When you want to buy a new toilet, in general, the first thing that you check is the type of the toilet. You can choose from a wide range of toilets: one-piece toilet, two-piece toilet, compact toilet, corner toilet, wall mounted toilet, elongated toilet, tankless toilet, etc. But you have to pay attention because besides the form of the toilet bowl or the type of the tank, there is another important thing to check. And this is the toilet rough-in size. Maybe, you have never heard about this term before, but it is essential to know what it means, and how you can measure it.
If you ignore or forget to check the toilet rough-in size, it can happen to you, that you go home with your newly bought toilet, but you won’t be able to install it. Then, there is two things, what you can do about it. Option 1: you go back to the shop and try to change it, or option 2: you rebuild your bathroom. The problem is with the first option, that you may feel embarrassed or stupid to take back the toilet for this reason. And the second option, it would cost you too much money and it needs a lot of time. Therefore, I think, it is just easier to check it before buying and choose a toilet in the correct size. Although, most of the toilets have 12 inches rough-in, in old houses it is not uncommon to have a rough-in of 10 inches or 14 inches. Therefore, when choosing a new toilet, you have to verify that you are buying the toilet in the good rough-in size.
But how will you know which size do you need? How can you measure it at home? If you would like to get an answer to these questions, then keep reading. I will explain to you what we call exactly a toilet rough-in, what is a toilet rough-in measurement, and what are the 4 dimensions that you need in order to measure the toilet rough-in. And don’t worry, you don’t have to be a professional to be able to measure it. The only thing that you need is a tape measure and a pencil. I offer you a step-by-step guide which is very easy to follow. So let’s start it!
What is Toilet Rough-in
Let’s see first what we call a toilet rough-in. Basically, the toilet rough-in means the distance between the wall (behind the toilet) and the center of the waste outlet. If you are wondering, the waste outlet is that pipe, where the waste leaves the toilet.
The Basics of Toilet Rough-in Measurement
The toilet rough-in measurement can be very easy if you are aware of the technical terms in connection with toilets and you can make the difference between the different types of toilets. Without getting into the boring details (different sizes of toilets, different dimensions, etc.), I want you first to get an overall picture of the toilet rough-in measurement. Basically, to measure the rough-in size, you have to measure the distance from the finished wall until the center of the drainpipe. It is possible that you won’t be able to measure until the center because for example, your toilet is still at its place built in, then take the distance from the wall until the bolt caps’ center. Usually, there are two bolts, one on the left side of the toilet, and one on the right side. When measuring the distance from the wall, you should measure it from the finished wall, and not from the molding or the baseboard. Do it as you can see it on this photo:
If you measure the rough-in well, you can be sure that no additional adjustment will be necessary, and also you don’t have to return the toilet because you won’t be able to build it in.
But what you should do if the waste outlet is not on the floor, but the waste is exiting through the wall? Then it means, that you have a rear-outlet toilet, and not standard. In this case, measure from the finished floor until the center of the outlet. Just like on this photo:
If You Want to Know More About How to Measure The Toilet Rough-in
Like in every situation, also here some difficulties can come up when you need to know more about the toilet rough-in measurement. You can have some problems especially if you are not just changing the toilet, but you are making full bathroom renovation. In that case, you will need to know for example how much space you should leave in front of the toilet bowl, where you should put the cold water supply line, or how much clearance do you need next to the toilet in both directions, etc. So if you want to be a toilet rough-in expert, you have to learn about 4 dimensions in connection with the toilet rough-in measurement.
First dimension: the distance between the wall behind the toilet and the closet flange
Basically, the first dimension is what was described above in “The Basics of Toilet Rough-in Measurement” section. When you are building a new bathroom, it is advised to put the toilet/closet flange 12 inches from the finished wall behind the planned toilet bowl. The 12 inches should be at the center of the flange and as explained before, don’t measure from the molding or the baseboard. If you don’t know what we call toilet/closet flange, here is a photo about it:
Please be aware also that if you have a stud wall, you need to take also the thickness of the wall into account. So if you want to install a standard toilet with a 12 inches rough-in (you can find this information on the specification sheet of the toilet) and you want to build in also a half inch drywall, then you have to place the center of the toilet flange 12 and a half inches far from the stud wall.
