How to choose a shower enclosure for your tray: a guide to sizes and types

Choosing a shower enclosure starts with the tray you already have or plan to install, before you open the catalogue. The tray shape, the actual opening between walls and the available bathroom space determine almost everything before you consider finishes or glass thickness. This guide explains what to measure, which opening style suits each situation and what to look for in the glass and profiles.

Measure first: the three details you need

Almost all installation problems stem from a measurement taken in a hurry. Before looking at models, you need three details, all measured in the bathroom with a tape measure and spirit level, rather than taken from renovation plans.

1. The installation opening

The opening is the clear distance between the surfaces supporting the enclosure: wall to wall in an enclosed recess, wall to the outer tray edge for a front enclosure, or the wall section where a fixed screen begins. Measure it at three heights: at the top, approximately where the upper profile will sit; in the middle, roughly at handle height; and at the bottom, just above the tray.

Write down all three measurements. They will usually differ. Always use the smallest, because the enclosure must fit through that opening: if you order using the largest measurement, the profile simply will not fit. Also measure the clear height from the tray to the ceiling or any obstruction, as this limits the enclosure height you can install.

2. Wall squareness and vertical alignment

The difference between those three measurements indicates how far the wall leans out of vertical. Check this with a long spirit level or plumb line against the tiles. In masonry walls and renovations involving older partitions, deviations often become clearly visible when a straight profile is placed alongside them.

This is usually manageable: most enclosures have an adjustable wall profile designed to accommodate this deviation and keep the glass vertical even when the wall is not. Each model's technical data sheet specifies its adjustment range, which you must compare with the actual wall deviation. If the wall leans further than the profile can compensate, use extension profiles or correct the wall before installation, rather than forcing the enclosure into place. Corner enclosures require another check: the angle between the two walls. If they do not form a true right angle, the two doors will not close together, even when each side has been measured correctly.

3. The tray type

Note the shape (rectangular, square, quadrant or semicircular), the tray's actual external dimensions and how it is installed: on the floor, flush with it or on a raised base. Check the edge supporting the bottom profile and whether the tray has a flange, apron or pronounced perimeter rim, as these determine where the enclosure is sealed. On flush, low-profile trays, the enclosure may sit almost directly on the floor, making floor flatness as important as wall alignment.

Enclosure types by tray shape

Each tray shape supports a particular set of solutions. Choosing correctly depends on where water escapes, where you enter and how much clear space remains in front of the shower.

Rectangular tray against a wall

This is the most common arrangement: the tray backs onto a wall and is open along its long side. The standard solution is a front enclosure with a fixed panel and sliding door, which does not project into the bathroom when opened and works well in a wide opening. For a narrow opening, a sliding door becomes less practical because the clear access is reduced to half the frontage; a hinged door works better if there is room for it to swing. When there is space for neither sliding nor swinging, a folding door offers a solution: the panel folds back on itself, leaving almost the entire opening clear.

Tray in a corner between two walls

The tray sits in a corner with two open sides. You need a corner enclosure closing both sides, usually with two fixed panels and two sliding doors meeting at the corner. A hinged corner version is also available, with a fixed panel on one side and an outward-opening door on the other. Here, the angle between the walls becomes critical.

Quadrant or semicircular tray

Curved trays require a curved enclosure with bent glass and tracks of the same radius, usually with corner sliding doors. These products are not interchangeable: the enclosure radius must match the tray radius, so the tray's technical data sheet is as important as the opening measurement.

Bath

A bath can have a single fixed screen, or a screen with two or three hinged or folding panels when you want to enclose more of the front while retaining easy access. The main difference from a shower is the support: the bottom profile is sealed onto the bath rim, which is narrower and often curved.

Walk-in: a fixed screen without a door

A walk-in screen is a single glass panel without a door or opening mechanism. It offers the cleanest visual appearance and is easiest to clean, but needs a long tray: water can escape through the access gap, so there must be enough distance between the shower outlet and the open edge, with the correct slope towards the drain.

