Another group of Christchurch homeowners is preparing to launch a legal bid over insurance claims, this time turning their sights at the EQC.

Lawyers for more than 100 quake-affected residents delivered a letter to the Earthquake Commission outlining the details of declarations they will seek from the High Court if a deal cannot be reached.

But unlike the group taking on government-owned insurer Southern Response in another case, the homeowners aren’t looking for a payout, but for rulings about how the EQC interprets insurance laws when settling claims.

Anthony Harper partner Peter Woods, who is representing the group with the help of 40 University of Canterbury law school volunteers, says the EQC is treating many of its clients differently to how a private insurer would, leaving them with substantial costs to handle themselves.

“EQC has said this part of the building is damaged, but because we have to do work to undamaged parts of the building, we’re not going to do the work to the undamaged part, you have to do it yourself. Most insurers will accept that they are liable to do all of the work,” he said.

“We’re saying EQC is liable for the related work as well.”

He said the group would also look to change the way the EQC was using thresholds set by the Ministry of Business, Innovation and Employment when deciding which work was covered.

“EQC would have to look at doing further repair to a lot of properties already repaired,” Mr Woods said.

Many homeowners would be bumped over EQC’s $NZ100,000 ($A90,375) cap by the declaration, meaning their claims would then be handled by private insurers, he said.

The group has asked the EQC to respond to the declaration in hopes of making a joint statement to clarify how the law should be interpreted.

If there’s no agreement with the commission, a ruling will be sought in the High Court, Mr Woods said.

A spokesman for the EQC said it had received the letter and would be reviewing it before making any comment.