5 Solutions for 16-Inch Rough-In Toilet Replacement

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Sometimes, in old houses or due to a construction error, you might across a toilet with an odd rough-in size like 16 inches. But toilets today come only in 10, 12 and 14 inch rough-in sizes. So what do you do for a 16-inch rough-in? I have helped many people solve issues with odd rough-in sizes like this. So, in this post I’d like to share with you five solutions I have come across that have worked for others who need a 16-inch rough-in toilet.

Here are the solutions for 16 inch rough in toilet replacement.

  1. Relocate rough-in to 12 inches
  2. Install TOTO Vespin II toilet with 14″ Unifit Adapter (Shortest 14″ toilet & max space saving)
  3. Install a normal 14-Inch Rough-in Toilet
  4. Build a short 3-foot Wall behind Toilet
  5. Install a Over-The-Toilet Storage Cabinet

Lets have a look at these solutions in detail below.

Note: I have add more details for solution two than others because that is the solution most people use for 16″ rough-in problems. Also these solutions will work equally well for any rough-in over 14 inches (e.g. 15″ rough-in, 17″ rough-in etc.)

1) Relocate rough-in to 12 inches (Best solution if possible)

If you have reasonable access to the toilet plumbing this is a good time to fix your rough-in to a standard size like 12 or 14 inches. If you can make your rough-in to 12 inches, you’ll have a much easier time of finding a great 12″ toilet in styles you like, at a prices you like. And if your bathroom is small, you’ll get more legroom this way than installing the shortest 14″ rough-in toilet on a 16″ rough-in. And if it a small bathroom (like many old house baths are) you can install a smaller toilet and save even more space.

But this may not always be practical or easy. There was probably a reason the toilet flange was set to 16″. Likely there is a floor joist that prevented the flange from being set at a closer distance. If there’s a floor joist or you’ve got a concrete floor this solution can become very difficult and expensive to make now.

2) Install TOTO Vespin II Toilet with 14″ Unifit Adapter

If relocating the rough-in proves to be unreasonably difficult, your second best option is to install a 14-inch rough-in toilet. Out of the many models of 14″ rough-in toilets, the best choice for a 16″ rough-in I have found so far is the Toto Vespin II toilet ( link to its Amazon.com page #ad) with 14-inch Toto UniFit Trapway Adapter (Amazon link #ad).

Reason number one I say this is the best choice is because it’s the shortest 14″ rough-in toilet you can buy in the market today. It measures only 28.5 inches long and when installed on a 14″ rough-in with the 14″ UniFit Trapway adapter is about 29 inches from  bowl front to wall. When installed on a 16-inch rough-in it measures 31 inches from the front of the bowl to the wall. It take no more space than a normal 12″ rough-in toilet installed on a 12″ rough-in would take.

Reason number two: Most other 14″ rough-in toilets from American Standard, Kohler etc. are more than 30 inches long. So when you install them on a 16″ rough-in they measure over 32 inches or more from bowl front to wall. So Vespin II gives you more legroom and space saving in front of the toilet than any other 14″ rough-in model.

Reason number three:  When installed on a 16″ rough-in, Vespin II has one of the smallest gaps between the tank and the wall. Its gap is normally about 2 3/4 inches between tank and wall. Other 14″ toilets have a similar and larger tank-wall gap when installing on 16″.

If the flange drain hole is large you may be able to pull the toilet even more towards the wall and reduce the gap and length of the Vespin II even more. (Click here to see a photo of a Vespin II installed on a 16-inch rough-in. In this photo, because the flange hole was large, the plumber was able to reduce the tank-wall gap to just 1 1/4″!)

Even if the gap is 2 3/4″, it isn’t a great deal more than many toilets with standard rough-ins have. The gap has its benefits too. It will prevent mold from growing on the wall and tank sweating and dripping issues. It also makes it easy to keep the whole toilet clean and nice.

This is why if you do a Google search for, “16 inch rough in toilet” you’ll find so many comments and recommendations on forums and websites by users and professional plumbers saying, Vespin II with 14″ Unifit Adapter is the best solution they have used for 16-inch rough-in settings. There are also several replies and reviews on Amazon by people who had used this for longer rough-ins than 14 inches, like 15-inch rough-in, and say it was especially great for moving the toilet back against the wall. (check this review Amazon #ad where reviewer talks about installing it on 15 inch roughin and this Amazon review)

Also keep in mind that most other 14″ rough-in toilets are really 12″ rough-in models with a thicker tank to hide the gap between tank and wall. They often use the same bowl that projects forward from the toilet flange. The only toilet models that actually adjusts the position of the whole toilet is a Toto that utilizes the UniFit adapter.

