Up to 1200 homes damaged by the Canterbury earthquakes may not have been properly repaired, according to New Zealand’s Ministry of Business, Innovation and Employment.

The ministry has surveyed 90 repaired properties that were exempt from building consent.

It says 32 are not compliant with the Building Code, with the vast majority of problems relating to “jack and pack” procedures, where a home is temporarily raised to allow packing to be inserted, to level floors. A further 23 homes were found to have minor defects.

The focus was on exempt repair work because it is considered at greater risk of non-compliance.

The ministry’s GM Building System Performance Adrian Regnault says while there are no concerns for occupant safety, the findings are disappointing.

“Jack and pack is a relatively simple repair job when done correctly and properly supervised,” he said. “More complex structural repairs inspected in the survey were generally done well, which suggests some corners were cut on the smaller jobs and they lacked adequate supervision and oversight.

“It’s not uncommon in boom times to see tradespeople being exposed to work they may not normally do, because of the sheer volume.”

The Earthquake Commission (EQC) says any non-compliance under its repair program will be put right at no cost to homeowners.

It will recheck files for 3600 homes, and where there is doubt about compliance the properties will be reinspected.

EQC CEO Ian Simpson estimates about 1200 homes – 1.7% of the total repair program – will need remediation.

“We accept that looking at some work again is not ideal for customers and we apologise for any inconvenience this may cause. However, we can reassure them that bringing repairs up to code will generally involve straightforward fixes, and therefore won’t take much time.”