Both National's and Labour's housing policies can begin to look like a house of cards when you get into the detail. But one seems more likely to give us more houses

Crisis, what crisis? That's been National's call when it comes to the rapidly rising price of houses in our main centres. The debate over what to do to address our runaway housing market, especially in Auckland, is one of the defining differences between the two parties, but both have problems with their policies.

National, in short, took their eyes off the ol'd kiwi dream during the global financial crisis. Despite some good sounding promises from then-Housing Minister Phil Heatley, nothing much happened in its first term. Heatley went so far as to admit "there are fundamental problems with how the market is operating", but then did little about it.

National kicked for touch with the Productivity Commission's report and figured the market would sort itself out. It didn't.

They've started to act in the past year, creating Special Housing Areas wherever they see a spare patch of grass, but National's MPs are hamstrung by ideology. They're depending on a market solution when there's little incentive for developers to build a large number of entry levels home at affordable prices. While some movement is happening, it's not nearly enough.

So National's latest approach is to throw money at the problem. It's ironic given the amount of time National spends criticising Labour and the Greens for doing the same thing. The problem for National is that the example it uses in its own promotion of the scheme only goes to show how its failed to deal with rising prices. Check this out:

“The package means a couple in Auckland each earning $50,000 who have contributed to KiwiSaver for five years will be able to withdraw $35,000 and receive a $20,000 KiwiSaver HomeStart Grant, giving them a $55,000 deposit on a new home. With the Welcome Home Loan scheme allowing only a 10 per cent deposit, they will be able to buy a home up to $550,000 in value."

But if you do the sums on that, the future for that young couple starts to look pretty bleak. Even with all that help – which economists have almost universally said will only increase house prices by creating more demand and putting more cash in the market before there's more supply built – they're looking at a life of debt. (And they only get the $20,000 grant if they build a new home).

With a 25 year mortgage at a relatively conservative 6.5% (and mortgages are expected to go higher than that in the next couple of years), that couple will have to pay almost half – 47% to be precise – of their take-home income on housing.

By international measures, spending more than 30% of your income on housing is considered unaffordable. Consider that the averag age of a first home buyer in Auckland, according to Westpac, is 34 years-old and you're talking about that mortgage being a huge, huge financial burden. And let's not forget many will have student loans as well.

Housing Minister Nick Smith shrugged off that burden on The Nation saying that he paid 70% of his income on his first house. John Key said, in essence, that's just the way it is.

It's an admission of failure.

Labour's solution involves a more hands-on government. So hands on it will swamp the market with 100,000 new homes. The devil, however, is in the details. Since the KiwiBuild policy was announced in 2012 the size of the home and its price have kept changing. Currently the promise is that the homes will typically be two-bedroom terraced homes for around $360,000. They'll be built off-site en masse and the saving will come from the fact they're pre-fab and companies can buy 10,000 door knobs at a time, for example.

But if that's the price of the house in the first year, I've never really had a clear answer, however, as to what the price of those same houses will be by year 10.

Still, Labour has long promised 100,000 homes in ten years – 10,000 homes a year. Yet on The Nation Twyford gave more detail about the practicality. The thing is, there aren't the factories around to build all these pre-fab houses, so it'll take time for things to scale up.

Given Twyford has taken much glee in pointing out that not a single house has been built in National's Special Housing Area in Auckland, it's a bit ironic when he admits that only 800 homes will be built in the first year of his scheme. Not 10,000.

The goal is 4,000 in year two, 8,000 in year three and not 10,000 a year until year four. You might say that's only reasonable and they can still make 100,000 over the decade, but it does make you wonder if they're basing their numbers on some pretty rough, back of the envelope calculations.

At least, however, you can be confident you'll get many thousands of new homes over a decade. With National's scheme our fate really still lies in the hands of the developers.

So that's the choice we've got on housing. Whadyarekon?