cropped Passion Built Alexandria Renovation Company Logo Horizontal

We can renovate a bathroom on a concrete slab

Renovating a bathroom on a concrete slab

renovating a bathroom on a concrete slab in Sydney

Believe it or not, we often get asked whether it is possible to renovate a bathroom that has been built on a concrete slab. Passion Built is a renovation contractor that can work on practically any type of site including homes built on piers or ones that are on a slab.

Renovating a structure that has timber floor boards with joists and bearers is normally easier, but a lot depends on the crawl space available under the building. If there is enough space it makes it relatively easy to access the plumbing through the floor to move a toilet, relocate a tap or change the layout of a bathroom.

You can do the same things on a concrete slab, the difference comes down to the approach that has to be taken, labour involved & the costs as it is typically more complex to deal with because it might require wet saw cutting into the slab.

It is mainly newer homes that have been built on slabs and of course, units, apartments, villas or townhouses as well. In fact most homes across Sydney have a bathroom with a concrete floor that is sitting on a concrete slab of some shape or form. That has been the modern construction technique for many years.

Therefore, it isn’t so much a question of ‘can you renovate on a concrete slab’ it is more relevant to consider what you would like to achieve and then the various costs associated with those ideas. You may even want to add a bathroom to a house with a concrete slab foundation which takes some planning to ensure the right steps are taken with the concrete floor.

concrete slab bathroom demolition

Demolishing a bathroom on a concrete slab

If you have decided to renovate your bathroom the first decision to make is whether you are doing a simple refresh with some new paint, taps and fixtures or will you do a complete renovation starting with demolishing the old bathroom?

The benefit of stripping everything back to the bare framework of the room is that you can build exactly what you want either using the current placement of toilet, shower, vanity and lighting or creating a new floor plan.

By demolishing the room, even on a concrete slab, your renovation contractor can get access to every electrical wire, water supply point, sewage waste pipes and the wall frames. From that stage things can be moved, new items added or new channels cut into the concrete for new plumbing.

By being able to access the structure of the property you can make nearly infinite renovation changes to your bathroom that are not as easily done if you leave the existing tiling or waterproofing in place. The other big benefit is that everything is built from scratch and together rather than in sections or areas of the room. This can help with the longevity of the room including managing water leaks.

During this part of the process we can even break the concrete floor to begin making spaces for the new plumbing. Breaking a concrete floor normally means using a jackhammer or wet cut saw to make the required channels to lay new plumbing. This will eventually mean you can install a new toilet on the concrete floor or even a new walk in shower. These are the things that you have to take into consideration with working out the cost of renovating a bathroom, especially for a house on a concrete slab.


Complete ensuite bathroom renovation on a concrete slab with bath and shower

Does it cost more to renovate a bathroom on a concrete slab?

The main factors that effect the cost of renovating doesn’t necessarily relate to being on a concrete slab or not. The biggest factors that lead to huge variations in the cost of renovating are;

  • Complexity; if all the existing services are being re-used then the cost to renovate on a slab vs other foundations are fairly similar as the work required is about the same. If you have to move a toilet or shower then doing so on a concrete slab might cost more vs a timber floor if lots of cutting has to be done to fit the new plumbing needed.
  • Time of year; like any product or service, pricing may change based on availability or time of year. So renovating at Christmas or school holidays may cost more vs other times of the year. Or during summer may cost more than winter because of industry demands.
  • Materials; you can buy a tap from Bunnings for $10 or choose a designer item for $1,000. That’s how quickly the cost of materials can vary and this applies to tiling, bathtubs, shower heads, vanities etc. So a fit out may cost you $5,000 or $15,000 depending on what you select to install in the new bathroom.
  • Access; if you live on a property with easy parking access, lots of space to move, on a single level then the cost of labour or time required to complete a renovation will be shorter vs trying to renovate a room on the top floor of an apartment block in the middle of Bondi Junction. Every tradesperson has to get in and out easily to complete the job quickly.
  • Size of the room; a bathroom that is 1×2 metres in size will be cheaper to renovate vs a 3×3 metre room because it will take longer, need more materials & may even need more trades. A smaller room might be expensive it only one tradesperson can fit into the room at a time to complete any work. So size does matter.
  • Labour; with any skilled labour there will always be industry average rates that you can research and compare. In some instances based on experience, reviews or industry standing a tradesperson may charge slightly more. The thing to be careful of is super cheap labour costs as typically this could be sub-contracted staff who are not extremely experienced or capable.


small bathroom renovated in a unit on a concrete slab with new sink taps

Is it hard to renovate a bathroom in a unit or apartment block with concrete floors?

The most common request we are fielding for renovations is for units or apartments with concrete floors. These are a bit more difficult to work with because of the shared walls, floors and ceilings with adjoining properties – but not impossible.

