How to Build a Shower Pan on Plywood Floor

To build a shower pan on a plywood floor, first check and secure your subfloor for damage or movement. Then, apply a waterproof membrane that extends up the walls to prevent leaks. Next, create a mortar bed with a 1/4 inch slope per foot toward the drain for proper drainage. Afterward, add a waterproof layer over the mortar to strengthen protection. If you keep exploring this process, you’ll find detailed steps to complete a durable, leak-proof shower pan installation.

Assessing and Preparing the Plywood Subfloor

Before you begin installing the shower pan, carefully inspect the plywood subfloor for any damage or uneven spots. You want to make sure the surface is solid and level to prevent future issues. Check for soft areas, rot, or water damage—replace any compromised plywood sections right away.

Use a straightedge or level to identify low or high spots. Sand down any high areas and fill low spots with a suitable patching compound. Secure loose plywood with screws to avoid movement.

Also, ensure the subfloor thickness meets local building codes, typically at least 3/4 inch. Proper preparation here sets the foundation for a durable shower pan installation, so take your time to get it right before moving on to the next steps.

Installing a Waterproof Membrane

A waterproof membrane plays a crucial role in protecting your shower from leaks and water damage. Start by choosing a high-quality membrane like a PVC or CPE liner, or a liquid-applied waterproofing membrane.

Clean the plywood subfloor thoroughly to ensure proper adhesion.

Lay the membrane flat, extending it up the walls at least 6 inches to create a continuous barrier.

Use waterproof tape or sealant to seal all seams and corners tightly.

If using a liquid membrane, apply it evenly with a brush or roller, making sure to cover every nook and cranny.

Allow adequate drying time before proceeding.

Proper installation of this membrane prevents water from penetrating your subfloor, safeguarding your home from costly damage and mold growth.

Building a Mortar Bed for the Shower Pan

How do you create a sturdy base that ensures proper drainage in your shower? Start by mixing a dry-pack mortar with just enough water to achieve a firm, crumbly consistency. Spread this mortar evenly over the waterproof membrane, focusing on filling low spots and creating a solid, level base.

Use a flat board or trowel to compact the mortar firmly, eliminating air pockets and providing stability. While you won’t shape the slope here—that comes next—make sure the mortar bed is thick enough, typically around 1.5 to 2 inches, to support the pan.

Allow the mortar to cure fully before moving on. This strong, well-compacted mortar bed forms the foundation for your shower pan, preventing movement and ensuring durability over time.

Creating Proper Drainage and Slope

Since water doesn’t drain properly on a flat surface, you need to shape the mortar bed with a consistent slope toward the drain. Aim for a 1/4 inch drop per foot to ensure water flows smoothly without pooling.

Start by marking the highest point at the shower edges and the lowest at the drain. Use a level and straightedge to guide your slope as you shape the mortar.

Work the mortar so it’s firm but moldable, allowing you to fine-tune the incline. Avoid creating any flat spots or low areas where water could collect.

Proper slope prevents water damage and mold growth, making your shower safer and longer-lasting. Take your time to double-check measurements before the mortar fully sets.

Applying a Waterproofing Layer Over the Mortar Bed

Before you lay tiles, you’ll need to apply a waterproofing layer over the mortar bed to prevent moisture from seeping through and causing damage. Choose a high-quality liquid waterproofing membrane or a sheet membrane designed for shower pans.

If you use a liquid membrane, apply it evenly with a brush or roller, covering every inch of the mortar bed, including corners and around the drain. Make sure to follow the manufacturer’s instructions for drying times and number of coats.

This layer creates a flexible, watertight barrier that protects the plywood floor beneath. Don’t forget to extend the waterproofing up the walls slightly to safeguard against splashes.

Proper application here is crucial for a durable, leak-free shower pan that will last for years.

Installing the Shower Pan Liner

Once you’ve waterproofed the mortar bed, you’ll install the shower pan liner to create a reliable moisture barrier beneath the final layers.

Start by cutting a piece of liner material, usually PVC or CPE, large enough to cover the pan and extend at least 6 inches up the walls.

Lay the liner flat over the mortar bed, pressing it into the drain flange to ensure a tight seal.

Secure the liner to the drain using the manufacturer’s clamping ring, tightening it firmly to prevent leaks.

Next, carefully press the liner up the walls and into the corners, smoothing out any wrinkles.

Make sure the liner remains intact and unpunctured, as it’s essential for preventing water damage beneath your shower.

Finalizing the Shower Pan Installation With Tile or Other Finishes

After securing the shower pan liner, you’ll want to carefully install the tile or other finishing materials to complete the waterproof barrier and create a polished look.

Start by applying a thin-set mortar over the mortar bed, ensuring full coverage without gaps. Press your tiles firmly into place, maintaining even spacing with tile spacers.

For other finishes like stone or acrylic panels, follow the manufacturer’s instructions for adhesion and sealing.

Once the tiles or finishes are set, grout the joints, wiping away excess promptly to prevent haze.

Finally, seal the grout and any exposed edges to protect against moisture.

Taking these steps ensures your shower pan remains watertight while delivering a durable, attractive surface that lasts.

Frequently Asked Questions

Can I Build a Shower Pan Directly Over Concrete Instead of Plywood?

Yes, you can build a shower pan directly over concrete. Just make sure the concrete is clean, level, and properly sloped for drainage. Use a waterproof membrane or liner to prevent leaks before installing the pan.

What Tools Are Essential for Building a Shower Pan?

You’ll need a utility knife, measuring tape, level, trowel, drill with mixing attachment, caulking gun, and a hammer. Don’t forget safety goggles and gloves to protect yourself while building your shower pan efficiently.

How Long Does It Take for the Mortar Bed to Cure Fully?

It usually takes about 24 to 48 hours for the mortar bed to cure enough for light work, but full curing can take up to 7 days. You should wait to ensure maximum strength and durability.

Can I Use a Pre-Formed Shower Pan Instead of a Custom Mortar Bed?

Yes, you can use a pre-formed shower pan instead of a custom mortar bed. They’re quicker to install and provide a waterproof base, but make sure it fits your space and drains properly before purchasing.

How Do I Fix Leaks if the Shower Pan Starts to Fail?

If your shower pan leaks, you’ll need to locate the source, remove damaged parts, and apply waterproof sealant or replace the liner. Sometimes, reinstalling a new pan or consulting a professional is necessary to prevent further damage.

Conclusion

Now that you’ve built your shower pan on a plywood floor, you’ve created a solid, waterproof base ready for tile or your preferred finish. Remember, proper preparation, waterproofing, and correct slope are key to preventing leaks and ensuring durability. Take your time with each step to avoid costly repairs down the line. With careful attention, your shower will not only look great but function flawlessly for years to come. You’re all set to enjoy your new shower!