'Super versus stupid': Superhome founder rails against code minimum
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'Super versus stupid': Superhome founder rails against code minimum

Nov 13, 2023

As the Superhome movement gears up for its annual house tour in Christchurch this weekend, founder Bob Burnett has taken the opportunity to push for further improvements in the building code.

“Most people think the building code is where it’s at, and while improvements have been made, it’s not enough. Tinkering with bits and pieces isn’t going to fix it. We need to look at the whole thing.”

Writing in the latest Superhome newsletter under the headline “Super versus Stupid: Build Superhomes, not Code Minimum”, Burnett singles out multi-unit projects “usually by greedy property developers” for special mention.

“Built with thin, 90mm wall framing, no ventilation systems and incorrect solar orientation, these homes are built to maximise profits and do not consider the health or wellbeing of the occupants or the planet,” Burnett says.

“They will, in most cases, be difficult and expensive to heat in winter, with moisture and mould likely developing in a short period of time. In summer, the large, unshaded windows will cause these units to overheat, making for uncomfortable living conditions and difficulty sleeping. “

And Burnett says the worst part is – they are built to code, albeit code-minimum.

“New Zealand’s building code is hopelessly outdated, decades behind other countries in the western world. This is why we need a push for change – it’s not just older housing that’s causing health problems for our families. The majority of new homes built today are sadly adding to the problem.”

Burnett shows a recent photo of a home being built in Christchurch.

“Despite already having been consented and approved, this home will not be built to a standard that will protect the health and wellbeing of its occupants,” he says. “The building code is still sub par, even after some recent piecemeal insulation upgrades that are too little too late. What's lacking is systems thinking, considering the design as a whole.”

Common problems highlighted by Burnett include a lack of foundation edge insulation and three stud corners and wall intersections where no insulation has been installed.

He says dwangs (the short horizontal timber pieces between studs in a framed partition) are not necessary and are better omitted so there is less thermal bridging. A lot of unnecessary timber is put into walls, which affects framing-insulation ratios. But companies building the framing get paid by the amount of timber they work with, so there is no incentive to change.

“Timber is a cold point in a house, and it has been assumed in the standards that the ratio of timber to insulation should be no more than 14-18%, but a research study by BRANZ two years ago showed that on average that ratio was 34%, and it can sometimes be over 50%, which is a lot higher than code minimum.”

Burnett also says 90mm-thick framing timbers are too thin to provide the required insulation.

And windows come in for criticism: “The government has improved the R value in the code, and we are seeing thermally broken aluminium windows in use, which is great, but they have done nothing about the detail of where the window is installed in the wall.

“The windows on the new build in the photo, although not pictured, will most likely be installed in the cold cladding cavity, meaning the better glazing now required by recent code changes will be somewhat of a wasted investment. People are not benefitting from that change.”

And while Burnett is pleased that roof insulation requirements have doubled, he says the insulation level in walls still needs to be addressed. “The issue is the industry is resistant to change. But if everyone has to build to the same [improved] regulations, then it is an equal playing field.”

Burnett says the demand for more energy-efficient, healthier homes is increasing, but he also says, when it comes to living in a warm, comfortable home “a lot of people don’t know what they don’t know”. “A lot of our clients are people from overseas who have experienced warm homes, or have experienced New Zealand’s cold homes, and they want something better.”

Meanwhile, Stephen McNeil, senior building physicist in the BRANZ Building Performance Research team says the building code is constantly evolving, and energy simulations are a key focus of some of the research and testing underway at BRANZ. These are likely to be included in the building code in future.

“This is part of the work undertaken by the Building for Climate Change Programme at MBIE. In the not-too-distant future, people will need to simulate their building performance to prove it meets required standards. The challenge will be to ensure it doesn’t cost too much money to do this. Incorporating this into good work flow practice is the way you get good outcomes.”

This weekend’s Superhome bus tour will visit seven homes designed and built, with sustainable materials, to a much higher specification than code minimum, with superior energy efficiency, insulation and mechanical ventilation systems.