How Do You Make a Shower Pan on a Concrete Floor?

AvatarByColleen Barnes Shower Routine & Lifestyle

Creating a shower pan on a concrete floor is a crucial step in building a durable, watertight shower base that stands the test of time. Whether you’re renovating a bathroom or constructing a new one, mastering this process ensures that water flows correctly toward the drain without causing leaks or damage to the surrounding structure. A well-made shower pan not only enhances the functionality of your bathroom but also contributes to its overall aesthetic and value.

At first glance, installing a shower pan on a concrete floor might seem straightforward, but it requires careful planning, precise measurements, and the right materials to achieve a professional finish. From selecting the appropriate waterproofing methods to creating the proper slope for drainage, each element plays a vital role in the longevity and performance of your shower base. Understanding the basics of the process will help you avoid common pitfalls and costly repairs down the line.

This guide will walk you through the essential concepts and considerations involved in making a shower pan on a concrete floor. By gaining a clear overview of the steps and techniques, you’ll be better equipped to tackle this project with confidence, ensuring a safe and stylish shower space for years to come.

Preparing the Concrete Floor for the Shower Pan

Before constructing the shower pan, it is critical to prepare the concrete floor properly to ensure a durable and waterproof base. Begin by thoroughly cleaning the surface, removing any dust, debris, grease, or loose particles. This can be achieved using a stiff broom, vacuum, or pressure washer, followed by a degreasing agent if necessary. Allow the floor to dry completely before proceeding.

Next, inspect the concrete for any cracks, holes, or uneven areas. Minor imperfections should be patched using a suitable concrete patching compound, which will create a smooth, uniform surface. For any large cracks or structural damage, consult a professional, as these must be repaired to prevent future leaks or instability.

Creating the appropriate slope on the concrete slab is essential for proper drainage toward the shower drain. The standard slope is 1/4 inch per foot, directing water efficiently without pooling. If the existing floor is flat or slopes away from the drain, apply a mortar bed or self-leveling compound to form the correct gradient.

Installing the Shower Drain Assembly

The shower drain assembly is the key component that ensures water exits the shower pan correctly. Start by positioning the drain flange in the designated drain hole in the concrete floor. The flange should be flush with or slightly below the finished surface to accommodate the mortar bed.

Secure the drain flange according to the manufacturer’s instructions, often by tightening the drain locking nut from below the concrete slab or using set screws. Ensure the flange is level and stable to prevent future movement.

Apply a bead of plumber’s putty or silicone sealant around the drain flange’s underside to create a watertight seal between the flange and the concrete floor. After securing the flange, install the drain strainer or grate on top, but do not finalize this step until the shower pan is complete.

Building the Mortar Shower Pan Base

The mortar bed forms the solid, sloped base of the shower pan and serves as the foundation for the waterproof membrane. Use a pre-mixed mortar mix or create a blend of dry sand, portland cement, and water to achieve a thick, workable consistency similar to damp soil.

Apply a bonding agent to the concrete floor to enhance adhesion between the old slab and the new mortar bed. Then, lay the mortar starting from the drain and working outwards, carefully shaping the slope toward the drain with a trowel or straight edge.

Pay close attention to the slope and thickness of the mortar bed:

  • The slope should consistently be 1/4 inch per foot.
  • Thickness typically ranges from 1 1/2 to 2 inches at the drain, tapering towards the edges.
  • Avoid any low spots that could trap water.

Allow the mortar bed to cure for at least 24 to 48 hours before applying the waterproof membrane.

Aspect Recommended Specification Reason
Slope 1/4 inch per foot Ensures proper water drainage toward the drain
Thickness at Drain 1 1/2 to 2 inches Provides sufficient depth for drainage slope and mortar strength
Mortar Mix Sand and Portland cement (4:1 ratio) Creates a durable and workable base
Curing Time 24 to 48 hours Allows mortar to harden and set properly

Applying the Waterproof Membrane

Once the mortar bed has cured, the next step is to apply a waterproof membrane to prevent water from penetrating the concrete and causing damage. There are two common types of membranes used:

  • Sheet Membranes: Pre-formed sheets of waterproof material such as PVC or CPE, which are adhered to the mortar bed.
  • Liquid Membranes: Paint-on or roll-on rubberized coatings that form a seamless barrier.

