The mansard revolution: a little YIMBY victory

Create Streets fellow Samuel Hughes, argues that we should preserve the new liberty to create mansards that ‘fit in’

Following a campaign by Create Streets, a new clause appeared in the NPPF (124(e)) explicitly permitting mansards on appropriate properties, provided that mansards emulate the style of mansards in the area at the time of the building’s construction. In recent months, a clutch of mansard applications have been approved on appeal on the basis of this clause, for example this scheme in Gloucester Road and this scheme in Chesterton Road. The Inspectorate is now clearly implementing the intention of the NPPF that, under the specified circumstances, mansards should be approved. As this becomes generally known, it will filter through to planning decisions by councils. Interestingly, there has been no significant pushback: a carefully designed YIMBY reform has apparently bedded in without controversy.

In 2023, the Department introduced National Development Management Policies (NDMPs). NDMPs are national policies on development that trump local policies wherever they conflict, meaning that many details of development management that were previously set by England’s 300-some local planning authorities will be determined nationally. NDMPs appear to enjoy cross-party support, and the new Government is expected to continue the process of rolling them out.

No NDMPs have been published yet, and the mansard policy is just a normal NPPF policy. But it constitutes an intervention in development management at a level of detail that was traditionally uncommon: the Government decided that a certain highly specific kind of development was in the national interest and announced that it would henceforth be permitted everywhere. There are many more such interventions that a vigorously pro-growth government could make through NDMPs, some of which may indeed go much further than re-permitting a traditional type of roof extension. The mansard revolution may prove to be just a prelude. We should expect much more to come.

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