How long should a house last? It’s not a question we ask very often, but perhaps we should. In New Zealand, the Building Code states that the main structure of a house is legally required to have a minimum life of 50 years. While different building elements are also assigned legal minimum lifespans depending on how accessible they are to replace and how easily damage can be detected. Non-structural elements such as cladding, roofing and joinery are expected to last 15 years, and easily replaceable items such as paint, sealants and minor fixtures are expected to last 5 years. I find these figures remarkable, and not in a positive way. If a building requires major replacement after half a century, and minor elements every five, it hasn’t simply reached the end of its life. It has consumed land, materials, labour and energy, only for us to begin the process all over again. Surely we should expect more.
Thinking Beyond the Building Code
Building regulations establish a minimum standard. That is exactly what they are intended to do. But minimum compliance and long-term value are not always the same thing. Designing a house to last fifty years is a very different exercise from designing one to last one hundred. When the time horizon changes, so do the decisions. You think differently about structure. You specify materials differently. You pay greater attention to moisture management and detailing. You think about maintenance, adaptability and how the building will weather over decades, not just how it looks when the keys are handed over. The question shifts from “Will this meet today’s requirements?” to “Will this still serve people well in fifty or one hundred years?”
What Older Homes Can Teach Us
I live in a bungalow built in the 1920s. Like many houses of its age, it isn’t perfect. In winter it’s cold. It needs ongoing maintenance. That’s to be expected after a century of use. But it is still standing. It has adapted to generations of occupants, survived changing fashions, evolving building practices and countless winters. What I find more curious is that many houses less than half its age have already required extensive renovations for moisture, cladding failures or mould. Some of the newest buildings have become some of our shortest-lived. That should give us pause. Somewhere along the way, speed, efficiency and lowest initial cost began to outweigh longevity.
Building Smaller, Building Better
I’ve been redesigning my own house recently. It’s now on its fourth iteration. One idea keeps returning: build enough. Not as much as the budget allows. Not as much as planning rules permit. Simply enough. I’ve found that reducing the footprint creates opportunities elsewhere. Budget that might have been spent on additional floor area can instead be invested in better materials, better detailing, improved thermal performance and a more robust structure. A smaller house, built well, will often outperform a larger house built to a minimum standard. It is likely to cost less to maintain, less to heat and cool, and remain useful for much longer.
Longevity isn’t always about building more. Often it’s about building more thoughtfully.
The Challenge of Modern Building
Today’s buildings are expected to perform better than ever. They’re warmer, more energy efficient and more airtight. These are all positive developments. But they also introduce new challenges. Older houses were often remarkably forgiving because they leaked air. They breathed. Modern buildings don’t. That means moisture management, ventilation and detailing become absolutely critical. If we don’t get those things right, we risk creating buildings that perform well on paper but struggle over time. The challenge for our industry is not choosing between energy efficiency and durability. It’s designing buildings that achieve both.
Designing for Change
A house that lasts a century will almost certainly outlive the family it was designed for. Children grow up. People work differently. Communities evolve. Technology changes. The best houses allow for that. They aren’t rigid objects designed around one moment in time. They’re flexible enough to adapt without requiring wholesale reconstruction every generation. In many ways, longevity is less about durability than adaptability.
Stewardship Rather Than Consumption
Perhaps this is really a question of stewardship. Every building uses resources that cannot easily be replaced. Timber. Steel. Concrete. Land. Energy. The most sustainable building isn’t necessarily the one with the latest technology. It may simply be the one that people are still happily living in one hundred years from now. Architecture shouldn’t only solve today’s problems. It should leave something worthwhile for those who come after us.
Looking Further Ahead
I don’t believe every house needs to become a heritage building. But I do think we should be asking more of the buildings we create. Not just whether they’ll achieve consent. Not just whether they’ll meet this year’s regulations. But whether they’ll continue serving people, adapting to change and ageing gracefully long after we’re gone. Perhaps that’s one of an architect’s greatest responsibilities: to think beyond today’s budget, beyond today’s trends, and design with the next hundred years in mind.
