Property inspections should be carried out at least twice a year. However, higher-frequency checks are recommended for high-traffic rental types such as HMOs.
The warning comes amid a highly competitive rental market with data from Zoopla showing that there are now an average of 12 renters chasing every available home to rent.
The number of households in the private rented sector at risk of homelessness due to landlords selling up has increased by a third since the end of last year.