How to Correctly Slope a Shower Pan (Pan Liner Installation)
- Isaac Ostrom
- Oct 7, 2025
- 7 min read
Alright guys, Isaac Ostrom here—thanks for stopping by another Tile Coach blog! In this one, we’re diving deep into one of the most important parts of a shower build: how to correctly slope your shower pan on a pan liner using deck mud (also called dry pack mortar).
If you’ve seen my older videos on floating shower pans, you probably noticed they weren’t my best produced videos — bad lighting, rough angles, and honestly, I just wanted to give you a closer, clearer look. So I redid it right in my shop so you can see exactly how to get that perfect slope and professional finish every single time.
So grab your level, a wood float, and let’s walk through this step-by-step together.
🎥 Watch the full tutorial: 👉 How to Slope a Shower Pan: Tile Coach Episode 18
Key Takeaways for Homeowners & Pros [TL;DR]
Use deck mud (dry pack mortar) for a firm, easily shapeable shower pan base.
Maintain a ¼ inch slope per foot toward the drain.
Always protect your weep holes with gravel or pea stone.
Keep your float clean to avoid dragging and gouging the surface.
Take your time to pack, screed, and smooth for a solid, long-lasting base.
Once you master the technique, you can float a pan in about 20 minutes.
Tools You’ll Need
Wood or foam float
Finishing trowel
2-foot level
Screed sticks or straight edges
Mixing bucket
Margin trowel
Tape for drain protection (blue or stucco tape)
Gravel or pea stone for weep holes
Materials
Deck Mud (Dry Pack Mortar): A mix of sand and cement, dry enough to hold shape when packed.
Vinyl or PVC Pan Liner: Keeps water from leaking into the subfloor.
Drain with Weep Holes: Allows any water that gets under your tile to escape properly.
Optional Drainage Mat: I used a Schluter Troba mat—not required, but it helps water drain under the mortar better.
Understanding the Slope and Setup
Before you even mix your mud, let’s get one thing straight—the slope is critical. The standard is ¼ inch per foot, which ensures any water that gets beneath your tile flows into the drain instead of pooling up and causing mold or mildew.
My longest run in this shower pan was about two feet, so I needed a ½ inch of fall from the perimeter to the drain. That’s what we’re shooting for.
Now, under that mortar, I’m using a drainage mat—that Schluter Troba I mentioned earlier. Troba, primarily used on exterior balcony assemblies, is basically a little network of channels that helps water move toward the weep holes instead of just sitting there. Totally optional, but I really like using it in my builds.
Step 1: Protect the Drain and Weep Holes
(Timestamp: 00:01:12 – 00:02:43)
This is one of those steps a lot of people overlook—and it can ruin your whole shower if you mess it up.
See those little holes around the drain collar? Those are weep holes, and they let water that sneaks under your tile escape into the drain. If those get clogged with mortar, your pan can trap water, which eventually leads to discoloration, odors, or worse—tile failure.
Here’s my fix: gravel or small pea stone. I pile it right up around the drain to the same height I want my deck mud—usually about an inch and a half thick. The gravel keeps those holes open and functional. Don’t skip this part.
Step 2: Mix and Pack Your Deck Mud
(Timestamp: 00:02:43 – 00:04:17)
Deck mud is simple stuff: sand and Portland cement, mixed just damp enough to clump when squeezed but not soupy. It’s called “dry pack” for a reason.
I start by packing mud right up to the drain. That anchors it and stabilizes it while I float the rest of the pan. Normally, on a job site, I’d tape off the drain with blue tape to keep it clean, but since I wanted you to see it clearly in the video, I left it open.
Use your wood float to press the mud firmly into place. Don’t just dump it—pack it tight. That’s what gives your pan its strength and prevents slumping later.
Step 3: Establish the Slope Reference Point
(Timestamp: 00:04:17 – 00:06:39)
Now that the drain area’s packed, it’s time to set your slope.
Grab your 2-foot level and figure out your fall. Since my run is two feet, I need a ½ inch of drop. I use a scrap piece of tile as a height gauge—it helps me visualize how high to go along the walls since the finished tile will sit just above that mud line.
Once I find the right height, I mark that perimeter point and start packing my mud there. Check your bubble—it should read level around the entire perimeter. This ensures your slope is consistent toward the drain no matter which direction the water runs.
Here’s a tip: when you tamp the mud with your float, you’ll notice little indentations. Those become your screed guides for flattening and shaping later.
