How Do You Build a Shower Curb Step by Step?

AvatarByColleen Barnes Shower Routine & Lifestyle

Building a shower curb is an essential step in creating a functional and stylish shower space. Whether you’re renovating a bathroom or constructing a new one from scratch, understanding how to build a shower curb correctly ensures water stays contained, preventing leaks and damage. A well-crafted curb not only serves a practical purpose but also adds a polished, professional look to your shower area.

Constructing a shower curb involves more than just stacking materials; it requires careful planning, the right tools, and knowledge of waterproofing techniques. The process balances durability with aesthetics, making sure the curb is sturdy enough to withstand daily use while complementing the overall design of the bathroom. For DIY enthusiasts and professionals alike, mastering this skill can elevate any shower installation project.

In the following sections, we’ll explore the fundamental principles behind building a shower curb, including the materials commonly used, essential construction tips, and best practices for waterproofing. Whether you’re a seasoned builder or a first-time renovator, this guide will equip you with the insights needed to create a reliable and attractive shower curb that stands the test of time.

Preparing the Base for the Shower Curb

Before constructing the shower curb, it is crucial to prepare a solid and waterproof base. This foundation will support the curb and prevent water damage. Begin by clearing the installation area of any debris, dust, or loose materials. The floor surface must be level and structurally sound.

If the existing subfloor is damaged or uneven, repair or replace it as necessary. Use a leveling compound to smooth out minor imperfections. Next, install a waterproof membrane over the floor and up the walls where the curb will be built. This membrane acts as a barrier to protect the subfloor from moisture infiltration.

When applying the membrane, ensure it extends at least 6 inches beyond the curb’s planned footprint. Overlap seams according to the manufacturer’s instructions to maintain a continuous seal. It’s also advisable to use a bonding agent to adhere the membrane securely to the substrate.

Framing the Shower Curb

The framing of the shower curb provides the structural shape and strength. Typically, the curb is constructed from pressure-treated lumber or moisture-resistant materials to withstand the humid environment.

  • Use a 2×4 or 2×6 board to create the frame, depending on the desired curb height.
  • Cut the board to the length needed for the shower entry.
  • Secure the frame to the subfloor using corrosion-resistant screws or nails.
  • Ensure the frame is square and level by checking with a carpenter’s square and level tool.
  • Fill any gaps between the frame and subfloor with a waterproof sealant to prevent water seepage.

The frame must be anchored firmly to avoid shifting, which could compromise the curb’s integrity and waterproofing.

Applying the Waterproofing Layer

Waterproofing the curb is essential to prevent leaks and water damage. After framing, cover the curb with a waterproof material such as cement backer board or a pre-formed shower curb kit. Cement backer board is preferred for its durability and compatibility with tile adhesives.

  • Cut the backer board to fit the frame’s dimensions.
  • Attach it securely using screws designed for cement board.
  • Seal all joints with fiberglass mesh tape and thin-set mortar.
  • Apply a liquid waterproofing membrane over the entire curb surface, extending onto the adjacent floor and walls.
  • Allow the membrane to dry completely according to the manufacturer’s instructions before proceeding with tile installation.

Proper waterproofing ensures the shower curb remains durable and prevents mold growth caused by trapped moisture.

Building the Slope for Drainage

To ensure water flows back into the shower base, the shower curb must be sloped correctly. A gentle slope of approximately 1/4 inch per foot away from the shower entrance is recommended.

  • Use a trowel to apply a mortar bed over the waterproof membrane on the curb.
  • Shape the mortar so the top surface slopes downward toward the shower floor.
  • Check the slope with a level, adjusting as needed.
  • Allow the mortar to cure fully before tiling to maintain the slope integrity.

This slope prevents water pooling on the curb and directs water back into the shower drain efficiently.

Finishing the Shower Curb

After the mortar has cured, the curb is ready for finishing. The most common finish is tile, which should match or complement the shower floor and walls.

  • Select tiles that are slip-resistant to enhance safety.
  • Use a high-quality tile adhesive suitable for wet environments.
  • Apply grout between tiles once adhesive has dried, and seal the grout to protect against moisture.
  • Install a metal or plastic edge trim to protect tile edges and provide a clean, professional look.

