Riser Diagram

By: Tim Carter

A Riser Diagram Gets You a Plumbing Permit

A riser diagram is a handy 3D drawing that shows all of the drain, waste, and vent (DWV) pipes that will be in a project. These drawings are required by cities and towns in order for you to obtain a plumbing permit.

riser diagram draw plumbing plans
This is an example of a riser diagram drawn by Master Plumber Tim Carter. Copyright 2024 Tim Carter

What Do You Need to Know to Draw One?

A deep understanding of the Uniform Plumbing Code is required to successfully draw a riser diagram. It is important to realize you must know the following:

  • the correct size pipe that connects to each fixture
  • the correct size pipe that vents each fixture
  • the correct location of the vent pipe for each fixture
  • how to collect vents and when to upsize vent pipes
  • the correct fittings to use in the DWV system
  • how to design the system for minimal friction loss

How Do You Indicate the Pipe Size on a Riser Diagram?

Pipe sizes are indicated using a small circle around each pipe. A small curved line is drawn between the circle and a number that calls out the inner diameter of the pipe. This is required for all DWV pipes on the drawing.

a toilet symbol on a riser diagram showing pipe size callout
This is how you note pipe sizes on a riser diagram. Note the different colors that make it easy to see if all pipes on the drawing are correct. Copyright 2024 Tim Carter

Tim Carter uses color-coding on his riser diagrams to make it easy for plumbers, homeowners, and plan examiners to see if all the pipe sizes are correct. Tim went to great lengths to ensure the colors used are color-blind safe so all can see the colors.

Call Tim now if you need help getting a permit:


plumbing pipes below a concrete slab apartment building
Look how many pipes there are! Do you understand now why you need a plumbing plan or riser diagram to get the correct sizing for the pipes? Copyright 2024 Tim Carter

Is a Plumbing Isometric Drawing the Same Thing?

Yes, a plumbing isometric drawing is identical to a riser diagram. They both show the same thing. It is a good idea to include General Notes on the drawings that speak to best plumbing practices to follow when installing all the pipes.

Who is Qualified to Draw a Riser Diagram?

Mechanical engineers, master plumbers, and some architects have the skills to draw these plans. Mechanical engineers have a track record of charging the most money.

Tim Carter, a master plumber, charges a very fair price to draw them and can fulfill an order in just a few days.

tim carter master plumber at bar harbor job site
This is Tim Carter, master plumber, taking a break from installing floor drains in the garage of his daughter’s home on Mt. Desert Island in Downeast Maine. Copyright 2024
tim carter master plumber seal
Tim Carter has been a master plumber since 1981 and WILL DRAW your riser diagram in days.