How to Draw a Plumbing Plan for Your Next Remodeling Project

A well-planned diagram is essential for any remodeling project that involves significant plumbing work. For example, a kitchen or bathroom plumbing layout drawing allows you to map out the system beforehand, which will help ensure the process runs as smoothly as possible. Professional plumbers usually map a plumbing job meticulously to prevent surprises during the project. You should, too, if you plan to DIY the work.

A plumbing plan illustrates the system that will bring water in and take waste back out. It typically includes water supply lines, drains, vent pipes, valves, and fixtures such as toilets and sinks. These plans often use a variety of official plumbing symbols to denote different elements, and it's relatively easy to produce plan views and riser drawings by hand or computer.

Making detailed drawings will save time and expenses later. Also, drawing the project helps you think through the job in detail, enabling you to spot something you might otherwise overlook. If you have all the necessary materials noted in the plan, it will almost certainly minimize extra trips to the plumbing supply store. A clear, professional-quality plan can also benefit projects requiring a plumbing permit. Although a plan might not be necessary to obtain a permit, it will likely make your initial meeting with the building department more productive. Be sure to check your local plumbing codes before you begin.

How to Draw a Plumbing Plan

A plan for new plumbing starts with a map of the existing plumbing. Use color codes and these universally recognized symbols on your drawings to denote each component of your plan clearly.

If you have architectural drawings, make several photocopies of them. If not, make several copies of an accurate scale drawing of the room. A gridded straightedge will help you draw parallel lines. You'll also need colored pencils, an eraser, and a 30-60-90-degree triangle. Use grid paper and establish a scale, such as 1/2 inch equals 1 foot. Drawing to scale makes it easy to note any problems with the layout. It also helps in estimating materials.

To make a plumbing plan:

• Draw all fixtures to scale size and make sure they are not too close together.
• Mark the drain lines and vents for the fixtures, then add the supply lines. Make riser drawings to show vertical pipe runs as well.
• Indicate pipe sizes and the exact type of every fitting so the inspector can approve them.
• Mark locations for valves, including stops at fixtures, and specify the type of valve.
• Make a shopping list of materials based on the drawings.

Elements of a Successful Plumbing Plan

To help your DIY remodel go smoothly, make sure your plumbing plan includes these essential elements.

Key Coding

It's a good idea to code your map to keep the different elements straight:

• Show drainpipes with solid lines and supply lines with broken lines. Indicate vertical runs with notes on the overhead view.
• Mark hot and cold supply lines with colored pencils.
• Color-code drains and vents.
• Point to pipe sizes with a curved leader line to avoid mistaking the leader for a pipe.

You might need to draw several versions of the plumbing plan before getting all the details right.

DWV Elevation

A drain-waste-vent (DWV) elevation describes the system that will carry water, waste, and air out of the house. Its primary purpose is to show how the fixtures will be vented. This part of your plumbing plan should note the upward path of the stack, vents, and re-vents, the length of drainpipe runs, and traps. It doesn't have to be drawn over an architectural drawing, although that can be helpful for reference.

Supply Drawing

A supply drawing indicates the estimated length of supply pipes. Be sure to include the pipe size as well. The primary purpose of this drawing is to determine the minimum size of the pipes. Refer to this plumbing plan as you make your shopping list of materials to ensure you purchase the correct sizes and lengths.