Family First senator Bob Day says a housing company he founded has had problems in the past, but has since improved its operations.
Huxley Homes, one of a number of housing construction companies linked to the South Australian senator, has been the subject of dozens of complaints.
One client, who declined to be named, said he had waited three years for a project home to be built.
Contractors and subcontractors had told the client they had not been paid by Huxley for completed work.
Over the time of the work there had been six project managers, the client said.
Dozens of clients have posted similar complaints online, with one group posting photographs of building faults and discussing legal action on a Facebook site, Huxley Homes Shame Page.
Senator Day said Huxley had been a “bugbear for quite some time” under previous management, but problems had been resolved.
“The company had some disputes with subcontractors which caused numerous delays,” he said.
“But tell me a home building company that: a) doesn’t have any problems and b) customers don’t complain how long their house has taken.”
A number of factors were behind delays including getting access to “tiny blocks in inner suburbs”, disputes with contractors and weather.
But Senator Day said the mistakes were always fixed.
Senator Day said he had resigned as a director when he entered politics in mid-2014, but after his long-time business partner left he was reappointed as a director in December 2014.
He said his wife was the sole shareholder of the group of companies, despite him being a director.
“It’s a sole-family-owned business,” he said.
“I obviously have the authority of an owner even if I am not legally or technically the owner.”
Senator Day, who was elected to the upper house in 2013, has a long history in the business, having been president of the Housing Industry Association.
He founded Homestead Homes in SA in 1983 and set up Home Australia in 1996, which now also owns Collier Homes in WA, Newstart Homes in Queensland, Ashford Homes in Victoria and Huxley Homes in NSW.
His parliamentary pecuniary interest register shows he is the director of nine housing-related companies including Huxley Homes.
The NSW Office of Fair Trading received more than 143,000 calls about home building in 2013/14.
Its Home Building Service issued 36 show cause notices, 391 penalty notices and took 166 offences to court for prosecution.