The Local Government Association says communities may have lost out on "desperately needed" affordable homes through the use of permitted development rights – which allow certain conversions without full planning permission.
Data from the Ministry of Housing, Communities and Local Government (MHCLG) shows 14 office-to-residential conversions in South Tyneside in the five years to 2019-20 were done this way.
A permitted development right is general planning permission granted by Parliament and allows developers to turn office buildings into homes without submitting a full planning application, as long as they meet recently introduced requirements such as having enough space and natural light.
It also means the typical requirement to provide a proportion of affordable housing cannot be enforced.
Nationally, 65,000 conversions have been carried out under the scheme in the last five years.
David Renard, the LGA’s housing spokesman, said: “Permitted development rules are resulting in the potential loss of thousands of desperately-needed affordable homes.
"Planning is not a barrier to house-building. Councils approve nine in 10 planning applications. It is vital that councils and local communities have a voice in the planning process."
An MHCLG spokesperson said the fast-track system contributed to the delivery of more than 243,000 extra homes of all types last year.
They added: “We are investing over £12bn in affordable housing and the infrastructure levy in our planning reforms will ensure developers deliver at least as much affordable housing as under the current system."