Whats Causing Leaky Homes?

Systemic Failure In Our Building Industry from 1990 - 2004

The Leaky Building Crisis 

No single cause can be blamed for the leaky building problem. Instead, the problem with leaky buildings arose out of a combination of factors that created the perfect storm of risky design, poor building practices, substandard materials and a general lack of knowledge and trade skills in the building industry.

From 1990 to 2004, a large number of houses were built using construction methods and systems that have not withstood the weather conditions in New Zealand. The majority of the leaky building problems have arisen in homes built with plaster cladding systems fixed directly to the timber framing. Once water or moisture gets behind direct fixed cladding, in the absence of a drainage and drying cavity (mandatory since 2004 for most cladding systems), the water becomes trapped in the wall structure.

During this period there was a prolific growth in the use of monolithic plaster cladding systems and few experienced and skilled tradespeople available to install these systems. There was no formal trade qualification or proper installation training available for these exterior plaster cladding systems. Consequently, a large number of the plaster cladding systems constructed during that period were installed by unqualified labour with inadequate supervision by experienced building professions.

The increased use of monolithic cladding systems and the flexible design options available with these systems brought changes in design trends. Higher risk designs became commonplace and have contributed to the leaky building problem. Higher risk design factors associated with leaky buildings include:

  • recessed windows
  • flat roofs with narrow or no eaves
  • solid balustrades with flat tops and no waterproofing
  • complex roof and envelope design 
  • cantilevered balconies with joists penetrating the cladding
  • waterproof membranes to decks and gutters   
  • penetrations through the claddings (i.e. pergola beams, rafters)

Untreated kiln-dried framing timber was extensively used for building homes between 1996 and 2004 and is highly susceptible to rot when moisture penetrates the building envelope. Whilst not the cause of leaky buildings, the use of untreated timber has increased the extent of damage to the timber framing and shortened the timeframe in which timber decay will occur. Since 2004, treated timber has become mandatory for timber framed construction.

Aluminium joinery has played a major role in the leaky building crisis with moisture often leaking into the wall structure through poorly flashed window penetrations in the cladding system and moisture leaking directly into the wall structure through the aluminium joinery mitres.

If you have leaky building issues and need the right team on your job, call us on (09) 479 8901 or call into our showroom / office at 19A Triton Drive, Albany.  

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