Branislav / Getty Images
Often the hardest part about installing plumbing in a bathroom is therough-instage.
If you get the rough-in right, you are most of the way toward project completion.
Roughing in bathroom plumbing is far less daunting when you understand how the system works.
Branislav / Getty Images
There are generally accepted plumbing rough-in measurements forsinks, toilets, and bathtubs or showers.
In addition, fixture manufacturers typically provide rough-in specifications in their product literature.
So, no guesswork or improvisation is needed.
The Spruce / Madelyn Goodnight
Simply follow the rough-in specs for perfect bathroom plumbing.
Check the standard dimensions against the manufacturer’s specs to verify they will work for your installation.
All dimensions must be cross-checked against the local code, as this is the ultimate authority for your project.
The Spruce / Madelyn Goodnight
Understanding Rough-In Dimension Terminology
When speaking of plumbing dimensions, it’s important to understand the terminology.
It’s not just a matter of semantics; it’s a matter of standardization and simplification.
You do not measure 10 inches between the edges of the pipes.
The Spruce / Madelyn Goodnight
Not all dimensions are set in stone; consider these dimensions to be general guidelines.
They will vary according to your bathroom.
Consult the instructions that come with the fixture (sink, tub, etc.)
for more precise dimensions.
Supply line/discharge or drain: With bathroom plumbing, pipes either bring water in or take water out.
Pipes that deliver fresh water to the bathroom are called supply lines or supply pipes.
So are the hot and cold lines under the sink or behind the wall of the shower.
Yet the thicker pipe under thesinkthat removes gray water is a drain line or discharge line.
