Apply the answer
Work through the condition before choosing the scope.
Use the symptoms, spread and repeat history first. RoofHub can help separate a plausible local repair from restoration, replacement or a case that needs inspection.
First separate surface wear from material failure
| What you can establish safely | More plausible pathway | Why |
|---|---|---|
| Coating looks tired or there is minor surface corrosion without holes | Assessment, preparation and restoration may be possible. | A coating system needs a suitable substrate and defects repaired first. Sources: Roofing Association of New Zealand; NZ Metal Roofing Manufacturers. |
| One or a few sheets/fixings/flashings are locally deteriorated | Targeted repair or component replacement may be possible. | The whole roof does not automatically fail because one component does, provided compatible local work leaves a serviceable system. Sources: Roofing Association of New Zealand. |
| Perforation, severe corrosion or leaks appear across multiple areas | Whole-roof assessment and reroof comparison become more important. | Repeated local work can leave widespread failure unresolved. Sources: Roofing Association of New Zealand; Roofing Association of New Zealand. |
Why did the corrosion start?
Exposure, areas that do not receive normal rain washing, debris, incompatible details, cut edges, fixings, ponding/poor drainage and coating breakdown can all change corrosion risk. The remedy should address the cause as well as the visible rust. Sources: COLORSTEEL; NZ Metal Roofing Manufacturers.
Questions that make the repair-vs-reroof decision clearer
- Is corrosion confined to one detail/sheet or repeated across multiple roof faces?
- Is there only coating/surface deterioration, or are there pinholes/perforations/missing metal?
- Are leaks present in one area or several unrelated areas?
- Have similar repairs already been repeated?
- Are flashings, fixings and valleys in comparable condition to the main sheets?
- What does the product/environment maintenance guidance require for this location?
If you are getting prices
Ask the contractor to separate local repairs, surface preparation/coating, sheet or flashing replacement and full reroof scope. A low repaint price and a higher reroof price are not directly comparable unless the coating proposal establishes that the substrate is actually suitable. Sources: Roofing Association of New Zealand; Roofing Association of New Zealand.
What RoofHub would ask next
The most useful next facts are roof system, whether corrosion is local or widespread, whether the metal is actually perforated, whether leaks recur in different areas, and whether there are safety/asbestos concerns. Those facts are more decision-relevant than roof age alone. Sources: Roofing Association of New Zealand.
Sources and review notes
Prepared by RoofHub editorial team. Reviewed . A source check confirms what a page states, not an independent inspection or invoice audit. Published project accounts are attributed to their publishers.
- primaryRoofing Association of New Zealand: Maintenance Tips - RANZ homeowner maintenance guidance covering drainage, signs of deterioration and working-at-height safety. Used as practical industry context alongside product-specific manufacturer requirements. Page checked 2026-10-21. Publication date not stated. · industry-technical
- primaryNZ Metal Roofing Manufacturers: Code of Practice v26.09: Overpainting - Current NZMRM generic preparation and overpainting guidance for metal cladding. It stresses correct preparation, compatible primers/coatings and following the coating supplier instructions. Page checked 2026-10-21. Publication date not stated. · industry-technical
- primaryRoofing Association of New Zealand: New Zealand Roof Coating Code of Practice - RANZ roof-coating trade guidance. It states that roof coating is not weatherproofing, requires an initial roof-condition assessment, and only extends the life of a suitable existing roof for a limited time. Page checked 2026-10-21. Publication date not stated. · industry-technical
- primaryRoofing Association of New Zealand: RANZ Re-Roofing Guide - RANZ describes this as an annually updated NZ consumer guide to reroofing materials, systems, terminology, scope and workmanship. Used for project-planning context rather than contractor ranking. Page checked 2026-10-21. Publication date not stated. · industry-technical
- marketHomeSmart Roofing: Corrugated iron and long-run roof repairs and painting - Practitioner guide describing individual panel replacement, fixing checks, rust treatment, ridge/flashing/valley repair and restoration before considering complete replacement. Commercial service source. Commercial interest: sells roofing services. Page checked 2026-10-21. Publication date not stated. · practitioner observation
- marketRoof Protect: Iron and corrugated roof repairs and repainting - Wellington practitioner guidance stating localised minor rust, loose fixings and worn coating may be repair/recoat candidates where the structure remains reasonable. Commercial restoration/repair source. Commercial interest: sells roofing services. Page checked 2026-10-21. Publication date not stated. · practitioner observation
- marketPaul Makuch Roofing: Re-roof vs roof restoration - Waikato roofing contractor comparison of restoration and reroofing. Useful for practitioner decision signals such as localised repairability versus widespread rust/failing sheets. Commercial service source; RoofHub does not treat its recommendation as independent technical proof. Commercial interest: sells roofing services. Page checked 2026-10-21. Publication date not stated. · practitioner observation
- marketRoof Repair Specialists: Reroofing services and recent reroof projects - Auckland contractor page with recent reroof examples and its stated repair/restoration/replacement distinctions. Commercial source; useful for field patterns and opening-up scope, not for universal lifespan claims. Commercial interest: sells roofing services. Page checked 2026-10-21. Publication date not stated. · practitioner observation
- primaryCOLORSTEEL: Warranty & maintenance - Current manufacturer guidance linking product suitability, warranty terms and maintenance to environmental exposure. Coastal distance is a guide only; local conditions, design and position can change the applicable category. Page checked 2026-10-21. Publication date not stated. · manufacturer
- primaryWorkSafe New Zealand: Check for asbestos before high-pressure spraying on roofs (2026-08-20) - WorkSafe safety alert published 20 August 2026 after incidents involving high-pressure roof spraying, including a 1970s Decramastic roof that tested positive for chrysotile asbestos. High-pressure water and compressed air must not be used on asbestos-containing material. Page checked 2026-10-21. Publication date shown above. · government
- primaryWorkSafe New Zealand: Roof restoration and maintenance - WorkSafe guidance for roof restoration and maintenance tasks. It applies the working-at-height control hierarchy and identifies brittle roofing, inspections, cleaning, repairs and coating work as roof-access hazards requiring suitable controls. Page checked 2026-10-21. Publication date not stated. · government
- primaryRoofing Association of New Zealand: Comparing Quotes - RANZ guidance reviewed 20 October 2026. Explains that roofing quotes may differ because of scope, materials, systems and how work will be carried out, so a price difference alone is not a quality conclusion. Page checked 2026-10-20. Publication date not stated. · industry-technical
Original calculations are labelled as examples. Historical prices stay dated, missing fields stay unknown, and conflicting specifications are flagged. Sources are not endorsements or paid rankings. Read our methodology or report a correction.
Keep exploring
Next step
Estimate it, refine it, or ask RoofHub.
Start with approximate information, use actual measurements when you have them, or ask RoofHub to explain the decision. A roofing contractor still needs to confirm the site, specification and final quotation.