The simplest way is to plan your unit bathroom layout to have the toilet, shower and vanity remain in the same locations as the existing fixtures. That way you can concentrate on remodelling the room without worrying about plumbing or cutting into the concrete to move things around.

In most cases you will have to get strata approvals anyway, so being able to demonstrate you will use the existing services will make that process much easier to manage.

bathroom renovated on a concrete slab with bath and shower

Can you add a bathroom on a slab without cutting the concrete?

Let’s say you want to build a new bathroom on concrete but not sure if you need to cut holes or new channels, what can you do? You call a plumber for an estimate, and they will tell you they have to break through the floor or drill through the concrete to install a drain line for the plumbing — a messy and time-consuming job with a high price tag.

Changing the floor layout or adding a bathroom without cutting a slab might be possible to achieve if the location and type of property allows for this to be done. How we can build a bathroom on a concrete slab will really depend on the site itself, obviously working on a house will be easier than in a unit or apartment block.

Some plumbers might suggest a sewage ejector system. Still, this would mean doing jackhammer or wet saw cutting to dig up the floor while not knowing what’s beneath. There are several possible hazards, such as not knowing how thick the floor is, unforeseen rocks or pipes. Plus, any time you disturb the concrete floor, there’s a chance of water from the outside seeping through.

The alternative is to consider electric products like a modern macerator pump. This is an innovative technology that allows you to add your septic plumbing into wall cavities and through the roof. This means that you do not even need to cut or boar into concrete at all. 

Instead of routing flush water through below-floor drainage lines to sewage access or a sewage ejector, the wastewater from the fixture drains through gravity into a macerator. The term “macerate” means to soften or break up. The macerator pump uses a stainless steel fast-rotating cutting blade to convert solids and fluids into a fine slurry that is discharged under pressure through small-diameter piping (¾-inch or 1-inch) and expelled into the sewage line or septic tank.

This means it can be installed on top of any floor in the home. This allows you to place a new bathroom wherever you want really and without costly excavation of the floor to install plumbing. 

Walls and floors remain intact, and installation is performed quickly and economically with minimal disturbance to room layout. 

This electronic system can be installed behind the toilet or in the wall. Once everything is broken down it can be pumped through a narrow pipe until it reaches the septic point. It means you could build a new bathroom in a garage, outdoor shed, external laundry or even in a second storey room.

Can you bypass the existing plumbing?

If your new bathroom is close to an exterior wall, another option might be to core drill into the concrete and then bore underground to that point.

Special care needs to be taken to make sure the structural integrity of the house is not compromised. This is because boring a new pathway underneath the footings may be up to a metre deep. This method allows you to install new sewage lines that run around the slab to a sewer point outside.

You have to use the ‘Dial Before You Dig’ service to make sure you are not going to hit any underground infrastructure. Sewage pipes in Australia need to be buried below ground level, so a trench would need to be dug all the way around until it meets with the sewerage point.

Cost to cut concrete slab for plumbing?

The cost to cut into a concrete slab for new plumbing will vary depending on the amount of time it takes, the labour charge will normally be an hourly rate. Plumbers in Sydney like Instaplumb can provide a cost estimate prior to any work commencing but the costs may change depending if there are any unforeseen issues that pop up once work starts.

It might take a couple of hours or a whole day to cut all the required channels in an existing concrete slab, it just depends how deep and the distance the cutting needs to be done. The cost for cutting a small channel will obviously be much less than something that needs to run through the bathroom, into other rooms or even the hallway to reach existing service lines.

We can provide a cost estimate when we are doing a quotation to renovate your bathroom.

Moving a shower drain, toilet or plumbing for a bathroom on a concrete slab

This will start to sound a bit repetitive, but if you want to move a shower drain, a toilet, your shower or the plumbing in your bathroom that has already been built on a concrete slab then you have to engage with a bathroom renovator & licensed plumber. Moving existing drainage or water supply lines is typically very extensive renovation work, especially when it has to be done on a room built on a concrete slab. 

The existing drain or connections need to be removed, the floor prepared for the new locations, new plumbing installed & then the hardware can be reconnected. We have seen some people try it themselves as a DIY project but remember you are dealing with waterproofing, tiling & of course plumbing connections. So there are lots of areas where errors can be made that can lead to water leaks or even bad odours coming from the pipes if they aren’t connected and sealed correctly.

Can a bathroom renovator reconfigure the bathroom layout?

If licensed bathroom renovator in Sydney like Passion Built can help you reconfigure your bathroom layout when we are doing a renovation for you. This can be done;

  • For an existing room where the locations of toilet, vanity, shower or bath are changed.
  • When walls are adjusted or moved to make the room a different shape.
  • When a bathroom and laundry are being combined.
  • If an existing laundry is getting converted into a full bathroom.

DO you need council approval to build a bathroom on a concrete slab?

