Most homeowners only think about their roof when something goes wrong. By that point the conversation moves quickly from "there's a problem" to "how much will this cost," without much understanding of what's actually up there or what the options are. Five minutes spent looking properly at your own roof, from the ground, before you make a single phone call, is some of the most valuable preparation you can do.
This guide walks you through what to look at and what each thing means. You don't need to climb anywhere. Most of what matters can be seen from the ground with a good pair of eyes and, if you have one, a phone camera with a zoom function for the parts higher up.
Step one: identify what your roof is made of
There are roughly nine common roofing materials on New Zealand homes. The four most common account for the majority of residential properties.
Corrugated steel (long-run iron)
Wave-form metal sheets fixed to the roof with exposed screws. The traditional shape is rounded and undulating. This is the most common metal profile on older residential homes in New Zealand. If your house was built between the 1960s and 2000s and has a metal roof, there's a strong chance it's corrugated.
Trapezoidal steel
Ribbed metal sheet with a sharp angular profile rather than the rounded wave of corrugated. More commonly found on modern or architectural homes. The two can look similar at a distance but the cross-section is the giveaway. Trapezoidal performs better at low roof pitches and is the more modern choice.
Decramastic
Stone-chip coated metal tile. Looks textured and granular up close rather than smooth. Produced in New Zealand from the 1960s onwards. If your home was built or re-roofed between approximately 1965 and the late 1970s and has a tiled-looking metal roof, it may be decramastic. This matters because decramastic tiles produced between the late 1960s and mid-1970s often contain asbestos in the surface coating. You cannot tell visually. Testing is the only way to confirm.
Concrete tile
Heavy moulded concrete tiles, usually with a flat ridge profile. Common on homes built between the 1950s and 1980s. Concrete tiles are heavy and as they age they become porous and brittle. By the time a concrete tile roof needs attention, it usually needs full replacement rather than spot repair.
Less common materials worth knowing about
Terracotta tile (fired clay, distinguishable from concrete by its raised curved ridge profile and orange-red colour). Super 6 (corrugated cement sheeting, white to grey in colour with a distinctive golf-ball dimpled surface, almost always contains asbestos). Onduline (corrugated bitumen-fibre sheeting from the 1990s and early 2000s, visibly thicker than corrugated iron with a fibrous texture, often showing fading or sagging by now). Aluminium tile. Cedar shingle.
Step two: assess the condition
Once you know what you're looking at, the next question is what state it's in. Here's what to look for, working roughly from "cosmetic" through to "structural concern."
Surface condition
On metal roofs, look for visible rust. Surface rust on the paint is one thing. Rust that has eaten through the coating into the substrate is another. Pay particular attention to flashings and the lower edges of sheets where water sits longest. On tiled roofs, look for chipped, cracked, or missing tiles. Concrete tiles in particular develop visible surface degradation as they age.
Sheet and tile alignment
Roofing sheets should sit straight and parallel. Tiles should sit in even courses. Any visible sagging, bowing, or wave pattern across the roof surface suggests structural movement underneath, which is a more serious finding than surface wear. A roof can have rusty sheets and still be structurally sound. A roof that's sagging has problems beneath the surface.
Ridge and flashings
The ridge runs along the top of the roof where two sloping sides meet. The flashings are the metal strips that seal junctions: around chimneys, against walls, over the ridge, along the edges. These are the most common leak points on any roof. Look for lifted, bent, or visibly damaged flashings. A well-installed roof can have the sheets in good condition and still be leaking through worn flashings.
Gutters and downpipes
Look for sagging gutters, visible joints where water might escape, downpipes that have come loose, or staining on the walls below the gutter line. Gutter condition often matches roof condition because both reach end of life at roughly the same time. Replacing them together while scaffolding is on site is usually cheaper than two separate jobs.
Step three: take stock of the penetrations
Anything that goes through the roof surface is a penetration: chimneys, plumbing vents, skylights, sky dishes, TV aerials, hot water cylinder overflows. Each one is a potential leak point and each one needs to be considered when a quote is being prepared.
Walk around the property and note what you can see. Count the penetrations. Take photos. A consultant turning up to a property already knowing there are three plumbing vents, a chimney and a sky dish will produce a more accurate quote than one who has to discover those things on site.
Step four: the age question
If you know when the roof was installed, that's the single most useful piece of information. Most metal roofs in New Zealand are warranted for 15 to 30 years depending on the product and environment. Most concrete tile roofs reach end of life around 40 to 50 years. Decramastic tiles often need replacement after 30 to 40 years. If you don't know the age, the previous owner or a building inspection report from the property's sale might tell you.
Age alone doesn't determine whether a roof needs replacing. A 20-year-old well-maintained steel roof in a sheltered location can be in better condition than a 10-year-old roof in a coastal environment. But age sets the question. Older roofs are more likely to be candidates for replacement or restoration; younger roofs more likely to need repair only.
What to do with all this
Five minutes of looking gives you four things: a rough material identification, a sense of condition, an awareness of the penetrations and a frame of reference for what comes next. When you do call a roofing company, you'll be able to describe what you have rather than asking them to tell you. You'll be able to ask better questions about scope. And you'll be able to spot a quote that doesn't match the reality of your roof.
If anything in the survey raised concern, particularly suspected asbestos in decramastic or Super 6, or visible structural movement, that's the right moment to get a professional opinion rather than guess.
Roofbuddy offers free condition reports and quotes from vetted roofers on the same specification, so you can compare like with like. Get started at roofbuddy.co.nz.