Glass thickness: what each millimetre means

Modern shower enclosures are made from tempered safety glass. Tempering is a heat treatment that increases resistance to impacts and sudden temperature changes and, crucially, changes how glass breaks: rather than splintering into sharp fragments, it breaks into small pieces with blunt edges. Tempered glass therefore cannot be drilled or cut after tempering; any holes must be made at the factory before treatment.

Thickness is the next specification you will see on the technical data sheet, usually between 4 and 8 millimetres for residential products. Thicker glass is more rigid: it vibrates less when opening and closing, feels more solid and stays flatter across larger panels. However, weight increases proportionally, and that weight must be supported.

This gives a practical rule: thicker glass needs stronger profiles and fixings. A thick panel requires larger profile sections, fittings and rollers rated for its weight and, during installation, wall plugs and screws suited to the actual wall material. A walk-in screen usually also includes a stabilising bar to the wall or ceiling because it has no perimeter frame to brace it.

Profiles and finishes

Profiles often receive the least attention, yet largely determine whether an enclosure will still work properly years later. The standard material is aluminium, treated in two ways: anodising, an electrochemical process that creates a protective oxide layer highly resistant to humid conditions, or coating with baked-on paint to provide coloured finishes.

The three finishes most frequently requested today are polished chrome, matt black and brushed gold. The practical recommendation is simple: match the enclosure finish to the taps and bathroom accessories, because they share the same visual space and unintended combinations stand out.

The wall profile's key function is adjustment. It incorporates a system allowing the glass to move a few millimetres relative to the wall to compensate for the deviation measured earlier, keeping the panel vertical and the door closing evenly at the top and bottom. Each model lists its adjustment range in the technical data sheet: compare this with your wall deviation before purchasing.

Glass falls into three main groups: clear, the most popular choice because it visually enlarges the bathroom; screen-printed, with a pattern or printed band providing partial privacy; and frosted or acid-etched translucent glass, which fully blurs the silhouette. The choice is aesthetic but has a practical consequence: clear glass shows everything, including limescale, so it requires more consistent cleaning.

Anti-limescale glass treatment

Many models offer anti-limescale treatment, which is a water-repellent coating applied to the glass surface at the factory. It reduces the glass's microscopic porosity and the adhesion of water: droplets slide off rather than spreading across the surface, and remaining deposits are much easier to remove.

Its limitations should be equally clear. It does not remove existing limescale, replace cleaning or last forever: it is a surface coating that degrades with use, especially when unsuitable products are applied. Abrasive cleaners, scouring pads and aggressive acids attack the coating and quickly render it ineffective. The best routine for treated glass remains the simplest: use a squeegee or microfibre cloth after showering and ventilate the bathroom.

If limescale is also affecting your taps, see our guide to removing limescale from taps without damaging the finish: the same product-selection principles apply to treated glass.

Common mistakes

These are the problems most frequently raised in customer enquiries, and almost all can be avoided with fifteen minutes of checks beforehand:

• Measuring before tiling. Measuring an unfinished partition and later finding that the tiles and adhesive have reduced the opening by several millimetres on each side.
• Ignoring wall alignment. Measuring at a single point, purchasing to that dimension and discovering that the door catches at the bottom or will not close at the top because the wall is not vertical.
• Choosing a sliding door for a narrow opening. A front sliding enclosure provides clear access of approximately half its frontage; in a narrow opening, this creates awkward entry that a hinged or folding door would handle better.
• Overlooking the bathroom door's opening direction. A hinged enclosure hitting the entrance door, toilet or basin unit is a planning error rather than a product fault.
• Buying the enclosure before the tray. The correct order is tray first, enclosure second: the tray's shape, radius and final position determine the model, rather than the other way around.
• Not inspecting the glass on delivery. Leaving the package unopened until installation day and only then discovering transport damage, after the reporting deadline has passed.