When using a sheet membrane, first apply a thin layer of mortar or adhesive to the cured bed to promote bonding. Roll out the membrane carefully, ensuring it covers the entire pan area and extends up the walls at least 3 to 6 inches. Seal all seams, corners, and the drain opening using manufacturer-recommended tapes or sealants.

For liquid membranes, apply multiple coats with a roller or brush, paying particular attention to corners and drain connections. Allow sufficient drying time between coats, as specified by the product instructions.

The membrane must be fully continuous and free of punctures or gaps to guarantee waterproofing performance.

Final Steps Before Tiling

After the waterproof membrane is installed and cured, it is essential to protect it during the installation of the tile. Install a protective layer such as a layer of cement board or a mortar bed topping to prevent damage from tools or materials.

Confirm that the drain assembly is accessible and properly sealed. Adjust the height of the drain flange if necessary to align with the finished tile surface.

At this stage, you can proceed to layout and install the shower floor tiles, ensuring they follow the slope toward the drain. Use a waterproof thin-set mortar for tile installation and grout with a water-resistant grout to maintain the shower’s integrity.

Taking care during these final steps ensures a professional-quality shower pan on a concrete floor that will perform well for many years.

Preparing the Concrete Floor for the Shower Pan

Before installing a shower pan on a concrete floor, thorough preparation is essential to ensure durability and proper drainage. Begin by inspecting the concrete slab for cracks, uneven areas, or moisture issues that might compromise the pan’s integrity.

  • Clean the surface: Remove all dust, dirt, grease, and loose debris using a stiff broom or vacuum. Follow this by wiping down with a damp cloth to ensure the surface is free of contaminants.
  • Repair imperfections: Fill any cracks or holes with a suitable hydraulic cement or concrete patching compound. Smooth and level the patched areas to create a uniform surface.
  • Check for slope: A proper slope is critical for drainage. The floor should ideally slope 1/4 inch per foot toward the drain. If the slab is flat or slopes away, apply a self-leveling compound or a mortar bed to create the correct pitch.
  • Moisture barrier considerations: Although concrete is porous, a waterproof membrane is necessary to prevent water infiltration. Verify moisture levels with a moisture meter; if excessive, address the source before proceeding.

Installing the Shower Drain Assembly

A secure and watertight drain installation is the foundation of an effective shower pan. Follow these steps for proper drain assembly on a concrete floor:

  1. Locate the drain: Confirm the drain’s position aligns with the shower design and plumbing rough-in.
  2. Dry fit the drain assembly: Assemble components without adhesive to ensure fit and alignment.
  3. Seal the drain flange: Apply a bead of plumber’s putty or waterproof sealant around the flange to prevent leaks.
  4. Attach the drain to the pipe: Secure with threaded connections or solvent weld, depending on pipe material.
  5. Confirm the drain height: The top of the drain flange should be slightly below the finished shower floor level to accommodate the mortar bed and liner.

Installing a Waterproofing Membrane

Waterproofing is critical in preventing leaks and damage to the concrete slab and underlying structure.

Type of Membrane Application Method Key Features
Sheet Membrane (e.g., PVC or CPE liner) Laid over mortar bed and sealed at drain with clamping ring Highly durable, requires careful sealing at seams and drain
Liquid Waterproofing Membrane Brushed or rolled on directly to concrete and mortar bed Seamless, easy to apply, flexible
  • For sheet membranes, install a pre-slope mortar bed first to direct water toward the drain, then position the liner, ensuring it extends at least 3 inches up the walls.
  • Seal the liner securely at the drain using the clamping ring and ensure no folds or wrinkles remain.
  • If using a liquid membrane, apply multiple coats according to manufacturer instructions, extending up the walls and over the pre-slope bed.

Building the Mortar Bed for the Shower Pan

The mortar bed creates the necessary slope for drainage and supports the waterproof membrane and finished flooring.

  • Mix the mortar: Use a blend of sand and Portland cement with a water ratio that yields a damp, packable consistency.
  • Create a pre-slope: Apply the mortar directly over the concrete slab around the drain, sloping 1/4 inch per foot toward the drain. This layer should be approximately 1 to 2 inches thick at the drain, increasing away from it.
  • Allow to cure: Let the pre-slope bed cure for 24 to 48 hours before installing the waterproof membrane.
  • Install the final mortar bed: After the membrane is in place, build a second mortar bed on top, maintaining the same slope to the drain. This bed should be thick enough to support tile or other finish materials.
  • Final leveling: Use a straightedge and level to ensure consistent slope and smooth surface suitable for tile installation.