Proper finishing not only improves aesthetics but also contributes to the curb’s waterproofing and longevity.

Step Material Purpose Key Considerations
Base Preparation Waterproof membrane, leveling compound Provide a level, waterproof foundation Extend membrane beyond curb area; ensure subfloor is sound
Framing Pressure-treated lumber (2×4 or 2×6) Form structural shape of curb Secure frame; fill gaps with sealant
Waterproofing Cement backer board, fiberglass mesh tape, liquid membrane Prevent water infiltration Seal all joints; allow membrane to dry fully
Slope Formation Mortar bed Direct water toward shower drain Slope at 1/4 inch per foot; check with level
Finishing Tile, grout, edge trim Provide waterproof, durable surface Use slip-resistant tile; seal grout

Choosing Materials and Preparing the Workspace

Constructing a durable and waterproof shower curb begins with selecting appropriate materials and preparing the workspace meticulously. The choice of materials directly influences the curb’s longevity, structural integrity, and waterproofing effectiveness.

Material Options for Shower Curbs:

  • Concrete Backer Board: Cementitious boards such as HardieBacker or Durock provide a water-resistant base that resists mold and mildew.
  • Pressure-Treated Lumber: Used as the frame or base structure, it resists decay and provides a sturdy foundation.
  • Mortar or Thin-Set Mortar: Utilized to shape and solidify the curb, ensuring it is waterproof and stable.
  • Waterproofing Membrane: Liquid-applied or sheet membranes like RedGard or Schluter Kerdi prevent water infiltration.
  • Tile or Stone Veneer: The finished surface material, chosen for aesthetics and durability.

Workspace Preparation Steps:

  1. Clear the Area: Remove debris, old materials, and ensure the subfloor is clean and dry.
  2. Verify Subfloor Integrity: Inspect the subfloor for rot, damage, or unevenness; repair or replace as necessary.
  3. Measure and Mark: Determine the exact dimensions of the shower curb, typically 4 to 6 inches high and 3 to 6 inches wide, then mark these clearly on the subfloor.
  4. Gather Tools and Materials: Ensure all necessary tools such as saws, drills, trowels, level, and waterproofing supplies are accessible.
Material Purpose Key Properties
Concrete Backer Board Water-resistant base for mortar and tile Mold-resistant, dimensionally stable, durable
Pressure-Treated Lumber Structural frame of the curb Rot-resistant, sturdy, easy to shape
Mortar (Thin-set) Shape and bond the curb components Strong adhesive, water-resistant once cured
Waterproofing Membrane Prevent water penetration Flexible, waterproof, adheres well to surfaces
Tile or Stone Veneer Finishing surface Durable, aesthetic, slip-resistant options

Constructing the Shower Curb Frame

Building a structurally sound shower curb begins with framing the base. This step provides the foundation upon which the mortar and tile layers will be applied.

Steps for Framing the Shower Curb:

  • Cut Pressure-Treated Lumber: Using a circular saw, cut two pieces of lumber to the length of the curb and two pieces to the width, forming a rectangular frame matching the marked dimensions.
  • Assemble the Frame: Use galvanized screws or exterior-grade nails to fasten the lumber pieces together securely, ensuring square corners.
  • Attach Frame to Subfloor: Position the frame on the subfloor and fasten it using screws or nails, verifying the frame is level and stable.
  • Seal Joints and Gaps: Apply a bead of exterior-grade sealant along all joints and where the frame meets the subfloor to prevent water infiltration.

Key Considerations:

  • The frame should be slightly wider than the final curb to allow for mortar buildup.
  • Ensure the frame height matches the planned curb height, typically 4 to 6 inches.
  • Use a level frequently to maintain a uniform height and prevent sloping.

Applying Mortar and Waterproofing

After framing, the next critical phase involves shaping the curb with mortar and applying waterproofing to prevent water damage.

