ASB economist Christina Leung said the April fall was not too concerning given the robust increase in March.
"This series tends to be volatile from month-to-month."
Continued rebuilding activity in Canterbury was "fairly encouraging" and should help alleviate the housing supply constraints in the region, she said.
ASB estimated dwelling consents issued in Canterbury increased by around 4.6% on a seasonally adjusted basis, indicating rebuilding activity would continue in the region.
Statistics New Zealand noted that earthquake-related consents totalled $28 million in April with $9 million earmarked for residential buildings and $18 million for non-residential buildings.
Since September 4, 2010, more than 1700 quake-related consents had been identified, totalling $381 million.
"We expect postquake rebuilding will gather momentum later this year. However, two reasonably large aftershocks in Christchurch last week risk hampering this rebuilding process," Ms Leung said.
Non-residential building consents remained weak in April, suggesting construction activity would remain subdued in coming months.
Worryingly, the weakness looked to be concentrated in private non-residential construction with issued consents for offices and retail outlets still at relatively low levels, she said.
"This is likely to reflect continued caution among businesses as the patchiness of the recovery in demand makes businesses wary about expanding their operations."
Overall, there remained little urgency for the Reserve Bank to increase the official cash rate from 2.5%, Ms Leung said.
