Basement Shower Drain Rough In: Building a Plumbing System

If you are thinking of adding a basement shower or bath to your house, you need to know the plumbing for this project. Homeowners must include rough plumbing for both a shower and a toilet. 

Let’s see the steps of getting started with creating a basement shower drain rough in the system. 

The Quick Answer

Here’s a quick summary of the steps you’ll take when creating rough in plumbing for your basement:

  1. Determine the shower and sink drain location
  2. Determine the toilet flange location
  3. Connect to existing venting or create a venting system
  4. Find the drain pipe (this will involve breaking concrete)
  5. Hook up the pipe
  6. Ensure proper draining
  7. Fill in the excavated area

Steps To Build a Rough in Plumbing for Your Basement Shower

The first thing that you need to do is to install the shower drain in place on the basement floor when installing a plumbing rough in:

  1. Use a jackhammer to dig a trench and space for the new plumbing line underground
  2. Cut away or remove the old shower drain 
  3. Apply primer to the location where you will put the fittings
  4. Add cement (like PVC Filling) to the material for extra bonding
  5. Keep a ¼” slope to help drain water out of the shower
  6. Analyze the level to ensure the fitting is oriented properly  
  7. Cut the height of the drain so it is flush with the concrete flooring 
  8. Attach an adjustable drain cover

After you have attached the shower drain, you need to install the plumbing for your shower and toilet. 

How To Plumb a Basement Rough In

Now that you can get started on the plumbing rough in for your basement, you need certain tools:

  • Screwdriver
  • Drill
  • Hammer
  • Level
  • Saw
  • Socket and ratchet set
  • Tape measure
  • Trowel

Once you have the necessary tools, gather the specific materials for the rough in plumbing:

  • 2” pipe and fittings
  • 2x4s 
  • 3” pipe and fittings
  • 4” pipe and fittings
  • Band couplings
  • Glue
  • Concrete

The total cost of materials you will need for this project comes to between $@00 and $300 for a DIY project, while paying a professional to do a rough in will cost on average between $1,000 and $1,800. 

Now, let’s get started on the project! 

  1. Find the main drain: The main stack should be a 3 or 4” vertical pipe on the basement floor.
  2. Measure the slope: Measure the depth, future depth of the pipe, and the maximum length to find the slope. 
  3. Plan the plumbing: Make a drawing and accurate measurements of the bathroom on the floor. 
  4. Trench the floor: Use a sledgehammer to break up the floor. 
  5. Cut the drain: Make space to install the Y-fit into the drain. 
  6. Add the material: Add the couples and Y-fitting onto the drain. 
  7. Fix the floor: Install concrete over the holes in the ground. 
  8. Build the vent: Put together the vent lines and connect them to an existing vent using a T or Y-fitting. 
  9. Place the shower drain: Assemble the drain and set it in place. 

Adding Basement Shower and Rough In Without Changing the Pre-Pitch

If you are thinking of installing a basement shower and toilet but you don’t want to change the pitch of your entire basement, there are often simpler solutions that require less work.

For example, if your current rough in pipe is only 2.5” and the drains are 3 or 3.5”, this may require additional work than you are looking for. To plan for a custom-made rough in, you will need to consider the basement space, headroom, and pitch. 

In this case, it could be helpful for homeowners to check for drain pipes in the concrete and analyze the area for any P-trap pipes below the concrete that could be easy to use

FAQs About Basement Shower Drain Rough In

Understanding current homeowners’ most common questions about installing a basement shower drain is key to determining the best way to do this project in your home. 

Do you need to use a P-Trap Waste Pipe?

The p-trap waste pipe helps connect the sink’s drain valve to an underground sewer system. When building a rough in, you should leave a hole and fit a P-trap and standpipe for the plumber to install. 

What should you use to fill the hole?

You can slag sand, cement, paver base aggregate fill, or concrete.

Can you connect the sewer line to any location?

Homeowners can connect the sewer line anywhere with the proper fitting, such as the correct drain or P-trap, to ensure no leaks or gaps. 

Is there a separate vent for the shower?

Every fixture in the basement, such as the shower, toilet, or bath, must have its own vent that can later connect to the current vents. 

The vent pipes are crucial in helping remove gasses while simultaneously letting air flow into the system to aid drainage. If you do not have individual vents for each fitting, they will not drain properly. 

What if my shower drain is off-center?

If you are doing a basement rough in for a bathroom, you may notice that your drain is off center. You still need to make it work to help with your toilet and shower supply. One of the best methods to make this work in your basement is to use an offset flange to help minimize the DIY work.

Homeowners should first see if an off-center drain works effectively for each fitting by checking to see if the water stays trapped underneath. 

The best way to see if the water is effectively draining is to cut the cap off, pour in water, and see if water is idling in the drain or if it continues through. 

Why an L-fitting?

Many homeowners need an L-fitting for their rough plumbing. The L-fitting is used for liquid flow in drainage systems, which is effective for horizontal turns and vertical-to-horizontal turns in the drain pipes. 

When do I use Y-fitting?

If you are building your own plumbing rough in, you may need to use a Y-fitting—but when does this come in handy? The Y-fitting helps connect horizontal pipes in a drainage system or vent system. You should use a Y-fitting when connecting a vertical waste pipe to a horizontal pipe to prevent clogging.

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