Don’t settle for ‘code’

Why do we settle for so little when it comes to buying a house — the single biggest purchase most of us will ever make?

I’m an American engineer. I grew up with winters in the North-East, where the snow can be two metres deep. We know about cold; and we know how to insulate and keep warm.

It was a shock, on moving to New Zealand, to discover how cold and miserable so many houses are.

In New Zealand, the build quality is pretty good. The labour is skilled and the quality of the build is better than in the US. But the standard to which New Zealand housing is built is not very good.

If we look specifically at insulation, the r-values specified by the Building Code are easy targets to reach. They are very much a compromise, negotiated between the Government and the building industry. There’s a short term focus that looks for a very quick pay-off.

Buildings use a huge amount of energy: about 40 per cent of the total primary energy consumption in developed countries. The Passive House standard is one way to dramatically reduce energy use in this sector and thereby mitigate climate change. It’s relevant to renovations and retrofits as well as new builds.

Buildings use a huge amount of energy: about 40 per cent of the total primary energy consumption in developed countries.

As an immediate pay off, we’d also be living in healthier, comfortable homes and workplaces and paying much less to heat or cool them.

Homes built to the current Building Code have more insulation, better glazing and are better at keeping the heat in. True.

However, old, un-insulated, draughty houses were really good at one thing: drying themselves out. Air could flow through wall cavities to dry out any moisture that penetrated through poorly built or maintained window flashings, for instance. But now wall insulation is mandated and if moisture gets in, it can’t evaporate. Over 10 or 20 years, that could lead to serious rot.
Second, the Building Code specifies double glazing in almost all New Zealand climates. Double-glazing is great! But if the joinery is aluminium without thermal breaks, it will conduct heat incredibly effectively. That means heat loss and condensation: more moisture.

Old, un-insulated, draughty houses were really good at one thing: drying themselves out.


Thirdly, your average family is estimated to produce some seven litres of water a day through cooking, washing and breathing. Without some way to extract it, that moisture will build up in a modern, more air tight home, much more so than a ‘60s weatherboard.

In short, if you’re building a new home (or commercial building) understand the Building Code to be the bare minimum, not a target.

  1. Choose Your Builder
    Hire builders you trust to not take shortcuts. Details matter.
  2. Insulate!
    Insulate underfloors, ceilings and walls above the minimums specified in the Building Code, appropriate to your climate.
  3. Get Quality Windows
    Buy the best quality windows you can afford (at least double-glazed with argon fill and low-e coatings, with timber or properly thermally broken aluminium frames). If you can’t afford them, make your windows smaller.
  4. Properly Ventilate
    Ensure the house is adequately ventilated. At an absolute minimum, ensure fans in bathrooms and extractors above cooktops. Consider mechanical ventilation: small, efficient units that exchange fresh, filtered air for stale.

If ‘it meets Code’, it’s just good enough to be legally acceptable. Why settle for that?