How to Safely Demolish a Corrugated Iron Garage Yourself

Demolishing a corrugated iron garage yourself is achievable for a capable DIYer, but it requires careful planning before you swing a single hammer. The key steps are checking whether you need a building consent, identifying any hazardous materials (particularly asbestos), working safely, and disposing of waste responsibly.

Do You Need a Building Consent?

In New Zealand, demolishing a detached garage may be exempt from building consent under Schedule 1 of the Building Act 2004, but this is not automatic. The exemption generally applies to small, single-storey detached buildings, but conditions apply — for example, if the garage is connected to the house or has plumbing or electrical services, the rules change.

Always confirm with your local council before starting work. You can also read the guidance on exemptions at MBIE Building Performance. Getting this wrong can cause problems when you sell your property.

Step 1 — Check for Asbestos First (Critical)

This is the most important step. Corrugated iron garages built or clad before 1990 may contain asbestos-cement (fibro) sheeting in the roof, walls, eaves, or soffit linings. Asbestos fibres are a serious health hazard.

• If your garage was built before 1990, assume asbestos may be present until proven otherwise.
• Do not drill, cut, sand, or break any sheeting until it has been tested.
• Engage a licensed asbestos assessor to sample and test suspect materials.
• If asbestos is confirmed, removal must follow strict rules under the Health and Safety at Work (Asbestos) Regulations 2016. Friable asbestos must be removed by a licensed removalist. Non-friable asbestos in small quantities may be handled by a trained homeowner in some circumstances, but check with WorkSafe NZ for the current rules before proceeding.

Step 2 — Disconnect Services

Before demolition begins, all services must be safely isolated:

• Electricity: Disconnecting a garage from the mains is restricted electrical work and must be carried out by a registered electrician. Do not attempt this yourself. Check the Electrical Workers Registration Board to find a licensed electrician.
• Plumbing/drainage: If the garage has a sink, toilet, or floor drain, disconnection is restricted work under the Plumbers, Gasfitters and Drainlayers Act and must be done by a licensed tradesperson. See the Plumbers Gasfitters & Drainlayers Board.
• Gas: Any gas disconnection must be done by a licensed gasfitter — no exceptions.

Once services are confirmed isolated and signed off, you can proceed.

Step 3 — Gather the Right Tools and PPE

Working safely with corrugated iron is important — the edges are razor-sharp and the sheets can be heavy and unwieldy.

Tools you'll need:

• Claw hammer, pry bar, and flat bar
• Cordless drill/driver with appropriate bits
• Tin snips or angle grinder (with metal cutting disc) for trimming
• Reciprocating saw for timber framing
• Wheelbarrow and skip bin

Personal protective equipment (PPE):

• Heavy leather gloves — corrugated iron edges will cut through lighter gloves
• Safety glasses or goggles
• Steel-capped boots
• Long sleeves and trousers
• Dust mask (P2 minimum) if any dusty materials are present
• Hard hat if working near falling materials

Step 4 — Demolish in the Right Order

Work top-down — always remove the roof before the walls, and walls before the floor slab.

Roof

1. Remove any ridge capping first.
2. Unscrew or pull out roofing screws/nails holding the corrugated iron to the purlins.
3. Slide sheets down carefully — have a helper on the ground to receive them. Never drop sheets from height.
4. Stack sheets flat in a safe area away from foot traffic.

Walls

1. Remove wall cladding sheets in the same way — unscrew from the bottom rail up.
2. Once cladding is off, dismantle the timber or steel framing using a pry bar and reciprocating saw.
3. Work methodically so the structure doesn't become unstable.

Concrete Slab

Leaving the slab in place is often the easiest option if you're building a new structure. Breaking it up requires a concrete breaker/jackhammer (hire from Bunnings or Mitre 10) and generates significant rubble. Factor in disposal costs.

Step 5 — Waste Disposal

• Corrugated iron is recyclable — contact your local scrap metal dealer. Some will collect for free or even pay you.
• Timber can go to a transfer station or be reused if in good condition.
• Concrete rubble must go to a licensed facility — check with your local council.
• Asbestos waste must be double-bagged, labelled, and taken to an approved disposal site. Never put it in general waste.

Hire a skip bin for general demolition waste — suppliers are widely available across NZ.

When to Call a Professional

Call a qualified demolition contractor if:

• Asbestos is confirmed in the structure
• The garage is attached to or structurally connected to your home
• There are complex service disconnections required
• The structure is large, multi-storey, or in poor condition
• You're unsure about any part of the process

A licensed demolition contractor will manage consents, hazardous materials, and disposal safely and efficiently. You can find experienced local demolition contractors on tradedirectory.co.nz.

Sources & Further Reading

• MBIE Building Performance — Building consents and exemptions
• WorkSafe NZ — Asbestos guidance for homeowners
• Electrical Workers Registration Board — Find a licensed electrician
• Plumbers Gasfitters & Drainlayers Board
• BRANZ — Building research and technical guidance
• Bunnings — Tool hire and PPE