How to Quote a Bathroom Renovation

Bathroom renos eat margin if you miss waterproofing, hidden plumbing or PC sums. Here is how to quote them so you make money instead of working for free.

Bathroom renovations are deceptively complicated. The room is small, the scope looks straightforward, and yet they have a habit of running over time and over budget more than almost any other residential job. The reason is simple. Half the work is hidden behind walls and floors that you cannot see until demo starts.

A solid bathroom quote anticipates the unknowns instead of pretending they do not exist. Here is how to structure the document so you protect your margin and keep the client happy.

Walk the room before you quote

Phone quotes do not work for bathrooms. Even a small ensuite needs a proper inspection. Check the existing waterproofing, look for signs of historic leaks, test water pressure, find the stop cock, and locate the soil stack.

Take photos of every wall, the floor, the existing fittings, and especially under the basin and behind the toilet. These are your reference points later when the client asks why something cost extra.

• Floor area and wall heights
• Existing plumbing layout and pipe material (copper, PEX, galvanised)
• Position of soil stack and waste runs
• Type of subfloor (timber joists, concrete slab, screed)
• Ventilation and natural light
• Power points and lighting circuits

Break the scope into trades

A bathroom is the only room in the house that needs almost every trade. Demolition, plumbing, electrical, waterproofing, tiling, glazing, joinery and painting all happen in roughly 8 square metres. Quote it as one project but break the scope by trade so the client can see how it all fits together.

If you sub work out, the trades you most need lined up are a reliable plumber, a tiler who knows their waterproofing, and an electrician. Get those three locked in before you commit to a start date.

Builders often run the project and sub the rest. That works fine but you need to mark up the subbie quotes by 10 to 20 percent to cover your coordination time. If you do not, you are project managing for free.

Use PC sums for fittings

Clients change their mind about taps, tiles and toilet pans about four times before the job starts. Do not absorb that risk. Use Prime Cost sums (PC sums) for anything the client picks. State the allowance in the quote, then adjust up or down based on what they actually buy.

For example: "PC sum of $ 4,500 allowed for tiles supplied. Final cost adjusted on selection." That one line saves you weeks of arguments. Setting up reusable free quote templates with your standard PC sum lines means you never forget to include one.

Sample PC sum allowances

• Wall and floor tiles: $ 4,500
• Mixer taps and shower set: $ 3,800
• Toilet suite: $ 2,200
• Vanity unit and basin: $ 5,500
• Shower screen: $ 4,000
• Mirror and accessories: $ 1,200

Price waterproofing as a separate line

Never bury waterproofing inside the tiling line. It is the single most important part of the job and it deserves its own line and its own warranty statement. Specify the system you use, the number of coats, and how high up the wall it goes.

If the existing room has signs of water damage, add a contingency line for substrate repair. "Allowance of $ 2,500 for substrate repair if damage discovered after demo. Confirmed before work proceeds." That covers you when the floor under the old shower turns out to be jelly.

Builders quoting bathroom renos who treat waterproofing as a serious line item win more repeat work because they get fewer callbacks. The same discipline pays off across the wider construction and building trades, where a clear itemised quote beats a vague lump sum every time.

Allow a realistic timeline

A full bathroom strip and refit is 3 to 4 weeks of actual work, plus drying time for screeds, waterproofing and grout. Do not promise 10 days because the client wants it. Promise the real number and finish on time.

Build the timeline into the quote with a payment schedule that matches it. Deposit on acceptance, second payment after demo and rough-in, third after waterproofing and tiling, balance on completion. That keeps cash flowing without you funding the whole job out of pocket.

If you want to see more on phasing payments to match the work, set the payment schedule against the build sequence so each invoice lands as the client sees real progress on site.

Sample bathroom quote total

For a typical 6 square metre family bathroom, full strip and refit, mid-range fittings, here is roughly how the numbers shake out:

• Demolition and removal: $ 3,200
• Plumbing rough-in and fit-off: $ 8,500
• Electrical (lights, fan, GPOs): $ 2,800
• Waterproofing (2 coats, full system): $ 3,500
• Tiling (walls and floor, including adhesive and grout): $ 9,000
• PC sums for fittings: $ 21,200
• Painting and finishing: $ 1,800
• Project management and overheads: $ 5,000
• Total indicative: $ 55,000

Common mistakes to avoid

• Quoting without seeing the room
• Burying waterproofing inside the tiling price
• Forgetting access for tradies (parking, lifts, stairs)
• Not using PC sums for client-selected fittings
• Promising a 2 week timeline to win the job

The bottom line

Bathrooms reward the contractor who quotes carefully and punish the one who guesses. Inspect properly, break the scope by trade, use PC sums for fittings, treat waterproofing as its own line, and give a real timeline. Do that and the bathroom job becomes one of the best margin earners on your books.

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