Yes, in most cases a New Zealand homeowner can pour a concrete pad for a heat pump outdoor unit themselves without a building consent — but this depends on the size and nature of the work. It's always worth checking with your local council before you start, as rules can vary and getting it wrong can cause headaches down the track.
Is a Building Consent Required?
Under the NZ Building Code and the Building Act 2004, many small concrete slabs fall under Schedule 1 exemptions, meaning they don't require a building consent. A low-profile concrete pad solely intended to support a heat pump outdoor unit is generally considered exempt work, provided it:
- Is not a structural element of a building
- Does not affect drainage or stormwater in a way that requires consent
- Is not located in a special area (such as a flood zone or heritage overlay)
However, always confirm with your local council before proceeding. What qualifies as exempt work can depend on your specific site conditions, district plan rules, and the size of the pad. You can find general guidance on consent exemptions at MBIE Building Performance.
What About the Heat Pump Installation Itself?
This is where it gets important: pouring the concrete pad is one thing, but connecting the heat pump is another matter entirely.
- Refrigerant handling and pipework on a heat pump must be carried out by a licensed refrigeration technician — this is restricted work under NZ law.
- Electrical connections to the heat pump unit are restricted electrical work and must be done by a registered electrician. Homeowners cannot legally connect a heat pump to the mains supply themselves. Check the Electrical Workers Registration Board (EWRB) for more information on what constitutes restricted electrical work.
So while you can prepare the pad, the actual heat pump installation should be handled by qualified tradespeople. You'll find experienced local installers on tradedirectory.co.nz.
Planning Your Concrete Pad
Size and Thickness
A typical heat pump outdoor unit pad is:
- 600 mm × 800 mm to 900 mm × 900 mm in footprint (check your unit's specifications)
- At least 75–100 mm thick for a standard residential unit
- Slightly raised above ground level to allow for drainage and airflow beneath the unit
Always refer to your heat pump manufacturer's installation manual for the recommended pad dimensions and clearances.
Positioning Considerations
| Factor | Recommendation |
|---|---|
| Airflow clearance | Follow manufacturer specs — typically 300 mm+ on sides |
| Drainage | Ensure the pad slopes slightly away from the building |
| Noise | Consider distance from bedrooms and neighbouring properties |
| Sun/shade | Shaded locations can improve efficiency in summer |
| Access | Leave room for servicing the unit |
Materials You'll Need
- Formwork timber (e.g. 100 × 25 mm timber from Mitre 10 or Bunnings)
- Compacted gravel base (75–100 mm of compacted AP20 or similar)
- Concrete — either bagged ready-mix (suitable for small pads) or ready-mixed delivered concrete
- Steel mesh reinforcing (optional but recommended for longevity)
- Plastic anti-vibration feet or rubber mounts — many installers recommend these between the unit and the pad to reduce noise transmission
Step-by-Step Overview
- Mark out and excavate the area to a depth of around 150–200 mm.
- Compact the subbase and lay 75–100 mm of compacted gravel.
- Set up formwork to the correct dimensions and check it's level.
- Place reinforcing mesh if using, supported on bar chairs.
- Pour and screed the concrete, finishing with a slightly textured surface.
- Cure the concrete — keep it damp and covered for at least 3–7 days before placing the unit on it.
Drainage and Stormwater
Be mindful of where water will drain from the pad. Under the NZ Building Code clause E1 (Surface Water), you must not direct stormwater onto a neighbouring property or in a way that causes nuisance. Keep the pad's runoff directed to a suitable area on your own property, or to an approved stormwater drain.
Healthy Homes and Rental Properties
If you're a landlord installing a heat pump to meet Healthy Homes Standards, note that the heating device itself must meet specific requirements. The concrete pad work is a minor part of the overall compliance picture — ensure the heat pump unit and its installation meet the standards set out by Tenancy Services.
When to Call a Professional
Consider hiring a qualified builder or concretor if:
- The pad needs to be larger or thicker than a standard unit base (e.g. for a ducted or commercial system)
- The ground conditions are poor (soft, fill, or sloping sites)
- You're unsure about drainage or proximity to the house foundation
- Your council flags that consent may be required
For the heat pump installation itself, always use a licensed installer and registered electrician. Find trusted local tradespeople at tradedirectory.co.nz.
Safety Note
Concrete work involves heavy lifting and skin irritation risks from wet cement. Wear gloves, eye protection, and waterproof boots. Keep children away from the work area. If you're cutting timber formwork with power tools, follow safe tool practices as outlined by WorkSafe NZ.
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