What is a shower pan and what does it actually do?

A shower pan, also called a shower base, is the waterproof floor of a shower: a one-piece molded tray with the slope, the threshold and the drain opening built in, so water runs to the drain instead of into the subfloor. Ella's Bubbles makes its own pans in finished acrylic, in three standard sizes and in custom rectangles, and they are ready to use once set, with no tile over the top. The pan arrives as the finished walking surface, and the wall panels or tile come down over the edge of the pan so water runs onto the pan and to the drain rather than behind it, which is why the surface is left exactly as shipped, as explained in Can You Tile Over an Ella Acrylic Shower Base?. The size list is in What Sizes Do Ella Shower Bases and Shower Pans Come In?, and this page explains what the pan does and how to choose one.

What the Pan Does in a Finished Shower

The pan carries three jobs at once. It gives the shower a floor that sheds water toward one point, it holds the drain fitting that your plumber connects to the house waste line, and its front edge sets the threshold you step or roll over. On an Ella base the slope, the threshold and the drain are molded into the acrylic at the factory, which is why the base must not be tiled over: tile would defeat the molded slope and the finished surface. Your contractor sets the base on the subfloor, connects the drain and finishes the walls around it. Everything else in the stall, the wall panels, grab bars, valve, shower head and door, sits on or around the pan, so the pan is the first piece that has to be right.

• Collects and drains water. The molded slope moves water to the drain opening. Your plumber connects that drain to the house waste line.
• Sets the step-in. The threshold along the entry edge sets how far you step over to get in. Ella offers low-threshold and barrier-free versions as well as standard bases.
• Seals to the walls. The pan meets the walls along its edges, and the wall finish comes down over that edge so water lands on the pan. This is the same principle as the tile flange on a walk-in tub.
• Carries the load from below. The acrylic shell is supported from underneath during installation, which is what makes the floor feel solid. Adding tile, thinset or a membrane on top would bury the slope and threshold and trap water with no path to the drain.

The installation video on this page shows why the pan comes first. Before the pan goes near the bathroom, the installer dry-assembles the unit with its wall panels in a clean open space to confirm the correct panels and the correct drain location were received, that the pan and panels are free from damage, and that everything aligns. Photograph the assembled unit, and delay demolition of the existing tub area until you are confident the new unit is the right size and condition. The framing pocket is then checked against the framing diagram in the installation manual for size, square, plumb and level, and the subfloor is inspected. A pan set into a pocket that is out of plumb leads to walls that do not sit flat and grout lines that wander, so when a wall is not plumb the video shows the fix of shimming the pan away from the wall or notching the stud. Refer to the installation manual for your model, and have a licensed plumber make the drain connection.

How to Make a Shower Pan: You Order One Instead

Many people searching for how to build a shower pan are really asking how to get a waterproof floor that fits their space. Ella's answer is a molded acrylic pan, standard or custom, rather than a site-built mortar bed. Standard bases are 30 by 60, 32 by 60 and 36 by 60 inches, all sharing the 60 inch length, each with a left or right drain that sits in a set position for that size. When none of those fits, a custom rectangle can be made from a 30 by 30 inch minimum up to a 44 inch wide by 80 inch long maximum, for a three-wall alcove or a corner installation, with corner bases topping out at 42 by 60 inches. Pans shorter than 60 inches are routine, and sizes such as 58 by 30 with a center drain, 46 by 46, 50 by 30, 36 by 44 and a 36 by 36 inch corner base have all been produced. A request such as 53 by 76 inches cannot be made. The drain can be placed left, right or center but must sit at least 9 inches from each wall, so a drain only 7 inches from the threshold edge is not possible even on a custom pan. Only rectangles are offered, with no angled or curved edges, as who makes custom shower pans for odd bathroom layouts explains.

Every pan is also offered in more than one drain position, and each position has its own rough-in. The Specification drawing for your exact model and drain position shows the distance from the back wall and the side wall to the center of the drain. As two examples, one right-drain base lists the drain center 15 1/2 inches from the back wall and 9 1/2 inches from the front, while one center-drain base places it 19 inches from the back wall and 24 inches from the side wall. Have your plumber compare those figures with your existing drain line before you order; the method is in Shower Drain Rough-In: How Far the Drain Sits From the Back Wall and Side Wall.

Types of Ella Pan and Their Thresholds

The lineup also includes seamless no-step-over bases in left- or right-side layouts, alongside the wheelchair roll-in models with left- or right-side configurations and custom acrylic bases made to fit a specific opening. The threshold is the figure that decides which pan you need. A 3 inch step-in or a custom base with its typical 3 inch edge holds water with a curb and suits most residential remodels. A curb-less roll-in base has no lip at all and relies on the rubber dam, which flattens under wheels and springs back, to keep water in. The 3/4 inch caregiver base sits in between and is a home-care product. If two pans look alike online, check the threshold figure on the spec sheet rather than judging from a photo, since a low step and a flush floor can look the same in a product picture.

The Best Pan for Wheelchair Accessibility

For a wheelchair user the pan to look at is the curb-less roll-in base, in a standard width or a custom size. ADA standards generally limit the threshold in a roll-in shower compartment to a maximum of 1/2 inch, which the barrier-free line is designed for and the 3/4 inch caregiver base is not, so commercial and public projects normally use the barrier-free line instead. Ella does not offer a floor insert or riser that lowers the drop of a stepped base, so if a project turns out to need a roll-in threshold, the answer is a different base rather than an add-on. State and local codes decide what passes inspection, so confirm the standard with your building department before you specify; is a 3/4 inch shower base threshold ADA compliant walks through that decision. The custom and standard options for accessible showers are compared in Who Makes Custom Shower Pans and Bases for Accessible Showers?.

What to Have Ready Before You Order a Pan

1. Measure the finished opening, not the framing, in length and width.
2. Find where the existing drain line sits in the floor, so the team can confirm a left, right or center drain for your size, and have your plumber compare it with the rough-in on the Specification drawing.
3. Decide on the threshold: curb-less roll-in, 3 inch step-in, or zero threshold flush with the floor.
4. Say whether the pan goes in a three-wall alcove or a corner, since the edges are placed differently.
5. Request the spec sheet for the base from your Ella dealer or the team at (800) 480-6850, and keep it for your contractor and any inspector.

Watch: Step-by-Step Low-Threshold Shower Installation for Remodeling | Ella’s Bubbles with chapters and a full transcript.

Related Guides

• What the Ella Acrylic Shower Base Is Made Of and How It Is Installed
• How do I measure for a new shower pan or base?
• Custom-Size Shower Bases: Size Ranges, Threshold Options, Drain Placement Rules, Construction, and How to Request One
• Shower Base Sizes and Thresholds Compared: AcrylX Barrier-Free, SMC Linear-Drain, Molded-Seat and Cultured Marble Bases

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