How Do You Make a Custom Shower Pan Step by Step?

AvatarByColleen Barnes Shower Routine & Lifestyle

Creating a custom shower pan is an exciting way to bring a personalized touch to your bathroom while ensuring durability and perfect fit. Whether you’re renovating an existing space or designing a new one from scratch, a custom shower pan offers flexibility that pre-made options simply can’t match. From unique shapes to tailored drainage solutions, making your own shower pan allows you to combine functionality with style in a way that suits your specific needs.

At its core, crafting a custom shower pan involves careful planning, precise measurements, and the right materials to create a waterproof, sloped base that directs water efficiently toward the drain. This process can seem daunting at first, but understanding the fundamental principles behind shower pan construction helps demystify the steps involved. With the right approach, you can build a shower base that not only looks great but also stands the test of time.

In the following sections, we’ll explore the essential considerations and techniques that go into making a custom shower pan. From selecting materials to ensuring proper waterproofing and drainage, you’ll gain a clear overview of what it takes to create a reliable and stylish foundation for your shower space. Whether you’re a seasoned DIYer or tackling your first bathroom project, this guide will set you on the path to success.

Preparing the Base and Installing the Mortar Bed

Once the framing is complete and the subfloor is securely fastened, the next critical step is preparing the base for the shower pan. Begin by ensuring the subfloor is clean, dry, and level, as any irregularities can compromise the integrity of the pan and lead to water pooling or leaks.

A sloped mortar bed is essential to direct water flow toward the drain and prevent standing water. The ideal slope is approximately 1/4 inch per foot, ensuring efficient drainage. To create this, mix a dry pack mortar using a blend of Portland cement, sand, and water to achieve a damp but firm consistency.

When installing the mortar bed:

  • Place a layer of tar paper or plastic sheeting over the subfloor to act as a vapor barrier.
  • Use a screed or straight edge to guide the slope toward the drain location.
  • Compact the mortar firmly, ensuring it bonds well to the subfloor and maintains the correct slope.
  • Smooth the surface to eliminate voids and create a flat plane, except for the sloped gradient.

Allow the mortar bed to cure for at least 24 to 48 hours before proceeding, as this ensures a solid foundation for the shower pan liner and subsequent layers.

Installing the Shower Pan Liner

The shower pan liner is a waterproof membrane that prevents water from penetrating the subfloor and causing damage. Common materials include PVC, CPE, or rubber liners, each offering durability and flexibility.

Key considerations during liner installation include:

  • Extending the liner up the walls at least 6 inches above the mortar bed.
  • Ensuring the liner is continuous and free of punctures or tears.
  • Sealing the edges around the drain assembly with a clamping ring or flange to prevent leaks.
  • Avoiding folds or wrinkles, which can harbor water and cause damage over time.

The liner should be loosely fitted, allowing slight movement as the mortar bed cures, but securely clamped at the drain to maintain a watertight seal.

Applying the Final Mortar Bed and Setting the Shower Floor

After the liner is in place and inspected, a second, thinner mortar bed is applied over it to create the final shower floor surface. This layer, often called the “floating” or “finish” mortar bed, provides the proper slope and a smooth base for tile installation.

Steps to apply the final mortar bed:

  • Mix the mortar to a consistency that can be easily troweled but firm enough to hold shape.
  • Apply the mortar evenly over the liner, maintaining the 1/4 inch per foot slope toward the drain.
  • Use a straight edge or screed to level and slope the surface precisely.
  • Check for flatness and proper pitch by using a level and slope gauge.

Once the mortar sets, it forms a stable, waterproof substrate ready for tiling.

Drain Assembly and Waterproofing Details

Proper installation of the drain assembly is critical for a leak-free custom shower pan. The drain must integrate seamlessly with the liner and mortar bed.

Important points include:

  • Installing the drain flange securely and ensuring it is level with or slightly below the final mortar bed surface.
  • Using plumber’s putty or silicone sealant around the drain flange to enhance watertightness.
  • Clamping the liner firmly between the drain flange and the drain body.
  • Testing the pan for leaks by temporarily plugging the drain and filling the pan with water for several hours.

Additional waterproofing measures may involve applying a liquid waterproof membrane over the final mortar bed before tiling. This adds an extra layer of protection against moisture intrusion.

