What is a shower pan, and should I choose prefab or custom?

A shower pan, also called a shower base, is the floor of a shower: the molded tray you stand on, with a slope that carries water to the drain and a threshold along the front that keeps water in the stall. On an Ella shower the pan is factory-molded acrylic and is the finished walking surface as shipped, so the prefab-or-custom question is really a choice between one of three standard sizes and a custom-size rectangle made to your measurements. Building a pan on site from a mortar bed only comes into play when the footprint cannot be a rectangle. Should I use a prefab shower pan or build a custom one? weighs those two routes, and this page starts further back, with what a pan is, how one is created and what to settle before you order.

What a Shower Pan Does

A bathtub is deep because it holds water. A shower pan is not meant to hold anything. Its job is to catch water and move it to the drain, and the only vertical dimension that changes how you use it is the threshold you step or roll over. Every Ella base has a textured, slip-resistant floor with the slope and drainage channels molded in, so water is carried to the drain by the shape of the floor, and a 2 inch threshold drains the same way a 4 inch one does. What does matter is where the drain sits, which is why the drain position is one of the first things the team asks about.

When people ask how deep a shower pan is, the threshold is almost always what they need to know. On Ella bases that height runs from flush with the floor on a barrier-free base to a low threshold that the published examples put at 2, 3 or 4 inches. How Deep Is a Shower Pan and Does Depth Matter? goes through each threshold style and when the height matters.

Two Meanings of Custom, and What Prefab Really Means

Custom can mean a pan built on site from a mortar bed and finished in tile, or a factory pan made to your dimensions. Ella's custom pans are the second kind. They are the same finished acrylic as the standard bases, made to your length and width for a three-wall alcove or a corner installation, with the drain placed left, right or center. Prefab, in Ella's lineup, means the three standard wheelchair-accessible roll-in sizes: 30 x 60 inches, 32 x 60 inches and 36 x 60 inches, each available with a left or right drain. If one of these fits, it is the simplest choice because the drain sits in a set position for that size.

The custom rectangle has published limits. The minimum is 30 by 30 inches, the maximum is 44 inches wide by 80 inches long with the threshold on the longer side, and the corner maximum is 42 by 60 inches. Pans shorter than the standard 60 inches are routine: sizes such as 46 by 46, 50 by 30 and 36 by 44 inches have been handled, and a 58 by 30 inch base with a center drain has been produced. A 38 by 80 inch base with a left drain is within the limits, while a request such as 53 by 76 inches cannot be produced. Only rectangles are made; bases with angled or curved edges are not offered.

What the differences mean: the molded pans, standard or custom, arrive as the finished floor, so the installer sets them, connects the drain and finishes the walls, while the site-built pan exists to carry tile and is a separate trade. The threshold column decides who can get in. A 3 inch custom base is a short step-in that is still a step, the 2 inch version of the 32 by 60 footprint is lower, and the barrier-free base is the one to plan around for a wheelchair. A 3/4 inch step and a flush floor can look alike in a product photo, so let the threshold figure on the spec sheet, not the picture, drive the decision.

Why a Molded Pan Is Never Tiled over

The reason a prefab pan and a built pan are not interchangeable is what sits on top. A site-built pan exists to carry tile. An Ella acrylic base is the walking surface itself, and tile, thinset or a waterproofing membrane should not be applied on top of it. Tile needs a rigid, absorbent substrate that mortar bonds to, and acrylic is smooth, so tile laid over it would not bond reliably and could trap water underneath with no path to the drain. Tiling over the pan would also bury the molded slope and threshold that move water to the drain. If you want a tiled look, plan it for the walls above the base. The wall finish comes down over the edge of the base so water runs onto the pan rather than behind it, the same principle as the tile flange on a walk-in tub. Can You Tile Over an Ella Acrylic Shower Base? covers that edge detail, and its advice when the base does not match your design is to choose a different base rather than cover one.

How a Shower Pan Is Created and Set

A site-built pan is created from a mortar bed and finished in tile. A molded Ella pan is created at the factory, so on site the job is to set it: your contractor sets the base, connects the drain to the house waste line and finishes the walls around it. The two installation videos on this page show that work for a low-threshold three-piece shower and for a barrier-free five-piece shower, and the first steps they show are the ones that prevent most problems:

1. Dry assemble the shower in any clean, dry, open space before it goes into the bathroom. This confirms you received the correct panels and the correct drain location, that the pan and panels are free of damage and defect, and that the panels align when assembled. Take a picture of the assembled unit.
2. Delay demolition of the existing bathtub area until you are confident the new unit is the correct size and condition, so nobody is left without a working bathroom while waiting on a replacement.
3. Check the framing pocket against the dimensions on the framing diagrams page of the installation instructions, then check the pocket for square, plumb and level. Adjustments are more common than not.
4. Hang a plumb bob from the framing at the back wall. If the wall is not plumb, either shim the pan away from the wall or notch the stud, because slight variances show up as out-of-plumb wall panels and uneven lines.
5. Inspect the subfloor before the pan goes down. The base is made solid by being supported from underneath, not by anything added on top.

The barrier-free video also covers receiving: an adult must be present when the unit arrives to inspect it and note any visible damage on the bill of lading before the driver leaves, and if the unit cannot be inspected on the spot, sign with the words subject to further inspection so concealed damage can still be reported.

What to Settle Before You Order

• Alcove or corner. The team asks which you have so the drain and edges are placed correctly, so measure the finished opening first.
• Drain position. Tell the team where your existing drain line sits in the floor. On a standard size the team confirms which drain position matches; on a custom base the drain can go left, right or center but must sit at least 9 inches from each wall, and a drain only 7 inches from the threshold edge is not possible.
• Threshold. Decide between a low threshold and a barrier-free entry, and on the 32 by 60 footprint say whether you want the 4 inch or the 2 inch version.
• Walls and accessories. Shower products are sold per item, so a complete shower is the base in your size and drain position, a wall system sized to it, and accessories such as grab bars or a shower door. Ella's wall panels are 98 inches high in a plain white finish.

Who Makes Custom Shower Pans and Bases for Accessible Showers? explains how the base, walls and kits are carried. Standard and custom bases are sold through your Ella dealer or the team at (800) 480-6850, and if you have questions along the way, visit ellasbubbles.com/support.

Related Guides

• What Is an Acrylic Shower Base and How Does It Compare?
• 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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