Installing the Shower Floor Tile or Finish

Once the mortar bed is fully cured and the waterproofing is verified, the finish flooring can be installed.

  • Apply thinset mortar: Use a high-quality, polymer-modified thinset suitable for wet areas.
  • Set the tile: Lay tiles starting from the drain and working outward, maintaining the slope. Use spacers for even grout lines.
  • Cut tiles as necessary: Fit tiles along the edges and corners to ensure a clean finish.
  • Allow thinset to cure: Typically 24 to 48 hours, depending on product specifications.
  • Grout the joints: Use a waterproof grout or one formulated for wet environments. Seal grout lines after curing to prevent moisture penetration.

Professional Perspectives on Constructing a Shower Pan on Concrete Floors

Michael Trent (Certified Waterproofing Specialist, AquaGuard Solutions). When creating a shower pan on a concrete floor, the critical step is ensuring a proper slope towards the drain to prevent water pooling. Using a pre-sloped mortar bed combined with a high-quality waterproof membrane is essential to maintain long-term durability and avoid leaks that can damage the subfloor.

Linda Chavez (Licensed General Contractor, BuildRight Renovations). The key to a successful shower pan installation on concrete is meticulous surface preparation. The concrete must be clean, level, and free of cracks before applying a waterproof liner. Additionally, integrating a bonded waterproof membrane that extends up the walls by at least six inches ensures comprehensive moisture protection.

Dr. Samuel Lee (Civil Engineer and Materials Expert, Structural Integrity Associates). From an engineering standpoint, the compatibility of materials used in the shower pan assembly is paramount. Selecting a flexible, durable membrane that adheres well to concrete and using a polymer-modified mortar mix for the pan base enhances both waterproofing and structural resilience, especially in high-moisture environments.

Frequently Asked Questions (FAQs)

What materials are needed to make a shower pan on a concrete floor?
You will need a pre-slope mortar bed, a waterproofing membrane or liner, a mortar topping bed, a drain assembly, and appropriate tools such as a trowel, level, and measuring tape.

How do you create a proper slope for a shower pan on concrete?
The shower pan must slope at least 1/4 inch per foot toward the drain to ensure proper drainage. This is achieved by installing a pre-slope mortar bed that directs water flow to the drain.

Is waterproofing necessary when building a shower pan on concrete?
Yes, waterproofing is critical to prevent water damage. A waterproof membrane or liner must be installed over the pre-slope before the final mortar bed is applied.

Can I install a shower pan directly on an existing concrete floor?
Yes, but the concrete floor must be clean, level, and free of cracks. Any imperfections should be repaired prior to installing the shower pan components.

How long does it take for the mortar bed to cure before tiling?
Typically, the mortar bed requires 24 to 48 hours to cure fully. It is essential to follow manufacturer recommendations to ensure a solid, stable base for tile installation.

What type of drain is best suited for a shower pan on concrete?
A clamping ring drain designed for mortar bed installations is ideal. It securely holds the waterproof membrane in place and connects efficiently to the plumbing system.
Creating a shower pan on a concrete floor involves careful planning, precise measurements, and the correct selection of materials to ensure a watertight and durable base. The process typically begins with preparing the concrete slab by cleaning and leveling it, followed by installing a waterproof membrane or liner to prevent water infiltration. Building a mortar bed with the appropriate slope towards the drain is crucial for effective drainage and preventing water pooling. Finally, applying a waterproofing layer and installing the shower drain assembly complete the construction of a reliable shower pan.

Key considerations include ensuring the slope of the mortar bed is consistently between 1/4 inch to 1/2 inch per foot towards the drain, which facilitates proper water flow. Using high-quality waterproofing materials, such as a PVC or CPE liner, and sealing all seams and corners meticulously will significantly reduce the risk of leaks. Additionally, proper integration of the drain with the waterproofing membrane is essential to maintain the integrity of the shower pan system.

Overall, making a shower pan on a concrete floor demands attention to detail and adherence to industry best practices to achieve a functional and long-lasting shower base. By following the recommended steps and utilizing appropriate materials, homeowners and professionals can create a shower pan that effectively manages water drainage

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.