For most people trying to renovate internal rooms you do not require planning permission to add something like a new bathroom unless it will change the structure of your home or is part of an extension.  Read our Free guide about getting renovation approvals in Sydney.


Want pricing information?

Dylan from Passion Built will be happy to answer any questions you might have & share information about current renovation package options available.


Free site inspection, consultation & quote

It’s really easy to find out the cost to renovate. We offer an obligation free site inspection, consultation & written price quote so that you can work out all the costs before you commit to renovating.

Get more bathroom renovation advice

Enjoy some of our free home renovation contractor guides that explain the practical steps to getting your home renovated without spending a fortune while making sure you get the job done right the first time.

Frequently asked questions

Here is a collection of the questions we get asked a lot when we get phone calls or emails and people want information about the cost to build a new bathroom.

Absolutely you can renovate a bathroom on a concrete slab in Sydney – house, unit, townhouse, villa or apartment. Most modern housing structures are built on concrete slabs. Even though all the plumbing is set into the slab during construction you can create new pathways by cutting holes into the existing slab and joining new plumbing connections.

The cost to achieve these types of bathroom renovations will vary based on complexity, size of room, access and materials chosen.

Absolutely you can move a toilet or shower on a concrete slab in Sydney – house, unit, townhouse, villa or apartment.

The cost to move these fixtures will depend on how far you want them moved & what access to the slab is like or how far plumbing has to be adjusted. 

Passion Built are renovation contractors in Sydney that can provide a fixed price quote and site inspection.

The cost of installing plumbing in existing concrete slab will be between $500 and $5,000 and the exact amount will depend on exactly what has to be installed, how thick the slab is and how much anticipated work is involved to complete the installation. You might want to install a new single tap on its own, so cutting into the existing slab will be simpler compared to putting in new plumbing for a shower, toilet, vanity and bath tub. We can provide a free quotation so you can calculate the costs of installing plumbing in your existing concrete slab in your home.

To plumb a bathroom that is in a concrete slab will usually mean it has to be cut into so that the pipes can be installed. Wet saw cutting is very common when it comes to doing building, renovating or installing new plumbing. The rest of the concrete foundation remains as is, but the area where the new items will be installed is what gets changed.

The cost of plumbing an existing concrete slab will be between $500 and $5,000 and the exact amount will depend on exactly what has to be installed, how thick the slab is and how much anticipated work is involved to complete the installation. You might want to install a new single tap on its own, so cutting into the existing slab will be simpler compared to putting in new plumbing for a shower, toilet, vanity and bath tub. We can provide a free quotation so you can calculate the costs of installing plumbing in your existing concrete slab in your home.

Cutting concrete slab for plumbing will cost between $500 and $5,000 and the exact amount will depend on exactly what has to be installed, how thick the slab is and how much anticipated work is involved to complete the installation. You might want to install a new single tap on its own, so cutting into the existing slab will be simpler compared to putting in new plumbing for a shower, toilet, vanity and bath tub. We can provide a free quotation so you can calculate the cutting concrete slab for plumbing costs that are required.

You put a new bathroom on a concrete slab quite easily. There is more work involved compared to a room that is on timber floorboards but it is still possible to be done. You might want to convert a bedroom on a concrete slab into a bathroom, so first step after demolition will be figuring out how to cut into the slab to get water and waste services installed for the shower, toilet, vanity sink or bath tub. Once the new plumbing is installed the pipes can be set into the wall then then fit off can be done once the walls are re-sheeted, waterproofed and tiled.

Installing a bathtub on a concrete floor is really easy. The simplest way is to replace your shower with a bathtub so it can be installed and use the same drain and tap mixer locations. It means the plumbing doesn’t have to move and we can use the existing services that are already installed in the slab. 

In other situations we can fit a new bathtub on a concrete slab by cutting into the concrete so we can fit a drain and fresh water supply. Once that is installed we can fit the new taps and mixer then connect the drain as well. We would make sure to check the slab can carry the weight of the tub when it is empty and of course when it is full of water as well. Some concrete slab floors might need to be re-enforced to make them stronger, but we would check this first.


Licensed builder and founder of Passion Built

About us

Passion Built, a premier licensed builder in Sydney, that provides bespoke bathroom renovation services tailored to meet the specific needs and visions of each client whether it is for a house, apartment or commercial use location. Recognised as one of the most modern bathroom renovation builders in Sydney, we specialise in transforming living spaces including a laundry

For those looking to revamp their bathrooms, our detailed bathroom renovation package brochure provides an array of options to renovate a bathroom in your house or apartment within your budget without compromising on quality. 

Unique services such as converting laundry to bathroom are handled with the utmost precision, showcasing our dedication to innovation. With a commitment to transparency and no hidden surprises, our fixed price bathroom renovation quotations ensure complete peace of mind for every single client. 

Trust Passion Built to design your new bathroom space; your dreams, our blueprint.