Mortar Application Procedure:

  • Mix Mortar: Prepare a thick consistency of thin-set mortar according to the manufacturer’s instructions.
  • Apply Base Layer: Using a trowel, spread mortar inside the frame, creating a solid base approximately 1 to 2 inches thick.
  • Shape the Curb: Build up the mortar gradually, smoothing the surface and rounding edges as desired to facilitate water runoff and aesthetics.
  • Allow to Cure: Let the mortar cure for 24 to 48 hours, ensuring it hardens fully before proceeding.

Waterproofing the Shower Curb:

  • Clean the Surface: Remove any dust or loose mortar particles.
  • Apply Waterproofing Membrane: Use a liquid waterproofing membrane, brush or roll an even coat over the entire curb surface, including the top and sides.

    • Professional Perspectives on How To Build A Shower Curb

    Mark Jensen (Licensed General Contractor, Jensen Home Renovations). When constructing a shower curb, it is essential to start with a solid, waterproof base. Using a mortar mix to form the curb ensures structural integrity and durability. Additionally, applying a waterproof membrane over the curb before tiling prevents water infiltration and potential damage to the subfloor and walls.

    Dr. Emily Carter (Civil Engineer and Building Codes Specialist). Proper slope and height are critical factors in shower curb construction. The curb should be at least 4 to 6 inches high to effectively contain water, and the shower floor must slope toward the drain at a minimum of 1/4 inch per foot. These specifications comply with building codes and reduce the risk of water leakage outside the shower area.

    Luis Ramirez (Tile Installation Expert and Trainer, National Tile Institute). When building a shower curb, attention to detail in waterproofing and tile application is paramount. After installing the curb frame and waterproofing membrane, use a high-quality thin-set mortar to secure tiles, ensuring full coverage and no gaps. Proper sealing of grout lines further protects the curb from moisture penetration and extends the lifespan of the installation.

    Frequently Asked Questions (FAQs)

    What materials are needed to build a shower curb?
    Essential materials include cement board or concrete backer board, mortar or thin-set, a waterproofing membrane, reinforcing mesh or wire, and tile or other finishing materials. Proper tools such as a trowel, level, and saw are also required.

    How do I ensure the shower curb is waterproof?
    Apply a waterproofing membrane over the entire curb after installing the cement board. Seal all seams and corners with waterproof tape or sealant to prevent water infiltration and protect the underlying structure.

    What is the recommended height for a shower curb?
    A standard shower curb height ranges from 4 to 6 inches, balancing effective water containment with ease of access. The exact height may vary depending on shower design and user needs.

    Can I build a shower curb without professional help?
    Yes, with proper planning, materials, and adherence to waterproofing and building codes, a skilled DIYer can build a shower curb. However, consulting professionals is advisable for complex designs or if unfamiliar with waterproofing techniques.

    How do I reinforce a shower curb to prevent cracking?
    Incorporate reinforcing mesh or wire within the mortar base and use a cement board designed for wet areas. Proper curing and avoiding excessive weight on the curb during installation also help prevent cracks.

    Should the shower curb slope inward or outward?
    The shower curb should have a slight inward slope toward the shower floor to direct water back into the shower area, preventing water from escaping into the bathroom floor.
    Building a shower curb is a fundamental step in creating a functional and water-tight shower enclosure. The process involves careful planning, precise measurements, and the use of appropriate materials such as cement board, mortar, and waterproofing membranes. Ensuring the curb is properly constructed and sealed is crucial to prevent water leakage and maintain the structural integrity of the shower area.

    Key considerations include establishing the correct height and width of the curb to accommodate shower doors or curtains, as well as creating a slight slope to direct water back into the shower pan. Using durable, water-resistant materials and applying a thorough waterproofing system are essential to protect against moisture damage over time. Additionally, finishing the curb with tile or other suitable surfaces enhances both the aesthetic appeal and functionality of the shower space.

    In summary, building a shower curb requires attention to detail, adherence to best practices, and the use of quality materials to ensure longevity and performance. By following these guidelines, homeowners and professionals can achieve a durable, effective shower curb that contributes to a safe and attractive bathroom environment.

    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.