Custom Shower Pans: Made-to-Measure Bases for Odd Openings

The moment an opening measures 55 in. instead of 60 in., or the walls are out of square by more than a filler strip can hide, standard pans stop being an option. A made-to-measure pan is the answer, and it is ordered almost entirely on measurements - which means the quality of the numbers you supply decides the quality of the result.

When a Standard Size Will Not Work

Four situations make a custom pan the practical choice. The opening falls between standard footprints, such as 54 in. or 57 in. The walls are out of square enough that a rectangular pan leaves a visible tapered gap. The drain is in a position no stock pan provides. Or the shower is a shape that stock pans do not cover, such as a corner with unequal legs or an angled front.

Filler strips and furring are the alternatives, and each has a cost: a filler at the base is a joint in the wettest part of the shower, and furring out a wall changes the whole room's finish line. Where either becomes visible, a custom pan usually costs less than the rework.

If you are still comparing a standard footprint against a custom one, the size comparison is in standard vs custom shower base sizes.

Measuring an Out-of-Square Opening

Measure the finished opening width at three heights - a few inches above the floor, mid-height and near the top - and record all three readings rather than an average. Do the same for the depth, front to back at both ends, and measure the two diagonals so the out-of-square is quantified rather than described. Take the drain centre from both reference walls, not from one corner.

Then photograph the opening with a tape visible at each measurement point. A fabrication drawing is made from those numbers, and the photographs resolve any ambiguity before the pan is cut. Where a wall is yet to be tiled, note the expected build-up so the pan is made for the finished opening rather than the current one.

Drain Relocation and What It Costs You

If the existing trap is not where a stock pan puts its drain, there are two ways forward: choose a pan made with the drain in the existing position, or move the trap to suit a standard pan. Moving the trap means opening the subfloor, checking the joist direction and re-connecting the waste run, which is plumber work and a floor repair.

A custom pan with the drain where the plumbing already is usually costs less than moving the plumbing, and it avoids the risk of a drain that has to cross a joist. That is the strongest argument for measuring the drain first: it turns a plumbing problem into a fabrication detail.

Lead Time and Price Drivers

Price is driven by footprint size, material, drain position, edge profile and the number of non-standard angles. Lead time follows the material and the backlog: a simple rectangular pan in a standard material is quick, while an angled footprint or a specialist finish takes longer. Both should be confirmed in writing before the order is placed, because the pan sets the schedule for the waterproofing inspection, the wall finish and the door.

Because the door is measured from the pan, the sequence matters. Order the pan first, set it, confirm the finished opening, then order the door. Ordering both from the same measurements at the same time is also workable if the measurements are taken to the expected finished surfaces and the drawings are checked together.

How to Specify a Custom Pan

A complete specification includes: finished width at three heights, depth at both ends, out-of-square measurement, drain centre from two walls, drain diameter, wall construction, intended wall finish and its thickness, threshold height and profile, material, and the intended door configuration and glass thickness.

Two additional details prevent delays. State whether the pan is to be set against studs or finished walls, because that changes the overall dimension. And state the intended door type, since a sliding door needs a flat, level front edge for its guide, while a hinged or pivot door needs a base that can accept the fixing loads that come with it.

Material Options for a Custom Pan

Custom pans are commonly made in moulded composite or solid surface materials, and in tile-ready form where the finish will be tile. Solid surface offers a repairable matt finish and a consistent colour; moulded composites are lighter and less expensive; tile-ready pans keep the finish continuous with the walls. Each has the same support requirement: a continuous setting bed over a flat, sound subfloor.

Where the pan will be tiled, the flange detail has to match the waterproofing system, and the wall membrane has to overlap the pan flange in a continuous layer. Wet-area methods are published by the Tile Council of North America and catalogued on the Whole Building Design Guide; plumbing and building code provisions for the drain and trap are published at iccsafe.org; and where a previous pan has leaked into the structure, the EPA moisture guidance explains how far the assembly should be opened up.

Verifying the Finished Opening Before Manufacture

Before the pan is fabricated, re-measure. Walls get furred out, tile thickness changes the opening, and a floor that was levelled after the first measurement moves the base line. A second measurement two or three days before manufacture catches nearly all of these changes, and it is far cheaper than a pan that arrives slightly too large.

Confirm the drawing as well as the numbers: check the drain position, the outside dimensions, the threshold profile and the flange direction on the drawing rather than assuming they match the brief. Component expectations for the surrounding assembly, including the glazing that will sit above the pan, are described in 16 CFR Part 1201 and by ASTM International.