Long-run trapezoidal vs corrugated iron

Corrugated iron — the classic Kiwi roof

Corrugate is the rounded, wavy steel sheet that's been covering New Zealand homes, villas and farm buildings for well over a century. These days it's almost always a modern coated steel like Colorsteel rather than old-school galvanised, so you get all the durability with a baked-on colour finish.

Its biggest strength is the look. Nothing suits a villa, a cottage or a classic Waikato farm shed quite like corrugate — it just belongs. It's strong, light and well proven, and it's a go-to when you're matching an existing roof or keeping a heritage home true to its era. Performance-wise it's excellent; the rounded profile is simply a slightly different shape to the bolder rib sheets.

• The traditional look for villas, cottages and sheds
• Modern coated steel, not old galv — tough and colour-fast
• Light, strong and thoroughly proven
• First pick when matching an existing corrugate roof

Trapezoidal long-run — the bold modern profile

Trapezoidal (rib or tray) profiles have sharp, angular ribs rather than rounded waves. They give a roof a clean, contemporary line that works beautifully on modern architecture, and they're a common sight on new builds and larger sheds.

The taller, squarer ribs can also carry water and span between purlins a little more efficiently, which can suit bigger roof areas and some lower pitches. In the same steel and colour as corrugate, it costs much the same — so the choice between them is really about the look and the roof, not the price. It's the natural pick when you want something that reads as modern rather than traditional.

• Bold, angular lines for modern homes
• Taller ribs can span a touch further
• Great on large roof areas and sheds
• Same steel and colours as corrugate

How to choose between them

Since both are the same coated steel with near-identical durability and cost, this is mostly an aesthetic and architectural decision. Look at your home: a villa, cottage or classic rural building almost always looks best in corrugate, while a modern or new build tends to carry a trapezoidal rib with more confidence.

Also think about matching. If you're re-roofing part of a house or adding to an existing roof, matching the current profile usually looks tidiest. On a fresh roof or a new build you've got a free hand. Pitch and roof size can nudge the decision too, and warranties vary by product and colour — we'll confirm the actual cover on whatever we'd fit.

Our recommendation

Because both profiles are the same steel at much the same price, the honest answer usually comes down to which look suits your home and whether you're matching an existing roof. Corrugate for traditional and rural character, trapezoidal rib for a bolder modern line — and roof size or pitch can tip it either way. The right answer depends on your roof, and Paul will give you a straight recommendation once he's seen it. Call Paul on 07 847 9785 for a free, no-obligation quote.