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What Plumbing Do I Need for a Renovation? A Complete Plumbing Guide

Planning a bathroom, kitchen, laundry or complete home renovation involves much more plumbing than simply installing new taps and fixtures at the end of the project.

Depending on the renovation, plumbing work may include disconnecting existing fixtures, relocating water and drainage services, installing new hot and cold water pipework, altering sewer drainage, gas fitting, rough-in plumbing, pressure testing and final installation of toilets, showers, baths, basins, sinks and appliances.

Getting the plumbing right during the early stages of a renovation is important. Once walls are plastered, floors are tiled and cabinetry is installed, changing the location of plumbing services can become considerably more difficult and expensive.

At J.PAC Plumbing, we provide renovation plumbing throughout Melbourne's South East, Bayside and surrounding areas, working with homeowners, builders and other trades from the initial planning and demolition stages through to final plumbing fit-off.

If you're planning a renovation, here's what you should consider.

When Should I Organise a Plumber for My Renovation?

Ideally, speak with your plumber before construction begins.

One of the biggest mistakes during a renovation is deciding where every fixture will go without first determining whether the required plumbing and drainage can practically be installed.

Moving a toilet, for example, can be considerably more involved than moving a basin because the sanitary drainage requirements are different.

Before work starts, your plumber can review the proposed layout and determine what plumbing alterations may be required.

This can help identify potential issues before you've committed to cabinetry, tiles, fixtures and other finishes.

What Are the Main Stages of Renovation Plumbing?

Most renovation plumbing can be divided into several stages.

1. Plumbing Disconnection

Before demolition begins, existing plumbing fixtures and appliances may need to be safely disconnected.

Depending on the renovation, this could include:

  • Toilets

  • Basins and vanities

  • Showers

  • Baths

  • Kitchen sinks

  • Laundry troughs

  • Dishwashers

  • Washing machines

  • Gas cooktops and ovens

  • Other connected plumbing appliances

Water and gas services may also need to be capped or made safe while construction takes place.

Having plumbing services properly disconnected before demolition reduces the risk of accidentally damaging live water or gas pipework.

2. Sanitary Drainage Alterations

If you're changing the location of fixtures, the existing sanitary drainage system may need to be altered.

Wastewater from toilets, showers, basins, baths, kitchen sinks and laundries needs to discharge through correctly installed drainage.

Depending on the property, drainage alterations may involve working:

  • Below concrete slabs

  • Under suspended floors

  • Within walls

  • Through existing floor penetrations

  • Underground outside the building

This is one of the reasons the plumbing layout should be considered early.

Relocating a toilet across a room isn't necessarily as simple as extending a pipe. The plumber needs to consider the existing drainage location, pipe sizing, fall, venting, available space and how the new connection can be installed.

3. Hot & Cold Water Rough-In

Once the layout is confirmed and framing is ready, the plumber can complete the hot and cold water rough-in.

This involves installing water services inside walls, ceilings or floors before they are covered.

Water may need to be supplied to:

  • Showers

  • Baths

  • Basins

  • Toilets

  • Kitchen sinks

  • Butler's pantries

  • Laundry troughs

  • Washing machines

  • Dishwashers

  • Refrigerators

  • Outdoor taps

  • Other plumbing fixtures

Getting fixture locations correct at this stage is extremely important because the pipework will eventually be concealed behind finished surfaces.

4. Shower Plumbing

A bathroom renovation may require new plumbing for the shower mixer, shower rail, overhead shower or handheld shower.

If you're changing from traditional separate hot and cold taps to a mixer, pipework alterations will generally be required during the rough-in stage.

The exact position of the mixer and shower outlets should be determined before waterproofing and tiling.

It's also important to have the actual shower fixtures selected early because installation requirements and dimensions can differ between products.

5. Toilet Plumbing

Changing or relocating a toilet can involve both water supply and sanitary drainage alterations.

Different toilets can also have different set-out requirements.

For example, an in-wall cistern needs to be planned during the framing and rough-in stages because much of the system becomes concealed inside the wall.

If you're purchasing your own toilet, make sure it's suitable for the existing or proposed drainage configuration before installation.

6. Bath Plumbing

Installing a new bath can require alterations to the water supply, waste connection and drainage.

