The costs people forget when they budget for a bathroom

A bathroom quote prices what the builder can see. It does not price what is behind your wall sheeting, because nobody has been behind it yet. On a house built before 1990, what turns up in there is asbestos, rot in the framing, or old steel pipework. Asbestos testing costs $200 to $500 and removal usually lands between $1,500 and $5,000. Framing repairs cost $1,000 to $3,000, and permits and compliance run $1,200 to $2,000. Those are the costs people leave out of the budget, and they are the reason you hold another $3,000 to $4,500 on a $30,000 bathroom.

My name is Michael. I am a registered builder and a licensed plumber, and I renovate bathrooms in Berwick, Officer, Pakenham, Narre Warren, Beaconsfield and Clyde North. The figures below are the ones we work to, and they are the ones I would want in front of me if I were the one paying.

Cost	When it applies	Typical cost
Asbestos testing	Any house built before 1990	$200 to $500
Asbestos removal	If the test comes back positive	$1,500 to $5,000
Rot and framing repairs	Older bathrooms where the original waterproofing failed	$1,000 to $3,000
Substrate levelling	Walls or floors out of true once the old finishes come off	$300 to $800
Rubbish removal	Every job, and it is included in ours	$250 to $380 a skip
Permits and compliance	When you change the room rather than refinish it	$1,200 to $2,000
Contingency	Every job, and the top of the range on older houses	10 to 15 per cent

Melbourne rates for a standard bathroom of six to eight square metres. These sit outside the trades and materials priced in a normal quote.

Why these costs sit outside the quote

A quote prices the work that can be seen on the day the builder walks through your house. Your walls are still lined, your floor is still tiled and your bath is still in. Every builder who quotes your bathroom, including me, is looking at the same closed room and pricing the same visible job.

The honest way to deal with that is a provisional sum, which is an estimate for work that cannot be priced exactly at signing. It gets reconciled against the real cost once the wall comes off. A quote with nothing set against these items is not a cheaper quote. It is the same job with the risk left on your side of the table.

Asbestos

$200 to $500 to test, and $1,500 to $5,000 to remove

If your house went up before 1990 there is a real chance of asbestos in the bathroom. It turns up in the wall and ceiling sheeting, in the backing under vinyl floors, and sometimes in the sheet under the floor tiles. It is common through the older fibro clad pockets of Dandenong, Narre Warren and Berwick, and it is safe while it is sealed up and left alone. The problem starts when someone puts a demolition bar through it.

Testing is the cheap part at $200 to $500 for a sample sent to a laboratory. Removal in Melbourne runs $50 to $150 per square metre, but licensed removalists carry a minimum job charge of around $1,500 to $2,500, so a single bathroom usually lands somewhere between $1,500 and $5,000 all up. The minimum charge is why a small area does not cost proportionally less.

WorkSafe Victoria sets the rules and they are not optional. Anything over ten square metres of bonded asbestos, and any friable asbestos at all, must be removed by a licensed removalist and taken to an EPA licensed site. A bathroom lined in asbestos sheet will usually clear ten square metres on the walls alone. Removal adds a day or two to the job while the area is sealed, stripped and cleared.

If we find it, we stop, we show you, and we price the removal before anything else happens. You will not get an invoice from us for work you did not agree to first.

Rot behind the wall

$1,000 to $3,000

When we strip an old bathroom we sometimes find that the original waterproofing failed years ago and the timber has gone soft. Water gets into the wall at the shower, sits in the bottom plate and the stud ends, and works outward from there. On a particleboard floor it swells and crumbles. The room above it looks fine the whole time.

Repairs run $1,000 to $3,000, depending on how far it has travelled and whether the damage is in a wall that carries load. The work has to happen, because a waterproof membrane needs sound timber and a sound substrate underneath it. Nobody can seal a wet area over rotten framing and expect it to hold.

There are signs before demolition day. Skirting boards lifting away from the wall outside the bathroom, a floor that gives slightly underfoot near the shower, a musty smell that does not clear, and grout that has gone dark along the bottom row of tiles. If your bathroom is over twenty years old and you have seen any of those, set the money aside rather than hoping.

