If you are building a new home, the conversation about air conditioning usually happens too late. By the time the builder asks about it, the wall framing is in, the ceiling is partly closed, and the cheapest options have already been quietly removed from the table.
The right time to plan aircon in a new build is at the same time you are talking about ceiling heights, electrical, and roofing. Get it right at that stage and you will save thousands and end up with a system that works properly. Leave it until later and you will pay for retrofits that should have been straightforward.
When aircon planning should happen during a build
The ideal sequence:
- Site plan / floor plan stage: Decide whether the house will use ducted, multi-split, or a hybrid system. This affects ceiling space requirements and roof penetration count.
- Electrical rough-in: The aircon supplier specs the circuit requirements. The builder’s electrician runs that circuit while the walls are still open.
- Frame and pre-line: Refrigerant lines and cable runs are installed inside the wall cavities so nothing is exposed at lockup.
- Roof and ceiling stage: Indoor unit positions confirmed. Roof penetrations done at the same time as the rest of the roof flashing.
- Practical completion: Aircon installer commissions the system and signs off.
Skip any of these stages and the install becomes a retrofit, which is more expensive, less neat, and harder to maintain.
Common new-build aircon mistakes
Choosing the system after design is finalised
Ducted reverse cycle needs ceiling space, typically 350 to 500mm clear above the ceiling line. If the design has 2.7m ceilings on the upper floor and a hip roof with limited cavity, ducted may not even be viable. Knowing that at design stage means choosing multi-split or zoning differently from day one.
Undersized electrical supply
A 14kW ducted unit plus the rest of a modern home (induction cooktop, electric hot water, EV charging on the horizon) easily pushes past what a standard 80-amp single-phase service can handle. If the build is going on three-phase or a higher main supply, that decision happens at the time of the supply application, not after the slab is poured.
No coordination between builder and aircon installer
This is the big one. The aircon installer needs to be on site at frame stage, again at pre-line, and once more for commissioning. If the builder hands you a finished house and says now book your aircon, some of the cheapest and cleanest install options are already gone.
Outdoor unit position chosen last
Outdoor compressor units make noise. Putting them next to the master bedroom window or right at the back deck is a common late-stage decision that haunts the homeowner forever. The position should be agreed at design stage, with consideration for line lengths, neighbour proximity, and acoustic impact.
The role of a good builder in getting aircon right
The builders who consistently deliver new homes with well-installed aircon do three things differently:
- They bring the aircon installer into the design conversation early. Not as a sales call, as a technical input on what the design needs to support.
- They coordinate trades so the aircon work fits inside the build sequence. No surprises about already-finished walls.
- They include realistic aircon allowances in the quote. Not a token line item that gets blown out at the end.
Brisbane custom builders like Iconic Homes and Construction bake this kind of trade coordination into how they run a build. Aircon is treated as a primary system from concept stage, not an afterthought once the slab is poured.
Costs to budget for in a new build
Realistic 2026 ranges for a new home in Australia:
- Ducted reverse cycle (4 bedroom home): $14,000 to $22,000 supplied and installed
- Multi-split (4 indoor heads): $9,000 to $15,000
- Hybrid (ducted living areas + splits in bedrooms): $12,000 to $18,000
- Switchboard upgrade if needed: $2,500 to $5,500
- Three-phase supply upgrade if needed: $3,500 to $8,000+
If your builder’s quote shows aircon as a line item under $8,000 for a 4-bedroom house, dig into it before signing. Either the system is undersized, the brand is bottom-tier, or the install is missing major components.
Five questions to ask your builder
- Which aircon system are you specifying for this design, and why that one?
- When in the build sequence will the aircon installer be on site?
- Is the electrical supply sized for the aircon plus future appliances?
- Where will the outdoor unit sit, and how was that decided?
- What warranty is on the aircon install, and who handles it if something goes wrong?
If the answers are vague, push for clarity before construction starts. The cost of getting aircon wrong in a new build is paid for years afterwards in noise, comfort issues, and energy bills.
