Which years were the leaky home era?

Mid-1990s to mid-2000s, with soft edges. The rule changes that opened the window arrived gradually from the early 1990s, and the fixes phased in between 2003 and 2005, with houses already consented under the old rules still being finished after that. A house built in 1994 or 2006 can carry the same risk features as one built in 1999. Treat the years as a flag for closer inspection rather than a boundary line.

The Building Act 1991 moved New Zealand to a performance-based Building Code, opening the door to new materials and methods that could be argued to meet performance requirements. Through the mid-1990s, untreated kiln-dried timber became accepted for wall framing on the basis that walls would stay dry. At the same time, fashion moved toward Mediterranean-styled homes: monolithic plaster-look cladding, flat or low-pitch roofs, parapets, minimal eaves and balconies over living spaces, with the cladding commonly fixed straight to the frame without a drainage cavity.

Each element might have been survivable alone. Together they were not. The fashionable designs gave water more chances to get in, the direct-fixed cladding gave it no path back out, and the untreated framing gave it something to destroy quietly. Junctions sealed with sealant rather than flashed metal aged badly, and by the time damage showed at the surface, framing inside the wall could already be badly decayed.

From around 2003 and 2004, treatment requirements for wall framing were reinstated. The Building Act 2004 rebuilt the regulatory system, and in 2005 the acceptable solution for external moisture, E2/AS1, was amended so that higher-risk wall claddings generally needed a drained and ventilated cavity. Council consenting and inspection practice tightened sharply through the same period. Homes designed and consented after those changes were built into a very different system.

The era narrows where to concentrate, and the design features do the rest. A 1998 brick-and-tile home with wide eaves is a different animal from a 1998 plaster-clad box with a flat roof, even though they share a birth year. For anything in the window with risk features, a weathertightness inspection with moisture testing is the step that turns a date and a look into actual information.