Banks operating in New Zealand need to work on how they will finance purchases of prefabricated homes. Up to 80 per cent of the homes built under the government's KiwiBuild affordable homes scheme may be prefabs, but the banking sector has traditionally not provided mortgages for prefabs until they are built and installed with code compliance on the property, which will leave first-home buyers and developers with a cashflow problem if they cannot secure a mortgage or finance for their prefab purchase. Westpac has begun a pilot scheme to look at financing prefabs, according to Newsroom. Over three months, it will finance the development of six prefab homes in Auckland and Waikato. Research by ASB suggests the number of foreign buyers buying New Zealand homes could be significantly higher than official figures are suggesting, which will make the incoming ban on non-New Zealanders buying homes have a "significant effect". Official statistics put the percentage of home sales to overseas buyers at around three percent, but  ASB Senior Economist Mark Smith says the settings are not broad enough, reports interest.co.nz.  He says a further eight per cent of purchases were made by New Zealand visa holders, and 10 per cent by corporate entities - the citizen status of which is unknown. As such, he says anywhere from 11 per cent to 21 per cent of reported purchases involved a non-NZ citizen, over the March 2018 year. Australian and Singaporean citizens will be exempt from the ban. New Zealand's acting Prime Minister has also said they want to see home affordability crash down to five times income. And not just average income. Winston Peters said people on the "living wage" of $20.55 an hour should be able to buy a family home for just five times their income. This translates to just over NZ $200,000. He refused to say if that meant he wanted house prices to fall. Critics point out  that at current wage rates and wage inflation levels it would take decades for incomes to lift sufficiently for that ratio to be achieved.