Why most bathroom renovations go over budget (and how to avoid it)

Bathroom renovations rarely blow out due to aesthetic choices. More often than not, they blow out due to lack of planning. Like deciding on your layout at the tile shop instead of taking a hard look at your budget first, then figuring out where the shower is going.

There are usually structural issues at play. Maybe you uncover asbestos when removing old sheeting. Or maybe there's a drain in the wrong spot. Or maybe there's a loadbearing wall in the way that nobody knew about. Moving plumbing can get expensive, as you'll need to have your plumber re-lay waste and supply pipes and depending on whether your house has a concrete slab foundation or timber subfloor, this cost can fluctuate significantly.

All plumbing must be done by licensed tradespeople. Every tap. Every waste. Every waterproofing installation. This is mandated by state and territory plumbing licensing legislation. There's no DIY approach here. It's illegal.

Another common issue is not having a scope of works ready. If you don't have one, your builder or plumber has nothing to quote against, and any variations raised midway through the project will feel like an ambush. Have everything documented, even the tiny stuff, like where your heated towel rail and exhaust fan should be, before any tiles are ordered.

Now that you know the reasons for budget blow-outs, here's how to set up a budget that reflects the actual cost of things in Australia at present.

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1. Setting a realistic budget and timeline before you start

A cosmetic makeover, including new tapware, a new vanity, new paint and accessories, will likely run $9,000 to $15,000 depending on the scope, location and finish level. A mid-level full renovation where everything gets replaced but plumbing doesn't move will likely fall between $15,000 and $25,000. A high-end renovation with relocated fixtures, large-format tiles, a freestanding bath and designer tapware could exceed $35,000 in Sydney or Melbourne (industry estimates, whatsthedamage.com.au/ hipages.com.au). These figures are all project costs including labour, not just product prices.

Renovation Tier	Estimated Cost (AUD)	Typical Scope	Plumbing Moved?
Cosmetic makeover	$9,000 - $15,000	New tapware, vanity, paint and accessories	No
Mid-level full replacement	$15,000 - $25,000	Everything replaced, fixtures stay in place	No
High-end with relocated fixtures	$35,000+	Relocated fixtures, large-format tiles, freestanding bath, designer tapware	Yes

Labour, waterproofing, tiling and skip bin hire (skip bins aren't cheap) are going to take up more of your budget than most people expect. As a rule of thumb, products and materials tend to account for just 40-50 per cent of total costs. The rest is labour.

Timing is also key. A regular bathroom renovation (not including planning time) usually takes two to four weeks from start to finish. Account for council approval turnaround time if you're making structural alterations or renovating in a heritage-listed area. And factor in contingency time. Things always run late.

Once your budget is set, the single biggest determining factor in whether you stick to it is your layout – or rather, which fixtures you're moving and which ones you're leaving exactly where they are.

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2. Planning your layout: What you can and cannot move

Keeping the toilet, shower and basin in their original positions is, pretty much without exception, the most financially responsible decision you can make. The instant your plumber needs to relocate a toilet outlet or shift a shower drain, the costs mount quickly, and if you live in a slab home, this means cutting into the slab itself, which is no easy feat.

Australian standards mandate a minimum 600mm clear floor space in front of a toilet pan, and a 900mm minimum for a shower recess in most configurations. Also keep in mind that your plumber and waterproofer will need to work within the constraints of the NCC waterproofing standards – shower walls must be waterproofed to a minimum of 1800mm (NCC 2025, ABCB Housing Provisions, Part 10.2) above the floor substrate. These are not guidelines; they are regulations.

Homes built with timber subfloors typically offer more options when it comes to moving plumbing around, as the pipework is located within the subfloor void. However, homes built on concrete slabs don't enjoy the same flexibility. Still unsure whether you have a timber subfloor or concrete slab home? Check with your plumber first, rather than settling on a bathroom layout that might not be achievable, or that may end up costing you significantly more than expected.

Once you've confirmed your bathroom layout and where your plumbing will be, you can then start selecting the right products and materials for your bathroom renovation.

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3. Choosing the right products and materials for your bathroom

Start with tiles, as they cover the largest surface area. In wet areas, especially shower floors, choose tiles rated P4 or P5 for slip resistance. Lower-rated tiles can be used for walls. Large-format porcelain tiles (600×1200 mm is a popular size) minimise grout lines and make cleaning much easier. DW Tile has a strong selection of large-format porcelain tiles.

When it comes to vanity cabinetry, the material you choose can be just as important as the colour. PVC is completely waterproof and is the most affordable material available. MDF is not waterproof but can still perform reasonably well in a bathroom with good ventilation. Plywood costs more but performs much better when exposed to moisture over time. Keep in mind that virtually all vanity cabinets come without the basin mixer and basin waste fitted – budget accordingly. Lukka wall-hung vanities start at $198 and run to more than $3,000.

All plumbing and drainage products installed in Australia must carry WaterMark certification. From 1 May 2026, all copper alloy products used for drinking water purposes must have Lead Free WaterMark certification. Check the specifications of any tapware product before you place an order. Both Meir and Fienza offer tapware with WaterMark certification in brushed nickel, matte black, and chrome finishes.

Ventilation is another compliance area you need to plan for during your bathroom renovation. The NCC mandates a minimum exhaust air flow rate of 25 L/s (NCC 2025, ABCB Housing Provisions, Part 10.8) for bathrooms. Your electrician will install the fan, but make sure you select a compliant model during the design phase, not after.

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4. Buying your bathroom renovation materials

It's very easy to purchase tapware online only to receive something that looks nothing like the photo you saw on screen. A trip to your local bathroom store will give you the chance to test out a mixer, gauge how heavy it is, see the finish in person, and ask if the item will suit your specific layout.

If you are browsing online, it is definitely worth stopping in at a bathroom store to check out the range of products and services, pricing, and product specifications before making a decision. If you live in Sydney, visit a local bathroom showroom before you finalise your bathroom renovation selection – it will pay dividends.

Take your floor plan, plumbing layout, dimensions, and photos of your current bathroom with you. Your showroom staff can help you locate WaterMark certified fixtures, identify products that won't fit your bathroom layout, and recommend other products that will help ensure your bathroom renovation stays on budget and to specification.

This is what separates the bathroom renovation quotes that stay on budget from the ones that blow out – being armed with sufficient information to make informed decisions before the first trade walks through your door.

Architecture & Design Team

MyHomeware

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