enough for the extender to fit ‘snugly’ when pushed down flush and still provide a water & gas tight seal. I have used the Set-Rite kits on several toilets, after finding that a vast majority were originally installed with a low flange. Obviously there are some plumbers out there that still believe they could throw an extra wax ring in there…especially knowing the check will have cleared by the time it begins to leak! If you haven’t checked out the video on the Set-Rite website I would…I put my laptop on the vanity in the first bathroom’s toilet I worked on…it helped to replay over and over while working!!

  2. kevin says


    Thanks for your feedback. I agree with you that Set-Rite offers some compelling reasons. and thank for letting me know of the 500lb max limit.

    One concern I still have is that all of their rings have per-determined “break” points to convert them into bay flanges. I know I have seen my share of brass flanges that were bent down in corners and it is conceivable that one or more ring can snap that results in the extender being out of alignment.

    I also wholeheartedly agree with you about not using regular silicone caulks between spacer rings as I have too seen them peel off. One caulking I have seen that truly works in a wet environment is 3M Marine Fast Cure 5200 Adhesive Sealant. I just did not want to use it in this project because I did not know if it would react with any of the foam gaskets.

    I have finished re-working on my toilet and will publish that post soon. I ended up using the Quik-Fix spacer rings and plenty of wax rings (not in the double stacked configuration) that I believe will last a long time.

    I will outline it in detail as to why I chose that particular path in the article.

    I look forward to your comment on that article.


  3. Tim says

    if you have access from below and the pipe is ABS the best is just cut the pipe, extend it and set it at the right height with a new flange. This can be done from above too if you are taking out subfloor. Best way to prevent leaks is start fresh. Most houses now are black ABS which is really easy to work with.

    I just replaced a toilet in my 70’s house where the flange was below the old tile and yes the toilet had leaked. Previous owners must not have cared about the smell because when I took that old toilet out you could see the wax ring never made full contact. That thing had been leaking 30 years. Ripped out the floor and did it right. Now I am thinking if they did that one wrong the others are probably wrong too. Plumbers estimate $200 plus. Doing it myself? About $20 in supplies. Albeit a good half day lost.

  4. kevin says


    thanks for your post. i agree that there is a certain satisfaction when doing the job yourself.

  5. Colm says

    Hi Kevin,
    Your first contributor, Tom, was a bit unfair. Your problem was finding a cure for your predicament with the products available from your local suppliers which we as consumers have at our disposal. But he did point out that the “Set-Rite Extender Kit” was the only code approved one yet all the rest of them are readily available out there to play with so all was not in vain.

    Thanks for your research, my problem is simple and before tiling my bathroom decided to have a look out in the void for possible solutions before the remodel.

    Thanks for flushing out all the possible cures, and giving us the poop on the how to’s and not to’s too! I know that doing it wrong will cause a stink. It’s only a pipe dream until you finally do it right?

  6. kevin says


    Thanks for your kind words. I didn’t mind Tom’s comments either. As long as everyone remains civil, we can agree to disagree on just about everything.

    Thanks again!


  7. Kathy says

    We had porcelain tile installed in our hall and adjacent half-bath by Home Depot. (Epic issues omitted here…but I will say that I had to dig major amounts of grout & mortar out of the flange.) Between the leveling needed in the half-bath and the thickness of the tile, not even an extra=thick wax ring came near to sealing the gap. We got the Quik-Fix extenders at Lowe’s and they were an easy solution to our problem. Merci beaucoup!!

  8. kevin says


    Thanks for your comment. Can you do me a favor and send me your marketing / spec sheets to: info (at) allthumbsdiy (com)?

  9. bob o says

    This is very informative and much appreciated guidance and discussion. So, your advice for this situation would be much appreciated. I have. a toilet that sat on concrete, so the cast iron flange sits level with the concrete. I have installed a floor in top of the concrete basement which required raising the subfloor which would suggest for the toilet when tile would be installed a 7 inch gap from the top of the flange to where the top of the tile would be, give or take a 1/4 inch. Aside from breaking up the concrete and installing and extension to the pipe and a new flange, any suggestions? Thanks

  10. kevin says


    I hate to say it, but I think 6.75-7.25″ gap is just way too much for any of the options I’ve mentioned here.

    Besides, being that this toilet is in the lowest part of the house, I think you would have potential for leakage issues, should there be a sewer line backup.

    As you said, I think the right solution here is to breakup the concrete using a small electric jack hammer and install a new p-trap with correct height.

    Let us know how it turns out.


  11. Don says

    We recently completed a new floor tile project. The project involved removal of the old linoleum and subfloor and adding thin set, Schluter Ditra XL floor base,motar and tile. This raised the surface approx. 1/2″ above the orig. toilet flange. The tiler suggested adding an extender ring or two, so I bought two rings and new longer T-bolts and a new standard wax ring. This sounded simple enough. I installed the two new bolts and the two pvc extender rings. I installed the new Oakey wax ring on the toilet with “easy” to remove plastic sleeve. The instructions say to press the wax ring to the toilet bowl and simply remove the plastic shell. The shell just pulls the wax ring with it and/or tears and comes of in (7) pieces. Kind of messy. This completed, I set the bowl onto the raised flange, tightened the bolts. Installed a new water connection line, since the old one was approx. 1/2″ short. Opened the water valve, filling the tank and bowl. All was well, until I was about the do the flush test and had a revelation, I don’t think I removed the rag in the floor drain, since I was distracted with the wax ring shell removal. I quickly backed away from the flush handle, scratched my head, had a few words with myself and put a do not touch sign on the toilet. The next day I picked up a new wax ring, shop vac’d the water from the bowl and tank, removed the bowl, confirmed the rag was present. I then gave thanks for small favors, realizing the wax ring did not make it to the lowest, original flange. This would have been problem with sewer gas and leaking under pressure. I thank you for your comments and I will take a moment to choose the best solution The two extenders did raise the surface just above the tile floor. I will check out the options mentioned..

  12. Don says

    Well I slept on it and determined the best solution was to take the wax ring previously installed, but new and transfer it directly to the original low flange plate, followed by an extender plate aligned on the new longer T-bolts. I compressed the extender plate until it was just above the new tile floor line and flat. The wax ring formed a great seal. I then placed a new reinforced Oakey was ring on the toilet bowl and positioned it on top of the extender plate and compressed it with the toilet, forming another great seal and sufficient T-bolts to secure the toilet to the original PVC flange plate. By the way this time made sure the rag was removed from the drain opening. Job completed. By using two wax rings and an extender plate preset with the first lower wax ring, it provided a very nice seal and foundation to set the toilet, as opposed to trying just to stacked wax rings.

  13. kevin says


    Thanks for letting me know. If you haven’t done so, I would recommend a bead of caulking around the toilet to minimize horizontal movement.



Leave a Reply

Your email address will not be published. Required fields are marked *