Shower base: preformed tray vs tiled set-down

TL;DR

The shower base is the waterproof floor of a shower, and there are two ways to build it: a preformed tray (acrylic or stone-resin, dropped in and connected to the waste) or a tiled set-down (a screed graded to fall, a membrane over it per AS 3740, then tiles). The preformed tray is faster, cheaper, and has a factory-formed fall with no grout lines, so fewer leak points. The tiled set-down looks more integrated and lifts resale, but it is a multi-day, multi-trade job and is where most shower leaks start when the waterproofing is done poorly. Pick the tray for speed and budget; pick the tiled floor for finish and a single-surface look.

Preformed shower bases

A preformed base is a single moulded floor piece that replaces the tiled shower floor. Two common materials (verified 2026-05-24, Elegant Showers):

Material	Notes
Acrylic (fibreglass-reinforced)	The workhorse: vacuum-formed, glossy, non-porous, warm underfoot, light to handle.
Stone resin / composite	High-end, stone look and feel, very durable, but heavy enough to usually need two people to set.

The single biggest advantage of any preformed base is the factory-formed fall: the slope to the waste is moulded in, so drainage meets AS 3740 without relying on a hand-screeded floor. No grout lines also means fewer places for water to get through. Indicative 2026 supply cost: roughly $150 to $700 for acrylic, up to about $1,500 for stone resin, install separate (verified 2026-05-24, Elegant Showers).

Tiled set-down

A tiled shower floor is built on site: a sand-cement screed is laid and shaped to the fall, a liquid or sheet membrane compliant with AS 3740 goes over the screed, then the floor is tiled. AS 3740 requires the finished floor to grade to the waste so water does not pond; confirm the current minimum-fall figures against AS 3740 itself, as commonly quoted ratios vary by enclosure type.

It is the more sophisticated finish and the only way to read the shower and bathroom floor as one surface (especially with a linear drain and large-format tiles), but it involves screeding, waterproofing, and tiling as separate steps and can add a week or more to the job. Done poorly, it is also the leading source of shower leaks and rectification (verified 2026-05-24, House Sanctuary Builders). Indicative installed cost runs much higher than a tray, often several thousand dollars once waterproofing, screeding, and tiling labour are included.

Under-tile tray (the hybrid)

An under-tile tray is a preformed tray you tile over: it gives the factory-formed fall and a reliable waterproof layer, with the tiled appearance on top. It is a middle path between a bare acrylic tray and a fully hand-built tiled set-down.

How it ties into the wall and substrate

However the base is built, the wall junction has to be right. Where water-resistant plasterboard meets a preformed base, NCC 2022 Housing Provisions 10.2.26 requires the cut bottom edge of the board to be waterproofed (verified 2026-05-10, corpus). The membrane (tiled floors) or the tray upstand (preformed) must carry water up the wall and tie into the wall waterproofing so nothing tracks behind.

Common defects

Tray not bedded properly: a preformed base set on an uneven or unsupported floor flexes, cracking the seal at the waste.
Hand-screeded fall ponding: a tiled set-down where the screed does not actually fall to the waste, leaving standing water.
Wall-to-base junction not sealed: water tracks behind the base or the bottom row of tiles where the upstand or membrane is not lapped into the wall waterproofing.
Cut plasterboard edge unsealed over a preformed base, against NCC 2022 HP 10.2.26.

References

Elegant Showers, Shower base vs tiled shower floor (elegantshowers.com.au) (verified 2026-05-24)
House Sanctuary Builders, Shower base vs tiles floor (housesanctuarybuilders.com.au) (verified 2026-05-24)
AS 3740:2021, Waterproofing of domestic wet areas (Standards Australia) (verified 2026-05-10, corpus)