How to Compare Bathroom Renovation Quotes Apples-to-Apples

You collect three quotes for the same Adelaide bathroom. The low one is $18,400. The middle sits at $26,800. The top lands at $34,200. Same room, same scope brief, nearly double the spread. This is not a fluke. It is the norm. Learning how to compare renovation quotes properly is the single highest-leverage skill a homeowner can bring to a bathroom project, and it is the difference between a clean outcome in Prospect and a half-finished wet area in Morphett Vale with a builder who stopped answering the phone.

Our network of Adelaide renovators sees this every week. The cheap quote is rarely a bargain. The expensive quote is rarely a rort. The real problem is that almost nobody is comparing the same thing. This guide walks you through exactly how to normalise three quotes to a like-for-like comparison, what inclusions a proper Adelaide quote must list, which payment terms are reasonable under SA Building Work Contractors rules, and the signs that a quote is hiding risk you will eventually pay for.

Why three quotes is the Australian norm (and why the variance is enormous)

Getting three quotes is the standard practice across Australian domestic building because it is the minimum sample size that tells you anything useful. Two quotes give you a midpoint with no context. One quote gives you a number with no reality check. Three gives you a low, middle, and high, which is enough to spot the outlier on either side.

On a typical Adelaide bathroom rebuild (roughly 5 to 7 square metres, full strip-out, new waterproofing, retiled, new fixtures), variance between three quotes for the same written scope is usually 30 to 60 per cent. That is not builders disagreeing about tile costs. That is builders including or excluding completely different work. One has assumed your floor waste stays put. Another has priced relocating it. One includes the vanity. Another expects you to supply it. One has a PC sum for tiles at $45 per square metre. Another has assumed you will choose $120 per square metre porcelain.

The quote is not the price. The quote is a theory about what the job is. Your job is to force all three theories into the same shape before you compare the numbers.

Line-item versus lump-sum: what a proper Adelaide quote looks like

A lump-sum quote gives you one number and a short paragraph. A line-item quote breaks the work into discrete stages with a price against each. Always, always ask for line-item. If a renovator refuses, that is information.

A proper Adelaide bathroom quote should show separate lines for:

• Demolition and rubbish removal: strip-out of existing fixtures, floor and wall tiles, old waterproofing, cart-away and tip fees. In Adelaide this often runs $1,800 to $3,200 depending on skip access and whether you are above ground floor.
• Waterproofing to AS 3740: this is non-negotiable in SA. The membrane must be installed by a licensed applicator and certified to the Australian Standard. Expect a line of $1,200 to $2,000. If there is no certification note, walk away.
• Tile supply and lay: usually split into two lines. Supply is often a PC (prime cost) sum you can adjust based on your tile choice. Lay is priced per square metre of wall and floor. Standard rectified porcelain in 2026 is costing Adelaide clients about $75 to $110 per square metre to lay, on top of supply.
• Vanity, basin, and tapware: either a PC allowance or a specific product spec. Named brand and model is better.
• Shower base and screen: tiled hob versus acrylic base, frameless versus semi-frameless, the glass thickness (10mm is standard).
• Plumbing rough-in and fit-off: licensed plumber only. If the quote does not name who is doing the plumbing, ask. In SA the plumber must hold a current Plumbers, Gas Fitters and Electricians Act licence.
• Electrical rough-in and fit-off: heated towel rail, exhaust fan (AS 3666 compliant), downlights, GPO relocation. Same rule: licensed SA electrician only.
• Finishing trades: silicone, paint touch-up, door architrave, skirting reinstatement, final clean.
• Project management and site supervision: this is a legitimate line. Anyone who pretends it is free is burying it in inflated material margins.

Every one of those lines should have a dollar value next to it. A quote that says “Bathroom renovation: $24,500, includes all labour and standard materials” is not a quote. It is a hope.

How to spot the cheap quote trap

The low quote is often low because it is incomplete, not because the builder is generous. Here is what you look for.

Missing inclusions

Scan for the lines that should be there and are not. Waterproofing certification is the biggest tell. Rubbish removal is the second. If either is absent, the builder is either assuming you will handle it or will come back with a variation once the walls are open.

Vague labour line

“Labour allowance: $8,000” with no breakdown of trade hours or day rates is a black box. You cannot tell if the builder has allowed for a tiler for five days or ten. When the real time is double the allowance, the variation hits you.

No asbestos contingency

Any Adelaide home built before 1987, and many built up to 1990, can contain asbestos in wall sheet, floor vinyl, or the sheet behind the vanity. A proper quote includes either a pre-demolition inspection line or an asbestos contingency (often $800 to $2,500 as a provisional). Silence on asbestos in a 1970s Payneham home means the builder is planning to bill you for it after discovery. Under SA WorkCover rules, licensed asbestos removal is required over 10 square metres, and the cost is real.

