Bathroom Rough-In Plumbing Dimensions

Properly planning bathroom rough-in plumbing dimensions is a crucial part of any bathroom remodel or new construction project. Getting the right measurements during the rough-in phase will ensure that your fixtures and pipes are in the optimal position when you are ready for final installation. As experts in bathroom remodeling, we have extensive experience determining the ideal rough-in dimensions to create a functional and visually appealing bathroom design.


The rough-in phase is when plumbers install drain, vent, and supply pipes within the stud walls and floors before the installation of drywall or finished surfaces. Determining the right rough-in measurements is critical to create proper clearances for the installation of toilets, sinks, tubs, and showers. Even small errors at the rough-in stage can cause big headaches later on when fixtures do not line up with pipes or the bathroom layout is off.

In this comprehensive guide, we will provide recommended rough-in dimensions for all major bathroom fixtures and plumbing components. Whether you are doing a simple toilet swap or a complete bathroom remodel, these measurements will help ensure your rough-in plumbing allows for ideal placement of fixtures and accessories when it’s time for the finished installation. Having the right rough-in dimensions is crucial for functionality and aesthetics, saving time, frustration, and unnecessary costs down the road.

Toilet Rough-In

One of the most important rough-in dimensions is toilet rough-in—the distance from the finished wall to the center of the drain pipe where the toilet will connect. This will determine placement of your new toilet.

Standard 12” Toilet Rough-In

The standard toilet rough-in for residential bathrooms is 12” on center from the finished wall to the toilet drain pipe center. This 12” rough-in allows a traditional round bowl toilet to fit and seal against the wall properly. All major toilet manufacturers make models that work with a 12” rough-in.

10” and 14” Toilet Rough-In

While 12” is the standard, you will also find some bathrooms with 10” or 14” toilet rough-ins. A 10” rough-in is typically used to allow more space for narrow powder rooms. A 14” rough-in allows for installation of ADA compliant and comfort height toilets that require more space from the wall.

If replacing a toilet, always measure the existing rough-in distance so you choose the correct new toilet. Ensure your floor flange is properly secured and sufficient room behind wall so new toilet can connect to drain pipe.

Tips for Toilet Rough-In

  • For standard 12” rough-in, have center of drain pipe 12” from finished wall surface
  • 10” rough-in best for small powder rooms; go 14” for ADA or comfort height toilets
  • Flushing performance can suffer if rough-in is significantly more than 12”
  • Check your local codes for any rough-in requirements or restrictions

Bathtub Rough-In Dimensions

Roughing-in the drain and supply lines for a new bathtub requires careful planning and precise measurements. Ensuring your bathtub will align properly on the finished walls depends on getting the rough-in dimensions right.

Drain and Vent

For the tub drain and vent pipes, you want the center of the drain pipe to be 2” higher than the finished tub bottom. This allows for proper drainage slope. The overflow tee should be about 18-19” above the floor.

Make sure drain pipes have 1/4” per foot slope. Vent pipe should extend at least 4” higher than the top of the tub rim, or tie into existing vent stack.

Supply Lines

Place supply lines 2-3” above the overflow, spreading them apart about 8” center to center. This allows clearance for spout and faucet valves. Ensure hot is on the left, cold on the right.

Run supply lines up from below floor or stub into room from behind wall. Leave at least 12” of exposed supply lines for installing valves and spout.

Bathtub Rough-In Tips

  • Drain height dictated by tub model; overflow tee typically 18-19” above floor
  • Mark studs where tub edges will be; allow 1-2” clearance all around
  • Check for any plumbing obstructions before installing drain/vent pipes
  • Extend vent at least 4” above tub rim; slope drain pipes 1/4” per foot

Follow manufacturer’s specifications for specialized tub types like whirlpools or air tubs.

Shower Rough-In Dimensions

A key part of framing and plumbing a new shower area is correctly roughing-in the supply and drain lines. Ensure your finished shower installs easily and functions properly by taking precise measurements during rough-in.

Shower Drain

For the shower drain, the center of the pipe should be 2” below the shower floor height. Position drain between 16-24” from corner, depending on shower size and layout. Drain assembly should be securely attached to floor joists or a concrete substrate.

Ensure proper 1/4” per foot slope on drain pipe. Place a 2” trap below floor level with an accessible cleanout. Vent pipe should extend at least 4” above shower head height.

Shower Supply Lines

Shower supply lines should mount 1-2” above the finished shower floor. Position hot and cold supply lines 7-12” apart depending on the planned valve installation. Extend supply pipes at least 18” from the stud face, allowing clearance for the valve and shower arm installation.

Run 1/2” supply lines up from below floor or stub into room no more than 4” from framing. Place a shutoff valve box within reach outside the shower area.

Shower Rough-In Tips

  • Mark studs where interior shower walls will be located
  • Slope shower floor toward drain at 1/4” per foot minimum
  • Check local codes for any specific drain or supply line requirements
  • Avoid supply line heat traps that could limit water flow
  • Coordinate dimensions with fixture specs before framing walls

Careful shower rough-in helps ensure everything fits and functions when you’re ready for the finished installation.

Kitchen Sink Plumbing Rough-In

The key components to focus on when roughing-in kitchen sink plumbing are correctly positioning the drain lines and hot/cold supply stops. Place these properly within the wall cavity during rough-in for easy installation of your sink later.

