4 Solutions for 8-inch & 9-Inch Rough-In Toilet Replacement

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Sometimes when you are replacing old toilets you may come across a 8-inch rough-in toilet or a 9-inch rough-in toilet. In such a situation how do you replace a 8-inch or 9-inch rough-in toilet as there are no toilets for sale today with 8-inch or 9-inch rough-in sizes?

The standard rough-in size today is 12-inch. So most toilets manufactured today are 12-inch rough-in toilets. A few models of 10-inch rough toilets and 14-inch rough-in toilets are made to cater to the small percentage of 10 and 14 inch rough in settings. But if you have a toilet with a 8 or 9-inch rough-in you have come across a very unfortunate and very rare situation in the plumbing world. However don’t despair, you can fix it.

Below are four solutions for your 8-inch rough-in toilets or 9-inch rough in toilet situation.

  1. For 8″ roughin use 1″ Offset Flange & install 10″ TOTO Drake Toilet (*See details below)
  2. For 9″ roughin install 10″ Toto Drake Toilet (*See details below)
  3. Wall Renovation
  4. Install A Wall-Mounted Toilet

I have explained these 4 fixes in detail below…

1) For 8″ Rough-in Use 1″ Offset Flange & Install 10″ Toto Drake Toilet

8 rough in toiletThe best and easiest option for 8″ rough-in settings is to dig out and replace your existing toilet flange or drain outlet at the floor with a toilet offset flange. “Toilet flange” is the drain outlet connection accessory on the floor, into which your toilet is bolted onto.

You will currently have a normal toilet flange hole that protrudes straight down from the floor surface to connect to the main toilet sewer drain pipe. What you need to do is, buy a “offset flange” with a one-inch offsetting ability. That’ll increase your 8″ rough-in size into a 9-inch rough-in. Then you’ll be able to install the 10″ roughin Toto Drake toilet (check at Amazon #ad) that also fits a 9 inch roughin. (I’ve discussed this toilet more below)

For example, this photo to the right, shows a popular offset flange called the SIOUX 889-GPOM offset flange sold on online (Check at Amazon #Ad). It is a 1-1/2″ (1.5″) offset and will increase your roughin to 9-1/2 inches. That will allow you to buy and install the 9″ roughin fitting 10″ Toto Drake toilet mentioned below.

Checkout these customer photos on Amazon #ad of someone who installed the SIOUX 889-GPOM and adjusted their roughin size. And in this review on Amazon #Ad, the reviewer describes how he used this offset to replace an old offset on a 8″ rough to install a 10″ rough in toilet. His 8″ roughin was a result of a concrete pouring mistake.

This is the most common solution adapted by people like you who have faced a situation with a 8″ toilet rough-in. Depending on the situation its also probably the quickest and easiest. Note, to replace your existing flange with the offset flange you will probably have to chisel out your bathroom floor.

There are also larger toilet offset flanges, which will allow you to ‘offset’ or increase your roughin size further to make it even a 12-inch rough-in. However it will require you to break the floor more and create a bigger hole to install those toilet offset than the above mentioned 1-1/2″ inch inch offset will need.

A bigger hole around the toilet flange can cause issues like wobbly flange or worse frequent clogs and blocks. Also in some areas, the building codes don’t allow toilets offset flanges. So you’ll need to check about it too.  Also we don’t know whether there are any cross beams under the toilet near the flange that caused the your bathroom builders to make a 8″ roughin instead of a standard 10 or 12 inch roughin. To be on the safe side, its better to get the smallest offseting flange and install the 9″ roughin fitting toilet mentioned below. It’ll limit the dig up damage and floor patching needed under your toilet.

2) For 9 Inch Rough-in Install 10″ Toto Drake CST744EF Toilet

9 roughin toilet The 10-inch TOTO Drake CST744EF.10 toilet (check at Amazon #ad) has been used by many people to fit shorter toilet rough-in less than 10 inches, like 9, 9.25, 9.5 and 9.75 inch rough-ins. This is because normally when you install this model on a 10″ rough-in, it leaves a gap of 1.1 inch clearance in the back between the tank and the wall.

I found several reviews and comments on Amazon and other online forums made by people who had successfully installed this model for their 9 inch rough in. This maybe because the horn of this 10″ Toto is 2-5/8″ and they might have shifted the bolts away from the wall by 1/4″ off center and got their 9″ rough-in.

I found two people on the 10″ TOTO Amazon sales page, saying it fit their 9-inch rough in outlet. Here is the Amazon link #ad to one of those customer reviews, where a Amazon verified purchaser says this Toto toilet fit their 9″ rough in. And here is another reply on Amazon #ad where another purchaser also says this Toto toilet worked for them too with only 9 inches to the wall.

9 inch toilet
Update: I found this diagram of the 10 inch Toto Drake toilet on its specification sheet. Notice the 1 1/8 inch gap between the back of the toilet and the wall where I have marked it with a pink arrow.

Here’s another comment confirming the 10″ Toto toilet fits 9″ rough in, this time from a forum thread on the terrylove.com website.

We had the same problem described above (only 9 inches to wall) and took a gamble on the 10″ Toto toilet described above and IT FIT! I wanted to post that it fit because we were so relieved and because no one ever followed up on this thread to say if it really fit. We only had 9 inches and the whole toilet fit great!

It’s fortunate one of the best 10-inch toilets is adaptable to an awkward situation like on a 9″ rough-in, because like I explain in my top 10″ roughin toilet comparison post, Toto toilets are probably the best toilets in the market for a number of reasons, though its price is also bit higher than normal. I also checked whether any other 10″ inch models fit 9″ rough in’s but couldn’t find any claims about for them.