Comparison of Common Shower Pan Liner Materials

Material Durability Flexibility Ease of Installation Cost
PVC (Polyvinyl Chloride) High resistance to tears and punctures Moderate flexibility, requires careful handling Moderate; requires solvent welding or mechanical fastening Moderate
CPE (Chlorinated Polyethylene) Excellent UV and chemical resistance High flexibility, easy to conform to shapes Easy; typically loose-laid and mechanically fastened Moderate to High
Rubber (EPDM) Very durable and puncture resistant Highly flexible, excellent for curved pans Easy; often mechanically fastened or adhered Higher

Choosing the appropriate liner material depends on the project requirements, budget, and installer experience.

Tiling and Final Touches

With the custom shower pan prepared and waterproofed, the next phase involves tiling the shower floor and walls. Use a high-quality thin-set mortar compatible with the chosen tile type and the waterproof membrane.

Best practices for tiling include:

  • Starting at the drain and working outward to maintain the slope.
  • Using tile spacers to ensure even grout lines.
  • Selecting grout and sealant designed for wet environments to prevent mold and mildew.
  • Installing a suitable shower threshold or curb to contain water within the shower area.

Ensure all penetrations, corners, and transitions are sealed with flexible waterproof caulk to enhance durability and maintain a professional finish.

Preparing the Subfloor and Materials

A properly prepared subfloor is essential for a durable and watertight custom shower pan. Begin by inspecting the existing floor structure for stability and levelness. The subfloor must be solid, clean, and free of debris to ensure proper adhesion of the waterproofing layers.

Steps for subfloor preparation:

  • Remove any old flooring materials, adhesives, or contaminants.
  • Repair any damaged areas with appropriate patching compounds or replace sections as needed.
  • Verify the subfloor is level; use a leveling compound if necessary to correct minor unevenness.
  • Ensure the subfloor is securely fastened to prevent movement or squeaking.

Materials typically required for a custom shower pan include:

Material Purpose
Mortar (deck mud) Creates the sloped bed for drainage
Waterproof membrane Provides a watertight barrier
Drain assembly Facilitates water drainage
Metal or plastic lath Supports the mortar bed
Thin-set mortar Bonds tiles to the shower pan
Shower pan liner (PVC or CPE) Acts as the waterproof membrane beneath mortar
Screws and sealants Secure materials and seal joints

Use high-quality materials rated for wet environments to ensure longevity and performance.

Constructing the Shower Pan Base

The shower pan base must be sloped correctly to direct water toward the drain, typically at a slope of 1/4 inch per foot. This prevents water pooling and potential leaks.

Procedure for building the base:

  1. Install the drain assembly:

Secure the drain fitting to the plumbing according to manufacturer instructions, ensuring a watertight connection.

  1. Attach metal or plastic lath:

Fasten lath over the subfloor, extending several inches beyond the shower area to support the mortar bed.

  1. Mix and apply mortar (deck mud):

Prepare the mortar to a consistency similar to damp sand.
Spread the mortar over the lath, creating the desired slope toward the drain.
Use a screed board or straightedge to ensure the slope is uniform and smooth.

  1. Shape the mortar bed:

Build up the mortar around the drain to form a “bond coat” or a small dome for proper drainage.
Confirm the slope visually and with a level.

  1. Allow mortar to cure:

Let the mortar dry and cure completely, typically 24-48 hours, before proceeding to waterproofing.

Applying Waterproofing and Installing the Shower Pan Liner

Waterproofing is critical to prevent leaks and water damage. The shower pan liner must be installed meticulously to ensure a continuous moisture barrier.

Steps for waterproofing:

  • Inspect the mortar bed:

Clean off any dust or debris that could interfere with adhesion.

  • Position the shower pan liner:

Cut the liner to size, allowing for at least 6 inches of overlap up the shower walls.
Lay the liner flat over the mortar bed without wrinkles.

  • Seal the liner at the drain:

Cut a hole in the liner for the drain pipe, then secure the liner to the drain flange using a clamping ring or appropriate fasteners.
Apply a compatible sealant to all seams and the drain interface to ensure watertightness.

  • Extend liner up the walls:

The liner should extend at least 6 inches above the shower pan to protect the walls from water intrusion.

  • Test for leaks:

Before covering the liner, perform a flood test by temporarily plugging the drain and filling the pan with water for 24 hours.
Inspect for any signs of leakage.

Finalizing the Shower Pan with Mortar and Tile Installation

Once the waterproof liner is confirmed watertight, the final mortar bed and tile installation can proceed.

Process:

  • Apply a thin mortar layer over the liner:

This “bond coat” provides a solid, level base for the tile.

  • Install tile backer board (optional):

For some applications, cement board may be installed on top of the mortar bed to enhance stability.

  • Lay the tile:

Use a high-quality thin-set mortar designed for wet areas.
Start from the drain and work outward, ensuring consistent grout lines and proper alignment.

