The honest cost answer: it depends on distance to your existing plumbing
We will not publish a fake single number for an ensuite, because two identical-looking ensuites can land far apart on price depending on what sits behind the walls and under the floor. What we do publish is our bathroom renovation pricing tiers, which apply to ensuite builds the same way they apply to full bathroom renovations, and every ensuite quote we issue is a fixed price on inspection, not an estimate that grows. The framing, waterproofing, tiling and fixtures are reasonably predictable. The wildcard is always the plumbing: how far the new toilet, shower and vanity sit from your existing water supply, and more importantly, from your existing sewer drainage with enough fall to work.
The cost levers, ranked by how hard they hit
| Cost lever | Impact | Why |
|---|---|---|
| Distance from an existing wet wall | High | Every metre of new supply and waste adds work, and waste needs fall |
| Concrete slab vs timber floor | High | Slab cutting for new drainage is slow, dusty, structural work |
| Toilet location | High | The 100 mm waste is the least flexible pipe in the house |
| Upstairs vs downstairs | Medium | Upstairs drainage can often drop through a floor cavity more cheaply than a slab cut |
| Fixture choices | Medium | A toilet suite install runs $350 to $750 plus the suite; premium fixtures scale from there |
| Window, fan and lighting changes | Medium | Other trades, coordinated but real money |
| Hot water capacity | Low to medium | An extra bathroom can push a small system past its limit; upgrades run $1,300 to $2,400 for electric storage up to $2,500 to $4,500 for a heat pump after rebates, typically $1,000 to $2,500, confirm current schemes at quote time |
Back the ensuite onto a wet wall and you keep the money in finishes
The cheapest ensuite is the one that shares a wall with an existing bathroom, laundry or kitchen, because supply and waste are already there and the new fixtures tee in over a short run. The most expensive is the one in a far corner of a slab-on-ground home, where we cut and excavate a trench through the slab, run new drainage at correct fall to the sewer connection, and reinstate the concrete before the fun parts even start. If your layout allows any flexibility at all, put the plumbing wall where the pipes already live and spend the difference on the parts of the room you actually see and touch every day.
The Queensland compliance stack for a new ensuite
An ensuite is not a cosmetic job in Queensland, it is regulated construction. Sanitary drainage is notifiable or permit work under the Plumbing and Drainage Act 2018, done by licensed plumbers and drainers with a Form 4 and council involvement where required, and inspections of new underground drainage before cover-up. Waterproofing must be done by an appropriately licensed person to AS 3740 with a waterproofing certificate you keep. Building work over the QBCC threshold requires a licensed contractor, and structural changes can trigger building approval through a certifier. This paperwork is not optional and it follows the property: when you sell, a buyer's inspector will ask for it, and an undocumented ensuite becomes a discount off your sale price. We coordinate the compliance trail as part of the job so the file is complete when we hand back the keys.
How to get a real number for your home
Getting from curiosity to a fixed price takes one site visit. We look at where your sewer runs, where the nearest wet wall is, what the floor is made of, and whether your hot water system can carry another bathroom. You get a fixed, itemised quote against our published renovation tiers, with the plumbing relocation scope spelled out rather than buried in an allowance. If a different ensuite position would save you serious money, we will tell you before you fall in love with a floor plan, because in our experience that conversation is worth more than any discount.
QLD compliance note: New sanitary drainage and plumbing for an ensuite is regulated work under the Plumbing and Drainage Act 2018 with Form 4 documentation, waterproofing requires a licensed installer and certificate to AS 3740, and building work above the QBCC threshold requires a licensed contractor.
Thinking about an ensuite? Call Hills Plumbing & Gas on 0472 657 042 for a site visit and a fixed quote against our published bathroom renovation tiers, under QBCC licence 15243081. Start at our bathroom renovations page.
Sources: Queensland Plumbing and Drainage Act 2018 and Regulation 2019, QBCC licensing and home renovation guidance, AS 3740 waterproofing of domestic wet areas.