A freestanding bath can require different plumbing arrangements from a traditional inset bath, particularly where the waste connection will be concealed underneath the bath.

This should be planned before flooring and waterproofing works are completed.

7. Kitchen Renovation Plumbing

A kitchen renovation may require more plumbing than people initially expect.

Depending on the new design, plumbing may be required for:

  • Kitchen sink

  • Sink mixer

  • Dishwasher

  • Refrigerator water connection

  • Filtered water system

  • Gas cooktop

  • Gas oven

  • Island bench sink

  • Butler's pantry

  • Additional sink or appliance connections

If the kitchen sink is being relocated to an island bench, drainage and water services may need to be installed through or beneath the floor before the new kitchen is installed.

8. Laundry Renovation Plumbing

Laundry renovations can involve water and drainage connections for washing machines, laundry troughs, sinks and tapware.

If you're changing the layout or installing cabinetry over existing plumbing, the services may need to be repositioned during rough-in so everything fits neatly inside the finished cabinetry.

Planning this before the cabinets arrive can avoid having to modify brand-new cabinetry later.

9. Gas Plumbing During a Renovation

If your renovation involves a gas cooktop, gas oven, gas hot water system or other gas appliance, gas fitting needs to be incorporated into the project.

Depending on the works, this may involve:

  • Altering existing gas pipework

  • Installing new gas appliance connections

  • Installing accessible isolation valves

  • Gas pressure testing

  • Appliance commissioning

  • Gas compliance requirements

Gas work should only be carried out by an appropriately licensed gas fitter.

At J.PAC Plumbing, we provide licensed gas fitting alongside our general renovation plumbing, which means the water, drainage and applicable gas components of the project can be coordinated together.

10. Plumbing Fit-Off

Once waterproofing, tiling, painting and cabinetry are complete, the plumber returns for the final plumbing fit-off.

This is when the finished fixtures and appliances are installed and connected.

Fit-off may include:

  • Toilets

  • Basins

  • Tapware

  • Shower mixers

  • Shower rails

  • Baths

  • Kitchen sinks

  • Laundry sinks

  • Dishwashers

  • Washing machine connections

  • Gas appliances

  • Other plumbing fixtures

The completed installation is then tested for correct operation and leaks.

Do I Need to Choose My Fixtures Before Plumbing Rough-In?

Where possible, yes.

Having your fixtures selected before rough-in can make the process significantly easier.

Your plumber needs to know the installation requirements and dimensions of fixtures such as toilets, in-wall cisterns, mixers, baths and shower systems.

Changing products after the plumbing has already been roughed in can sometimes require pipework to be altered again.

Even if the products haven't physically arrived yet, having the manufacturer specifications and installation instructions available can be extremely helpful.

Can I Move My Toilet During a Bathroom Renovation?

Usually it's possible, but how difficult and expensive it is depends on the existing drainage and building construction.

Moving a toilet on a suspended timber floor may present different challenges from relocating one on a concrete slab.

Where concrete needs to be cut and excavated to alter sanitary drainage, the cost and scope of the renovation can increase significantly.

This is something worth discussing with your plumber before finalising the bathroom layout.

Can I Move My Kitchen Sink?

In many cases, yes.

However, moving a sink requires more than extending the hot and cold water pipes. The waste drainage also needs to be relocated with appropriate fall and connection to the existing sanitary drainage system.

Moving a sink several metres or placing one within an island bench can therefore require additional drainage work.

Again, early planning makes a significant difference.

Who Organises Waterproofing?

Waterproofing is an important part of bathroom, shower and other wet-area renovations.

Plumbing and waterproofing are separate components of the renovation, but they need to work together.

Your plumbing penetrations, wastes, shower outlets and fixture positions should generally be established before the waterproofing and tiling stages.

Waterproofing should be completed by an appropriately qualified person where required.

Poor coordination between plumbing, waterproofing and tiling can create problems that aren't discovered until the bathroom is already finished.

What Order Do Trades Come in for a Bathroom Renovation?

Every project is slightly different, but a bathroom renovation will commonly involve a sequence similar to:

Planning → plumbing/electrical disconnection → demolition → framing/building works → plumbing and electrical rough-in → wall/floor preparation → waterproofing → tiling → cabinetry → plumbing/electrical fit-off → shower screen and finishing works.

