What Is the Safest Order to Demolish a Small Outbuilding Yourself?

Demolishing a small outbuilding — a garden shed, sleepout, or detached garage — is a project many NZ homeowners can tackle themselves, but only if you follow the right sequence and take hazardous materials seriously. Work from the inside out and from the top down, always dealing with services and dangerous materials before you swing a single sledgehammer.

Step 1: Check Whether You Need a Building Consent

Before anything else, confirm whether your demolition requires a building consent. In New Zealand, many small outbuilding removals fall under Schedule 1 exemptions — but this depends on the building's size, construction type, and your local council's rules. Always check with your council directly rather than assuming you're exempt. You can find general guidance at MBIE Building Performance. Getting this wrong can cause problems when you sell your property.

Step 2: Identify and Disconnect All Services

This is the most critical safety step. Before any physical work begins, identify every service connected to the building:

• Electricity: Any electrical wiring must be disconnected by a registered electrician. In New Zealand, connecting or disconnecting fixed wiring is restricted electrical work under the Electricity Act. Do not attempt this yourself — contact a licensed electrician. Check the Electrical Workers Registration Board (EWRB) to verify a tradesperson's registration.
• Gas: If the outbuilding has any gas supply, this must be disconnected by a licensed gasfitter. This is restricted work under the Plumbers, Gasfitters and Drainlayers Act. Find a licensed professional through the Plumbers, Gasfitters and Drainlayers Board (PGDB).
• Water and drainage: Isolate and cap any water supply or drainage connections. Depending on the complexity, this may also require a licensed drainlayer.

Safety note: Never assume a building is de-energised. Treat all wiring as live until a qualified electrician confirms otherwise.

Step 3: Test for Hazardous Materials

Older NZ outbuildings — particularly those built before the 1990s — may contain asbestos in roofing (corrugated cement sheets are a classic example), wall linings, or floor tiles. Lead paint may also be present.

• Have the building inspected and tested by a qualified assessor before demolition.
• If asbestos is confirmed, removal must comply with WorkSafe NZ regulations. Friable asbestos must be removed by a licensed asbestos removalist. Non-friable (bonded) asbestos in small quantities may in some circumstances be handled by a homeowner under strict conditions — but check the current WorkSafe guidelines carefully, as rules can change.
• Dispose of asbestos-containing materials at an approved facility — contact your local council for approved disposal sites.

Step 4: Strip Out the Interior

Once services are disconnected and hazardous materials are dealt with, remove the interior contents and fittings:

• Remove doors, windows, shelving, and any fixed fittings.
• Strip out insulation (wear a P2 dust mask and gloves).
• Set aside materials that can be reused or recycled — timber framing, corrugated iron, and windows often have good second-hand value.

Step 5: Remove the Roof First

Always work top to bottom. Removing the roof first prevents it from collapsing on you unexpectedly as the walls are dismantled.

• Remove roofing iron or tiles carefully, working from the ridge down to the eaves.
• Take off roof purlins and rafters once the cladding is clear.
• Use appropriate fall protection if working at height — even a low roof carries real risk. Refer to WorkSafe NZ guidance on working at heights.

Step 6: Take Down the Walls

With the roof gone, the walls are much safer to dismantle:

• Remove exterior cladding (weatherboards, iron, or fibre cement sheets) panel by panel.
• Dismantle wall framing stud by stud, working around the structure rather than pushing walls over — a falling wall can cause serious injury.
• Never work alone during structural dismantling.

Tip: Brace Before You Remove

If a wall section looks unstable, brace it temporarily with timber props before removing adjacent sections.

Step 7: Remove the Floor and Foundation

Once the structure above is cleared:

• Remove timber flooring or concrete slabs as required.
• Concrete foundations may need a concrete saw or breaker — hire equipment from Bunnings or Mitre 10 if you're comfortable operating it safely.
• Check with your council whether the foundation needs to be fully removed or can be left in place.

Step 8: Sort and Dispose of Debris

Responsible disposal is both a legal and environmental obligation:

Contact your local council for approved disposal facilities and any restrictions on what can go to the transfer station.

When to Call a Professional

Some situations call for a qualified demolition contractor rather than a DIY approach:

• The building is larger or more complex than a simple shed or garage.
• Asbestos or other hazardous materials are confirmed.
• The structure is close to boundaries, fences, or neighbouring buildings.
• You're unsure about the structural stability of the building.
• Electrical, gas, or drainage disconnection is needed.

A licensed demolition contractor will have the right equipment, insurance, and knowledge of NZ regulations to get the job done safely. You can find qualified local demolition contractors on tradedirectory.co.nz.

Sources & Further Reading

• MBIE Building Performance — Building Consent Information
• WorkSafe NZ — Asbestos and Working at Heights
• EWRB — Electrical Workers Registration
• PGDB — Licensed Gasfitters and Drainlayers
• BRANZ — Building Research