The Labour Party's citing new housing figures to back its case the country's not building enough affordable homes.

Statistics New Zealand data shows the average size of a Kiwi home has increased from 110 square meters in 1974 to over 180 square meters now.

Labour MP Phil Twyford sees it as a sign of a skew in the housing market saying developers always choose to maximise their profit margin by building more expensive, and thus larger houses.

"What we've seen over the same period of time is a big reduction in the percentage of new homes that are affordable, it's only about five per cent now. 30 years ago it was more like 35 per cent.

"There are very few homes that are modest and affordable homes that are designed for first home buyers."

Twyford said where we're at now, compared to the historical performance of the construction industry, we're still a long way short of the peak in 1974 when 38,000 new homes were consented.

"Currently we're only looking at 30,000 and yet there's been a very large increase in population over that time."

This @StatisticsNZ graph shows fewer homes are being built now than in the 70s, but those homes are bigger. @NewstalkZB pic.twitter.com/I0s0o0eeiH

— Michael Sergel (@michaelsergel) October 5, 2016