Category: New Homes, Granny Flats & Construction

A granny flat may be smaller than a full house, but it still needs the same basic plumbing systems to be planned properly. Water supply, sewer, hot water, kitchen, bathroom and laundry connections all need to work together with the site layout and building design.

For more detail on the service itself, see our granny flat plumbing page.

Water and sewer connections

The first question is how the granny flat will connect to existing water and sewer services. Distance, levels and the position of existing infrastructure can affect how the new plumbing is routed.

Bathroom plumbing

Toilet, shower, basin and floor waste locations should be confirmed early so underground and rough-in work can be positioned correctly.

Kitchen and laundry

Even compact granny flats often need a kitchen sink, dishwasher connection, washing machine point and laundry waste. These should be included in the plumbing plan from the beginning.

Hot water

The hot water system needs to suit the expected number of occupants, available energy source and installation location. Space and service access should also be considered.

Gas services

If the granny flat will use gas for cooking or hot water, the gas supply and appliance locations need to be designed into the project rather than added at the end.

Stormwater and external drainage

Roof water and surface drainage still need somewhere suitable to go. The stormwater plan should be coordinated with the building footprint and site works.

Plan the complete plumbing scope

A clear scope should identify underground works, rough-in, fit-off, external connections and appliance services so important items are not missed between trades.

Related plumbing services

You may also find these related service pages useful: granny flat plumbing, water and sewer connections, hot water systems for granny flats.

Need help with this type of plumbing?

If you are planning this work or dealing with a problem now, see our granny flat plumbing service page for the relevant plumbing options and next steps.

Adding plumbing to an existing shed or detached building is not always as simple as extending a few pipes. The building may be a long way from existing services, floor levels may not suit gravity drainage and the internal layout may not have been designed with plumbing in mind.

For more detail on the service itself, see our shed conversion plumbing page.

Distance from existing services

Longer runs between the main house and the new building can affect pipe sizing, trenching, pressure and cost. The route should be planned before landscaping or paving is completed.

Drainage levels

Wastewater generally relies on suitable falls, so the relationship between the new fixtures and the existing sewer connection is important. Difficult levels may change the design approach.

Concrete floors and existing structures

Retrofitting plumbing into an existing slab can require more work than plumbing a new build. Where possible, fixture locations should be chosen with the existing structure in mind.

Hot water location

The hot water system should be positioned for practical pipe runs, ventilation or electrical requirements, service access and the needs of the occupants.

Bathroom and kitchen layout

Keeping wet areas reasonably grouped can simplify plumbing. A scattered layout can increase the amount of pipework and make future servicing more difficult.

Plan for the finished use

A simple shed bathroom has different plumbing needs from a self-contained granny flat with kitchen, laundry and hot water. The intended use should guide the plumbing scope.

Get the plumbing design sorted early

Before finishes are selected, confirm how water, sewer, hot water, gas and stormwater will work. That makes the rest of the conversion much easier to coordinate.

Related plumbing services

You may also find these related service pages useful: shed conversion plumbing, granny flat plumbing, shed bathroom installation.

Need help with this type of plumbing?

If you are planning this work or dealing with a problem now, see our shed conversion plumbing service page for the relevant plumbing options and next steps.

Construction plumbing happens in stages, and each stage needs to be coordinated with the builder and other trades. Understanding the sequence helps explain why plumbing decisions need to be made well before the fixtures are installed.

For more detail on the service itself, see our construction plumbing page.

Underground plumbing

Before slabs and finished surfaces are completed, sewer, drainage and water services may need to be installed below ground. Accuracy is critical because these services become difficult to alter later.

Slab and pre-pour work

Where plumbing passes through or below a slab, the set-out must match the building plans. Fixture locations and penetrations need to be confirmed before the concrete stage.

Rough-in plumbing

During rough-in, water, waste and other services are run through walls, floors and ceilings before linings are completed.

Fit-off

Fit-off is when toilets, taps, basins, sinks, showers and other fixtures are installed and connected after the building has progressed to the appropriate stage.

External and final connections

Depending on the project, final work may include hot water systems, external taps, rainwater, sewer connections and other site services.

Testing and handover

Plumbing should be tested at the relevant stages and checked again when the system is complete. Problems are easier to fix before finishes and handover.

Coordination is the key

A good construction plumbing program follows the build schedule and makes sure fixtures, plans and service requirements are available before each stage begins.

Related plumbing services

You may also find these related service pages useful: construction plumbing, underground plumbing, rough-in plumbing.

