Re-roofing FAQs · Choosing your roof

Is longrun roofing the same as corrugated iron?

Nearly, but not quite. "Longrun" describes how the roof is made: steel sheets roll-formed to run the full length of the roof. Corrugate is one longrun profile. "Corrugated iron" is the older name for the galvanised version, and today's sheets are a better coated steel.

How the terms fit together

  • Corrugated iron. Until the 1980s it was New Zealand's most common roofing: steel sheet galvanised with zinc. It has since been largely replaced by aluminium-zinc coated steel, such as ZINCALUME®.
  • Longrun today. Painted roofing like COLORSTEEL MAXAM® is built on a ZINCALUME® steel base, so "longrun iron" is really coated steel.
  • Two main profiles. Corrugate is the classic wave. Trapezoidal rib has flat-topped ribs. Both are longrun.
  • Pitch matters. Standard corrugate needs at least 8°. Trapezoidal rib can go down to 3–4°, depending on rib height.
Which should I ask for on a quote?

Ask for the profile and the product by name, such as corrugate in COLORSTEEL MAXAM®, rather than "iron".

Sources: Te Ara: building materials · COLORSTEEL: MAXAM® · NZ Metal Roofing Manufacturers: minimum pitch

Related: Re-roofing FAQs · Longrun roofing in the Waikato · How long can longrun sheets be? · Replacing your roof in Hamilton

Written by the CTR Roofing team, Hamilton. Updated October 2026.