- What roof painting actually involves
- When painting is worth doing
- When it is money down the drain
- Before anyone water blasts: check for asbestos
- Comparing the cost honestly
- What Dunedin does to a painted roof
- Frequently asked questions
Painting buys years on a roof that is structurally sound and looking tired. It does nothing for a roof that has rusted through, and a fresh coat over corroded steel hides the problem rather than fixing it. The test is simple: if the metal is sound and the coating has faded, paint is a good buy. If the metal has gone, paint is money you will spend twice.
What Roof Painting Actually Involves
A proper roof repaint is mostly preparation. The roof is cleaned and treated for moss and lichen, loose coating is removed, rusted spots are wire brushed back and primed, cracked sealant and failed flashings are repaired, and then the roof gets a primer and two topcoats of a roof-grade paint system. The painting itself is the quick part.
Skip the preparation and the result is obvious within a couple of years: paint lifting where moss was never treated, and rust bleeding through where bare metal was coated without a primer. When you compare quotes, compare the preparation, not the paint brand.
At Roof Craft Dunedin we do the roofing side, the repairs, flashings and fixings, and arrange the painting through a painter we work with. The roofing work carries our workmanship guarantee, and the paint system carries the painter’s.
When Painting Is Worth Doing
Painting is a maintenance job, not a repair. It suits a roof where the steel is still doing its job and the coating has given up first.
| What you can see | Usually means |
|---|---|
| Colour faded or chalky, surface dull | Paint. The coating has weathered, the steel is fine |
| Moss and lichen, no rust underneath | Treat, clean, then paint |
| Surface rust in patches, no holes | Repair those areas, then paint |
| A few leaking fixings or a worn flashing | Repair, then decide on paint |
| Rust along the laps and sheet ends | Replacement territory, paint will not stop it |
| Light visible through the roof from inside | Replace |
| Concrete tiles, porous and crumbling at the edges | Replace. A coating will not restore a tile that has gone porous or is crumbling |
A good rule from the inside: go into the roof space on a bright day with the light off. Pinholes of daylight along the laps or around fixings mean the steel has perforated, and no coating fixes that.
When It Is Money Down the Drain
Three situations where painting is the wrong call, no matter how good the quote looks.
- The steel has perforated. Rust that has eaten through at the laps, the sheet ends or around nail holes is structural, not cosmetic. Paint bridges the hole for a season and then splits.
- The roof is already near the end of its life. Spending on a repaint for a roof with a few years left is money that would have gone into the replacement, and you pay for access twice. Scaffolding on a Dunedin hill site is not cheap, and it costs the same whether the crew is painting or reroofing.
- The substrate is the problem. Old concrete tiles that have gone porous, or a roof where the battens and underlay have failed, will not be helped by a coating. Those jobs need the roof off.
Before Anyone Water Blasts: Check for Asbestos
This one matters in Dunedin, because of the housing stock. Decramastic tiles, the pressed metal tiles with the stone chip finish that went on thousands of New Zealand homes from the 1960s to the 1980s, can contain asbestos in the coating. So can older corrugated cement sheet roofing.
High-pressure water blasting of asbestos-containing material is prohibited under the Health and Safety at Work (Asbestos) Regulations 2016. WorkSafe defines high pressure as above 350 kPa, or 50 psi, and the penalties run to a $9,000 infringement fee or up to $30,000 on conviction, plus the cost of a licensed clean-up if the site gets contaminated. In August 2026 WorkSafe issued a safety alert after exactly this happened at a 1970s house with decramastic tiles: the tiles were later confirmed to contain chrysotile asbestos and the property needed remediation.
If your roof is decramastic, cement sheet, or simply pre-2000 and you are not sure what it is, get it identified before anyone turns a water blaster on it. A soft wash or chemical clean is the alternative. Do not sweep debris into piles, use a leaf blower, or otherwise disturb suspect material, because that releases fibres.
Source: WorkSafe New Zealand, Check for asbestos before undertaking high-pressure spraying on roofs (August 2026), and its earlier alert on high-pressure water blasting of asbestos roofing and cladding.
Comparing the Cost Honestly
Painting costs a fraction of a reroof, which is exactly why it is tempting. The fair comparison is not the two prices side by side, it is the price divided by the years you get.
A repaint on a sound roof usually buys somewhere around 8 to 12 years before a recoat, depending on the coating system, how well the roof was prepared, how exposed it is and whether it gets maintained. A new long-run steel roof is a multi-decade decision that also replaces the underlay, the flashings and the fixings, and comes with a material warranty on the steel. If a roof has fifteen years left in it, painting is good value. If it has five, you are paying twice for scaffolding and buying time you will not get.
Get both quotes. Any roofer worth using will tell you when a repaint is the better buy, and our reroofing page sets out what a full replacement covers so you can compare like with like.
What Dunedin Does to a Painted Roof
Three local factors shorten the life of a coating here more than in most of the country.
- Moss and lichen. Cool, damp and shaded south-facing slopes grow it fast, and it holds moisture against the surface. A painted roof that is never treated will lose its coating from the shaded side first.
- Salt air. Coastal suburbs from St Clair round to the Peninsula carry a salt load that attacks any break in the coating. Paint slows that down, it does not stop it.
- Access. Steep hill sections need scaffolding or rope access, which is a real share of the cost. It is worth doing everything the roof needs in one visit.
Moss is the one you can do something about between jobs. Our guide to removing roof moss covers treating it without damaging the coating.
Frequently Asked Questions
Is it cheaper to paint a roof or replace it?
Painting costs much less up front. Whether it is cheaper depends on how much life the roof has left. On a sound roof, a repaint buys about a decade for a fraction of the price of a replacement. On a roof that is rusting through, painting delays a replacement you will still have to pay for, and you pay for access twice.
How long does roof paint last in Dunedin?
Often around 8 to 12 years before a recoat, depending on the coating system and the preparation underneath it. Expect the shorter end on shaded south-facing slopes where moss takes hold, and close to the coast. Treating moss and clearing gutters makes a measurable difference.
Can you paint a rusty roof?
Surface rust in patches can be wire brushed back, primed and painted as part of a repaint. Rust that has perforated the steel cannot. If you can see daylight through the roof from inside, the roof needs replacing, not coating.
Can you paint decramastic tiles?
They can be coated, but they must be identified first, because decramastic tiles from the 1960s to the 1980s can contain asbestos. High-pressure water blasting of asbestos-containing material is prohibited in New Zealand. Get the roof tested and use a soft wash or chemical clean.
Does painting a roof affect the warranty?
Painting does not extend the steel’s material warranty, and on a newer roof, coating it can affect that warranty, so check before you start. The paint system carries its own warranty from the painter or the paint manufacturer.
Should I paint a roof before selling the house?
A clean, freshly painted roof presents well and can be worth doing if the roof is sound. If it is not, a buyer’s builder’s report will find the rust anyway, and a fresh coat over a failing roof reads as something being covered up.
Not sure which side of the line your roof falls on? Send us a few photos, or we will come and look at it, and you will get a straight answer on whether it is worth painting or worth replacing.
