What is Toilet Rough-In? A Guide to Bathroom Plumbing Measurements

As we all know, the toilet is an essential sanitary fixture in our daily lives. So, what does "toilet rough-in" mean? Let's take a closer look.

What does toilet rough-in mean？

Toilet rough-in refers to the distance from the center of the toilet's drain pipe to the wall. Typically, this measurement is 30, 40, 45, or 50 cm. When selecting a toilet, if you are planning to renovate and lay tiles, it is essential to measure the rough-in after the tiles are installed. Otherwise, you may encounter the issue of buying a toilet that cannot be installed.

What are the common sizes for toilet rough-in？

Generally, the rough-in size is either 30 cm or 40 cm. During the installation of the toilet, a space of 20 mm should be reserved from the wall for the tiles. Specifically, the distance from the centerline of the toilet's drain to the wall is usually 32 cm or 42 cm, with a normal error margin of within 1 cm.

How to measure toilet rough-in？

1、First, during the measurement of the toilet rough-in, it is important to understand the structure of the drainage pipe and then measure the rough-in from the toilet's drainage outlet. There are primarily two types of drainage for toilets: horizontal discharge and floor discharge. Horizontal discharge toilets can only use direct flush models, while floor discharge toilets offer various options, such as direct flush or siphonic flush, depending on the layout of the unit and the drainage structure. The distance for horizontal discharge is typically 180 mm, while the distances for floor discharge can vary, such as 20 cm, 30 cm, 40 cm, and 58 cm, among others.

2、Next, during the measurement process, you simply need to measure from the center of the drainpipe to the wall. This distance represents the rough-in. By correctly measuring this distance, you will know what rough-in size toilet can be installed.

For example, if the measured rough-in is 40 cm and you install a toilet with a 30 cm rough-in, there will be a 10 cm gap between the tank and the wall. Conversely, if the rough-in is 30 cm but you install a toilet with a 40 cm rough-in, the toilet will not fit due to a mismatch between the drain hole and the drainage pipe. Therefore, it is crucial to measure the rough-in before installing the toilet. Additionally, remember to account for the thickness of the tiles during the measurement.

Editor’s Summary：After reading the above introduction, you should have a better understanding of what toilet rough-in means. If you would like to learn more related information, please continue to follow our website, as we will present more exciting content in the future.