Metropolitan areas that have built more homes in relation to their population since 2015 are more likely to have seen rent affordability improve, it’s been claimed.

Activist group Generation Rent has analysed government data and claims that across 90 urban areas in England, an increase of 20 homes per 1,000 people culminated in reduced rent as a proportion of average income by 2.8%.

The analysis uses new rent data published by the Office for National Statistics.

Generation Rent also states that in contrast, the data apparently also shows there is no relationship between rent affordability and the size of the private rented sector as a proportion of all homes. The activist group says this “casts doubt on the claims of some that encouraging landlords to buy more properties would help.”

Generation Rent warns that boosting overall supply will not ease the housing crisis for people experiencing the worst conditions, unless much of it is social housing.

The group adds that between 2015 and 2023, 70 of 91 urban areas in England saw houses built at a faster rate than the local population grew. Of these, 42 saw rent as a proportion of the average local salary fall – that is, affordability improved.

Some 26 areas saw rent as a proportion of the average salary increase – that is, affordability deteriorated.

From this data, Generation Rent estimates that for every 20 additional homes built per 1,000 people in a given urban area, rent as a proportion of average salary falls by 2.8%.

But – in another criticism of private landlords – the group claims “there is no evidence that the private rented sector taking up a larger share of the housing stock would make rents more affordable.”

It claims that to prove this, between 2015 and 2021, some 85 of 93 urban areas saw the PRS shrink as a proportion of the total housing stock. Of these, 45 areas saw rent affordability improve, while it worsened in 37 areas.

Deputy chief executive Dan Wilson Craw says:  “The evidence of the last eight years shows a clear relationship between housebuilding and affordability. Areas where building failed to outpace the local population saw rents rising faster than incomes.

“Importantly, the evidence shows that it’s the building that matters, not tenure. Simply encouraging landlords to buy up existing homes will do nothing to make homes more affordable.

“But policymakers must also recognise that it still takes a lot of building to make a difference to affordability … so the government must do much more to build social homes, and make sure Local Housing Allowance keeps up with market rents.”