A council used a plane with thermal imaging to catch unscrupulous landlords that allowed tenants to live in substandard conditions.
Several people were found to be living in appalling conditions, including some residing in sheds, thanks to the aerial thermal imaging.
A total of 21 such sheds were discovered and closed by Oxford City Council and 31 enforcement notices served on landlords in the past 18 months, supported by a £274,942 government grant.
Inspections found a number of buildings with overcrowded conditions, fire safety problems, electrical hazards and structures without heating, hot water and basic sanitary provisions.
The inspections also revealed more than 70 privately-rented homes needing inspection and a number of unlicensed houses in multiple occupation (HMOs) which have been referred to the HMO enforcement team to investigate
Cllr Linda Smith, cabinet member for housing, said: “Oxford has the highest proportion of private rented homes in the country and every private tenant should have a decent roof over their head.
“We work proactively to drive up standards in private rented housing and we won’t tolerate rogue landlords exploiting tenants by providing substandard and dangerous housing – whether this is a bed in a shed, a house in multiple occupation or a family home.
“Conditions in some of these beds in sheds are appalling and we won’t accept this.”