The seasonally adjusted number of new houses authorised in July, excluding apartments, slumped 5.3 per cent, Statistics New Zealand (SNZ) says.

That followed a 1.1 per cent rise in June.

When the volatile apartment category is included, the number of new housing units authorised rose 3.1 per cent, following a 3.3 per cent rise in June.

Last month consents were issued for 1473 new housing units, of which 203 were for apartments.

It was the highest monthly number of apartment units authorised for more than a year, with more than half for retirement units, SNZ business statistics manager Louise Holmes-Oliver said today.

The value of consents issued for residential buildings was $490 million - $48m or 11 per cent higher last month than in July 2009. In contrast, the value for non-residential buildings fell $78m or 21 per cent to $293m, SNZ said.

The value of consents for all buildings was down 3.6 per cent from a year earlier to $783m.

Reflecting long-term behaviour, the trend for the total number of new housing units authorised had been rising since early 2009, but the level was 49 per cent lower than the peak in January 2004.

Excluding apartments, the trend appeared to have reached a turning point and had fallen in recent months following increases that began in April 2009.

For the year to July the value of consents for all buildings fell $170m or 1.7 per cent to $9.57b, with residential buildings up $753m or 15 per cent to $5.79b and non-residential buildings down $922m or 20 per cent to $3.78b.