Built In Baths

A built-in bath sits inside a surround. That's the short version. Walls on one, two or three sides, or dropped into a tiled hob in the middle of the room. The format covers inset baths with a tile flange, drop-in baths without one, alcove bathtubs, island baths, corner baths, and the rarer undermount setup where the rim disappears under a stone benchtop.

It suits most Australian family bathrooms, ensuites with tight footprints, and any reno replacing like-for-like without moving the plumbing. It's also the go-to for shower-over-bath setups, which still account for a big slice of homes built before 2010.

This page covers what you need to check before you order: size, waste position, material, tile flange handing, and the compliance rules that quietly govern the install. We stock Caroma, Decina, Parisi and others across the format. If you're still weighing the two main options, the freestanding baths collection is the other side of the same decision.

Inset, drop-in, island or corner

The terms get blurred online. They shouldn't be. Each one changes how the bath is supported, sealed and tiled around.

The Caroma Luna range shows the contrast cleanly. It comes in both a four-tile-flange version and an island version at the same 1525 and 1675 lengths.

What to check before you order

Four decisions cause most of the returns and re-plumbing call-outs. Get these right and the rest is finish selection.

Defence Housing Australia's property checklist sets the floor at 1500 mm long and 400 mm deep for a usable bath. Most stocked baths sit between 1500 and 1800 mm. Going shorter saves space but cuts comfort fast.

- Size and depth: 1500 mm is the practical minimum. 1675 mm is the common upgrade. Measure the alcove before you fall for a length.
- Waste position: left-hand, right-hand or centre. It has to match your existing rough-in, or you're paying a plumber to move it.
- Material: acrylic runs light and warm (Fienza's 1500 mm Sentor is 45 kg, 181 L). Solid surface is heavy and holds heat (Fienza Shinto: 205 kg, 475 L). Cast iron sits between them (Kohler Diapason 1.5 m: 82 kg, 152 L). Filled stone baths can clear 500 kg, so check the floor structure.
- Tile flange handing: stand facing the bath. The tap end determines left or right. Shower-over setups need the flange on the shower wall.

Fienza notes floor prep may be needed for off-centre wastes on the Shinto. Worth knowing before delivery day.

Installation and Australian compliance

A licensed plumber is required, and the bath plus waste need WaterMark certification. That's non-negotiable for any plumbing fixture sold in Australia.

Waterproofing under the lip

The NCC 2022 Housing Provisions are specific about inserted baths. Part 10.2.20 says non-freestanding baths must have an upturn lip, be recessed into the wall, and the water-resistant substrate of the wall must pass down inside that lip. Part 10.2.4 requires walls to be waterproof to at least 150 mm above the bath lip, a waterstop under the lip on any adjoining shelf area, and waterproof junctions within 150 mm of the bath. AS 3740 covers the wet-area waterproofing standard the work has to meet.

For shower-over setups, the 150 mm rule extends up the shower wall too. That's where a fitted bath screen earns its keep. Confirm trap type before ordering. S-trap drops through the floor. P-trap exits the wall.

Tapware that works with built-in baths

Inset and corner baths almost always run wall-mounted spouts and mixers, because there's no rim to drill into. Island built-ins with a tile flange can take deck-mounted tapware on the wider end. Floor-mounted bath fillers suit freestanding baths, not built-ins, since the supply lines need to clear the surround. Match the finish across the bath outlet, mixer and shower head. Browse bath outlets and mixers suited to wall installs.

Built-in bath FAQs

What's the difference between an inset, drop-in and built-in bath?
Built-in is the umbrella term. Inset baths have a tile flange (upturn lip) that the wall tiles sit against, sealing the join. Drop-in baths have no flange and rely on the surrounding hob or benchtop for the seal. Both are built-in. The Caroma Luna is sold in both an inset (four tile flange) and an island version, which is the clearest way to see the difference.

Do I need a licensed plumber to install a built-in bath?
Yes. Connecting a bath to water and waste is licensed plumbing work in every Australian state. The bath itself needs WaterMark certification, and the waterproofing around it has to meet NCC 2022 Part 10.2 and AS 3740. That means walls waterproof to 150 mm above the lip and a waterstop under the lip where it meets any shelf.

What size built-in bath fits a standard Australian bathroom?
1500 mm long by 400 mm deep is the DHA-stated minimum for a functional bath. Most renos go to 1650 or 1675 mm for a more comfortable soak. 1750 to 1800 mm suits larger main bathrooms. Measure the alcove width, length and depth before locking in a length, and leave clearance for the tile substrate.

Acrylic, stone resin or cast iron?
Acrylic is light, warm to touch, and the most common choice. Stone or solid-surface baths hold heat longer and feel substantial, but they're heavy. A 1500 mm solid-surface bath filled with water can push past 500 kg, so a structural check matters on suspended floors. Cast iron sits in between for weight and holds heat well, but the price reflects it.

Can I run a shower over a built-in bath?
Yes, and it's still common in single-bathroom homes. Choose a bath with an anti-slip base, fit a bath screen, and make sure the waterproofing carries higher than 150 mm above the lip on the shower wall. Shower baths with one squared end (the Decina Modena range, for example) give you more standing room than a straight-sided bath.

Left-hand or right-hand bath: how do I tell?
Stand at the foot of the bath, facing it. If the tap end and waste are on your left, it's a left-hand bath. On your right, right-hand. Get this wrong and the waste won't line up with the rough-in.

If you're unsure on waste position or rough-in, send through the existing measurements and we'll match a bath to them.

Why buy your built-in bath from us

We're a specialist online bathroom retailer shipping Australia-wide, not a marketplace. The range covers Caroma, Decina, Parisi, ADP, Abey, Geberit and others across baths, tapware, vanities and the rest of the fit-out. Our team knows what WELS and WaterMark actually require, why S-trap versus P-trap matters before you order, and what the NCC waterproofing rules mean for your tiler. Help is available before you buy, which is when it counts. Most of the ordering mistakes we see (wrong waste position, wrong handing, bath too long for the alcove) are five-minute fixes if you ask before checkout, not after delivery.

Related bathroom collections

Most built-in bath buyers also look at bath screens for shower-over setups, bathtub tapware to match the bath outlet and mixer finish, and bathroom accessories like towel rails and hooks for the finished space. If you're shortlisting brands, the Parisi and Caroma collections cover most of the inset, island and shower-bath formats stocked on this page.