Have you ever experienced this: after taking a shower, your bathroom floor is either soaked or has a puddle of water? It’s not just a hassle to clean—it’s also a slipping hazard. If this sounds familiar, the culprit might be your shower pan—or perhaps it wasn’t installed correctly in the first place.
Though often overlooked, the shower pan plays a crucial role: it directs water quickly and efficiently to the drain, preventing leaks, backflow, odors, and long-term dampness. Whether you’re building a brand-new bathroom, upgrading an old shower, or trying to fix persistent water pooling issues, a properly installed shower pan is essential.
In this tutorial, Giving Tree Home will walk you through every step of shower pan installation, from preparation to execution, and from detailed tips to important precautions—making DIY installation straightforward and ensuring your bathroom stays dry.
Step 1: Start with the Right Shower Pan
If you’re renovating your bathroom, the first step is to measure your space accurately. Then, select a shower pan shape and size that fits your bathroom layout. Common dimensions include 32"×32", 48"×32", and 60"×34", but your choice should consider the size of the room, usage needs, and door swing direction.
If you’re unsure which size to pick, you can refer to our dedicated “Shower Pan Size Guide”, which details suitable sizes and shapes for various scenarios. We won’t go into all the specifics here.
Step 2: Dry Fit Test
Before any permanent installation, one of the most critical steps is a dry fit test. This ensures the shower pan aligns properly with the drain and fits your floor perfectly, avoiding issues after applying mortar.
1. Place the Shower Pan in the Opening
Set the pan into the designated area and check that it sits flat against the subfloor. No adhesive or mortar is used at this stage—just a trial placement to ensure the positioning is correct.
2. Mark the Edge
Once positioned correctly, trace the outline of the pan onto the subfloor. This line serves as a reference, helping you place the pan back in exactly the same spot later.
3. Pre-Drill Mounting Holes
On the pan flange (the edge that touches the wall), pre-drill 3/16-inch holes at each stud location. This makes securing the pan easier during final installation and reduces errors.
4. Check Drain Alignment
Ensure the pan’s drain hole lines up with the floor drain. If it doesn’t:
- Mark the correct position on the subfloor
- Remove the pan
- Use a jigsaw or hole saw to cut the correct opening
Tip: Drain openings generally shouldn’t exceed 5 inches in diameter, but always follow the manufacturer’s instructions.
5. Adjust Plumbing Below
If the drain height or position needs tweaking, adjust the P-trap or drain pipe so that it extends about 1 3/4 inches above the floor (or as recommended by the manufacturer). This ensures the pan’s drain assembly installs properly and seals completely.
Step 3: Apply Leveling Mortar
Before installing the shower pan, ensuring the subfloor is perfectly level is crucial. A flat base determines whether the pan will be stable, avoid wobbling, prevent water pooling, and reduce noise over time.
1. Inspect the Floor
Use a level to check the floor from side to side and front to back.
✔ If the floor is level, proceed to the next step.
✘ If uneven, you need to level it first.
2. Choose the Right Self-Leveling Mortar
For uneven floors, select a self-leveling mortar compatible with your subfloor material. Common bases include:
- OSB (Oriented Strand Board)
- Cement board
- Plywood
- Other structural subfloors
Using compatible mortar ensures a durable leveling layer.
3. Apply the Mortar
Pour the mortar within the installation boundary outlined in Step 1. If you’re concerned about overflow, temporarily attach a 1x2 wood strip along the line as a barrier. Mix and pour the mortar according to manufacturer instructions, allowing it to flow and fill low spots naturally.
4. Let It Cure
Allow the mortar to fully harden before proceeding. Curing times vary by product, typically 4–24 hours.
Step 4: Install the Drain Flange
Before placing the shower pan permanently, the drain assembly (drain flange) must be installed to ensure a tight seal and prevent future leaks or odors. This step includes trial fitting, sealing, and securing the flange.
