Got a roof that's seen better days? Either path costs real money, but the gap between painting and a full replacement runs $15,000 to $30,000. Knowing when paint will stretch your roof's life, and when the metal is too far gone to save, keeps you from spending more than you need to. Here's how to work it out.
The Core Question: Structural Integrity
| Roof Condition | Recommended Action | Why |
|---|---|---|
| Cosmetic wear only | Painting | Cheaper, adds 12-15 years |
| Surface rust, no structural damage | Painting | Rust treatment + coating stops it spreading |
| Leaks from worn coating | Painting (with repairs) | New coating restores waterproofing |
| Rusted-through panels | Partial replacement then paint | Isolated damage doesn't require full reroof |
| Widespread structural rust | Full replacement | Paint won't fix a safety problem |
| Failed substrate (rotted sarking) | Full replacement | Must fix the structure underneath |
| Roof 40+ years old | Replacement | End of design life regardless of appearance |
The simple rule: If the roof structure is sound, painting is nearly always better value. If the structure is compromised, replacement is the only safe call.
Cost Comparison: Real Wellington Numbers
Typical metal roof (180m² home):
| Option | Cost Range | Lifespan | Cost Per Year |
|---|---|---|---|
| Professional painting | $7,000-$10,000 | 12-15 years | $583-$833/year |
| Full replacement (long-run steel) | $25,000-$35,000 | 30-40 years | $625-$1,167/year |
| Full replacement (metal tiles) | $30,000-$45,000 | 30-40 years | $750-$1,500/year |
The thing to notice: Painting costs 30-40% of a replacement but gives you 40-50% of the lifespan. When the structure is sound, the maths leans toward paint.
When Roof Painting Is the Right Choice
1. Cosmetic Deterioration Paint fading or chalking, minor surface rust, a colour you've gone off, roof otherwise sound.
2. Early-Stage Rust Surface rust that hasn't eaten through the metal. Wire brush it and treat it before it spreads.
3. Age Under 30 Years Roofing made after 1990 has a structural life of 40-50 years. Painting at 15-20 years adds a good chunk to that.
4. Recent Roof in Poor Paint Builder-grade paint often fails before the roof does. A proper repaint outlasts the original coating.
5. Minor Leak Repairs Needed Small flashing issues or loose screws can be sorted during prep. No point replacing a whole roof for a couple of local problems.
Wellington note: Our southerly winds work fixings loose over time. We check every fastener during a roof paint, which often stops a minor leak without any replacement at all.
When Roof Replacement Is Necessary
1. Structural Rust Once rust has eaten right through the metal, the panels have lost their strength. Quick test: push firmly on a rusty area. If the metal flexes or crunches, it's structural.
2. Widespread Panel Failure When more than 30-40% shows severe rust or damage, replacement works out cheaper than heavy repairs plus painting.
3. Substrate Failure Rotted timber sarking, failed insulation, or a sagging structure all mean the roof has to come off for the repair.
4. Asbestos Roofing Pre-1990 fibre cement or "Super Six" roofing can't be painted safely. It needs replacing with modern materials.
5. End of Design Life Corrugated iron past 40 years, even if it still looks intact, is near the end of its safe life. Wellington's weather speeds that up.
6. Insurance Requirements Some insurers won't cover roofs over a certain age, or require replacement to keep covering you. Check your policy before you paint.
7. Severe Wind Damage Wellington's winds can lift and tear large sections of roof. Once the damage is spread out, replacement is usually the more practical route.
The "In-Between" Scenario: Partial Replacement
Often the smartest option. Replace the badly damaged sections (valleys, lower edges, north faces), then paint the whole roof so it matches. Total cost runs 60-70% of a full replacement, with a lifespan of 15-20 years.
Common Wellington cases: Valley iron rusted through where water flow is heaviest, a northern roof plane that's failed under full sun, lower sections worn by splash-back off the ground.
How Wellington's Climate Affects Your Decision
Wellington weather is its own thing. Average wind speeds of 27 km/h make it the windiest city of its size in the world, and over 2,000 sunshine hours a year combined with 1,250mm of rain put roofs here through more than most of the country. They wear out faster as a result.
- North-facing slopes cop the most UV and usually need attention 2-3 years before the south-facing ones
- Coastal suburbs (Seatoun, Island Bay, Lyall Bay, Miramar) get salt in the air that speeds up rust, so budget for more frequent maintenance
- Wind-exposed ridgelines (Karori, Wadestown, Brooklyn) see fastenings loosen within 5-7 years, opening up small leak points before the paint itself fails
- Valley iron on any Wellington roof takes concentrated water flow, so that's where rust shows up first no matter the roof's age
When you collect quotes, ask each contractor exactly how they prep for Wellington conditions. A painter who treats a Wellington roof the same as one in Christchurch hasn't worked out our weather.
