Better housing material options needed for New Zealand's building industry

Stellaria NZ director Robyn MacPherson holds up an example of a solid clay building block, designed to move moisture and air across a house.
Stellaria NZ director Robyn MacPherson holds up an example of a solid clay building block, designed to move moisture and air across a house.

New Zealand's rush to build a large quantity of housing may come at the cost of quality, suggests one Waikato company.

Stellaria NZ director Robyn MacPherson said building low-performing homes today, could have the same detrimental effect as the leaky homes of the past 20 years.

Her concerns were prompted by Minister of Housing Phil Twyford's push to build 10,000 homes within the next 10 years through KiwiBuild.

Poor quality building materials could further damage the reputation of the building industry, she said.

"Pre-fabricated and very low cost homes, is a real concern," she said.

Stellaria NZ is a Cambridge-based company which was the New Zealand distributor for Wienerberger building products.

MacPherson had  invested time and money to find solutions for better building material options.

Stellaria had partnered with the world's leading clay block manufacturer to import sustainable building materials.

MacPherson agreed KiwiBuild would produce the quantity of housing but questioned the quality.

"The use of pinus radiata for framing and plaster cement board cladding, combined with poor installation has led to damp, cold and mouldy homes.

"Tanalised for durability and now having to be laminated for strength, the resulting outgassing and toxicity is a known cause of respiratory illness in New Zealand."

A report from the Building Research Association of New Zealand (BRANZ) raised concerns about the air tightness of new homes causing damp and mould.

The report found although most homes had some level of insulation it was generally "suboptimal" and there was a need for more effective ventilation.

Looking for a remedial solution, MacPherson pointed to the past where homes were built for durability, using clay and lime, and had withstood the test of time.

"For centuries, solid clay construction has remained the primary building throughout Europe and is used extensively throughout the world.

"Our company now uses Porotherm on new builds which is a natural fired, solid clay block construction system."

MacPherson is promoting the ability of clay construction material to the New Zealand building market.

The design of the clay block alleviates concerns raised in the BRANZ report by acting as a hygrometric regulator moving moisture and air across the block allowing the house to "breathe".

Other advantages included its interlocking system and design, making the clay bock quicker to construct than other masonry systems.

Using clay blocks generated self-regulatory temperatures, keeping the house consistently between 20-26 degrees Celsius, providing natural acoustic values and is earthquake and fireproof.