Ray White Whanganui was also censured and fined $5000. The agents and the agency itself had to each pay $600 towards the complainant's legal costs.
The agency was also ordered to allow its business be inspected over the way it handles information around houses with weathertightness issues.
The authority's Complaints Assessment Committee found that while the complainant was aware of some leaking in the house, the extent of it was not passed on.
It said the agents did not talk about the house being a potential leaky home.
It was presented as a home with some leaking which the vendor had attended to or was attending to.
"The committee has found as fact that the complainant was aware the property had leaking problems but that, by their conduct, the licensees under-represented and minimised the leaking problems at the property," Real Estate Authority decision said.
"Also, licensee Vanderschantz did not disclose the 2015 building report or that the 2015 sale had failed because of a building report."
The authority said the conduct didn't lead directly to the complainant buying the house, but the buyer missed an opportunity to decide not go through with the purchase.
"The licensees' errors or omissions were not directly causative of the complainant purchasing the property.
"However, had the complainant been made fully aware of the nature and construction of the property, and that a previous sale had failed due to a building report, he may have carried out further due diligence and discovered more about leaking problems with the property.
"Had the complainant understood the full extent of the weathertightness issues with the property, he may not have purchased the property.
"So the consequence of the error or omission is the complainant has been denied the opportunity to not purchase the property."
The complainant asked for a number of orders be made — that the agents pay for the cost of repairing the building (estimated at $253,000); they pay for a building report; a weathertightness report; and pay legal fees totalling $7000.
There were a number of other costs claimed by the complainant.
The authority ruled that it would award only $3000 in legal costs, saying the $7000 the complainant asked for was excessive.
It said it wouldn't award the other costs for several reasons.
The authority said there may have been other parties to blame for the issues, such as the vendor or the builder, and that couldn't be addressed by the Real Estate Authority.
It also said there had been some negligence on behalf of the complainant and that there were "other remedies in general law", that could be pursued.