Step 4: Screed and Shape the Pan
(Timestamp: 00:06:39 – 00:09:45)
With your perimeter set, it’s time to connect the dots. I work in pie-shaped sections from the perimeter toward the drain—think of it like slicing a pizza.
Use your straight edge or screed stick to drag across the surface, shaving off excess mud and filling low spots. The goal is a smooth, even slope that’s level at the edges and drops evenly to the drain.
Keep your float clean while you work. If mud builds up, it’ll drag through the surface and ruin your finish. Knock off any buildup and keep things tidy.
If you’re new to this, try placing a tile in each corner of your pan at your reference height. It’s a great visual check so you don’t dig too deep or accidentally change your slope.
Step 5: Tamp and Smooth the Surface
(Timestamp: 00:09:45 – 00:11:31)
Once your sections are all screeded, go back over the surface and lightly tamp it down again. This locks everything together and preps it for the final finish.
Then, grab your foam float (or wood float if that’s what you’ve got) and work in a circular motion. This is where your pan starts to look pro. Circular motions blend high and low spots and smooth out the texture.
Dampen the surface lightly—just a mist of water—to help with final compaction and smoothing.
Step 6: Final Finishing Touches
(Timestamp: 00:10:39 – 00:12:51)
Now, for that professional-grade finish.
Switch to a finishing trowel and use some muscle. Press down firmly, packing the surface tight while smoothing out every last imperfection. This step does two things:
It hardens the surface, making it denser and more durable.
It gives you that clean, flat finish ready for tile.
Any tiny low spots can be filled later with thinset, but I like my work to look sharp—right out of the gate.
And that’s it. The whole thing only takes about 15–20 minutes once you get the hang of it. When you’re done, you’ve got a perfect shower pan that’s ready for waterproofing and tile.
Pro Tips for Best Results
Keep your float clean. Buildup drags grooves through your surface.
Use scrap tile as height gauges. Great for setting consistent slope references.
Don’t overwork the mud. Once it’s smooth, stop messing with it.
Work in manageable sections. Keeps you from losing control of your slope.
Peel away mud at the perimeter. Keeps your screed line clean and visible.
Use foam floats for that final pass—they’re smoother and less aggressive.
Why Deck Mud Beats Wet Mortar
Stability: Deck mud doesn’t slump, even on slopes.
Permeability: Allows water to pass through it freely.
Control: You can shape it precisely—it stays where you pack it.
Durability: Once cured, it’s rock solid and ideally suited for tile installation.
Ease of Work: No rushing against cure times—just pack, screed, and finish.
If you’ve only ever worked with wetter mortars, you’re going to love deck mud. It’s dry enough to hold its form but workable enough to shape however you need.
Common Mistakes to Avoid
❌ Blocking weep holes—this is the #1 cause of pan failure.
❌ Forgetting to factor in tile thickness when setting the slope.
❌ Letting your mud dry out before finishing.
❌ Over-troweling—can cause weak or uneven spots.
❌ Not cleaning your tools as you go.
FAQ — Frequently Asked Tile Coach Questions
Q: What’s the ideal slope for a shower pan? A: A quarter inch per foot toward the drain is the industry standard. So if your longest run is two feet, you’ll need a half-inch total drop. A three foot run would require 3/4" total drop.
Q: Can I use regular mortar mix instead of deck mud? A: I wouldn’t recommend it. Regular mortar is too wet, tends to slump, and doesn't allow water to pass through it, causing back ups. Deck mud packs firm and stays where you put it.
Q: How thick should my deck mud be? A: Around 1 ½ inches thick at the drain and thicker toward the perimeter depending on your slope.
Q: Do I really need gravel around the weep holes? A: Yes! It keeps the holes from clogging with mud so water can properly drain out.
Q: How long should I wait before tiling? A: You can usually tile the next day once the deck mud has hardened, but check your local conditions—cooler temps may extend drying time. If you are good, you can tile on deck mud while it is still wet. But I only recommend that for pros.
Final Thoughts
Floating a shower pan might look intimidating, but once you understand the process, it’s honestly pretty straightforward. Take your time, double-check your slope, and keep those weep holes clear—and you’ll end up with a base that’ll last for decades.
This method works for both DIYers and seasoned tile pros. After a few pans, you’ll be able to knock one out in under 20 minutes, no problem.
If you found this helpful, subscribe to the Tile Coach channel for more tile installation tips and tutorials. For more resources and pro discussions, join the Tile Coach Forum.
Rock on, guys—see you on the next one!