Choosing a shower tray sounds simple until you're actually doing it. Low profile or anti-slip? Which waste? Do you need a riser kit? And why does the same tray come in thirty different sizes?
This guide walks through the decisions in the order you'll actually face them, using the Kartell K-VIT Unity range as the example. Most of it applies whatever brand you end up buying.
Start with the shape, not the size
The shape of your tray is dictated by the space, and getting it wrong is expensive because trays can't be modified.
- Square — for a corner or a recess where the two walls are roughly equal. Sizes from 700 x 700mm up to 1000 x 1000mm.
- Rectangle — the most common choice, and the one to reach for where a bath has come out and left a long alcove. Sizes run from 900 x 700mm all the way to 1800 x 800mm.
- Quadrant — a curved front between two equal walls. The curve keeps the floor open in a small bathroom, which matters more than the numbers suggest.
- Offset quadrant — same curved front, but one wall longer than the other. This is the shape for a corner where the runs aren't equal.
Offset quadrant trays are handed
This catches people out. An offset quadrant tray comes in left hand and right hand versions, and they are not interchangeable. Stand with your back to the corner looking out into the room: if the long wall runs to your left, you need a left hand tray.
Worth knowing that the enclosure that sits on top is usually reversible even though the tray isn't — so don't assume that because the screen doesn't care, the tray doesn't either.
Low profile or anti-slip?
This is the decision most people skim past, and it's the one that has real consequences.
Low profile
A standard smooth-finish tray, 45mm high. Clean-looking, easy to wipe out, and what most bathrooms have. Fine for most households.
Anti-slip
The anti-slip version is the same tray with a textured surface, rated Class C to DIN 51097 — the highest of the three barefoot-wet classifications, and the standard used for changing rooms and communal showers.
Choose it if anyone using the shower is elderly, unsteady, or recovering from surgery; if it's a family bathroom used by children; or if the shower is over-bath height and there's a step to manage. The texture is noticeable underfoot but not uncomfortable.
The trade-off is honest: a textured surface takes more cleaning than a smooth one. Soap residue sits in the texture, and it wants a brush rather than a wipe. If nobody in the house is at risk of slipping, low profile is easier to live with.
Getting the size right
Measure the space at floor level, in both directions, at the back and at the front. Bathroom walls are rarely square, and it's the smallest figure that matters.
Trays are made to size and cannot be cut down. If you're between sizes, go smaller and tile down to the tray — a 5mm gap filled with sealant is invisible, whereas a tray that doesn't fit is a tray you can't use.
A note on comfort: 760mm is the practical minimum for an adult to shower in without touching the walls. A 700mm tray fits where nothing else will, but it's tight.
Choosing a waste
Every tray needs a waste, and it isn't included. The Kartell fast flow waste comes in four finishes — chrome, black, brushed brass and white — and you pick it from the dropdown on the tray page.
The finish is cosmetic, so match it to your taps and shower valve rather than to the tray. A black waste in a white tray looks deliberate alongside black brassware and accidental alongside chrome.
Fast flow matters more than it sounds. A modern shower can deliver more water than a standard 50mm waste will clear, and the result is water pooling round your feet. A 90mm fast flow waste keeps up.
Do you need a riser kit?
Only sometimes — and this is where people either over-buy or get caught out.
A low profile tray sits directly on the floor, and the waste pipe runs underneath it. If your floor is solid concrete, there's nowhere for that pipe to go, so the tray has to be raised. That's what a riser kit does — it lifts the tray on adjustable feet and provides a panel to hide the gap.
On a timber floor you can usually run the pipe between the joists and lay the tray flat, which is both cheaper and better-looking.
Riser kits are size-specific and shape-specific:
- 760mm square trays have their own kit
- Square and rectangle up to 1200mm
- Square and rectangle 1300–1800mm
- Quadrant and offset quadrant each have their own
What about stone resin?
Everything above assumes an acrylic-capped tray, which is what most showers use. Stone resin trays are the step up: heavier, more rigid underfoot, and available in colours and textures that acrylic can't do — slate-effect greys and blacks rather than gloss white.
They cost more and they are genuinely heavy, so factor in help on delivery and fitting day. If you want a shower floor that doesn't flex at all and doesn't look like a builder's white tray, it's worth the difference.
A short checklist before you order
- Measure at floor level, front and back, both directions — work to the smallest figure
- Confirm the shape, and the hand if it's an offset quadrant
- Decide low profile or anti-slip based on who's using it
- Pick a waste finish to match your brassware
- Check your floor — concrete usually means a riser kit, timber usually doesn't
If you're unsure on any of it, particularly handing or whether you need a riser, it's worth a quick call before ordering rather than after.