The exact sequence should be coordinated between the builder and relevant trades.

The important part is making sure plumbing services are correctly positioned and tested before they're permanently covered.

Should Plumbing Be Pressure Tested Before Walls Are Closed?

Where appropriate, plumbing should be tested as part of the installation process before services become inaccessible.

Finding a problem while the framing and pipework are exposed is considerably easier than discovering it after plaster, waterproofing and tiles have been installed.

At J.PAC Plumbing, testing forms an important part of our rough-in and completion process.

What Plumbing Do I Need for a Full House Renovation?

For a larger renovation, the plumbing scope can extend well beyond an individual bathroom or kitchen.

A full renovation may involve:

  • New hot and cold water services

  • New sanitary drainage

  • Additional toilets and bathrooms

  • Kitchen and butler's pantry plumbing

  • Laundry plumbing

  • Gas fitting

  • Hot water system upgrades

  • Stormwater drainage

  • New external taps

  • Pressure control

  • Appliance connections

  • Sewer alterations

  • New fixtures throughout the property

Older properties may also have existing plumbing that should be assessed before significant money is spent covering it with new finishes.

In some situations, replacing ageing pipework while the building is already open can make more sense than accessing it again several years later.

Renovating an Older Home? Inspect the Existing Plumbing

If you're renovating an older property, don't assume the existing plumbing is in perfect condition simply because it currently works.

Depending on the age and history of the property, existing drainage, water or gas services may have deteriorated or undergone previous alterations.

Where appropriate, this can be a good opportunity to inspect existing services and determine whether anything should be upgraded while access is available.

For drainage, a CCTV drain inspection can also provide information about the condition of existing underground sewer pipework before a major renovation.

How Much Does Plumbing Cost for a Renovation?

There isn't a single price for renovation plumbing because every property and layout is different.

The plumbing cost can be affected by:

  • Number of fixtures

  • Existing plumbing locations

  • How far fixtures are being relocated

  • Concrete cutting and excavation

  • Accessibility beneath floors and inside walls

  • Drainage alterations

  • Gas requirements

  • Type of fixtures selected

  • In-wall cisterns

  • Freestanding baths

  • Kitchen islands

  • Hot water requirements

  • Condition of existing plumbing

  • Number of plumbing attendances required

A bathroom where every fixture remains in approximately the same position will generally involve considerably less plumbing than one where the toilet, shower, basin and bath are all relocated.

For this reason, providing your plumber with plans, fixture selections and photos of the existing property can help produce a more accurate quotation.

Why Use the Same Plumber From Rough-In to Fit-Off?

Having the same plumbing contractor involved throughout the renovation provides continuity.

The plumber completing the fit-off understands how the services were installed during rough-in, where the drainage runs and what was planned for each fixture.

It also provides one clear point of contact for the plumbing component of the renovation.

At J.PAC Plumbing, we can work through the project from initial disconnection and drainage alterations through to rough-in, testing and final fit-off.

Renovation Plumber Melbourne South East

J.PAC Plumbing provides professional bathroom renovation plumbing, kitchen renovation plumbing, laundry plumbing and complete home renovation plumbing throughout Melbourne's South East and Bayside.

We service areas including Mordialloc, Mentone, Parkdale, Chelsea, Cheltenham, Beaumaris, Black Rock, Brighton, Hampton, Sandringham, Dingley Village, Patterson Lakes, Carrum Downs, Seaford, Frankston, Langwarrin, Mornington, Mount Eliza, Somerville and surrounding suburbs.

We work with homeowners, builders and other trades on projects ranging from individual bathroom renovations through to extensive residential renovations and architectural homes.

Planning a Renovation? Speak to Your Plumber Early

If you're planning a bathroom, kitchen, laundry or complete home renovation, getting your plumber involved early can save considerable headaches later.

Before finalising fixture positions, cabinetry and finishes, make sure the proposed plumbing layout actually works.

At J.PAC Plumbing, we can review the plumbing requirements, discuss the proposed layout and provide a quotation covering the required stages of the project.

Plan it properly. Rough it in correctly. Fit it off professionally.

J.PAC Plumbing – Punctual. Professional. Precise.

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