Corrugated iron cladding that had to be taken off an old house near the Appleby Straights.

ANALYSIS: Many Kiwis probably buy a house assuming they have bought a house for life. Not necessarily so.

New Zealand homes actually have surprisingly short lifespans. Maynard Marks Limited director Stuart Wilson said many Kiwis became "quite upset when they found out" houses have minimum lifespan requirements of just 50 years for the building's structure and 15 years for the durability of the exterior cladding.

Wilson, a chartered and registered building surveyor, said when cladding started to deteriorate after 15 years it still satisfied its legal requirements under the Building Act, "which often surprises people - when you consider that you build a house and you expect it to last essentially forever".

There was a "disposable" attitude towards building stock in New Zealand, he said.

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"We seem to have a disposable attitude, or culture, towards buildings. Part of that comes down to the fact that we're often building with different kinds of materials to those commonly used overseas," he said.

SUPPLIED Maynard Marks Limited director Stuart Wilson says many clients get "quite upset" when they find out their houses are only built to last a minimum of 50 years.

WHY CLADDING IS VITAL

Cladding is what offers protection to building structures - or, as Wilson describes it, "the skin that keeps the water out of a building".

"Mould and mildew tends to be mostly to do with moisture getting into the cladding, which creates a damp environment internally."

Many people who worked in the building industry believed cladding systems should last 50 years like the houses' structural requirements, Wilson said.

While New Zealand's building standards were improving, people still needed to keep in mind that "the systems we build with are far more reliant on maintenance than buildings of a comparable type overseas", he said.

"If you've got a brick building in the UK or stone in the Mediterranean somewhere, the need for the level of maintenance that we require here is quite different.

"A building in the UK that's 100 years old isn't considered an old building, necessarily. It's not uncommon for a UK building to be stood 100 years after construction.

"We also suffer from UV exposure and UV breakdown, so paint coatings and other components are submitted to a much harsher environment than they are overseas."

WHY WE BUILD CHEAP

Wilson believed the desire, or need, to build cheap properties stemmed from a number of different factors.

"One of those influencing factors is that it's very expensive to build in New Zealand. We seem to cut corners everywhere to be able to afford to build, and we're often importing products from overseas."

But current building standards demanded a higher standard of insulation and energy performance compared to older constructions, he said.

"I've often heard people say that we don't have central heating in houses in the North Island, the upper North Island, because we have this sub-tropical climate. Whereas actually, we don't. I think what it really comes down to is we tend to always try to build cheap."

IMPACT ON RENTERS

The quality of buildings available to renters in New Zealand was "appalling", Wilson said.

"Some kind of warrant of fitness to try to drive a minimum standard is a great idea," he said.

"The problem with that, though, would be if it became a mandatory requirement. Landlords are often working to low returns, so if you pushed the standard up for a warrant of fitness scheme you would obviously end up pushing up the cost of rental accommodation too. So you do end up in a Catch 22."

Philip O'Sullivan, director of property valuing and building surveying firm Prendos, said a rental warrant of fitness was not the answer, however.

"I think a warrant of fitness has turned out to be a very limiting thing for rental properties. At the end of the day we've got to make sure we build buildings that are robust, and when they require maintenance, they should be able to be maintained," he said.

"We don't want to be in a position where we have to pull the house down."

LAWRENCE SMITH/STUFF Exterior cladding that has deteriorated over time and left a New Zealand house susceptible to leaks.

DEPRECIATION

Both Wilson and O'Sullivan agreed that many homebuyers did not fully understand how property depreciation worked.

"The majority of our clients have stretched themselves to their absolute limits to buy either their dream house or the house they can afford to live in - and have quite often found they've got a problem on their hands that can result in a cost that's 50 per cent of the actual building, and that is crushing for people," Wilson said.

The reality was that all houses needed to be maintained, he said. "If you buy a house that's 30 years old, you are buying a house that may need repairs in 10 years' time."

O'Sullivan agreed, adding: "People don't take into consideration the proper depreciation of the house, or the land value. In a sense, the desire for the house and the location tends to drive the price, rather than the physical condition of the house. If you buy an old villa in Ponsonby, the house is probably not worth much."

The reality of home ownership was often quite different to what many buyers expected, he said.

"I feel very sorry for people who've bought a house in good faith and it has turned out to be a complete disaster. I've seen that many times.

"I've said to people you have to forgive yourself and move on. That's the only thing you can do. Now, you own a problem."

Buyers in New Zealand often had no idea what they were buying, he said.

"People do their best, and as long as the building has got good systems then it should give the owners good service over the years. But there are many cases where things aren't built well, and then fail to meet expectations."

THE MOST VULNERABLE HOUSES

Weather tightness issues were at their peak in New Zealand from the 1980s to the 2000s, and the leaky homes crisis was from 1994-2004.

"We have got houses that were built in the 1980s through the 2000s which are vulnerable to failure because of weather tightness issues and because they didn't have cavities behind them," O'Sullivan said.

"But our systems have improved. We still have issues, and we always will - that's a fact of life.

"Are they perfect? No. Is there room for improvement? Always."

People living in New Zealand did not generally maintain houses very well, he said.

"That's been the results of many studies over the years. There are always going to be issues with maintenance, but most people tend to work on a reactive basis. That's just a case of human nature."

IS OUR HOUSING REALLY THAT BAD?

Although there was a 50-year minimum requirement for a residential property structure, O'Sullivan said the actual life of the building would typically be about 80 years.

"If you look at old villas, 80 years is about the time they start to fail."

New Zealand's housing standard was "pretty good" compared to many other countries, he said.

"I've just been to Mexico and I can tell you we're very good quality compared to them and the States," he said.

"The leaky building problem is a problem, but generally speaking the housing standard is pretty good in New Zealand."

Prospective homebuyers had simply "got to do the homework", he said.

MINDSET CHANGES

Wilson said Kiwis traditionally started building with timber, and that timber was ingrained in our culture, but construction in New Zealand was starting to move towards high-density construction.

"Our mindset is probably starting to change in terms of the types of buildings we are building. When you build a high-rise apartment or commercial building, there is a need for it to last much longer than a traditional house. They're so large that you can't replace them so readily."

WEATHERTIGHT RESOLUTION CLAIMS:

If you have a home that is not weathertight (a leaky home), the Ministry of Business, Innovation and Employment (MBIE) can assess your home and see if you meet the criteria to claim for weathertight damage repair under the Weathertight Home Resolution Services Act.

In the month of March, MBIE received 7384 claims for 12,778 properties nationwide.