What to Expect During a Professional Roof Paint
Day 1-2: Preparation High-pressure water blast (2,500-3,500 PSI) strips off moss, lichen, and loose paint. Then a 48-hour drying period, which the adhesion depends on. Every fastener gets checked and tightened or replaced. Rust spots are wire brushed and treated with a rust converter. Flashings re-sealed, minor repairs done.
Day 3: Priming Rust-inhibiting primer on bare metal, such as Resene Quick Dry primer. Full prime coat over any heavily stripped areas. Allow 6-12 hours to cure before the topcoat.
Day 4-5: Topcoats First topcoat goes on by spray or brush. Full dry before the second coat (4 hours minimum, 24 is better). Second topcoat finishes the system, using a roof coating like Resene Sonyx 101. Ridge capping, flashings, and valleys are hand-finished with a brush.
Total job runs 5-7 working days for an average Wellington home. Weather delays are normal. Good painters schedule around weather windows rather than fixed deadlines.
Decision-Making Process
| Roof Age | Typical Recommendation |
|---|---|
| 0-15 years | Paint only if cosmetic issues |
| 15-25 years | Paint if structurally sound |
| 25-35 years | Detailed inspection, could go either way |
| 35-45 years | Lean toward replacement unless excellent condition |
| 45+ years | Replace, near the end of safe life |
Future Plans: Selling within 5 years? Painting lifts the look for less money. Staying put long term? Replacement may pay off better. Planning renovations? Line up the roof work with the rest.
Hidden Costs to Consider
Painting hidden costs: Gutter replacement, spouting painted to match, flashing repairs or replacement, broken tile replacement on tile roofs, ventilation improvements.
Replacement hidden costs: Consenting fees ($1,500-$3,000 in Wellington), asbestos removal if present ($3,000-$8,000), scaffold hire on steeper Wellington roofs, spouting and gutter replacement often needed, temporary weatherproofing during a multi-day install, possible ceiling repairs where leaks got in.
Lifespan Expectations
Painted roof (Wellington conditions): Metal roofs 12-15 years near the coast, 15-18 inland. Concrete tiles 15-20 years. That assumes proper prep, a quality paint system, and regular upkeep.
New roof: ColorSteel/long-run 30-40 years. Metal tiles 30-40 years. Concrete tiles 50+ years. Butynol membrane 25-35 years.
Wellington factor: Knock 10-15% off the national averages for our harsh coastal conditions.
Frequently Asked Questions
Will roof painting fix my leaks?
Sometimes. If the leaks come from worn coating or failed sealant around flashings, a proper repaint with good prep and re-sealing will fix them. If they come from structural rust holes, failed flashings, or substrate rot, those need repairing first. Paint on its own won't solve it.
How do I know if my roof has asbestos?
Corrugated "Super Six" profiles and flat fibre cement sheets on homes built before 1990 are high-risk. Get samples tested by a professional ($50-$100) before any work starts. Disturbing asbestos roofing without proper containment and removal is illegal and a serious health hazard.
What warranty should I expect?
Reputable painters offer 5-10 year workmanship warranties. We back our work with a 5-Year Workmanship Guarantee. Paint manufacturers offer separate product warranties of 10-15 years. Get both in writing, including what voids each one.
Does roof colour affect my home's temperature?
Yes, quite a bit. Dark colours can run 15-20°C hotter at the surface than light ones. If your ceiling has little insulation, a lighter roof colour is worth thinking about when you repaint.
Real Wellington Case Studies
Case 1: 1970s Corrugated Iron, Khandallah
Age 45 years, rust right across it. Recommendation: full replacement. Reason: past safe structural life, so paint would fail within 3-5 years. Cost: $28,000 (long-run ColorSteel).
Case 2: 2005 Long-run, Miramar
Age 18 years, faded paint, minor rust. Recommendation: professional painting. Structure in great shape, 20+ years of life left. Cost: $7,500 (Resene Hi-Glo). Extra life expected: 15 years.
Case 3: 1985 Concrete Tiles, Johnsonville
Age 38 years, tiles intact, coating failed. Recommendation: painting with a membrane system. Tiles have 20+ years left. Cost: $11,500. Replacement would have been $42,000.
Red Flags in Quotes
Painting quotes, watch out for: No mention of rust treatment, single-coat systems, "budget" or unnamed paint brands, no detail on surface prep, an offer to start straight away with no weather planning.
Replacement quotes, watch out for: Pressure to replace when painting would do, no substrate inspection mentioned, suspiciously low pricing, no mention of consents where they're needed, payment in full upfront.
Ready to Get Started?
Painting or replacement, the first step is an honest assessment. If paint will stretch your roof's life for less money, we'll say so. If replacement is the safe, sensible long-term call, we'll explain why.
Contact Wellington Decorators for a free roof inspection and a written quote, or read more about our residential roof painting services. We've helped hundreds of Wellington homeowners make this call. We'll help you pick the right path for your home and your budget.
Wellington Decorators Limited, Registered Master Painters | Resene Eco Decorator
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