No allowance for substrate repair

Once the old tiles come off, the wall sheet underneath is sometimes damaged, water-rotted, or non-compliant. A good quote has a provisional sum for substrate replacement. No allowance means every square metre of bad sheet becomes a variation.

Provisional sums set unrealistically low

A tile PC of $35 per square metre in 2026 is fantasy pricing unless you want builder-grade white gloss. If you know you want stone-look porcelain, the real supply cost is $80 to $140 per square metre. A low PC sum artificially compresses the quote total. You pay the difference later.

Normalising three quotes to apples-to-apples

This is where most homeowners give up and just pick the one they liked best on the phone. Do not. Spend 40 minutes with a spreadsheet instead.

Build a simple comparison grid. Down the left, list every inclusion category from the proper quote list above (demolition, waterproofing, tile supply, tile lay, vanity, basin, tapware, shower base, screen, plumbing, electrical, finishing, project management, asbestos contingency, substrate contingency). Across the top, put three columns for Quote A, Quote B, Quote C.

Now go through each quote and drop the dollar figure into the matching cell. Where a quote has bundled items (for example “plumbing and electrical $6,400”), split it proportionally using the other quotes as a guide, or ring the builder and ask for the split. Where a line is missing entirely, write “NOT INCLUDED” in red.

When the grid is full, three things become immediately obvious:

1. Which quote is actually the cheapest once you price in the missing lines at the other quotes’ rates.
2. Where each builder has made genuinely different scope assumptions (different shower screen, different vanity width, different tile grade).
3. Where the variance is pure margin and where it is scope.

Ring each builder back with the grid. Ask them to confirm or revise. Any builder who refuses to engage with line-by-line questions is telling you how the project will be run.

Payment schedule red flags

Under the SA Building Work Contractors Act, a domestic building contract over $12,000 must be written, and deposits on residential work are capped. For any contract over $20,000 the deposit is limited to 5 per cent. For contracts between $12,000 and $20,000, deposits are capped at 10 per cent. That is the law, not a negotiation.

A healthy Adelaide payment schedule for a $25,000 to $40,000 bathroom looks like:

• 5 per cent deposit on contract signing (or 10 per cent if under $20,000).
• Progress payment on demolition and rough-in complete: around 30 per cent.
• Progress payment on waterproofing and tiling complete: around 35 per cent.
• Progress payment on fit-off and fixtures installed: around 25 per cent.
• Final 5 per cent on practical completion and defects walk-through.

Red flags:

• 50 per cent upfront: this is a warning sign, often illegal on a contract above $20,000, and means the builder is using your money to fund someone else’s job.
• Payment due on “material delivery to site” with no inspection: tiles sitting in the driveway should not trigger 30 per cent.
• Cash discounts for off-book payment: you lose GST credit, you lose SA Home Building Compensation Fund cover (required on work over $12,000), and you lose warranty recourse.
• No retention on final payment: keeping 5 per cent until defects are resolved is standard and reasonable.

Variation policy: what should be in the contract

Every bathroom has variations. The question is how they are priced. A good contract defines:

• A variation threshold: changes under (say) $300 can be verbally agreed and invoiced. Anything above must be written, signed, and priced before work proceeds.
• Margin on variations: usually 15 to 20 per cent on top of cost. Higher than that and you are being farmed.
• A cap on total variation: good contracts flag that if total variations exceed 10 per cent of the contract value, both parties sit down for a full review.

An acceptable total variation on an Adelaide bathroom that went reasonably well is 5 to 10 per cent of contract value. Over 15 per cent usually means the original scope was poorly defined, and that is partly the builder’s fault.

Why the middle quote is usually right

Having seen this pattern run hundreds of times across Adelaide projects, the middle quote is correct more often than either edge. The low quote is usually missing scope or margin. The high quote is usually over-speccing, padding PC sums, or pricing in a premium brand halo. The middle is often the builder who has quoted accurately on what was asked, with a realistic margin, and who has no incentive to lowball or gold-plate.

This is not a rule. It is a tendency. Your job is to confirm it by running the spreadsheet comparison above. If the middle quote is correctly specced and the low is missing two inclusions that, when added, push it past the middle, the middle was always right. If the high quote is specced to an identical standard but 20 per cent more expensive, that 20 per cent is pure margin and you negotiate or walk.

What to do next

You do not have to run this process alone. Our network of vetted Adelaide bathroom renovators quotes in line-item format by default, carries SA HBCF cover, and works within the deposit and progress-payment rules above. Tell us your suburb, rough scope, and budget band, and we will match you with three renovators whose pricing you can compare on equal footing.

Get 3 free Adelaide quotes →