What Is a Shower Pan, and Why Does It Matter?
A shower pan is the waterproof, sloped floor under your shower tile. It decides whether water goes down the drain or into your subfloor, which is why it is the most important part of any tile shower.
By Steve & Angelo, Tile & Stone Installation · Published September 29, 2026
What is a shower pan?
A shower pan is the floor of a shower, built to slope toward the drain and sealed so water cannot get through. In a custom tile shower, the pan is usually a sloped mortar bed (often called a mud bed) that falls about 1/4 inch per foot toward the drain, with a waterproof layer that sends any water that soaks through the grout back to the drain. The tile you see sits on top. A well-built pan is invisible for decades. A poorly built one leads to leaks, loose tile, cracked grout and mold, often hidden under the floor until the damage is serious.
Every walk-in tile shower we build in Thousand Oaks, Newbury Park, Westlake Village, Agoura Hills and Camarillo starts with a pan made by hand on site, sized to the exact shower. See our tile showers and bathroom remodels page for the full range of bathroom work we do.
A custom shower pan has
- A solid, level baseThe subfloor is checked and repaired before anything goes down.
- A true slope to the drainAbout 1/4 inch per foot, so water never puddles.
- A waterproof layerKeeps water that gets past the grout out of the subfloor and walls.
- A matched drainCenter drain or linear drain, set at the right height for the tile.
- Tile set on a flat planeSmall mosaics follow the slope; larger tile is cut to it.
How do I know if my shower pan is failing?
Most shower pan failures show up outside the shower first. Look for water stains on the ceiling below an upstairs bathroom, loose or lifting baseboards next to the shower, a musty smell that does not go away, dark or crumbling grout on the shower floor, tiles that sound hollow when tapped, or water that stands on the floor instead of draining. Any one of these can mean water is getting under the tile.
Regrouting will not fix a failed pan. The only lasting fix is to remove the shower floor and build a new pan. That is also why we will not set new tile over old tile: covering an old floor hides the problem instead of fixing it. If you are not sure what is going on, our tile repair and tear-out page explains how we check.
Signs to watch for
- Stains or bubbling paintOn a ceiling or wall next to or below the shower.
- Loose or hollow tileTiles that move or sound hollow when tapped.
- Dark, crumbling groutEspecially near the drain and corners.
- Standing waterPuddles that stay after the shower is off.
- A lasting musty smellOften the first clue of hidden moisture.
Custom mortar pan or a prefab shower base?
A prefab base is a one-piece plastic or acrylic tray; a custom mortar pan is built by hand to fit the space and is covered in tile. Prefab bases are quick and inexpensive, but they come only in set sizes and shapes, and they look like what they are. A custom pan can be any size, fit an odd-shaped or extra-large shower, include a built-in bench, and be finished in the same tile as the rest of the bathroom.
A custom pan is also what makes a curbless shower possible: a shower with no step at the entry, where the bathroom floor flows straight in. We build curbless, low-curb and standard curbed showers, with a center drain or a linear drain along one wall.
Custom pan vs. prefab base
- Size and shapeCustom: any size. Prefab: set sizes only.
- Curbless entryCustom: yes. Prefab: usually needs a curb.
- LookCustom: tile that matches your bathroom. Prefab: plastic or acrylic.
- Benches and nichesCustom: built in and waterproofed together.
- Cost and timePrefab is usually faster and cheaper; custom lasts and looks the part.
Showers Built on Custom Pans
Shower Pan FAQs
How long does a shower pan last?
A properly built mortar pan with good waterproofing can last as long as the tile on top of it, often 20 years or more. Pans that fail early were usually built without enough slope or without a sound waterproof layer.
Can you just replace the shower floor?
Often, yes. If the walls are in good shape, we can remove the floor tile and pan, build a new pan and tile the floor. We will look at the walls first and tell you honestly whether they need work too.
Can new tile go over my old shower floor?
No. We do not set tile over old tile. Covering an old floor hides any water damage underneath and adds height at the drain. We remove the old tile so we can check and properly prepare what is underneath.
Do you build curbless showers?
Yes. We build curbless, low-curb and curbed showers, with center or linear drains.
How much does a new shower pan cost?
It depends on the shower size, the drain, the tile and how much tear-out is needed. Estimates are available on request. Text a few photos to 805-341-5986 to get started.
Have Steve Look at Your Shower
Call or text Steve & Angelo directly. Texting a few photos of your shower floor is the fastest way to find out what it needs.