The Parts of Your House Nobody Photographs Cost More Than the Kitchen

Six hidden systems add up to more than a kitchen

At Going Rate's prices, a hot water system ($3,450), ducted air conditioning ($14,000), rewiring ($14,300), a switchboard upgrade ($2,950), whole-house guttering ($4,850) and a garage door ($4,550) come to about $44,000. A kitchen renovation ($32,500) costs about $11,600 less.

Nobody gets that $44,000 as one bill. These are six separate systems that wear out on different clocks, and most owners replace them one at a time over decades, often after something fails. The sum shows what a house costs to keep running underneath the parts people photograph. Add a bathroom renovation ($22,500) to the kitchen and the six hidden systems still come to about 80% of both rooms together.

Much of the housing stock needs the work. AHURI reported in 2024 that 70% of existing Australian houses rated 3 stars or lower for energy efficiency, and that 70% of homes had a building quality problem, most often cracks (44%), mould (35%) and plumbing (27%). HIA noted the same year that a surge of homes built in the early to mid 1990s was reaching the 30 to 35 year age bracket, when owners tend to undertake major renovations.

Hot water system replacement cost

Replacing a hot water system ($3,450) is the second cheapest of the six, after the switchboard, at about a tenth of a kitchen renovation ($32,500). It also carries the shortest guarantee. YourHome lists warranties of 5 to 10 years for glass-lined steel tanks and 10 to 15 years for stainless steel. A warranty sets the minimum the manufacturer will stand behind and says nothing about how long a tank will last. Spread across a 5 to 10 year warranty the Going Rate price works out at about $345 to $690 per warranted year. The ducted air install price, without running costs, spread across CHOICE's 15 to 20 year lifespan comes to about $700 to $933 a year. At the short end of its warranty, the hot water tank costs nearly as much per covered year as ducted air.

Hot water also runs up the power bill. Energy.gov.au says water heating is the second largest share of household energy use, between 15% and 30%, and the largest source of household greenhouse emissions at up to 25%. Electric storage systems are in around 50% of Australian households. A heat pump uses 30% of the energy of a conventional electric system, according to energy.gov.au, and CHOICE puts the payback on a heat pump at typically about five years.

Victorians can claim part of the price back. Solar Victoria's hot water rebate covers 50% of the price of an eligible system, up to $1,000, or $1,400 for one made locally. Households must earn under $150,000 and the old system must be at least three years old. Only heat pump and solar systems qualify, and the 50% applies to the product price. If the product makes up most of a typical replacement ($3,450), the rebate would reach the $1,000 cap.

Ducted air conditioning cost and running cost

Installing ducted air conditioning ($14,000) is the second most expensive of the six. CHOICE said in 2023 that buyers would be hard-pressed to get a ducted reverse-cycle system for less than $5,000, with a typical house costing $10,000 or more and large or multi-storey homes $15,000 or more. Going Rate's price sits above CHOICE's typical-house figure, which is three years older.

Going Rate puts the annual running cost ($1,300) on top of the system price. Over 15 years, the low end of the 15 to 20 year lifespan CHOICE gives for air conditioners, install plus running costs come to about $33,500, roughly $1,000 more than a kitchen renovation ($32,500). Over 20 years the total is about $40,000. Both figures hold today's running cost flat for the whole period, so any tariff rise would push them higher.

Houzz found 27% of Australian renovators upgraded their cooling in 2022, the third most common system upgrade after electrical and plumbing.

Rewiring a house and upgrading the switchboard

Rewiring a house ($14,300) is the most expensive of the six, and a switchboard upgrade ($2,950) often goes with it. Together they cost about $17,250, or 53% of a kitchen renovation ($32,500). Rewiring prices vary more than any other item here, because the job depends on the size of the house, how easy the roof and walls are to get into, and how much of the old wiring survives.

The NSW Government says 40% of house fires in the state are caused by electrical faults and appliances, and that wiring checks and safety switches could prevent up to 1,800 house fires a year. It advises that homes built before the 1980s should consider an electrical inspection. Homes built in or after 2000 will usually have safety switches. Older homes without them can have one installed for a few hundred dollars, the NSW Government says, and owners should test them twice a year.

Electrical work was the most common system upgrade in the Houzz 2023 study, done by 36% of renovating homeowners.

Gutters and the garage door

Replacing the guttering on a whole house ($4,850) and supplying and installing a garage door ($4,550) are the two mid-priced items, each about a seventh of a kitchen renovation ($32,500). If only part of the roofline needs work, a smaller gutter replacement ($3,750) costs less. The $44,000 total uses the whole-house figure and does not count gutters twice.

Gutters move roof water away from walls and footings. AHURI found mould in 35% of homes. Houzz found 23% of renovators upgraded gutters or downpipes in 2022.

What Australian renovators actually upgrade

In the Houzz and Home Australia 2023 study, which covered work done in 2022, 36% of renovating homeowners upgraded electrical, 33% plumbing, 27% cooling, 23% gutters and downpipes and 21% roofing. Kitchen projects were a priority for 33%, and the master bathroom for 25%.

The same Houzz study put the median kitchen renovation at $30,000 and the median overall renovation at $35,000. Those are Houzz survey medians, separate from Going Rate's prices. A kitchen is a single project with a single budget, while the hidden systems arrive one at a time, so they rarely get counted together.

HIA reported in 2024 that renovation lending had more than doubled from before the pandemic.

Which system to check first

Age decides most of the order. A hot water tank carries the shortest warranty of the six systems, and at the replacement price ($3,450) it is one of the cheapest to plan for. Replacing it before it fails also leaves time to compare a heat pump, and Victorians to claim the rebate, rather than taking whatever the plumber has in the van.

For a home built before the 1980s, the NSW Government's advice is to get the wiring inspected. An inspection will show whether the house needs a switchboard upgrade ($2,950) and safety switches or a full rewire ($14,300). Ducted air, gutters and the garage door can usually wait for signs of wear, but an owner planning a kitchen renovation ($32,500) in an older house should price the hidden systems first, because together they can cost more.

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