Farm animals that escaped during the Port Hills fires will no longer roam lost this week.

Building new fences is one of many jobs being ticked off the list by three businesses volunteering in fire-affected areas.

Jim the Builder, Complete Earthworks and Alpha Hire are into their second day of work on more than 20 properties, mainly on Worsley's Road and in Hoon Hay Valley.

Jim the Builder's spokesman Andrew Clark said huge efforts to build fire breaks saved homes, but they now need to be cleaned up, with his builders handling the fences.

"They just basically had to bulldoze their way through to stop the scrub that everyone had on their boundary, so our job has been to pull down all the broken fence posts, all the stuff that was buried and re-laying it flat with the digger so the guys can go back in and fence."

The volunteers are hoping to wrap things up by next Monday.