Police have searched a home, had dive teams check local waterways and even turned over a landfill, but admit they are no closer to solving the mystery of missing man Michael McGrath.

The 49-year-old builder from Christchurch has not been since May and although Operation Renovation was wide-ranging, Detective Inspector Darryl Sweeney says no significant developments have arisen since August.

The investigation remains active and is being worked on by a dedicated team of detectives, he said.

"This is a long-term investigation and one that Canterbury Police are determined to resolve," he said.

"Myself and the team come to work each day with the goal of solving Michael's disappearance and providing answers for his family.

"No stone will be left unturned."

Detective Inspector Sweeney said while he appreciates the public interest and the assistance to this date, due to the nature of the investigation police will be unable to regularly provide detailed accounts of ongoing enquiries.

McGrath was last seen at his home on about May 21 and his disappearance was described as out of character.

- NZ Newswire