Bonnyrigg Heights 2177 · Fairfield City
Home Extensions in Bonnyrigg Heights: Moving the Kitchen Back
You want the kitchen at the back. The sewer pipe has opinions.
The most common extension request in Bonnyrigg Heights is simple: move the kitchen from the middle of the 1980s house into a new family room at the back, facing the yard. It's a great change. Where the sink and dishwasher can actually go depends on something nobody sees: how the drains fall.
Short answer
Can I move my kitchen into a rear extension in Bonnyrigg Heights?
Usually, but drainage decides it. Waste pipes need enough fall to the sewer, which may mean cutting the old slab or raising the new floor. Gas lines get extended by a licensed gasfitter, or you switch to induction on a dedicated circuit. A kitchen fit-out is $19,500 to $22,000 on Rawlinsons, and a 75 to 125m² brick veneer addition runs $1,835 to $1,980 per m².
Written and reviewed by Oliver Alameri
Licensed builder, NSW Contractor Licence 487805C · Founder, Buildana
Fact-checked
Water only runs downhill
Every waste pipe from a sink, dishwasher or floor waste has to fall towards the sewer at a minimum grade set by the plumbing standard. For small fixture pipes that's commonly around 1 in 40, and for a 100mm drain around 1 in 60. Over a long run, those falls add up to a lot of depth.
In a 1980s Bonnyrigg Heights house, the sewer often leaves from the side or front, near the old kitchen and bathroom. Put the new sink eight or ten metres away at the back and the pipe has to drop the whole way. If the existing connection isn't deep enough, the fall runs out.
The fixes are known. Bring in a new connection point closer to the extension. Run a deeper drain. Or shift the sink. What doesn't work is ignoring it until the plumber arrives with a laser level and bad news.
The kitchen layout starts with the drainage plan, not the benchtop.
Cutting the old slab
When new drains have to run under the existing house, the plumber saw-cuts trenches through the slab and lays the pipe at the right grade. Then the trench gets filled with fresh concrete. Routine. Also messy, noisy, and it has to be priced.
On Bonnyrigg Heights' reactive clay, the engineer also cares about where those trenches go. Cutting near a slab edge beam or a footing needs care, and the reinstatement is detailed so it doesn't become a weak line.
It's also the right moment to camera-inspect the old sewer. Clay pipes from the 1980s can have cracked joints or root intrusion, and replacing a section while the ground is open is far cheaper than doing it later.
- Survey the existing sewer depth and junction position
- Plan the new drainage route before the kitchen layout is fixed
- Saw-cut and reinstate slab trenches where drains cross the house
- Camera-inspect the old sewer while it's accessible
- Relocate gas and power at the same time
Moving your kitchen to the back?
Send the Bonnyrigg Heights address and a rough floor plan. I'll check where the sewer is, what fall we've got and where the new sink can realistically go before any design is fixed.
0476 300 300Gas, power and the new kitchen
If you're cooking with gas, the line has to be extended to the new cooktop by a licensed gasfitter. Many owners take the chance to go induction instead, which needs a dedicated circuit and often a switchboard upgrade in an older house.
Numbers. A mid-range kitchen, services included, is $19,500 to $22,000 in Rawlinsons for Sydney. The room it sits in, a brick veneer rear addition in the 75 to 125 square metre range, is $1,835 to $1,980 per square metre before the kitchen. Drain relocation and slab cutting go on top, priced from the plumber's survey.
Approvals in Bonnyrigg Heights
A lot of single-storey rear extensions on Fairfield's R2 land qualify for a certifier's CDC under the state code. The rest go to Fairfield Council, typically 8 to 12 weeks. Quick, by Sydney standards.
Once the extension is approved, the kitchen and plumbing inside it come under the same approval. No separate paperwork to move a sink.
Before you draw the new kitchen
Six plumbing and services checks that decide the layout.
- 01
Depth and location of the existing sewer junction
- 02
Distance from the new sink to the sewer, and the fall available
- 03
Whether drains need to cross under the existing slab
- 04
Condition of the old sewer line, by camera
- 05
Gas line extension, or a switch to induction
- 06
Switchboard capacity for new kitchen circuits
Kitchen extension questions
Can I move my kitchen to a new rear extension?
Usually, yes. The main constraint is drainage fall to the sewer. If the existing connection isn't deep enough, a new connection point or deeper drain may be needed.
Does moving a kitchen mean cutting the slab?
Often, if new drains need to run under the existing house. The plumber saw-cuts trenches, lays pipe at the right grade and the slab is reinstated.
Is it cheaper to leave the kitchen where it is?
Usually, because the drains, gas and power are already there. Moving it adds drainage and slab work. Most owners still move it, because a kitchen facing the yard changes how the whole house is used.
Can I switch from gas to induction when I extend?
Yes, and many people do. It needs a dedicated circuit, and older switchboards often need upgrading to handle it.
Sources and references
Costs are from the Rawlinsons handbook with the local cost index applied; rules and timeframes are checked against the sources below.
A kitchen that faces the yard, with drains that work.
Plan the plumbing first and the new Bonnyrigg Heights kitchen falls into place.