With so many sources claiming this 10″ Toto Drake fits 9″ rough ins, we can safely say its the best and easiest solution if you find yourself with a 9″ roughin situation. However, in case you buy the Toto Drake CST744EF.10 and it doesn’t work for you, you can still use it as the 10-inch toilet you will need by following the solution 1 or 3 explained here. So why not give it a try?

If this solution works for you, it will probably save you the trouble of breaking up the floor and installing a offset toilet flange as suggested in solution one.

In case you need a 9.25 inch rough in toilet or 9.5 rough in toilet, I found even more comments in forums and websites where people have said this Toto Drake worked perfect as a 9 1/4 inch rough-in toilet or 9 1/2 inch rough-in toilet.

3) Wall Renovation

Your second option is to renovate your wall to increase the rough-in distance between the toilet’s drain and the wall surface. Depending on whether you have a 8 or 9 inch toilet rough-in you will need to move the wall back one or two inches to accommodate a 10-inch rough-in toilet. Note, only types of walls that you can move without professional assistance are non-load-bearing walls (also called partition walls). However for this option we highly recommend you consult a professional for assistance.

4) Install A Wall-Mounted Toilet

In case you can’t dig up the floor to shift your outlet flange or you want to avoid using your existing toilet flange altogehter you might consider installing a wall mounted toilet or a rear outlet toilet and diverting the outlet drain through the wall.

Wall mounted toilets is becoming a very popular option in cities and new apartment buildings as they are space saving, easy to clean and drain through their rear side. However, solution requires to plumb a new toilet waste line through your wall and installing a wall mounted toilet carrier to affix the toilet on the wall. Also depending on the toilet model this solution will probably be very costly as you will have to get professional help as well.

The rear outlet toilets are a cheaper alternative to wall mounted toilets. They are exactly like a normal standard floor mounted toilet except the drain outlet is in the rear.


About Aksam Zarook

Aksam is a 36-year-old dad of two. He is into marketing bathroom fixtures since 2012. He likes learning all he can about bathroom fixtures and writing about them here. He is also handy with tools and loves improving and fixing things around the house.

View all posts by Aksam Zarook →

15 Comments on “4 Solutions for 8-inch & 9-Inch Rough-In Toilet Replacement”

  1. Our home was built in 2017, but the basement toilet was mistakenly roughed at 9 inches. Desperate to find a quick solution (we had already scheduled a plumber), we found this site and possible solution. We bought the TOTO Drake toilet from Amazon with lid and screws using Amazon Prime. We did not have a millimeter over 9 inches, and the TOTO Drake toilet fit!!! It is right against the back wall, but it isn’t pushing on it. Good news for us, the builder is covering the full cost due to their mistake! Thank you to everyone who went before us and posted about their success.

    1. Thank you very much Marianne for taking the time to come back here and report your success with the 10 inch Toto Drake toilet fitting a 9 inch roughin. I’m very happy to hear this solution worked for you.


  2. Hello I have and old flange 7 in diameter and the rough is 8 1/2 ,you post for 8 and 9 rough I think in my case is gone work but i need to be sure before buy a new toilet of 10 rough
    alone with the offset flange ….Thanks

    1. Hi Jose,
      Yes, any 10 inch rough toilet can be installed on your 8 1/2 inch rough in provided you dig out the old flange and installed something like the 1.5 inch offset flange I mentioned above. It’ll essentially make your rough into a 10 inch rough in.

      The Toto toilet mentioned here will work even with a 1/2 inch offset toilet flange.

  3. Thanks for this article. It was key for my situation. I had to cut a replacement subfloor for my renovation and the rough in was only 8.5 inches. I recut a new one and was able to get it to 9.5 (whoever built my house put the joist 12 inches from the outside wall). Being limited in toilets it was great to find one that would work, even if it wasn’t the exact style I wanted. It sucks there aren’t more 10 in rough in toilets to choose from in the big box stores, but I guess it is just not the standard so it is understandable.

  4. I wanted to follow up to make sure you got this feedback. My toilet was old, dirty and kept leaking so I went to replace it and, surprise!!! It didn’t fit (note even close). I measured and my rough-in was 9.5 inches. I tried a 10 inch American Standard from Home Depot and it didn’t fit either (base fit but tank didn’t). I found this page and read the Amazon reviews and decided to try the TOTO 10″ rough-in toilet. It worked, thank you!
    I will note that on this model, the very bottom of the toilet initially did not fit (the other model the base fit but top portion of the base I had to cut into the drywall). The reason the TOTO did not fit at first was because of the baseboard along the bottom of the bathroom wall. I cut away the bottom lip of the baseboard, just enough to fit the end of the toilet base and was good to go (did not have to cut into drywall). Thank you for providing a solution for me with the TOTO toilet! Breathing a sigh of relief!

    1. Hi Eric,
      Thank you for coming back and providing valuable feedback and confirmation that this solution work.

  5. I have a 8.5 inch rough in in concrete not wanting to cut up concrete anyway to do this? The offset would require concrete to be cut up correct so it would still sit flush on the concrete? Or is there a toilet that will work? Its a 4 inch drain

    1. I’m afraid there’s no alternative, you’ll have to break or drill out the concrete. It’s a fairly easy job for a professional. To do it yourself, easy way is to rent a multi-tool or similar cutting device, along with a hammer drill.

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