The rental, at 1/8 Freyberg Ave in Sandringham, was advertised on TradeMe as being for "singles, students, full workers, groups" and going for $650 per week.
"I think it is disgusting - that is tenant exploitation," he said.
"You have four full-grown adults sleeping in one bedroom in single beds, it is overcrowding, it is not healthy - everything about it is morally wrong."
Kerri Ferguson, from Auckland Council's Compliance Investigations team said that based on the advertisement the rental would be classified as a boarding house.
"However, the council has checked the records for this address and there is no indication this property has a permit to operate as a boarding house.
"As such, the council compliance officers will be investigating this matter."
The Herald has approached the company advertising the rental for comment.
But Faulkner has said the rental demonstrated why the property management industry needed regulation.
His company was among 70 organisations backing a Real Estate Institute campaign urging the Government to review the property management industry and announce reforms before the 2020 election.
The REI estimated property managers managed 184,000 homes, or about one-third of all Kiwi rental properties.
It meant they had keys and personal information, billions of dollars of housing and millions in rent and bond money in their care.
"While rents have gone up the fines have stayed the same," he said.
"So you've got to have really meaningful enforcement where it acts as such a disincentive for a landlord to do something like this that the risk of doing it is too great."