Old pipework

Plenty of homes built before 1990 still have galvanised steel supply pipes. Galvanised steel corrodes from the inside out, so the pipe narrows year by year and the pressure drops. Most people put the weak shower down to the shower head. Some of it is the pipe.

Replacing the supply pipes serving the bathroom while the walls are already open is a small addition to a plumbing scope. Doing it later, on its own, means opening the same walls again and retiling behind the work. A full house repipe in Australia sits somewhere between $8,000 and $20,000 depending on the size of the house and how easy the pipes are to reach, which is the number you are trying to avoid growing into.

If your plumber tells you the pipework is on its way out while the room is stripped, that is the moment to deal with it.

Rubbish removal

$250 to $380 for a 4 cubic metre skip

Stripping out a bathroom produces one to three cubic metres of mixed waste, which is more than most people picture when they imagine one small room. Tiles, mortar bedding, wall sheets, the old vanity, the old screen and the bath all have to leave the property. A 4 cubic metre skip in Melbourne costs $250 to $380, and Melbourne sits at the higher end nationally because of the landfill levy. Asbestos cannot go in that skip at all. It is bagged, wrapped and taken to a licensed site separately, which is part of why removal costs what it does.

Rubbish removal is included in our price. It is not included in every quote, and when it is left out it tends to appear after you have signed, at the point where you have nothing left to negotiate with. Ask the question before you sign, not after.

Waterproofing done properly

$1,000 to $1,800

Waterproofing is about five per cent of the job and it is the only line that can cost you the whole renovation twice. Melbourne waterproofers charge roughly $50 to $100 per square metre, and the work has to comply with AS 3740, the Australian standard for wet areas. It takes one to two days, because the first coat has to cure before the second goes on.

That cure time is what a cheap operator sells you out of. The coats get thinned, the bond breakers at the corners get skipped, and the second coat goes on before the first is dry because the tiler is booked for Thursday. You cannot see any of it, and the bathroom will look perfect for a year or more. Then a stain appears on the ceiling of the room below, or the skirting outside the bathroom door starts to lift. Putting that right means pulling out the bathroom you just paid for.

I have been called out to bathrooms other people built and had to tell the owner the room has to come out. Ask any renovator what warranty covers their waterproofing and ask to see it in writing. Ours is a ten year structural warranty.

Levelling and preparation

$300 to $800

This one only shows up after the old finishes are off. Walls in older houses are often out of true by enough to matter, and floors that had a thick mortar bed under the tiles need grinding back flat before anything new goes down. Neither is difficult work and neither is expensive on its own.

It matters more if you have chosen large format tiles. A big tile needs a flat surface to sit on, because it cannot follow a bump in the wall the way a small tile can. If the wall is out, it has to be levelled or screeded first, and that preparation happens before the first tile is laid rather than as a surprise halfway through.

Permits, certificates and insurance

$1,200 to $2,000

The paperwork runs $1,200 to $2,000 in Victoria once you count the building permit, the plumbing compliance and the electrical certification. What decides whether a permit is needed is whether you are changing the room or only refinishing it, so it is one of the first things to settle, because a permit has to be issued before the work it covers begins. Applying is the builder’s job on our sites, and the fee sits in that $1,200 to $2,000 rather than arriving separately.

Three documents apply to almost every bathroom. A licensed plumber must issue a Compliance Certificate of Plumbing Work for any plumbing work valued at $750 or more and lodge it with the regulator within five days, and your bathroom will always clear that threshold. An electrician must issue a Certificate of Electrical Safety. For domestic building work valued at more than $20,000, Home Warranty applies. It replaced Domestic Building Insurance on 1 July 2026. Your cover starts when you sign the contract, the builder pays the premium to the Building and Plumbing Commission within 10 business days of signing or before work starts, whichever comes first, and you receive a Notice of Cover. Cover runs to $400,000, and you can claim where the work is incomplete, defective or non-compliant and the builder is unable or unwilling to fix it.

The builder pays the Home Warranty premium, so ask whether it sits inside the quoted price or is added on top, because that is a real difference between two quotes that look the same. While you are asking, the deposit on a contract over $20,000 is capped at 5 per cent, so the most you can be asked for on a $30,000 bathroom is $1,500.

