Over the past four years, there was an increase in "accidental investors" in Australia, according to a study by MCG Quantity Surveyors.

According to the study, around one in four investors last year had once lived in their investment property as a principal place of residence. These owners-turned-investors lived in their former homes for an average of four years and two-and-a-half months before moving out and retaining them as investment properties.

The share of these accidental landlords in the overall number of investors rose from 23% in 2018 to 25.7% last year. Over the past four years, the number of investors who lived in their property prior to renting increased by 14.7%.

In New South Wales, 31.5% of landlords lived in their investment properties before renting them out. This trend was also apparent in Victoria and Queensland, where the share of accidental investors increased to 21.3% and 16% over the same period.

The study also found changes in the buying habits of investors, who are now more interested in townhouses and are turning away from houses and units.

This could be driven by affordability, with investors seeking high-growth blue-chip locations at accessible price points, the study said.

Furthermore, townhouses offer a balance with a yield that tends to exceed that of detached homes. At the same time, townhouses include a more substantial land component than a unit, making it more open to capital growth opportunities, the study said.