The Local Government Association said there are 475,000 homes across the UK with planning permission that are yet to start on site, with 56,891 in the North West, the highest backlog since 2008.
According to the study, commissioned by the LGA and carried out by Glenigan, the number of unimplemented units across the region has increased over the past four years, from 36,523 homes in the 2011/12 financial year to 56,891 in 2014/15.
Nationally, the figure has increased rapidly, with the total of unimplemented planning permissions at 381,390 in 2012/13, reaching 443,265 by 2013/14 and rising to 475,647 units in the last financial year.
The LGA said that the figures underline the need for councils to be able to invest in building more homes and also for the skills shortage affecting the construction industry to be addressed.
According to the LGA, which represents more than 370 councils in England and Wales, developers are taking longer to complete work on site. It now takes an overage of 32 months, from sites receiving planning permission to building work being completed, 12 months longer than in 2007/8.
The number of planning applications being granted planning permission across the UK in 2014/15 was 212,468, up from 187,605 in 2007/08 and higher than all previous years.
Cllr Peter Box, LGA housing spokesman, said: “These figures conclusively prove that the planning system is not a barrier to house building. In fact the opposite is true, councils are approving almost half a million more houses than are being built, and this gap is increasing.
“While private developers have a key role in solving our chronic housing shortage, they cannot build the 230,000 needed each year on their own. To tackle the new homes backlog and to get Britain building again, councils must have the power to invest in building new homes and to force developers to build homes more quickly.”
The LGA commissioned Glenigan to undertake an analysis of the extent and scope of unimplemented residential planning permissions in England and Wales in financial years 2013/14 and 2014/15. The analysis undertaken updated work published by the LGA in 2013, and the findings have been combined to examine unimplemented planning permissions from 2007/08 – 2014/15. The analysis uses data taken from Glenigan’s database of construction projects. This data is also used by other government departments, such as Communities & Local Government, to monitor planning permissions.