A building company and its supervisor have been fined a total of $45,000 after their negligence contributed to the roof of one of their West Australian houses blowing off and another being damaged during a storm.

Both buildings were damaged due to roof uplift during a storm south of Perth in June 2012, with parts of one roof found in a neighbouring yard.

The Building Services Board found Danmar Homes failed to comply with engineering details in the approved plans for the construction of the two double-storey brick and steel roofed dwellings in Singleton between 2008 and 2011.

The State Administrative Tribunal fined Danmar Homes $30,000 plus costs of $1500, while supervisor Robert George Williams was fined $15,000.

Building Commissioner Peter Gow said the negligence resulted in significant risk to the public.

“Flying roof debris may have struck and seriously injured or killed residents and damaged property, especially with the storm having occurred during daylight hours,” he said.

Repairs to both properties are covered by the owners’ insurance, and in one case the insurer is recovering its costs from the builder having reached an out-of-court settlement.

Danmar Homes was previously fined $2500 for negligence and incompetence in 2002 and $7000 for negligence in 2003 for failing to ensure a building licence was obtained before work began.

Williams was also fined $500 over the 2002 case.