Being without the bathroom

We finish in three to four weeks, and for all of it the room is unusable. If you have a second bathroom, this is an inconvenience. If you do not, it is a cost, and it is the one people leave out of the budget entirely.

Work out where you are showering before the job starts rather than in the first week. A relative nearby, a gym membership, the neighbour, or a few nights elsewhere at the messiest end of the job. Ask your builder whether the toilet can stay connected for part of the work, because on some layouts it can and it makes a real difference to the household. Move everything out of the bathroom cupboards the weekend before, and expect dust in the hallway even with protection down.

The other thing worth knowing is what this does to your decisions. A family showering somewhere else while the invoice grows is a family that says yes to things quickly. Choose your tiles, your vanity, your tapware and your screen before demolition day, and have them ordered. Selections made under that pressure are the ones people regret.

What the contingency is really for

Hold 10 to 15 per cent, so $3,000 to $4,500 on a $30,000 bathroom. If your house was built before 1990, sit at the top of that range.

Most of the money in this article never gets spent on a newer house. On a project home from the 2000s the framing is pine, the walls are plasterboard on studs, and there is no asbestos to find. On an older place with hardwood framing and solid brick walls, more of it does get spent, and it gets spent in the first three days of the job when the room is open and you have to decide something.

The contingency is what lets you make the right decision at that point instead of the cheapest one.

And if you are holding a quote for an older house with no allowance against any of this, that quote is not cheaper than the others. It is less complete, and the difference will be settled later, by you.

What to do next

Take the seven costs in the table above to every quote you collect and check that each one is either priced, allowed for, or ruled out in writing. If you would rather talk it through with the person who will be on site, you can book a time with me here.

FAQ

How much should I budget on top of a bathroom quote? 10 to 15 per cent, so $3,000 to $4,500 on a $30,000 bathroom. Houses built before 1990 should sit at the top of that range, because asbestos and rot are more likely.

What does asbestos testing and removal cost? Testing is $200 to $500. Removal runs $50 to $150 per square metre, with a minimum job charge of around $1,500 to $2,500, so a bathroom usually lands between $1,500 and $5,000.

Do I have to use a licensed asbestos removalist? In Victoria, yes, for anything over ten square metres of bonded asbestos and for any friable asbestos at all. It must go to an EPA licensed site. A bathroom lined in asbestos sheet normally passes ten square metres on the walls alone.

What happens if you find rot behind the wall? We show you, price the repair, and get your approval before we carry on. Framing repairs run $1,000 to $3,000. The work cannot be skipped, because waterproofing needs sound timber underneath it.

Is rubbish removal included in a bathroom quote? It is in ours. It is not in every quote. A 4 cubic metre skip in Melbourne is $250 to $380, and a bathroom strip-out produces one to three cubic metres of waste.

Who applies for the building permit? We do, on our jobs, and the fee sits inside the $1,200 to $2,000 the paperwork costs. Ask any other renovator whether the application is their job or yours, and whether the fee is in the quote.

What certificates should I be given at the end? A Compliance Certificate of Plumbing Work from a licensed plumber for any plumbing work valued at $750 or more, lodged within five days, and a Certificate of Electrical Safety from the electrician.

How much deposit can a builder ask for? On a contract over $20,000 the deposit is capped at 5 per cent, so $1,500 on a $30,000 bathroom. Under $20,000 the cap is 10 per cent.

Is my builder required to have Home Warranty cover? For domestic building work valued at more than $20,000, yes. Home Warranty replaced Domestic Building Insurance on 1 July 2026. Cover starts when you sign, the builder pays the premium to the Building and Plumbing Commission within 10 business days of signing or before work starts, and you receive a Notice of Cover. Cover runs to $400,000.

Should I replace old pipes while the bathroom is open? If they are galvanised steel and corroding, it costs far less to do it while the walls are already open than to come back later and retile.

How long will I be without the bathroom? Three to four weeks on our jobs. Work out where you are showering before the job starts, and ask whether the toilet can stay connected for part of it.