Things are looking up for cashflow-focused Auckland property investors for the first time in three years.

Rents in the city have not kept pace with the rate of house price growth over recent years. That means, while property investors have done well on capital gains, it has been hard to find property investments that offered rent returns that would beat what you could get with your money in the bank.

But real estate agency Barfoot & Thompson said gross rental yields had risen in the first half of the year compared to the same time a year earlier, for three-bedroom homes. This measure does not take into account the cost of borrowing or maintenance.

"On the whole, this is good news for rental property owners. A change in direction of rental yields is exactly what you would expect to happen at some point in response to moderate, but consistent increases in rent, and slowing of house sales prices," Barfoot & Thompson director Kiri Barfoot said.

Gross rental yield is typically calculated by dividing annual rent by sales price. A hypothetical home purchased for $100,000 and renting for $3000 per year has a 3 per cent yield.

Barfoot data shows that the average rent for a three-bedroom home in Auckland was $537 a week as at July 1, or $27,924 a year, while the average sale price was $917,415, giving a gross yield of 3.04 per cent.

"While that's only slightly up on 2016 for the same period, which had a gross yield of 3 per cent it does arrest the fall in yield seen since 2015, when the city-wide average was 3.25 per cent, and 2014, when it was 3.7 per cent," Barfoot said..

"The upward trend in rental yield was most obvious in the central suburbs – which include most of the old Auckland City suburbs west of the southern motorway – as well as on the North Shore."

Central Auckland, where there are a lot of apartments that command comparatively high rent, had the highest rental yield, at 3.94 per cent. By comparison, the central suburban areas only had a yield of 3.63 per cent.

Across Auckland, average rent increased by 4.9 per cent in the April to June quarter of 2017, compared with the same quarter the year before. Average weekly rent across all property types and locations was $531, up from $506.

Auckland Property Investors Association president Andrew Bruce said it was not hard to find tenants for properties. Members of his organisation had indicated that there was pressure for rents to rise, he said.

But he said landlord costs were likely to increase if the Healthy Homes Bill becomes law, introducing new standards for heating and insulation in rental properties.