Note: When you buy a TOTO Vespin II toilet it comes default with a 12-inch Unifit Adapter. To make it a 14″ toilet you have to order the 14″ Unifit Adapter in addition to the toilet. The Vespin II is one of the few, special Toto models that accommodate the Unifit Adapter system. The Unifit Adapter is an interchangeable part that replaces the lower half of the trapway, adapting the toilet to either a 10″, 12″, or 14″ rough-ins.

If you check other 14 inch toilets you will see Toto Vespin is shorter than other 14-inch rough-in round bowl toilets and much shorter than the other 14 inch rough-in elongated bowl toilet models. With Toto you pay more, but you get a better toilet and more usable space in the bathroom.

3) Install a 14-Inch Rough-in Toilet

The next option for 16″ offset toilet is to install a normal 14-inch rough-in toilet. 14-inch toilets are a good choice for 16 rough-ins because they minimize the projection of the toilet into the room and minimize the space behind it. However there are only a few 14″ rough-in toilets for sale in the U.S. so your choice is limited. Below I have discussed those 14 inch rough-in toilet models and their suitability for our issue.

Currently, there is only one 14″ rough in American Standard model for sale. It is the 30-1/8″ long American Standard Cadet PRO Compact Right Height Elongated 14″ Rough-In 1.28 GPF Toilet (Amazon page link #ad) According to its specification sheet here, when you install it on a 14″ rough-in, it leaves a gap of 1-1/16″ between the wall and the toilet tank. That means it can fit even on a 13 inch rough in. So when you install on a 16″ rough in, you’ll have a gap of around 3 inches at the back, between the tank and the wall. That’s too wide and will look awkward.

Kohler also has several 14″ rough-in toilet models. One is the Kohler Wellworth K-3947-0 14-inch rough-in toilet. The Kohler Highline Comfort Height 1.28 GPF Toilet K-3949-0 is another 14-inch Rough-In toilet from them.

But these 14 rough in Kohler also are designed to fit rough-ins shorter than 14 inches. Wellworth fits even a 13-1/4 inch rough in. Same is true if you check other brand models. So you might end up with a gap well over 2 inches if you install a 14 inch without checking how much gap it will leave.

4) Build A Short 3 Foot Wall Behind Toilet

This is a ingenious and cheaper solution. I heard this from someone who encountered a 16″ rough-in when they were replacing an old toilet. Instead of trying to finding larger rough-in toilet, this guy put in a normal 12-inch rough-in toilet. Then he built a small, 3-inch thick and 3 feet tall wall behind the toilet that filled in the 4-inch gap between the tank and the wall. He aligned the wall top with toilet tank top and it was beautiful and harmonic. The wall top can even be used as ledge shelf. This person I heard it from finished it with a oak board to match the rest of his room decor.

5) Install a Over-The-Toilet Storage Cabinet

Above Toilet Cabinet One of the easiest solution for your 16″ rough-in issue is to install or place cabinet/rack above and behind the toilet. That way you can even install a 12-inch rough in toilet and use the unexpected space you get for something useful. There are even many ready-made over-the-toilet cabinets and racks for sale online. (Check Amazon best seller over-toilet-cabinets #Ad.)

These over-the-toilet storage cabinets and racks are built to be placed around normal size rough-in toilets. In 16″ rough-in toilets they are ideal to hide the extra gap between the tank and the wall.

Over-toilet storage solutions are becoming very popular due to their convenience and space saving ability in small bathrooms. They range from very cheap racks to over-toilet-shelves and beautiful elaborate cabinets.

More Options for 16-inch Rough-in Toilet Issue

* Fill Tank-Wall Gap with Filler – A work around for filling in the gap caused by shorter rough-in toilets on 16″ rough-ins, is to put porcelain filler between the toilet tank and the wall.

* Get a separate tank and bowl toilet – Another solution for 16-inch rough-in is the historic High Tank Toilet perspective. In olden days the toilet tank was installed on the wall, separate from the bowl. They were connected only through a half-bend flush valve that extended from the tank on the wall to the toilet bowl. A version of these historic toilets are now available as specialty toilets called Pacific Style Toilet.

If 16″ rough-in toilet replacement causes space issues

If you already had a 16 rough in toilet, I think you may not lack space by the new toilet you put in. But in case if you lack space by the new toilet you installed, jutting out more than the old one, consider changing the swinging door to a pocket door. This will greatly increase the usable floor space in a small bathroom.

Benefit of Gap Between Toilet Tank and Wall

Many 12″ & 14″ rough-in toilets are designed so that they leave a gap between the tank back and wall when installed on a rough-in of exactly 12 or 14 inches. Toilet manufacturers have designed this gap because they know many rough-ins will not be exactly 12 or 14 inches due to construction errors and other reasons.

But there are benefits from having a gap between the tank and wall. The main one is for easy cleaning and preventing mold growth on the wall behind the tank. It also helps avoid tank dripping and sweating due to water condensation issues.