Kitchen Sink Drain

For a single bowl sink, position the drain pipe centered with the sink base cabinet – typically 21-24” from adjacent wall or cabinets. Cut a minimum 12” x 12” opening in floor for the drain assembly. Top of drain pipe should be 3-4” below sink rim height; allow for slope and trap depth.

For a double bowl kitchen sink, place two drain lines spaced evenly to align with each sink basin. Maintain proper clearance beneath sink base. Vent pipes should always extend at least 24” above flood rim of sink.

Kitchen Sink Supply Stops

Hot and cold supply lines should be positioned 12-18” apart, protruding 2-3” from the wall or stud face. This allows clearance for valves and supply connections. Top of supply stops should be 4” above sink rim height. Ensure proper hot/cold position for faucet installation.

Place stops in open wall cavity or stub through rear wall so they can be accessed behind sink. Shutoff valves should be accessible from below sink or in an adjacent cabinet for ease of maintenance.

Kitchen Sink Rough-In Tips

  • Allow space below sink for disposer, if applicable
  • Coordinate sink and faucet placement with cabinet layout
  • Ensure proper clearance from wall or adjoining cabinet edges
  • Connect vent pipes for proper drainage and trap seal
  • Shutoff valves must be reachable for maintenance
  • Avoid supply line heat traps that restrict water flow

Proper planning of your kitchen sink rough-in makes installing the finished sink much simpler.

Bathroom Sink Plumbing Rough-In

Bathroom sink drain and water supply rough-ins should be prepared based on the sink dimensions and style. Ensure proper clearances and accessory placement to fit your bathroom vanity or pedestal sink when complete.

Bathroom Sink Drain Height

The drain pipe centerline should be positioned 4-6” above the floor to allow clearance for the p-trap below. Top of tailpiece or drain flange above sink basin should be about 31-34” above finished floor. This accommodates standard bathroom sink heights.

Offset drain toward the wall to allow room for the sink basin and any backsplash. Maintain at least 12” clearance from adjacent walls for widespread faucet installation.

Bathroom Sink Supply Lines

Typical mounting height for bathroom sink supply stops is 32-36” above the finished floor. This positions the water connections just above the sink basin rim for most bathroom sinks. Place supply stops 12-16” apart to allow for faucet and accessory placement.

Run supply risers up inside wall cavity. For an island sink, stub lines through floor or cabinet face within reach below sink. Shutoffs should be easily accessible.

Bathroom Sink Rough-In Tips

  • Tailpiece centerline 4-6” above floor; 31-34” to top above floor
  • Offset drain to open space for sink basin and backsplash
  • Supply stops 12-16” apart and 32-36” above floor
  • Venting must meet drain slope and length requirements
  • Shutoff valves readily accessible below sink or in vanity
  • Follow manufacturer specs for vessel, pedestal, or wall-mount sinks

Accurate bathroom sink rough-in measurements prevent issues when installing sinks, faucets, and drains.

Roughing in Plumbing: Frequently Asked Questions

Properly planning rough-in plumbing dimensions can seem complicated, but just remember the key measurements and best practices covered above. Here are answers to some frequently asked questions about roughing-in bathroom and kitchen plumbing:

What are the standard bathroom toilet rough-in dimensions?

The standard toilet rough-in is 12” on center from the finished wall to the centerline of the toilet flange/drain pipe. This allows proper fit and function for a round bowl toilet.

How high should tub drain and vent pipes be?

Position the tub drain pipe with center 2” above finished tub bottom. Overflow tee is typically 18-19” above floor. Vent pipe penetrates roof at least 4” above tub rim height.

What are the key measurements for shower plumbing rough-in?

Shower drain 2” below floor, 16-24” from corner. Supply lines 1-2” above floor, 7-12” apart. Drain vented 4” above shower head, 1/4” per foot slope.

Where should I locate the kitchen sink drain?

Rough-in kitchen sink drain opening 12” x 12” in floor. Drain centerline 21-24” from wall. Top of drain pipe 3-4” below sink rim height. Vent 24” above sink flood rim.

How high should bathroom sink drain and supplies be?

Bathroom sink drain height is 4-6” above floor to centerline. Supply stops 32-36” above floor. Tailpiece top 31-34” above floor. Space stops 12-16” apart.

Can I adjust pipe positions if rough-in is slightly off?

Minor adjustments in drain height and supply position can sometimes be made during finished installation. But best to get rough-in dimensions right according to fixture specs to prevent problems.

What if I’m not sure about the right measurements for my project?

Always refer to manufacturer specifications for any fixtures. Follow local codes and recommended best practices. Consult a professional if you have any questions or concerns.


Planning bathroom and kitchen plumbing rough-ins with precise measurements will ensure your finished installation goes smoothly. Use the drain heights, supply positions, and clearances recommended above as a guideline for your project. Taking the time to get the rough-in right will prevent headaches downstream.

While some minor adjustments can be made later, you will avoid problems, costs, and delays by correctly measuring and positioning all pipes during rough-in. Understanding standard toilet, tub, shower, and sink rough-in dimensions takes the guesswork out. Follow our tips along with fixture specs and local codes to create an optimal rough-in plumbing layout.

With attention to detail during the rough-in phase, your bathroom or kitchen plumbing project will have an easier final installation. Your fixtures and accessories will fit and function properly, with pipes and drains concealed neatly inside the walls and floors. While rough-in work is not always glamorous, properly planning this crucial first stage will lead to a trouble-free and visually appealing finished bathroom or kitchen space.