Yes, you can often use a hired mini excavator to demolish a small concrete block (also called concrete masonry unit or CMU) wall yourself — but only after checking a few critical things first. Rushing in without preparation can lead to injuries, damage to underground services, or even a building consent issue. Here's what you need to know before you fire up the machine.
Do You Need a Building Consent?
Demolition work in New Zealand can require a building consent, depending on the size and nature of the structure. Under Schedule 1 of the Building Act 2004, some minor demolition work is exempt — but the rules are not always straightforward.
As a general guide, demolishing a small, free-standing garden or boundary wall that is not part of a building's structure is often exempt. However, if the wall:
- Is a retaining wall holding back soil or a slope
- Is part of your home's foundation or structural system
- Is over 1.5 metres in height
- Is on a heritage-listed property or in a special character zone
…then you will very likely need consent, and possibly input from a structural engineer. Always confirm with your local council before starting any demolition work. Check MBIE Building Performance for guidance on consent requirements and Schedule 1 exemptions.
Check for Underground Services First
This is the step most DIYers skip — and it can be catastrophic. Before any excavator bucket touches the ground, you must locate all underground services in the area, including:
- Water pipes (plastic or copper)
- Stormwater and wastewater drains
- Electrical cables (striking one can be fatal)
- Gas lines
- Telecommunications cables
Contact Dial Before You Dig (0800 248 344 or dialbeforeyoudig.co.nz) to request a service location. Your local council may also have records. If in doubt, hire a cable and pipe locator — these are available from most hire centres alongside the excavator.
⚠️ Safety note: Striking a live electrical cable or gas line with an excavator is a life-threatening emergency. Never assume an area is clear without checking.
Choosing the Right Excavator
For a small concrete block wall, a 1.5–3 tonne mini excavator is usually the right tool. These are widely available from hire companies across New Zealand. Key things to consider:
- Bucket type: A standard digging bucket works for pushing and pulling the wall apart. A hydraulic breaker (rock hammer) attachment is useful if the wall has a concrete footing.
- Access: Mini excavators can be as narrow as 1 metre in transport width — check your gate and site access before hiring.
- Ground conditions: Soft or wet ground can make operating a mini excavator hazardous. Check the site is stable.
Most hire companies will give you a brief induction on operating the machine. If you have never operated an excavator before, consider booking a half-day training session — some hire companies offer this, or you can find short courses through industry training providers.
Is the Wall Reinforced or Retaining?
Concrete block walls are sometimes reinforced with steel rebar and filled with concrete grout, especially if they are retaining walls or boundary walls over 1 metre tall. A reinforced wall:
- Is much harder to demolish and may require a hydraulic breaker attachment
- Will produce heavy, awkward chunks of concrete and tangled rebar — plan your waste removal carefully
- May be structurally significant, meaning you should get engineering advice before touching it
If the wall is retaining soil on one side, removing it without proper planning can cause a slip or soil collapse, which is a serious safety hazard.
Preparing the Site
Before you start demolition:
- Fence off the work area — keep children, pets, and bystanders well clear.
- Arrange waste removal — concrete rubble is heavy. Hire a skip bin or arrange for a concrete recycling drop-off. Many NZ concrete recyclers will accept clean broken concrete.
- Check for asbestos — older NZ properties may have asbestos-containing materials nearby. If you suspect asbestos in any associated render, roofing, or cladding, stop and get a licensed asbestos assessor involved. See WorkSafe NZ for guidance.
- Notify neighbours if the wall is on or near a boundary — good communication avoids disputes.
- Wear appropriate PPE — hard hat, safety glasses, steel-capped boots, and gloves at minimum.
The Demolition Process
Once you are satisfied the site is safe and consents are sorted:
- Start at the top of the wall and work downward — never push the base of a wall first, as it can topple unpredictably.
- Use the bucket curl and crowd action to break blocks apart rather than ramming the wall at speed.
- Work in short, controlled movements — mini excavators are powerful and can shift a lot of material quickly.
- Keep the excavator stable — avoid overreaching or working on a steep side slope.
- Break up large chunks on the ground before loading them into a skip or trailer.
Disposing of Concrete Rubble
Concrete is a controlled waste in many NZ councils — you cannot simply dump it. Options include:
- Skip bin hire (many companies accept clean concrete)
- Concrete recycling facilities — search your local council's waste website
- Reuse on site as fill or drainage aggregate (check with your council first)
When to Call a Professional
Hire a qualified earthmoving contractor or demolition specialist (find one at tradedirectory.co.nz) if:
- The wall is retaining soil or is part of a building's structure
- The wall is over 1.5 metres tall or heavily reinforced
- You are not confident operating an excavator safely
- There are services nearby that cannot be clearly located
- Asbestos is suspected anywhere on the site
- Your council requires a licensed building practitioner (LBP) to oversee the work — check LBP for more information
A professional earthmover will have the right equipment, insurance, and experience to get the job done safely and efficiently.
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