Removing old galvanised steel roofing is a job many Kiwi homeowners tackle themselves, but it carries real risks — sharp edges, heights, and potentially hazardous materials. With the right preparation, personal protective equipment (PPE), and a methodical approach, you can do this safely and legally. Here's what you need to know before you start.
Check for Asbestos and Hazardous Materials First
Before touching a single screw, consider the age of your roof. If your home was built or re-roofed before the mid-1990s, there is a chance that asbestos-containing materials (ACM) may be present — not in the steel itself, but in associated materials such as ridge capping fillers, flashing compounds, or roof underlay. Some older corrugated roofing that looks like steel may actually be fibrous cement (Super Six), which can contain asbestos.
If you are unsure, arrange for a sample to be tested by a qualified asbestos assessor before proceeding. WorkSafe NZ has clear guidance on identifying and managing asbestos. Disturbing asbestos without proper controls is illegal and extremely dangerous.
Do You Need a Building Consent?
In most cases, removing and replacing roofing on an existing dwelling falls under Schedule 1 of the Building Act 2004 as exempt work — but this depends on the scope of the project and your local council's interpretation. Structural changes, changes to the roof form, or work on certain types of buildings may require consent. Always confirm with your local council before starting. You can find general guidance at MBIE Building Performance.
Gather the Right PPE and Tools
Working on a roof is classified as working at height, and falls are one of the leading causes of serious injury on NZ worksites. Even on a domestic roof, treat this seriously.
Essential PPE
- Safety harness and lanyard anchored to a certified roof anchor point
- Non-slip footwear (rubber-soled boots)
- Heavy-duty leather gloves — galvanised steel edges are razor-sharp
- Safety glasses or goggles — especially when cutting
- Dust mask (P2 rated minimum) — old galvanised coatings can release zinc dust and fumes when cut
- Long-sleeved clothing to protect against cuts
Tools You'll Need
- Cordless drill or impact driver with the correct bit (usually hex or Phillips) to remove roofing screws
- Claw hammer or flat bar for lifting nailed sheets
- Tin snips or aviation snips for trimming sheets to manageable sizes
- Angle grinder with a cutting disc (use sparingly — generates heat and sparks near zinc coating)
- Roof ladder or crawl boards to spread your weight
- Skip bin or trailer for disposal
Step-by-Step Removal Process
- Set up safe access. Use scaffolding or a properly secured ladder. Fit roof anchors if working on a pitched roof. Never work alone at height.
- Start at the ridge. Remove ridge capping first, working carefully to expose the top edges of the sheets.
- Remove fixings methodically. Back out screws or pull nails from each sheet, starting at the top and working down. Keep count of fixings so none are left loose.
- Lift sheets carefully. Galvanised sheets are long and unwieldy. Have a helper on the ground or on a lower section of roof. Carry sheets flat — never let them flex sharply, as this creates jagged edges.
- Cut sheets if needed. Use tin snips for small cuts. For longer cuts, aviation snips or a circular saw with a metal-cutting blade work well. Avoid angle grinders where possible — they heat the zinc coating and can release fumes. Always cut away from your body.
- Lower sheets to the ground safely. Never throw sheets off the roof. Use a rope and pulley system or pass them hand-to-hand.
- Inspect the roof structure once sheets are removed. Check purlins, rafters, and sarking for rot or damage before re-roofing.
Disposing of Old Galvanised Steel
Galvanised steel is recyclable and many scrap metal dealers in NZ will accept it, sometimes at no cost or even for a small payment. Alternatively, hire a skip bin and confirm with your waste contractor that steel roofing is accepted. Do not burn old roofing — zinc fumes are toxic.
Working Near Electrical Lines
If your roof is close to overhead power lines, contact your lines company before starting work. Long steel sheets can easily make contact with live lines. This is a serious electrocution risk. WorkSafe NZ requires safe distances to be maintained from live conductors at all times.
When to Call a Professional
Some situations mean you should step back and engage a qualified tradesperson:
- Confirmed or suspected asbestos — removal must be done by a licensed asbestos removalist where required by WorkSafe regulations — confirm the applicable thresholds with WorkSafe NZ before proceeding
- Steep or high roofs — anything above single-storey or with a pitch over 25° significantly increases fall risk
- Structural concerns — if rafters or purlins look damaged, a Licensed Building Practitioner (LBP) should assess the structure before work continues
- Large-scale commercial or multi-unit projects — these typically require a licensed demolition contractor
- Proximity to live electrical infrastructure — always get your lines company involved
For peace of mind, you can find experienced local demolition contractors and roofers on tradedirectory.co.nz.
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