As I have mentioned before the most common size is 12 inches for the toilet rough-in. If you measured at home the distance between the center of the flange and the wall, and the result is 10 inches, then when you go to buy a new toilet bowl, ask for one with 10 inches rough-in. And the same goes for the case, if you measured 14 inches, choose the toilet with 14 inches rough-in. Keep in mind that it is always easier to measure the rough-in before buying, than replacing toilet insides (for example the toilet flange), or return the toilet bowl what you just bought.
Second dimension: the necessary clearance on both sides of the toilet (left and right)
The second dimension comes in handy in three cases: firstly, when you are planning your new bathroom and you want to know how far you should put the door or the bathroom sink from the toilet. Secondly, when you are changing your bathroom sink or some furniture near to the toilet. And the third case is when you want to change your toilet for a new with different types or sizes.
In all three cases, it is crucial to measure the clearance from the center of the toilet bowl until any sidewall, furniture, bathroom sink, bathtub or any other fixture next to the toilet. Pay attention also to the placement of grab bars around the toilet. But why is it so important? It’s important not just because the toilet should fit in the place, but also because when using a toilet, you should feel comfortable. Just imagine that you buy a new toilet, and after installation, you realize that you would hit your elbow into the bathroom sink all the time. And in this case, even a luxury toilet with Omigo seat won’t be enough to make you feel relaxed.
So how much space should you leave next to the toilet? It is advised to have 15 inches of clearance. Of course, you can leave more, but this is the minimum what you should have. Therefore, at least 15 inches of distance should be measured from the center of the toilet to any object next to the toilet (in both directions: 15 inches to the left, 15 inches to the right) and you should pay attention again to the molding, baseboard, or stud wall.
Third dimension: the clearance in front of the toilet
The third measurement that you should definitely be aware of is the clearance in front of the toilet. It is important to keep some distance there because otherwise, you could get into trouble. When you open the door, you should be able to pass next to it and sit on the toilet, or if there is a wall in front of the toilet, you should feel comfortable and have enough place for your feet when using the toilet. Therefore, always leave sufficient clearance in front of the toilet.
You may be wondering now, that how much inches should be the distance. The interesting thing is, that there is a regulation on this clearance, so the distance depends on your local plumbing code. The good news is, that there are only two options.
Option Nr. 1: your local jurisdiction utilizes the International Plumbing Code (IPC). In this case, it is obligatory to leave at least 21 inches distance.
Option Nr. 2: your local jurisdiction utilizes the Uniform Plumbing Code (UPC). Then you should leave at least 24 inches distance.
But how should you measure the distance? From the center of the flange? No, this clearance should be measured from the edge of the toilet bowl in the front until any obstruction, what can be found there. The most common thing that can be there is a wall or a door. If you have a door in front of the toilet bowl, measure the clearance from the closed door. But why don’t we measure it from the opened door? You may ask. The answer is simple. Because this distance is important for being able to use the toilet comfortably, and people used to close the door after entering the toilet or bathroom.
4. dimension: the distance to the cold water supply line
The fourth measurement that you should know about is the distance to the cold water supply line. The position of the water line is especially important when you are building a new bathroom. If you put it too low, and later on, you install the molding, it is possible that you have to cut the trim. And if it has to be cut, it is ugly and at the same time, it means plus work for you. So it is better to be smart and put the water line at a good place.
Usually, if you place it 7 inches above the floor, it must be sufficient for any kind of base molding. To measure this distance correctly, at first, measure 6 inches to the left side of the toilet starting from the center of the toilet flange, and after this, measure up these 7 inches above the floor. It is super easy, isn’t it?
I hope that this guide helped you to learn the basics of toilet rough-in measurement and you will be able to measure by yourself. Usually, it is not something very difficult, but there are some conditions that you should keep in mind in order to measure correctly. There are also some circumstances, when you may get confused about the distances. For example, if you want to build a new house and you are planning the position of the toilet. Also, if you want to change your round front type of toilet to an elongated one, but the wall in front of the bowl would be maybe too close and would not meet the necessary 21 or 24 inches. In these cases, if you are not sure about something, it is always better to call a professional. A good technician can save you some time and also money in the long term.