History of 16-Inch Toilets

According to an old master plumber from Arizona, there were some 16-inch and even 18-inch rough-in toilet models made in the 1930s and 1940s. This was before the rough-in standardization that came later on. These uncommon rough-in sizes have not been made since then.

Conclusion of 16 Offset Toilet Solutions

You are fortunate you got a 16 inch rough-in. Even though you won’t find a exact fitting toilet, any toilet will fit on what you have. Your easiest option is to install a 14 inch rough-in toilet. But best option in long term would be to relocate the rough-in to 12 inch (if its not too costly or difficult). The short wall solution is also a good option. The shelf over toilet will solve this issue and give you more storage space.

So you have a lot of options to choose from. How are you going to solve your 16-inch rough-in issue? Feel free to share what you are going to do and any other thoughts, experience and concerns in the comments below.


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 →

9 Comments on “5 Solutions for 16-Inch Rough-In Toilet Replacement”

  1. I already have the toilet which the distance is 15.78 inch from the wall. The plumber had piped it for the standard 1 foot. How can I adjust it to the 15.78 inch

    1. Hi Jessica,
      I’m sorry, I don’t know whether I understand your issue correctly. Do you mean, you have got a toilet with a 15.78 in rough-in size and your floor rough-in is 12 inches from the wall? That’s a very usual size toilet. If you want to install it you’ll have to break the floor and install a 4-inch offset toilet flange which will increase rough in to 16 inches.

      I haven’t come across any 15+ rough in size toilets in the US. If you are in the US, it’s better to get a standard 1 foot rough in size toilet to fit your piping than adjust it to fit that 15.78 inch rough toilet.

  2. Thank you for this helpful post. Is there a reason you didn’t talk about using an offset flange? I’ve read mixed reviews about them online. This is for a 3rd floor bath where a 16 inch rough in had to be done due to floor joists.

    Thank You!

    1. Thanks for bringing up offset flanges. I missed to add it, but its also a option. Like other options here it has its pluses and minuses. Some area building codes don’t allow it. So look out for that too.

  3. This is a very helpful article. My existing rough-in is 15.75 inches. I want to replace the existing toilet. You think the best option is to get the Toto Vespin II with 14″ Unifit Adapter? The Vespin on Amazon you link to in the article says the toilet is elongated, but you mention in the article that the shape is round. Which is better given the rough-in dimensions? Thank you!

    1. Hi Steph,
      Thanks for your comment. You are correct. The Vespin is an elongated bowl toilet. I’ll edit that mistake in the article.

      Toto Vespin is a great toilet and given the limited selection for 14″ rough, its probably the best toilet currently in the market to install on a 14″ rough in and hence 16″ rough in too. However any 14″ rough in toilet will work.

      Also like another commenter mentioned above, you can dig out the old toilet flange and use a new toilet offset flange with a offset of 1 or 1-1/2″ to reduce the 16″ rough into a 14 1/2″ rough-in or 15″ rough-in, thereby reduce the gap behind the toilet. You can get a offset flange from a local store or order one like this 1-1/2″ toilet offset flange on Amazon #ad.However be cautious while using a offset flange on a 16″ rough in. Some area building codes don’t allow it. And depending on the layout of pipes and direction the flushed waste water flows, adding a offset can reduce the waste flow pressure in the toilet drain after flushing.

    2. As an alternative to Vespin and if you want to save even more space, you might try out the new Toto Aquia IV toilet (link to its Amazon page #ad) and install it with new TOTO TSU08W.14 SELLABLE AQUIA IV Rough-in 14″ adapter (Amazon link #ad). The Toto Aquia IV has a depth of 27.5″, one inch shorter than Vespin. Its the shortest depth toilet currently in the market for 14 inch rough in. According to its spec sheet here, when you install it on a 12″ or 14″ rough in, with the gap between tank and wall, the length from the wall to the front of the toilet is 28-1/4″. Installed on a exact 16″ rough in, the length from wall to front of toilet will be 30-1/4″. That’s about 1″ shorter than Vespin will save you. And about two or more inches shorter than any current 14″ roughin American Standard or other brand model will give you.

      Toto Aquia IV has also got a 18-1/2″ elongated toilet bowl like Vespin, and comes in Comfort and Standard Height level. So you get same level of seating comfort, in a more compact setting. Aquia is also in the same price range as Vespin. (Note the Toto Unifit Adapters are different. The Vespin 14″ adapter won’t fit Aquia IV model and vise versa)

  4. Thank you very much for this super helpful post! Is there some reason why you wouldn’t think about a round bowl to reduce the footprint? Thx.

    1. Hi Betsy,
      Sorry about the delayed reply. All the 14 inch rough in round bowl toilet models I checked are longer in depth/length than the Toto Vespin II and Toto Aquia IV models. So space-saving wise they are better. As they come with elongated bowls you have more comfort too.

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