Leaky Homes in New Zealand – The History Behind the Crisis

Leaky Homes Start to Attract Media Attention

In the late 1990s, early 2000s it started becoming interesting that there was a leaky homes problem with homes and buildings constructed during the previous decade. The media started reporting buildings with serious weatherproof issues and water damage. It did not seem to affect only the lower priced end of the market. Multimillion dollar homes were becoming uninhabitable. A new word was invented, weathertightness.

Boron Treatment Protects Framing From Borer and Rot

After native heartwood started to become scarce by the 1920s, and the use of native sapwoods led to wood borer and moisture problems, from about the 1930s various building industry parties began to investigate ways to protect the newly planed pinus radiata (pine trees) against rot and insect attack. From the 1950s onwards, timber framing built from pinus radiata was treated with boron. Leaky homes could withstand a small amount of leaking as long as their timber framing was treated.

After World War II, material shortages affected construction and design. This led to a repetitive appearance to the housing stock of the post war period, with lightweight construction and either timber timberboard or brick veneer cladding. Roofs were pitched and used corrugated iron or concrete tiles with wide eaves.

This lightweight construction houses did withstand the wet and windy New Zealand climate, and leaky homes were never an issue through to the 1980s.

Buoyant Stock Market Contributes to Leaky Homes

With a long Bull Run on the stock market and plenty of surplus money about, a lot of this money was channeled into the commercial property boom. The boom led to a shortage of labor and materials, leading to a decline in commercial building quality.

Residential properties were not safe either. A government established body, the Timber Preservation Authority (TPA) determined to treat timber with an alternative conservative based on ammonia because of controversial over the use of boron. This was an abject failure with wooden decks collapsing because of decay. Leaky Homes still was not an issue, but it should have provided warning signs to Government agencies.

In this instance the Government paid compensation since it was a government body which had approved the ammonia treatment. The TPA was disbanded soon afterwards.

Unfortunately governments do not seem to learn from past experiences.

Changes to the Building Act First Step Towards Leaky Homes

In 1991 the National Government (with agreement from all parties) passed the Building Act which started coming into effect from the 15th of February 1992, with most sections of the Act in force by 1st of July of that year. The Act watered down many controls and standards. The assumption was that building quality would be driven by market forces. This naive view led to many developers, builders and architects to take advantage of the new Act and construct buildings with numerous faults and using any shortcuts they could think of. The changes to the Act also coincided with architectural design trends towards Mediterranean style flat roofs, low-angle mono-pitch roofs and buildings without eaves, all design features intended for dry climates.

Two government funded agencies (including the Building Research Association of New Zealand) also approved the use of cheap monolithic claddings during this time. Monolithic claddings are a textured plaster finish over the top of fiber cement or polystyrene backing material. There were cases where these claddings were not installed correctly or were used outside the supplier's specifications. Many buildings built in the Mediterranean style used these types of cladding. This style of building often featured recessed windows, flat roofs, minimal or no eaves, multiple stories, complex roofs, solid balustrades, balconies, and joints through the exterior cladding.

All these features increased the likelihood of houses becoming leaky homes.

Architects, Building Designers, Councils and Apprentice Shortages All Part of The Leaky Homes Problem

Architects and building designers have been blamed for not supplying detailed enough drawings to builders that showed how these new building materials were to be made weather tight. There has been some blame placed on the breakdown of the apprenticeship programs that exist prior to this time giving rise to the number of unqualified builders in the industry.

Council staff that carried out building inspections also did not have the knowledge or experience with these new building materials and weather sealing techniques, but rather signed off the leaky homes as built to adequate standards.

Most Leaky Homes Built During The Mid 1990s to Early 2000s

Many leaky homes and buildings were built during the 1990s and early 2000s using these methods that have not withstood the New Zealand climate. These structures were doomed from the start by poor design, use ofappropriate materials and poor construction methods by unqualified builders.

Source by Grant Lord

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