1. Trial Fit the Drain Flange
Insert the drain flange (also called the drain basket or body) from the top of the shower pan into the drain hole. Gently set it in place and check that it:
- Sits flush with the pan surface
- Passes through the pan smoothly
- Does not require force to fit
If the fit isn’t perfect, adjustments can be made at this stage.
2. Apply Sealant to the Flange (Crucial!)
Follow the manufacturer’s instructions and apply a thin, even layer of sealant around the bottom edge of the drain flange. Common options include:
- Latex caulk
- Acrylic sealant
- Silicone (most common)
⚠ Important: Do not use plumber’s putty indiscriminately! Some shower pan materials (especially solid surface or acrylic) can be damaged by putty. Always follow the manufacturer’s recommendations.
3. Press the Flange into Place
Insert the flange from above and press down gently onto the sealant.
- Do not twist or turn the flange, as this may damage the seal
- Wipe away any excess sealant with a paper towel
At this point, the flange should be firmly attached to the pan.
4. Install the Bottom Sealing Components
On the underside of the pan:
- Rubber Gasket: The primary seal, snug against the pan bottom
- Friction Washer: Usually made of plastic or cardboard, distributes pressure
- Locking Nut: Screws onto the flange threads, pressing the gaskets tightly against the pan
Hand-tighten first; if necessary, use an adjustable wrench gently—do not overtighten, as it may crack the pan.
Step 5: Install and Secure the Shower Pan
With the drain assembly in place, you can now secure the shower pan in its final location. Installation methods vary slightly by brand—some pans require adhesive, while others rely on mortar for support. Always follow the manufacturer’s instructions.
1. Prepare the Support Material (Adhesive or Mortar)
Depending on your pan, you may use either:
Option A: Adhesive Support
- Apply adhesive evenly to the subfloor in the pan footprint
- Ensures the pan is stable and prevents shifting
Option B: Mortar Bed
- Mark the pan footprint on the subfloor
- Place small mounds (“piles”) of mortar or a thin layer per product instructions
- Supports the pan and prevents future cracking or noise
2. Place and Press the Pan
Carefully lower the pan onto the adhesive or mortar bed, aligning the drain and reference lines.
- Press down evenly so the pan sits flush on the support
- Apply gentle pressure; stepping lightly inside the pan is okay to ensure full contact
3. Level the Pan (Critical)
Check with a level in all four directions:
- Side to side
- Front to back
Even a slight tilt can affect drainage and cause water pooling. Adjust before the adhesive or mortar sets.
4. Secure the Pan to the Wall
The pan flange should be attached to the wall studs for long-term stability:
- Use pre-drilled holes as guides
- 1¼-inch exterior-grade screws (rust-resistant) work well
- Do not overtighten to avoid flange damage
Step 6: Install the Drain Pipe Components
Once the pan is level and secured, attach the drain components to ensure a leak-free system.
1. Slide on the Rubber Gasket
Place the rubber gasket over the drain pipe, ensuring a tight fit against the shower pan drain flange. This flexible seal prevents water from leaking downward.
2. Secure the Gasket
Use the provided screws to lock the gasket in place. Apply firm but controlled pressure—do not overtighten. Some kits include a special tightening tool; otherwise, a screwdriver works fine.
3. Install the Drain Cover
Finally, position the drain cover over the flange and secure it with screws or clips. The cover should sit flush with the pan surface for both aesthetics and proper water flow.
Ending
Installing a shower pan may seem intimidating at first, but with careful preparation and step-by-step execution, it’s completely doable—even as a DIY project. From measuring your space and choosing the right pan, to leveling the floor, installing the drain, and securing the pan, each step is essential for a leak-free, safe, and long-lasting shower.
Remember, the key is patience and precision. Take the time to dry fit, level properly, and follow manufacturer instructions. Rushing through any step can lead to leaks, water pooling, or future maintenance headaches.