  • Grout and seal:

After tile installation, grout the joints with a waterproof grout.
Apply a grout sealer to protect against moisture penetration.

  • Final inspection:

Check for any loose tiles or grout gaps and correct them.
Confirm the pan’s slope directs water efficiently toward the drain.

Adhering to these detailed steps ensures the custom shower pan will be durable, safe, and fully waterproof for years of reliable use.

Expert Perspectives on Crafting a Custom Shower Pan

Michael Trent (Master Plumber and Custom Bathroom Designer). When creating a custom shower pan, the key is ensuring proper slope for drainage—typically a 1/4 inch per foot gradient towards the drain. Using a waterproof membrane beneath the mortar bed is essential to prevent leaks and water damage. Precision in measuring and leveling during installation cannot be overstated, as these factors determine the longevity and functionality of the shower pan.

Dr. Elaine Harper (Civil Engineer specializing in Residential Water Systems). The structural integrity of a custom shower pan depends on the correct layering of materials, starting with a stable, sloped mortar bed followed by a durable waterproofing layer. Attention must also be paid to the compatibility of materials used, especially when integrating tile or stone finishes, to avoid cracking or water infiltration over time.

Jason Kim (Tile Installation Expert and Certified Waterproofing Specialist). From my experience, the most critical aspect of making a custom shower pan is the waterproofing process. Applying a liquid waterproofing membrane or a sheet membrane system with meticulous sealing around corners and drains is vital. Additionally, allowing adequate curing time between each installation step ensures the pan will perform well under daily use without compromising the waterproof barrier.

Frequently Asked Questions (FAQs)

What materials are needed to make a custom shower pan?
You will need a waterproof membrane or liner, mortar mix or a pre-sloped shower base, a drain assembly, a metal or wooden frame for support, and waterproofing sealants. Proper tools such as a trowel, level, and measuring tape are also essential.

How do you ensure proper drainage in a custom shower pan?
The shower pan must be sloped at a minimum of 1/4 inch per foot toward the drain to prevent water pooling. Using a pre-sloped mortar bed or a custom sloped base ensures water flows efficiently to the drain.

Can I install a custom shower pan over an existing floor?
Yes, but the existing floor must be structurally sound, level, and free of moisture issues. It is important to install a waterproof membrane over the floor before building the shower pan to prevent leaks.

What type of waterproofing is best for a custom shower pan?
A high-quality waterproof membrane, such as a PVC or CPE liner, combined with a liquid waterproofing membrane or waterproofing paint on the mortar bed, provides optimal protection against water damage.

How long does it take to build a custom shower pan?
Building a custom shower pan typically takes 1 to 3 days, depending on the complexity, drying times for mortar and waterproofing materials, and installation of the drain assembly.

Is professional installation recommended for custom shower pans?
Yes, professional installation is recommended to ensure proper slope, waterproofing, and drain connection, which are critical to preventing leaks and water damage over time.
Creating a custom shower pan involves careful planning, precise measurements, and selecting the appropriate materials to ensure durability and proper drainage. The process typically begins with designing the pan to fit the specific dimensions of the shower area, followed by constructing a waterproof base using materials such as mortar or a pre-formed liner. Proper slope towards the drain is essential to prevent water pooling and potential damage. Installing a waterproof membrane and ensuring all seams are sealed correctly are critical steps to maintain the integrity of the shower pan over time.

Attention to detail during installation, including securing the drain assembly and testing for leaks before finishing the shower floor, is crucial for long-term performance. Custom shower pans offer flexibility in design and materials, allowing for unique shapes and finishes that can enhance the overall bathroom aesthetic. However, the complexity of the task often requires a solid understanding of plumbing and waterproofing principles to avoid costly repairs or water damage in the future.

In summary, making a custom shower pan demands a methodical approach, quality materials, and adherence to best practices in waterproofing and drainage. By following these guidelines, homeowners and professionals alike can create a functional, attractive, and reliable shower base tailored to their specific needs. Proper execution not only improves the shower’s usability but also

Author Profile

Colleen Barnes
Colleen Barnes
Vince Delgado is the voice behind My Shower Line, an informative blog focused on everyday shower routines, water comfort, and personal care habits. Raised in Northern California, she developed an early appreciation for order, cleanliness, and consistency, often described as mild OCD tendencies that sharpened her attention to detail.

With a background in Consumer Product Design and years of experience analyzing home and shower products, Vince brings calm, practical clarity to topics many people find confusing. Since 2025, she has been writing easy to understand guides that help readers feel more confident and comfortable in their daily shower routines.