Need help with this type of plumbing?

If you are planning this work or dealing with a problem now, see our construction plumbing service page for the relevant plumbing options and next steps.

A renovation may reuse much of an existing plumbing system, while an extension can introduce entirely new wet areas, drainage runs and service connections. The visible finishes may look similar, but the work behind the walls can be very different.

For more detail on the service itself, see our renovation plumbing page.

Renovation plumbing

Renovation plumbing often involves altering existing water and waste lines to suit a new layout. The condition and location of the original services can influence what is practical.

Extension plumbing

An extension can require new underground drainage, new water services and longer pipe runs before the new rooms are even built.

Existing pipework matters

Older or poorly positioned plumbing can complicate both renovations and extensions. Opening walls or floors can reveal previous alterations that were not obvious from the plans.

New wet areas need careful set-out

Adding a bathroom, kitchen or laundry creates new fixture loads and drainage requirements. The set-out should be checked before structural and finishing work locks the layout in place.

Coordination with other trades

Plumbing alterations can interact with framing, electrical services, cabinetry and waterproofing. Good coordination reduces clashes and rework.

Plan from the whole building, not one room

Even when only one area is being changed, it is worth understanding how the new plumbing connects back into the existing system.

Related plumbing services

You may also find these related service pages useful: renovation plumbing, extension plumbing, construction plumbing.

Need help with this type of plumbing?

If you are planning this work or dealing with a problem now, see our renovation plumbing service page for the relevant plumbing options and next steps.

Many plumbing decisions are difficult or expensive to change once construction begins. A new home plumbing checklist helps make sure the important service, fixture and access decisions are discussed while the plans are still flexible.

For more detail on the service itself, see our new home plumbing page.

Bathrooms and wet areas

Confirm the position of toilets, showers, baths, vanities and floor wastes. If fixtures are wall-hung or concealed, final product information may be needed early.

Kitchen and laundry

Plan sink, dishwasher, fridge, washing machine and laundry connections around the final cabinetry and appliance layout.

Hot water

Choose an appropriate hot water approach and location. Consider household demand, available services, access and pipe runs to frequently used fixtures.

Water and sewer services

The connection points and underground routes should be coordinated with the building footprint, driveway and landscaping.

Stormwater and rainwater

Roof drainage, pits, downpipes and any rainwater system should be integrated with the overall site drainage plan.

Gas and outdoor plumbing

If gas appliances, barbecue points, outdoor kitchens, garden taps or future sheds are planned, allow for them before the site is finished.

Future servicing

Isolation valves, hot water equipment and other serviceable plumbing should remain reasonably accessible after landscaping and cabinetry are complete.

Related plumbing services

You may also find these related service pages useful: new home plumbing, new home underground plumbing, new home plumbing rough-in.

Need help with this type of plumbing?

If you are planning this work or dealing with a problem now, see our new home plumbing service page for the relevant plumbing options and next steps.

Owner-builders take on more responsibility for sequencing trades, which makes plumbing coordination especially important. The plumber may need to attend the project at several stages, and each visit depends on other work being ready.

For more detail on the service itself, see our owner-builder plumbing page.

Start with a complete plumbing scope

List every bathroom, kitchen, laundry, hot water unit, external tap, gas appliance and drainage requirement so the project is not priced or scheduled in fragments.

Coordinate underground work

Sewer, stormwater and water services may need to be installed before slabs, driveways or other site works. Missing this stage can be costly.

Have fixture information ready

Concealed cisterns, mixers, baths, vanities and specialty fixtures may affect rough-in positions. Product selections should be available before the relevant plumbing stage.

Schedule rough-in with framing

Walls need to be ready for rough-in but not closed before plumbing is complete. Communication with the builder, framer and electrician helps avoid clashes.

Plan waterproofing and fit-off

Bathroom plumbing needs to coordinate with waterproofing, tiling and cabinetry so fixtures can be fitted without damaging completed finishes.

Allow for inspections and testing

Do not assume every stage can be covered by one final visit. Plumbing work may require checks and testing throughout the build.

Keep the plumber updated

Changes to room layouts, fixture selections or construction timing should be communicated early. Small plan changes can affect multiple plumbing stages.

Related plumbing services

You may also find these related service pages useful: owner-builder plumbing, new home plumbing, builder plumbing for new homes.

Need help with this type of plumbing?

If you are planning this work or dealing with a problem now, see our owner-builder plumbing service page for the relevant plumbing options and next steps.